- Email: [email protected]
An AIE based fluorescent probe for digital lifting of latent fingerprint marks down to minutiae level
Sensors and Actuators B 258 (2018) 184–192
Contents lists available at ScienceDirect
Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb
Research paper
An AIE based fluorescent probe for digital lifting of latent fingerprint marks down to minutiae level Raghupathy Suresh, Senthil Kumar Thiyagarajan, Perumal Ramamurthy ∗ National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai, 600 113, India
a r t i c l e
i n f o
Article history: Received 29 July 2017 Received in revised form 2 November 2017 Accepted 10 November 2017 Available online 21 November 2017 Keywords: Acridinedione Aggregation induced emission Fingerprint Enhancement Visualization
a b s t r a c t Acridinediones, a new addition to the family of dyes having aggregation induced emission characteristics have been reported. Facile hydrophobic interactions between the acridinedione aggregates and fingerprint residues were exploited to lift the latent fingerprint marks on a non-porous substrate. By employing this preferential adhesion approach, a portable wet method for the enhancement and visualization of latent fingerprint marks using hand held UV light and mobile camera was demonstrated. Using this simple, rapid, cost effective, eco and user friendly method the latent fingerprints, its primary and secondary level of information’s can be easily decoded. These acridinedione derivatives also show strong blue luminescence in solid state with high fluorescence quantum yield. © 2017 Elsevier B.V. All rights reserved.
1. Introduction Fingerprints are unique patterns, made by friction ridges and furrows which appear on the pads of the human fingers. The ridge patterns found in finger prints are characteristic to each person and unchangeable as they are formed deep in the skin and leave marks on objects handled with bare hands [1]. Fingerprints continue to be a significant tool in our day today life for many purposes such as access control, safety examination and individual identifications [2,3]. Fingerprint recognition has been used to identify suspects and solve crimes for more than a century, and it remains an exceptionally valuable tool for law enforcement and in Integrated Automated Fingerprint identification Service (IAFS) [4,5]. Fingerprints are classified into two types, patent and latent based on their visibility to the naked eye. In which, latent fingerprint is invisible and it is commonly found in most crime scene. So, it becomes essential to enhance those invisible latent fingerprint marks (LFMs) for further identification and to solve the crime scene. A variety of methods have been developed to enhance the LFMs; using physical methods [6], chemical methods [7], combining physical and chemical methods [8], optical imaging techniques [9–11], using nanomaterials [12] and fluorescent organic aggregates [13]. Even though there are plentiful analytical processes that have been proposed for finger print enhancement and detection, powder dusting method
∗ Corresponding author. E-mail address: [email protected] (P. Ramamurthy). https://doi.org/10.1016/j.snb.2017.11.051 0925-4005/© 2017 Elsevier B.V. All rights reserved.
is still the most commonly used technique during forensic investigations [14]. But lifting latent finger prints using magnetic and fluorescent powders have some drawbacks, viz., unavoidable damage to the fingerprint details and health hazard to the examiners. To overcome these, Yan Li et al., has recently reported an alternative methodology to lift the LFMs by applying the aggregation induced emission (AIE) phenomenon [15]. Visualization of LFMs using the AIE strategy is an outright wet method and hence it is more eco and user friendly than the conventional powder dusting method. However, the reported AIE methods to lift the LFMs require sophisticated imaging instruments. So, a simple, portable and cost effective alternate is needed for the enhancement and visualization of LFMs especially during real time analysis. A new class of organic fluorogens with aggregation induced emission (AIE) and aggregation enhanced emission (AEE) features have been developed in recent years. The phenomenon AIE is quite opposite to the conventional ‘aggregation caused quenching (ACQ)’ behavior commonly observed in most of the planar aromatic fluorogens [16,17]. The AIE or AEE fluorogens are nonemissive or weakly emissive in dilute solution and becomes highly emissive in the aggregated state, which has been due to the restriction of intramolecular motions (RIM) in the aggregated state [18,19]. By considering the importance of this AIE phenomenon, enormous efforts have been dedicated to synthesize new organic fluorogens exhibiting this unusual property [20]. These molecules have been recognized as one of the most promising candidate for optoelectronic materials such as organic light emitting and electroluminescence devices [21–28]. Among the different AIE flu-
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
185
Fig. 1. Structural formulae of two ADD derivatives ADDPh & ADDSi.
orogens, blue light emitting materials play a key role in white light generation. However, these are the materials which are the most challenging to attain because of the difficulty in charge injection across the larger energy gap and lack of balance in charge transport [29–32]. Despite, there is a large scope for researchers to develop new blue light emitting materials with high efficiency and stability. Among the blue light emitting materials reported in the literature most of them are aromatic hydrocarbons [33–43] and only a few blue emitting heterocyclic compounds were reported [44–50]. Acridinedione (ADD) dyes are heterocyclic compounds having structural similarity with NADH [51–53], they are known for its high lasing efficiency and as a potential fluorescent probes for metal ions, anions and biological imaging [54–58]. They can also function as electron donors and acceptors in the excited state [59–61]. Even though a detailed studies on the emission characteristics of the ADD dyes in solutions have been reported by our group [62], aggregation induced emission characteristics of these compounds have not been explored until now. This is the first report that establishes the aggregation induced emission characteristics of the ADD dyes and this unusual phenomenon has been strategically applied for lifting the LFMs on different non-porous surfaces by a wet AIE method. The overall process for the enhancement and visualization of LFMs by this method takes less than five minutes with the use of simple hand held UV lamp and mobile camera. This method is fast, user and eco-friendly, more importantly it doesn’t require sophisticated imaging instrumentations. 2. Results and discussion 2.1. Aggregation Induced Emission (AIE) feature of ADD derivatives Two ADD derivatives ADDPh & ADDSi bearing different aromatic rotors at the 9th position were prepared to explore the aggregation induced emission behavior (Fig. 1). In good solvent like THF, these molecules exhibit negligible intermolecular interactions under dilute condition. In THF, ADDPh shows emission maximum at 414 nm with fluorescence quantum yield (f ) of 0.024 and ADDSi shows emission maximum at 425 nm with f of 0.135. Upon increasing the water fraction (fw ) from 0 to 90%, the emission intensity of ADDPh shows enhancement with continuous red shift (Figs. 2 and 3). When the volume fraction of water reaches 90%, it shows emission at 441 nm with quantum yield of f = 0.628, which is 26 times greater than that in THF (Fig. 3, Table 1). The classical AIE curve was plotted as a function of different water fraction which is
Fig. 2. Images show the change in emission intensity of a) ADDPh and b) ADDSi upon addition of different fractions of water in THF. Table 1 Photophysical data of ADDPh and ADDSi in solution (S), aggregated state (A) and powder form (P). Compound
em (nm)
f,S
f,A
f,P
␣AIE
ADDPh ADDSi
414 425
0.024 0.135
0.628 0.586
0.415 0.276
26 4.34
shown in Fig. 3c. This unusual enhancement in the emission intensity with red shift is due to the contribution from two different fundamental aspects, (1) Formation of molecular aggregates; upon increasing the water fraction (poor solvent) there is a decrease in solubility of ADDPh in the THF/Water mixture due to its intrinsic hydrophobic nature. It results in an increase in the intermolecular interactions which induces the isolated molecules to involve in aggregate formation. This aggregation process constraints the free space available for intramolecular rotation and vibration, which in turn restricts the rotation of the phenyl rotors and suppresses one of the predominant non-radiative decay pathways. Hence, the excited molecules come back to their ground state primarily via fluorescence (emission enhancement). (2) General solvent effect; the molecular absorption in ADD dye is due to the intramolecular charge transfer (ICT) from the ring nitrogen to the carbonyl moiety [62]. Hence, adding high polar solvent like water enhances the ICT process by stabilizing the more polar excited state. It also results in a considerable enhancement in the emission intensity with a red shift as shown in Fig. 3d. Hence, the classical AIE curve reflects the contribution from both the polar as well as the poor solvation tendency of the solvent water. But, it is difficult to resolve the indigenous influence of each aspect spectrometrically. For ADDSi, the situation is slightly different, the emission intensity enhances with red shift on increasing the fw from 0 to 60% (4.34 fold enhancement), but further increase in fw (70–90%) dramatically quenches the emission intensity (Fig. 2b & 3). Also, the absorption spectrum shows light scattering tails at fw > 70% (Figure SD1). These results indicate the formation of larger molecular aggregates and the photograph in Fig. S1 shows the existence of larger molecular aggregates of ADDSi visible to naked eye observed at fw > 70%. Such larger molecular aggregates were often observed for AEE fluorogens at higher water fraction. In general, when water
186
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
Fig. 3. Emission spectra of (a) ADDPh and (b) ADDSi in THF/water mixtures at different water fractions (fw ). Plots of (c) quantum yield and (d) maximum emission wavelength (max ) versus the different compositions of the THF/water mixtures of ADDPh and ADDSi.
(non-solvent) is added the isolated molecules tend to aggregate into either (1) crystalline or (2) amorphous like larger molecular aggregates. The former always leads to an enhancement in the emission intensity, while the latter results a decline in emission intensity [63]. So, the resultant emission intensity depends upon the morphology of the aggregates formed. But it is difficult to control the morphology of these aggregates, especially at higher fw . Hence, in most of the AEE cases the classical AIE curve often shows irregularity at higher fw [64]. Analogously, the ADDSi exhibit a drastic decline in the emission intensity at higher water fraction (>70%) which indicates the formation of the amorphous like molecular aggregates. Although, both ADDPh and ADDSi are AIE active as depicted in Fig. 2, there is an inherent difference in their fluorescence behavior. ADDPh exhibit relatively weaker emission (f = 0.024) in THF than ADDSi (f = 0.135). However, their aggregates formed in THF/Water mixture at fw = 60% shows strong emission with a quantum yield (f ) of 0.628 and 0.586 respectively. It results in a much enhanced AIE amplification factor (␣AIE = f,agg /f,sol ) for ADDPh (26) than ADDSi (4.34) which is presented in Table 1. Although the molecular aggregates of ADDPh and ADDSi have similar f , ADDPh has a better AIE performance than ADDSi. The significant difference in the AIE amplification factor between the two ADD derivatives is primarily due to the large difference in their f value in solution state (∼5.5 times). In ADDPh, the phenyl moiety at the 9th position acts as a free rotor and the tricyclic ADD ring can be considered as a stator. In good solvent like THF, the intermolecular interac-
tions are negligible and hence the phenyl rotors can effectively rotate around the stator. It results in depopulation of the excited state through non-radiative decay pathway and lead to very low fluorescence quantum yield (f = 0.024). In contrast, the phenyl ring in ADDSi carries bulkier silyl enol ether substituent at its para position which hinders the free rotation of the phenyl ring. Hence, the depopulation of the excited state through non-radiative decay process is relatively lesser in ADDSi which results in much higher fluorescence quantum yield for ADDSi (f = 0.135) in the solution state. After aggregation, the strong intermolecular interactions in both ADDPh & ADDSi hinder the free rotation of the phenolic unit and enhances the fluorescence quantum yield. Strong photoluminescence of the aggregates of ADDPh & ADDSi encouraged us to unravel the feasibility of solid state luminescence of these ADD derivatives. As shown in Fig. S2, both these ADD derivatives have shown unprecedented bright luminescence in solid state (as shown in inset) with the emission maximum at ∼450 nm, and the absolute f value of ADDPh and ADDSi in solid state were determined to be 0.415% & 0.276% respectively (Table 1). Even though, extensive investigations on the photoluminescence behavior of various ADD derivatives in different environments (in polar & apolar solvents) [62], in micelles [65], in PMMA matrix [66], in macrocyclic host [67], in urea dimers [68] were carried out, this is the first report that unveils the solid state luminescence of the ADD family. Moreover, the luminescence in the solid state was observed in the blue region, ∼450 nm which certifies that the ADD dyes are suitable candidates for optoelectronic applications. However, there is a significant decrease in the f of ADDPh and
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
187
Fig. 4. a) Change in the size of the molecular aggregates upon addition of different fractions of water in THF. b) Variation in the polydispersity index (PDI) of the medium upon addition of different fractions of water in THF.
ADDSi in the solid state when compared to its molecular aggregates, which might be due to the stronger intermolecular interactions and relatively shorter intermolecular distance in the solid state. By tailoring suitable substitution, it is possible to tune the intermolecular interactions and hence the photoluminescence behavior of ADD derivatives in the solid state. The emission spectrum of both ADDPh & ADDSi in three different physical states viz., dissolved in THF, aggregated state and solid state were shown in Fig. S2. The emission maximum of both ADDPh and ADDSi in the solid state is ∼10 nm red shifted relative to the emission maximum from their respective molecular aggregates. 2.2. Characterization of aggregates by DLS and FE-SEM To further understand the size distribution of these molecular aggregates, dynamic light scattering (DLS) studies were carried out. All the solutions were appear transparent and macroscopically homogeneous, except for ADDSi at fw > 70% (Fig. S3). The size distribution of the molecular aggregates (hydrodynamic diameter) at different fw is shown in Fig. S4. At fw < 10%, there is no detectable amount of aggregates were observed for both these ADD
derivatives. On increasing the fw from 20 to 50%, the average hydrodynamic diameter of the molecular aggregates of ADDPh increases from 3.66 to 16.57 nm and the polydispersity index (PDI) value of the respective solution increases from 0.122 to 0.267 (Figs. 4 & S4, Table S1). The increase in the particle size as well as the PDI of the medium strongly supports the formation of molecular aggregates while increasing the water fraction. With further increase in the fw from 60 to 90% leads to the formation of larger molecular aggregates with the multi-modal distribution, whose average hydrodynamic diameter increases from 54.33 to 461 nm and the corresponding PDI value of the solution increases from 0.393 to 0.645 (Figs. 4 & S4, Table S1) [69]. In case of ADDSi, increasing the fw from 20 to 90% dramatically increases the average size of molecular aggregates from 3.92 to 2868 nm and also the PDI value of the respective solution from 0.153 to 0.896 (Figs. 4, S4, Table S1). From Fig. 4 it is clear that the ADDSi forms larger molecular aggregates even at fw ∼ 40% relative to ADDPh of similar concentration. In ADDSi, the presence of extra hetero atom (oxygen) and three phenyl rings facilitates the molecule to involve in strong intermolecular interactions to form larger molecular aggregates. But in case of ADDPh, the lone phenyl ring cannot interact much effectively with the neighboring
Fig. 5. FE-SEM image of ADDPh a) In powder form b) A drop of 0.3 mM THF solution was drop casted on aluminum foil after evaporation the substrate was imaged c) In 90% water fraction. FE-SEM image of ADDSi d) In powder form e) A drop of 0.3 mM THF solution was drop casted on aluminum foil after evaporation the substrate was imaged. f) In 90% water fraction.
188
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
Fig. 6. Variation in the fluorescence lifetime of a) ADDPh and b) ADDSi upon addition of different fractions of water in THF.
molecules and hence it forms relatively smaller molecular aggregates. This is further supplemented by the steepness in the classical AIE curve of ADDSi, compared to ADDPh. These results have conclusively proven two important factors, (i) the observed enhancement in the emission intensity is not simply due to the increase in the solvent polarity but due to the aggregate formation. (ii) Stronger intermolecular interactions (as in ADDSi) facilitate the aggregate formation even at lower water fraction which in turn sharply raises the AIE curve. To have an account on the surface morphology of these molecular aggregates, we have intended to image them using field emission scanning electron microscopy (FE-SEM). For that we have dropcasted 0.3 mM solution (fw ∼ 80 & 90%) of ADDPh and ADDSi on an aluminum foil and allowed them to dry at room temperature. The dried sample was then imaged using FE-SEM technique and it is shown in Figs. 5 & S5. The images show that ADDPh forms spongy type molecular aggregates and ADDSi forms spherical molecular aggregates with the particle size of ∼1–3 m, which matches well with the average hydrodynamic diameter obtained using DLS studies. However, simple recrystallization during evaporation may sometimes result such images. To subdue such arguments, we have carried out similar investigation with the 0.3 mM solution of ADDPh & ADDSi in neat THF as well as for their powder form (solid state). The FESEM image of both ADDPh & ADDSi (Fig. 5b,e) dropcasted using their THF solution shows that the molecules are arranged in rod like structure i.e., crystalline, and the images look akin to the powdered sample images (Fig. 5a,d). Molecules that are isolated in THF, a low boiling solvent, undergo fast evaporation yet it forms ordered rod like structure analogous to the powder form (solid state). But the solution of ADDPh & ADDSi in THF:water mixture undergoes slow evaporation, the condition favorable for forming more ordered structure, yet they form spongy and spherical aggregates (Figs. 5c,f & S5). Hence, it can be concluded that the aggregates of ADDPh & ADDSi were preformed in the solution itself and it gets deposited on the aluminum foil after the evaporation of the solvent. Thus, the obtained SEM images of ADDPh & ADDSi in THF:water mixture indubitably establishes the aggregate formation in the mixed aqueous medium. Consequently, the formation of spongy like aggregates in ADDPh must be due to its weak intermolecular interaction, whereas for ADDSi, the strong intermolecular interactions result in the formation of spherical molecular aggregates. Thus the DLS and FESEM analyses complements well with one another.
2.3. Mechanism for AIE To further supplement the aggregation induced emission enhancement, time resolved fluorescence studies were carried out at different fw , using Time Correlated Single Photon Counting technique (TCSPC). The fluorescence lifetime decay of ADDPh in neat THF fits single exponential, with a lifetime value of 0.378 ns. This short fluorescence lifetime and low quantum yield (0.02) of ADDPh in THF implicates the involvement of strong non-radiative decay process (knr = 2.58 × 109 s−1 ) in depopulating the excited state. On adding water to this THF solution, the lifetime decay remains single exponential but there is a continuous enhancement in the lifetime value and it reaches 8.98 ns at fw ∼ 90% (Figs. 6 & S6, Table S2). The increase in the fluorescence lifetime must be due to the suppression of the non-radiative decay process that depopulates the excited state. The plot of non-radiative decay rate as a function of water percentage shows that there is a rapid decrease in the non-radiative decay rate upto fw ∼ 40%; it indicates that the isolated ADDPh molecules involves in aggregation which in turn blocks one of the vital non-radiative decay channel by restricting the intramolecular rotation (Fig. S7, Table S3). At fw > 40%, there is not much change in the non-radiative decay rate which accounts for the saturation in the classical AIE curve. Our DLS study already indicates that at fw > 50%, the aggregates of ADDPh begins to agglomerate to form larger molecular aggregates (multimodal distribution) and hence it doesn’t bring much change in the non-radiative decay rate, so do the quantum yield. The AIE amplification factor calculated using the fluorescence lifetime value of ADDPh is ∼23.74 which matches well with the amplification factor measured using the emission intensity (Figs. 6 & S6, Table S2). In case of ADDSi, the fluorescence lifetime decay in neat THF fits single exponential and the corresponding lifetime value is determined to be ∼1.51 ns. It is about ∼4 times higher than ADDPh under the same experimental condition and the corresponding non-radiative decay rate is estimated to be knr = 0.57 × 109 s−1 . Relatively slower non-radiative decay rate of ADDSi indicates that the bulkier silyl enol ether functionality at the top of the phenyl ring considerably decreases the intramolecular rotation and hinders the depopulation of the excited state (Fig. S7, Table S3). On adding water to this THF solution, there is a continuous enhancement in the fluorescence lifetime upto fw ∼ 70%, but after 70% there is a marginal decline in the lifetime value. The plot of non-radiative decay rate of ADDSi at different water fraction is analogous to
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
189
Fig. 7. Fluorescence image of LFMs developed by ADDPh (0.3 mM) aggregates on microscopic glass plate. a) Simple Arch type Fingerprint b) Loop type Fingerprint c) Concentric Whorl type Fingerprint. All the LFMs have been developed using 70% water fraction in THF and then visualized under 365 nm UV lamp.
ADDPh and the rapid decline in the non-radiative decay rate is observed at fw < 30% which is due to the relatively stronger intermolecular interaction furnished by the silyl enol ether functionality (Figs. 6 & S6, Table S2). At fw > 70%, the larger (from DLS) and spherical (from FESEM) molecular aggregates of ADDSi have strong intermolecular interactions, which opens other new non-radiative decay channels which depopulate the excited state and quenches the fluorescence lifetime [70]. These results indubitably establish that “Restriction of Intramolecular Rotation” is the active mechanism which accounts for the observed aggregation induced emission behavior in these ADD derivatives.
2.4. Enhancement and recognition of latent fingerprint marks Both ADDPh and ADDSi show typical AIE characteristics, and hence these dyes can be used as a fluorescent probe to enhance and visualize the LFMs using the wet method. Since this is the wet method, the visualization of the LFMs is possible only on the non-porous surface and not on the porous surface such as wood or paper. The strong fluorescence of these molecular aggregates has the advantage of low background noise even while imaging it using a mobile camera. We have used different concentration of ADDPh & ADDSi and several combinations of THF/water mixture to visualize the LFMs. Finally, it was optimized that 0.3 mM solutions of ADDPh
Fig. 8. Fluorescence image of LFMs developed by ADDPh (0.3 mM) aggregates on glass plate showing different secondary level information such as core, island, ending ridge, crossover, short ridge, bifurcation. The secondary level information’s are very clear even after digital magnification which was shown separately as a magnified image.
190
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
and ADDSi in 60% and 70% water fraction in THF/water are the combinations that work very well to enhance, visualize and lift the LFMs (Fig. S8). For this study, three volunteers donated sebaceous fingerprints by wiping their finger on the forehead and stamped the finger with nominal pressure on the non-porous substrates. The substrates with latent fingerprints were incubated for 2 min in THF/water mixture (2:3) containing 0.3 mM of ADDPh or ADDSi. The developed latent fingerprints were rinsed with distilled water, to wash of the excess and unwanted dye molecules. It was then dried using air drier for 1 min and photographed using mobile camera (Moto G, 2nd generation, 8 Mega Pixel camera) under 365 nm UV light (Handheld UV lamp DL01 with Radium F4T5/BLB, 4W G5 UV light). Depending on the quality of the LFMs, three levels of information can be attained. (1) Primary level information; pattern of LFMs (2) Secondary level information; describing minutiae points like core, delta, bifurcation, independent ridge, ridge termination, crossover, etc., (3) Final level information; pores and ridge contours. For recognizing and identifying the LFMs, information about papillary ridges are also important. Three basic types of papillary ridges viz., (a) Arch type (b) Loop type (c) Whorl type [5] are commonly present in human fingers. By using our current method, we have extracted the primary and secondary level information of LFMs and identified all three types of papillary ridge patterns and it is shown in Fig. 7. The secondary level information such as core, delta, bifurcation, independent ridge, and lake are clearly well resolved by this method (Fig. 8), which are considered to be an important tool in matching the fingerprint to solve the crime cases. We have also lifted the LFMs of their other fingers and are shown in Fig. S9, S10 & S11. In all these LFMs, only the papillary ridges are lit up by the UV light, the furrow areas (i.e., space between ridges) are remain black because of the preferential hydrophobic interaction of the probes with the fatty acid residues present in the finger print papillary ridges. The time and equipment needed to develop these LFMs are much better when compared to other reported AIE based wet methods [71,72]. In order to test the applicability of this wet method on different non-porous substrates we have developed the LFMs on the aluminum sheet and stainless steel plate which are shown in Fig. S12. In both the cases, the images are clearly lit up in the UV light and the corresponding primary and secondary level information can be easily extracted. When compared with microscopic glass plate and aluminum sheet, LFMs on the stainless steel plate shows a low resolution image. The solid state emission of the developed LFMs substrates were recorded to establish the preferential interaction of ADDPh/Si aggregates to the papillary ridges and the corresponding solid state emission spectrum is shown in Fig. S13. We have also developed the LFMs of the aged samples; the papillary ridges of the aged samples are clearly lit up in the UV light (Fig. S14). The primary and secondary level information are well resolved even for the aged sample.
3. Conclusion Aggregation induced emission behavior of two acridinedione derivatives were experimentally demonstrated using steady state and time resolved fluorescence studies, Dynamic light scattering and scanning electron microscopy studies. These studies complement each other and undeniably establish that the ‘Restriction in Intramolecular Rotation’ is the active mechanism which induces the emission during aggregation in both ADDPh & ADDSi. These easy to prepare ADD derivatives are the new addition to the AIE family. Strong hydrophobic interaction between these ADD aggregates and finger print residues were strategically exploited to enhance and visualize the latent finger print marks on a non-porous substrate. Using simple hand held UV lamp and mobile camera,
the primary and secondary level of information in the LFMs were easily decoded by this rapid, cheap, eco and user friendly method. These ADD dyes also exhibit bright blue luminescence in the solid state. The molecular arrangement and the intermolecular interaction which tunes the luminescence of ADD dye in the solid state are currently under investigation. Conflict of interest None. Author contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Acknowledgment RS and SKT thank CSIR (New Delhi) for the award of Senior Research Fellowship. Thanks are due to Prof. S. Balakumar, NCNST, University of Madras for extending the FE-SEM facility. We also thank Dr. K. J. Sriram, CSIR-CLRI,Chennai for extending the DLS facility. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.snb.2017.11.051. References [1] C. Champod, C. Lennard, P. Margot, M. Stoilovic, Fingerprints and Other Ridge Skin Impressions, CRC Press LLC, USA, 2004. [2] P. Hazarika, D.A. Russell, Advances in fingerprint analysis, Angew. Chem., Int. Ed. 51 (2012) 3524–3531. [3] L. Xu, Y. Li, S. Wu, X. Liu, B. Su, Imaging latent fingerprints by electrochemiluminescence, Angew. Chem., Int. Ed. 51 (2012) 8068–8072. [4] P. Komarinski, Automated Fingerprint Identification Systems, Elsevier Academic Press, USA, 2005. [5] R. Saferstein, An Introduction to Forensic Science, Ninth edition, Pearson Education, Inc., L, USA, 2007, pp. 426–457 (Chapter 14). [6] N. Jones, M. Stoilovic, C.J. Lennard, C. Roux, Vacuum metal deposition: factors affecting normal and reverse development of latent fingerprints on polyethylene substrates, Forensic Sci. Int. 115 (2001) 73–88. [7] S. Wiesner, E. Springer, Y. Sasson, J. Almog, Chemical development of latent fingerprints: 1 2-Indanedione has come of age, J. Forensic Sci. 46 (2001) 1082–1084. [8] A.A. Cantu, Silver physical developers for the visualization of latent prints on paper, Forensic Sci. Rev. 13 (2001) 29–64. [9] W. Song, Z. Mao, X. Liu, Y. Lu, Z. Li, B. Zhao, L. Lu, Detection of protein deposition within latent fingerprints by surface-enhanced Raman spectroscopy imaging, Nanoscale 4 (2012) 2333–2338. [10] M. Tahtouh, P. Despland, R. Shimmon, J.R. Kalman, B.J. Reedy, The application of infrared chemical imaging to the detection and enhancement of latent fingerprints: method optimization and further findings, J. Forensic Sci. 52 (2007) 1089–1096. [11] M. Bailey, M. Ismail, R. Webb, D. Everson, S. Bleay, N. Bright, M.L. Elad, Y. Cohen, J. Watts, M. de Puit, Enhanced imaging of developed fingerprints using mass spectrometry imaging, Analyst 138 (2013) 6246–6250. [12] M. Wang, M. Li, A. Yu, J. Wu, C. Mao, Rare earth fluorescent nanomaterials for enhanced development of latent fingerprints, ACS Appl. Mater. Interfaces 7 (2015) 28110–28115. [13] B.S. Kim, Y. Jin, M.A. Uddin, T. Sakaguchi, H.Y. Woo, G. Kwak, Surfactant chemistry for fluorescence imaging of latent fingerprints using conjugated polyelectrolyte nanoparticles, Chem. Commun. 51 (2015) 13634–13637. [14] Lee and Gaensslen’s, in: S. Robert Ramotowski (Ed.), Advances In Fingerprint Technology, third edition, CRC Press Taylor & Francis Group, Boca Raton, 2013. [15] Y. Li, L. Xu, B. Su, Aggregation induced emission for the recognition of latent fingerprints, Chem. Commun. 48 (2012) 4109–4111. [16] J.D. Luo, Z.L. Xie, J.W.Y. Lam, L. Cheng, H.Y. Chen, C.F. Qiu, H.S. Kwok, X.W. Zhan, Y.Q. Liu, D.B. Zhu, B.Z. Tang, Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole, Chem. Commun. 174 (2001) 1740–1741. [17] B.K. An, S.K. Kwon, S.D. Jung, S.Y. Park, Enhanced emission and its switching in fluorescent organic nanoparticles, J. Am. Chem. Soc. 124 (2002) 14410–14415.
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192 [18] J. Chen, C.C.W. Law, Y. Lam, S.M.F. Lo, I.D. Williams, D. Zhu, B.Z. Tang, Synthesis, light emission, nanoaggregation and restricted intramolecular rotation of 1,1-substituted 2,3,4,5-tetraphenylsiloles, Chem. Mater. 15 (2003) 1535–1546. [19] Y. Dong, J.W.Y. Lam, A. Qin, J. Sun, J. Liu, Z. Li, J. Sun, H.H.Y. Sung, I.D. Williams, H.S. Kwok, B.Z. Tang, Aggregation-induced and crystallization-enhanced emissions of 1,2-diphenyl-3,4-bis(diphenylmethylene)-1-cyclobutene, Chem. Commun. 325 (2007) 3255–3257. [20] J. Mei, N.L.C. Leung, R.T.K. Kwok, J.W.Y. Lam, B.Z. Tang, Aggregation-induced emission together we shine, united we soar, Chem. Rev. 115 (2015) 11718–11940. [21] B.Z. Tang, X.W. Zhan, G. Yu, P.P.S. Lee, Y.Q. Liu, D.B. Zhu, Efficient blue emission from siloles, J. Mater. Chem. 11 (2001) 2974–2978. [22] Z. Li, Y.Q. Dong, J.W.Y. Lam, J. Sun, A. Qin, M. Haüssler, Y.P. Dong, H.H.Y. Sung, I.D. Williams, H.S. Kwok, B.Z. Tang, Functionalized siloles: versatile synthesis, aggregation-Induced emission, and sensory and device applications, Adv. Funct. Mater. 19 (2009) 905–917. [23] L. Duan, L. Hou, T.W. Lee, J. Qiao, D. Zhang, G. Dong, L. Wang, Y. Qiu, Solution processable small molecules for organic light-emitting diodes, J. Mater. Chem. 20 (2010) 6392–6407. [24] T.P.I. Saragi, T. Spehr, A. Siebert, T. Fuhrmann-Lieker, J. Salbeck, Spiro compounds for organic optoelectronics, Chem. Rev. 107 (2007) 1011–1065. [25] R.J. Tseng, R.C. Chiechi, F. Wudl, Y. Yang, Highly efficient 7,8,10-triphenylfluoranthene-doped blue organic light-emitting diodes for display application, Appl. Phys. Lett. 88 (2006) 093512–093513. [26] K.T. Kamtekar, A.P. Monkman, M.R. Bryce, Recent advances in white organic light-Emitting materials and devices (WOLEDs), Adv. Mater. 22 (2010) 572–582. [27] J. Yang, J. Huang, Q. Li, Z. Li, Blue AIEgens: approaches to control the intramolecular conjugation and the optimized performance of OLED devices, J. Mater. Chem. C 4 (2016) 2663–2684. [28] Q. Li, Z. Li, The strong light-Emission materials in the aggregated state: what happens from a single molecule to the collective group, Adv. Sci. (2017) 1600484. [29] W. Li, L. Yao, H. Liu, Z. Wang, S. Zhang, S. Zhang, R. Xiao, H. Zhang, P. Lu, B. Yang, Y. Ma, Highly efficient deep-blue OLED with an extraordinarily narrow FHWM of 35 nm and a y coordinate <0. 05 based on a fully twisting donor?acceptor molecule, J. Mater. Chem. C 2 (2014) 4733–4736. [30] C. Chien, C. Chen, F. Hsu, C. Shu, P. Chou, C. Lai, Multifunctional deep-blue emitter comprising an anthracene core and terminal triphenylphosphine oxide groups, Adv. Funct. Mater. 19 (2009) 560–566. [31] K.V. Rao, K.K.R. Datta, M. Eswaramoorthy, S.J. George, Highly pure solid-state white-Light emission from solution-processable soft-hybrids, Adv. Mater. 25 (2013) 1713–1718. [32] J. Ye, C. Zheng, X. Ou, X. Zhang, M. Fung, C. Lee, Management of singlet and triplet excitons in a single emission layer: a simple approach for a high-efficiency fluorescence/phosphorescence hybrid white organic light-emitting device, Adv. Mater. 24 (2012) 3410–3414. [33] Y. Dong, J.W.Y. Lam, A. Qin, J. Liu, Z. Li, B.Z. Tang, J. Sun, H.S. Kwok, Aggregation-induced emissions of tetraphenylethene derivatives and their utilities as chemical vapor sensors and in organic light-emitting diodes, Appl. Phys. Lett. 91 (2007) 011111–011113. [34] G. Mu, W. Zhang, P. Xu, H. Wang, Y. Wang, L. Wang, S. Zhuang, X. Zhu, Constructing new n-Type ambipolar, and p-Type aggregation-induced blue luminogens by gradually tuning the proportion of tetrahphenylethene and diphenylphophine oxide, J. Phys. Chem. C 118 (2014) 8610–8616. [35] B. Xu, Z. Chi, H. Li, X. Zhang, X. Li, S. Liu, Y. Zhang, J. Xu, Synthesis and properties of aggregation-induced emission compounds containing triphenylethene and tetraphenylethene moieties, J. Phys. Chem. C 115 (2011) 17574–17581. [36] Y.T. Wu, M.Y. Kuo, Y.T. Chang, C.C. Shin, T.C. Wu, C.C. Tai, T.H. Cheng, W.S. Liu, Synthesis, structure, and photophysical properties of highly substituted 8, 8a-dihydrocyclopenta[a]indenes, Angew. Chem. Int. Ed. 47 (2008) 9891–9894. [37] C.J. Bhongale, C.W. Chang, C.S. Lee, E.W.G. Diau, C.S. Hsu, Relaxation dynamics and structural characterization of organic nanoparticles with enhanced emission, J. Phys. Chem. B 109 (2005) 13472–13482. [38] S. Kim, Q. Zheng, G.S. He, D.J. Bharali, H.E. Pudavar, A. Baev, P.N. Prasad, Aggregation-Enhanced fluorescence and two-photon absorption in nanoaggregates of a 9, 10-Bis[4 -(4 -aminostyryl)styryl]anthracene derivative, Adv. Funct. Mater. 16 (2006) 2317–2323. [39] J. He, B. Xu, F. Chen, H. Xia, K. Li, L. Ye, W. Tian, Aggregation-induced emission in the crystals of 9,10-distyrylanthracene derivatives: the essential role of restricted intramolecular torsion, J. Phys. Chem. C 113 (2009) 9892–9899. [40] Y. Wang, T. Liu, L. Bu, J. Li, C. Yang, X. Li, Y. Tao, W. Yang, Aqueous nanoaggregation-Enhanced one- and two-Photon fluorescence crystalline J-aggregation-induced red shift, and amplified spontaneous emission of 9,10-Bis(pdimethylaminostyryl) anthracene, J. Phys. Chem. C 116 (2012) 15576–15583. [41] Y.X. Li, Z. Chen, Y. Cui, G.M. Xia, X.F. Yang, Substitution position directing the molecular packing electronic structure, and aggregate emission property of bis[2-(9-anthracenyl)vinyl]benzene system, J. Phys. Chem. C 116 (2012) 6401–6408. [42] J.W. Chen, B. Xu, X.Y. Ouyang, B.Z. Tang, Y. Cao, Aggregation-induced emission of cis,cis-1,2,3,4-tetraphenylbutadiene from restricted intramolecular rotation, J. Phys. Chem. A 108 (2004) 7522–7526.
191
[43] H. Tong, Y. Dong, Y. Hong, M. Haeussler, J.W.Y. Lam, H.H.Y. Sung, X. Yu, J. Sun, I.D. Williams, H.S. Kwok, B.Z. Tang, Aggregation-induced emission effects of molecular structure, solid-state conformation, and morphological packing arrangement on light-emitting behaviors of diphenyldibenzofulvene derivatives, J. Phys. Chem. C 111 (2007) 2287–2294. [44] K. Shiraishi, T. Kashiwabara, T. Sanji, M. Tanaka, Aggregation-induced emission of dendritic phosphole oxides, New J. Chem. 33 (2009) 1680–1684. [45] H.C. Su, O. Fadhel, C.J. Yang, T.Y. Cho, C. Fave, M. Hissler, C.C. Wu, R. Reau, Toward functional -Conjugated organophosphorus materials: design of phosphole-Based oligomers for electroluminescent devices, J. Am. Chem. Soc. 128 (2006) 983–995. [46] Y. Ren, F. Biegger, T.J. Baumgartner, Molecular engineering of the physical properties of highly luminescent -conjugated phospholes, J. Phys. Chem. C 117 (2013) 4748–4758. [47] C.T. Lai, J.L. Hong, Aggregation-Induced emission in tetraphenylthiophene-derived organic molecules and vinyl polymer, J. Phys. Chem. B 114 (2010) 10302–10310. [48] J. Xu, L. Wen, W. Zhou, J. Lv, Y. Guo, M. Zhu, H. Liu, Y. Li, L. Jiang, Asymmetric and symmetric dipole-dipole interactions drive distinct aggregation and emission behavior of intramolecular charge-transfer molecules, J. Phys. Chem. C 113 (2009) 5924–5932. [49] R. Hu, E. Lager, A. Aguilar-Aguilar, J. Liu, J.W.Y. Lam, H.H.Y. Sung, I.D. Williams, Y. Zhong, K.S. Wong, E. Pen˜a-Cabrera, B.Z. Tang, Twisted intramolecular charge transfer and aggregation-induced emission of BODIPY derivatives, J. Phys. Chem. C 113 (2009) 15845–15853. [50] W. Jia, H. Wang, L. Yang, H. Lu, L. Kong, Y. Tian, X. Tao, J. Yang, Synthesis of two novel indolo[3,2-b]carbazole derivatives with aggregation-enhanced emission property, J. Mater. Chem. C 1 (2013) 7092–7101. [51] P. Shanmugasundaram, P. Murugan, V.T. Ramakrishnan, N. Srividya, P. Ramamurthy, Synthesis of acridinedione derivatives as laser dyes, Heteroatom Chem. 7 (1996) 17–22. [52] S. Singh, S. Chhina, V.K. Sharma, Cationic hydrogenation of benzyl alcohols and arylethylenes using acridane derivatives as hindered NADH models, J. Chem. Soc. (1982) 453–454. [53] C. Selvaraju, P. Ramamurthy, Excited-State behavior and photoionization of 1,8-acridinedione dyes in micelles–comparison with NADH oxidation, Chem. Eur. J. 10 (2004) 2253–2262. [54] V. Thiagarajan, D. Thirumalai, V.T. Ramakrishnan, P. Ramamurthy, A novel colorimetric and fluorescent chemosensor for anions involving PET and ICT pathways, Org. Lett. 7 (2005) 657–660. [55] R. Koteeswari, P. Ashokkumar, V.T. Ramakrishnan, E.J. Padma Malar, P. Ramamurthy, Unprecedented formation of an N-benzamidobisthiourea derivative and its role in the formation of a new CT state specific towards fluoride ion, Chem. Commun. 46 (2010) 3268–3270. [56] P. Ashokkumar, V.T. Ramakrishnan, P. Ramamurthy, Specific Ca2+ fluorescent sensor: signaling by conformationally induced PET suppression in a bichromophoric acridinedione, Eur. J. Org. Chem. (2009) 5941–5947. [57] R. Koteeswari, P. Ashokkumar, E.J. Padma Malar, V.T. Ramakrishnan, P. Ramamurthy, Highly selective, sensitive and quantitative detection of Hg2+ in aqueous medium under broad pH range, Chem. Commun. 47 (2011) 7695–7697. [58] P. Ashokkumar, V.T. Ramakrishnan, P. Ramamurthy, Photoinduced electron transfer (PET) based Zn2+ fluorescent probe: transformation of turn-on sensors into ratiometric ones with dual emission in acetonitrile, J. Phys. Chem. A 115 (2011) 14292–14299. [59] H.J. Timpe, S. Ulrich, S. Ali, Spin-trapping as a tool for quantum yield determinations in radical forming processes, J. Photochem. Photobiol. A: Chem. 61 (1991) 77–89. [60] H.J. Timpe, S. Ulrich, J.P. Fouassier, Photochemistry and use of decahydroacridine-1, 8-diones as photosensitizers for onium salt decomposition, J. Photochem. Photobiol. A: Chem. 73 (1993) 139–150. [61] S. Ulrich, H.J. Timpe, J.P. Fouassier, F. Morlet-Savary, Photoreduction of decahydroacridine-1, 8-diones by amines, J. Photochem. Photobiol A: Chem. 74 (1993) 165–170. [62] N. Srividya, P. Ramamurthy, V.T. Ramakrishnan, Solvent effects on the absorption and fluorescence spectra of some acridinedione dyes: determination of ground and excited state dipole moments, Spectrochimica Acta Part A 53 (1997) 1743–1753. [63] Z. Yang, Z. Chi, T. Yu, X. Zhang, M. Chen, B. Xu, S. Liu, Y. Zhang, J. Xu, Triphenylethylene carbazole derivatives as a new class of AIE materials with strong blue light emission and high glass transition temperature, J. Mater. Chem. 19 (2009) 5541–5546. [64] S. Dong, Z. Li, J. Qin, New carbazole-Based fluorophores: synthesis, characterization, and aggregation-Induced emission enhancement, J. Phys. Chem. B 113 (2009) 434–441. [65] C. Selvaraju, P. Ramamurthy, Excited-State behavior and photoionization of 1, 8-acridinedione dyes in micelles—comparison with NADH oxidation, Chem. Eur. J. 10 (2004) 2253–2262. [66] V. Thiagarajan, C. Selvaraju, P. Ramamurthy, Excited state behaviour of acridinedione dyes in PMMA matrix: inhomogeneous broadening and enhancement of triplet, J. Photochem. Photobiol. A 157 (2003) 23–31. [67] V.K. Indirapriyadharshini, P. Karunanithi, P. Ramamurthy, Inclusion of resorcinol-Based acridinedione dyes in Cyclodextrins: fluorescence enhancement, Langmuir 17 (2001) 4056–4060. [68] R. Kumaran, P. Ramamurthy, PET suppression of acridinedione dyes by urea derivatives in water and methanol, J. Phys. Chem. B 110 (2006) 23783–23789.
192
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
[69] L. Wang, Y. Shen, Q. Zhu, W. Xu, M. Yang, H. Zhou, J. Wu, Y. Tian, Systematic study and imaging application of aggregation-induced emission of ester-isophorone derivatives, J. Phys. Chem. C 118 (2014) 8531–8540. [70] S. Mukherjee, P. Thilagar, Fine-tuning solid-state luminescence in NPIs (1, 8-naphthalimides): impact of the molecular environment and cumulative interactions, Phys. Chem. Chem. Phys. 16 (2014) 20866–20877. [71] L. Xu, Y. Li, S. Li, R. Hu, A. Qin, B.Z. Tang, B. Su, Enhancing the visualization of latent fingerprints by aggregation induced emission of siloles, Analyst 139 (2014) 2332–2335. [72] P. Singh, H. Singh, R. Sharma, G. Bhargava, S. Kumar, Diphenylpyrimidinone–salicylideneamine – new ESIPT based AIEgens with applications in latent fingerprinting, J. Mater. Chem. C 4 (2016) 11180–11189.
Biographies Raghupathy Suresh received his M. Sc. Organic Chemistry from University of Madras, India in 2010. Currently he is pursuing Ph. D in chemistry at University of Madras. His research interests focused on synthesis of organic fluorophores, aggregation induced emission, solid state luminescence and fluorescent sensors.
Senthil Kumar Thiyagarajan received his M. Sc. Chemistry from Madras Christian College, Chennai, India in 2008. Currently he is pursuing Ph. D in chemistry at University of Madras. His research interests focused on photophysics and photochemistry of organic fluorophores, light induced excited state processes, and fluorescent sensors. Perumal Ramamurthy is a professor in University of Madras. He started his academic career as a lecturer in the department of Inorganic chemistry in 1987 and contributed significantly in the field of Ultrafast Spectroscopy and Photosciences not only through his scientific publications but also dedicating himself to establish the National Centre for Ultrafast Processes with state of art facilitites, which is unique of its kind among University researchers in our country. His major areas of research interest are ultrafast spectroscopy, nanomaterials, photophysics and photochemistry of organic molecules, fluorescent sensors.
Contents lists available at ScienceDirect
Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb
Research paper
An AIE based fluorescent probe for digital lifting of latent fingerprint marks down to minutiae level Raghupathy Suresh, Senthil Kumar Thiyagarajan, Perumal Ramamurthy ∗ National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai, 600 113, India
a r t i c l e
i n f o
Article history: Received 29 July 2017 Received in revised form 2 November 2017 Accepted 10 November 2017 Available online 21 November 2017 Keywords: Acridinedione Aggregation induced emission Fingerprint Enhancement Visualization
a b s t r a c t Acridinediones, a new addition to the family of dyes having aggregation induced emission characteristics have been reported. Facile hydrophobic interactions between the acridinedione aggregates and fingerprint residues were exploited to lift the latent fingerprint marks on a non-porous substrate. By employing this preferential adhesion approach, a portable wet method for the enhancement and visualization of latent fingerprint marks using hand held UV light and mobile camera was demonstrated. Using this simple, rapid, cost effective, eco and user friendly method the latent fingerprints, its primary and secondary level of information’s can be easily decoded. These acridinedione derivatives also show strong blue luminescence in solid state with high fluorescence quantum yield. © 2017 Elsevier B.V. All rights reserved.
1. Introduction Fingerprints are unique patterns, made by friction ridges and furrows which appear on the pads of the human fingers. The ridge patterns found in finger prints are characteristic to each person and unchangeable as they are formed deep in the skin and leave marks on objects handled with bare hands [1]. Fingerprints continue to be a significant tool in our day today life for many purposes such as access control, safety examination and individual identifications [2,3]. Fingerprint recognition has been used to identify suspects and solve crimes for more than a century, and it remains an exceptionally valuable tool for law enforcement and in Integrated Automated Fingerprint identification Service (IAFS) [4,5]. Fingerprints are classified into two types, patent and latent based on their visibility to the naked eye. In which, latent fingerprint is invisible and it is commonly found in most crime scene. So, it becomes essential to enhance those invisible latent fingerprint marks (LFMs) for further identification and to solve the crime scene. A variety of methods have been developed to enhance the LFMs; using physical methods [6], chemical methods [7], combining physical and chemical methods [8], optical imaging techniques [9–11], using nanomaterials [12] and fluorescent organic aggregates [13]. Even though there are plentiful analytical processes that have been proposed for finger print enhancement and detection, powder dusting method
∗ Corresponding author. E-mail address: [email protected] (P. Ramamurthy). https://doi.org/10.1016/j.snb.2017.11.051 0925-4005/© 2017 Elsevier B.V. All rights reserved.
is still the most commonly used technique during forensic investigations [14]. But lifting latent finger prints using magnetic and fluorescent powders have some drawbacks, viz., unavoidable damage to the fingerprint details and health hazard to the examiners. To overcome these, Yan Li et al., has recently reported an alternative methodology to lift the LFMs by applying the aggregation induced emission (AIE) phenomenon [15]. Visualization of LFMs using the AIE strategy is an outright wet method and hence it is more eco and user friendly than the conventional powder dusting method. However, the reported AIE methods to lift the LFMs require sophisticated imaging instruments. So, a simple, portable and cost effective alternate is needed for the enhancement and visualization of LFMs especially during real time analysis. A new class of organic fluorogens with aggregation induced emission (AIE) and aggregation enhanced emission (AEE) features have been developed in recent years. The phenomenon AIE is quite opposite to the conventional ‘aggregation caused quenching (ACQ)’ behavior commonly observed in most of the planar aromatic fluorogens [16,17]. The AIE or AEE fluorogens are nonemissive or weakly emissive in dilute solution and becomes highly emissive in the aggregated state, which has been due to the restriction of intramolecular motions (RIM) in the aggregated state [18,19]. By considering the importance of this AIE phenomenon, enormous efforts have been dedicated to synthesize new organic fluorogens exhibiting this unusual property [20]. These molecules have been recognized as one of the most promising candidate for optoelectronic materials such as organic light emitting and electroluminescence devices [21–28]. Among the different AIE flu-
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
185
Fig. 1. Structural formulae of two ADD derivatives ADDPh & ADDSi.
orogens, blue light emitting materials play a key role in white light generation. However, these are the materials which are the most challenging to attain because of the difficulty in charge injection across the larger energy gap and lack of balance in charge transport [29–32]. Despite, there is a large scope for researchers to develop new blue light emitting materials with high efficiency and stability. Among the blue light emitting materials reported in the literature most of them are aromatic hydrocarbons [33–43] and only a few blue emitting heterocyclic compounds were reported [44–50]. Acridinedione (ADD) dyes are heterocyclic compounds having structural similarity with NADH [51–53], they are known for its high lasing efficiency and as a potential fluorescent probes for metal ions, anions and biological imaging [54–58]. They can also function as electron donors and acceptors in the excited state [59–61]. Even though a detailed studies on the emission characteristics of the ADD dyes in solutions have been reported by our group [62], aggregation induced emission characteristics of these compounds have not been explored until now. This is the first report that establishes the aggregation induced emission characteristics of the ADD dyes and this unusual phenomenon has been strategically applied for lifting the LFMs on different non-porous surfaces by a wet AIE method. The overall process for the enhancement and visualization of LFMs by this method takes less than five minutes with the use of simple hand held UV lamp and mobile camera. This method is fast, user and eco-friendly, more importantly it doesn’t require sophisticated imaging instrumentations. 2. Results and discussion 2.1. Aggregation Induced Emission (AIE) feature of ADD derivatives Two ADD derivatives ADDPh & ADDSi bearing different aromatic rotors at the 9th position were prepared to explore the aggregation induced emission behavior (Fig. 1). In good solvent like THF, these molecules exhibit negligible intermolecular interactions under dilute condition. In THF, ADDPh shows emission maximum at 414 nm with fluorescence quantum yield (f ) of 0.024 and ADDSi shows emission maximum at 425 nm with f of 0.135. Upon increasing the water fraction (fw ) from 0 to 90%, the emission intensity of ADDPh shows enhancement with continuous red shift (Figs. 2 and 3). When the volume fraction of water reaches 90%, it shows emission at 441 nm with quantum yield of f = 0.628, which is 26 times greater than that in THF (Fig. 3, Table 1). The classical AIE curve was plotted as a function of different water fraction which is
Fig. 2. Images show the change in emission intensity of a) ADDPh and b) ADDSi upon addition of different fractions of water in THF. Table 1 Photophysical data of ADDPh and ADDSi in solution (S), aggregated state (A) and powder form (P). Compound
em (nm)
f,S
f,A
f,P
␣AIE
ADDPh ADDSi
414 425
0.024 0.135
0.628 0.586
0.415 0.276
26 4.34
shown in Fig. 3c. This unusual enhancement in the emission intensity with red shift is due to the contribution from two different fundamental aspects, (1) Formation of molecular aggregates; upon increasing the water fraction (poor solvent) there is a decrease in solubility of ADDPh in the THF/Water mixture due to its intrinsic hydrophobic nature. It results in an increase in the intermolecular interactions which induces the isolated molecules to involve in aggregate formation. This aggregation process constraints the free space available for intramolecular rotation and vibration, which in turn restricts the rotation of the phenyl rotors and suppresses one of the predominant non-radiative decay pathways. Hence, the excited molecules come back to their ground state primarily via fluorescence (emission enhancement). (2) General solvent effect; the molecular absorption in ADD dye is due to the intramolecular charge transfer (ICT) from the ring nitrogen to the carbonyl moiety [62]. Hence, adding high polar solvent like water enhances the ICT process by stabilizing the more polar excited state. It also results in a considerable enhancement in the emission intensity with a red shift as shown in Fig. 3d. Hence, the classical AIE curve reflects the contribution from both the polar as well as the poor solvation tendency of the solvent water. But, it is difficult to resolve the indigenous influence of each aspect spectrometrically. For ADDSi, the situation is slightly different, the emission intensity enhances with red shift on increasing the fw from 0 to 60% (4.34 fold enhancement), but further increase in fw (70–90%) dramatically quenches the emission intensity (Fig. 2b & 3). Also, the absorption spectrum shows light scattering tails at fw > 70% (Figure SD1). These results indicate the formation of larger molecular aggregates and the photograph in Fig. S1 shows the existence of larger molecular aggregates of ADDSi visible to naked eye observed at fw > 70%. Such larger molecular aggregates were often observed for AEE fluorogens at higher water fraction. In general, when water
186
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
Fig. 3. Emission spectra of (a) ADDPh and (b) ADDSi in THF/water mixtures at different water fractions (fw ). Plots of (c) quantum yield and (d) maximum emission wavelength (max ) versus the different compositions of the THF/water mixtures of ADDPh and ADDSi.
(non-solvent) is added the isolated molecules tend to aggregate into either (1) crystalline or (2) amorphous like larger molecular aggregates. The former always leads to an enhancement in the emission intensity, while the latter results a decline in emission intensity [63]. So, the resultant emission intensity depends upon the morphology of the aggregates formed. But it is difficult to control the morphology of these aggregates, especially at higher fw . Hence, in most of the AEE cases the classical AIE curve often shows irregularity at higher fw [64]. Analogously, the ADDSi exhibit a drastic decline in the emission intensity at higher water fraction (>70%) which indicates the formation of the amorphous like molecular aggregates. Although, both ADDPh and ADDSi are AIE active as depicted in Fig. 2, there is an inherent difference in their fluorescence behavior. ADDPh exhibit relatively weaker emission (f = 0.024) in THF than ADDSi (f = 0.135). However, their aggregates formed in THF/Water mixture at fw = 60% shows strong emission with a quantum yield (f ) of 0.628 and 0.586 respectively. It results in a much enhanced AIE amplification factor (␣AIE = f,agg /f,sol ) for ADDPh (26) than ADDSi (4.34) which is presented in Table 1. Although the molecular aggregates of ADDPh and ADDSi have similar f , ADDPh has a better AIE performance than ADDSi. The significant difference in the AIE amplification factor between the two ADD derivatives is primarily due to the large difference in their f value in solution state (∼5.5 times). In ADDPh, the phenyl moiety at the 9th position acts as a free rotor and the tricyclic ADD ring can be considered as a stator. In good solvent like THF, the intermolecular interac-
tions are negligible and hence the phenyl rotors can effectively rotate around the stator. It results in depopulation of the excited state through non-radiative decay pathway and lead to very low fluorescence quantum yield (f = 0.024). In contrast, the phenyl ring in ADDSi carries bulkier silyl enol ether substituent at its para position which hinders the free rotation of the phenyl ring. Hence, the depopulation of the excited state through non-radiative decay process is relatively lesser in ADDSi which results in much higher fluorescence quantum yield for ADDSi (f = 0.135) in the solution state. After aggregation, the strong intermolecular interactions in both ADDPh & ADDSi hinder the free rotation of the phenolic unit and enhances the fluorescence quantum yield. Strong photoluminescence of the aggregates of ADDPh & ADDSi encouraged us to unravel the feasibility of solid state luminescence of these ADD derivatives. As shown in Fig. S2, both these ADD derivatives have shown unprecedented bright luminescence in solid state (as shown in inset) with the emission maximum at ∼450 nm, and the absolute f value of ADDPh and ADDSi in solid state were determined to be 0.415% & 0.276% respectively (Table 1). Even though, extensive investigations on the photoluminescence behavior of various ADD derivatives in different environments (in polar & apolar solvents) [62], in micelles [65], in PMMA matrix [66], in macrocyclic host [67], in urea dimers [68] were carried out, this is the first report that unveils the solid state luminescence of the ADD family. Moreover, the luminescence in the solid state was observed in the blue region, ∼450 nm which certifies that the ADD dyes are suitable candidates for optoelectronic applications. However, there is a significant decrease in the f of ADDPh and
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
187
Fig. 4. a) Change in the size of the molecular aggregates upon addition of different fractions of water in THF. b) Variation in the polydispersity index (PDI) of the medium upon addition of different fractions of water in THF.
ADDSi in the solid state when compared to its molecular aggregates, which might be due to the stronger intermolecular interactions and relatively shorter intermolecular distance in the solid state. By tailoring suitable substitution, it is possible to tune the intermolecular interactions and hence the photoluminescence behavior of ADD derivatives in the solid state. The emission spectrum of both ADDPh & ADDSi in three different physical states viz., dissolved in THF, aggregated state and solid state were shown in Fig. S2. The emission maximum of both ADDPh and ADDSi in the solid state is ∼10 nm red shifted relative to the emission maximum from their respective molecular aggregates. 2.2. Characterization of aggregates by DLS and FE-SEM To further understand the size distribution of these molecular aggregates, dynamic light scattering (DLS) studies were carried out. All the solutions were appear transparent and macroscopically homogeneous, except for ADDSi at fw > 70% (Fig. S3). The size distribution of the molecular aggregates (hydrodynamic diameter) at different fw is shown in Fig. S4. At fw < 10%, there is no detectable amount of aggregates were observed for both these ADD
derivatives. On increasing the fw from 20 to 50%, the average hydrodynamic diameter of the molecular aggregates of ADDPh increases from 3.66 to 16.57 nm and the polydispersity index (PDI) value of the respective solution increases from 0.122 to 0.267 (Figs. 4 & S4, Table S1). The increase in the particle size as well as the PDI of the medium strongly supports the formation of molecular aggregates while increasing the water fraction. With further increase in the fw from 60 to 90% leads to the formation of larger molecular aggregates with the multi-modal distribution, whose average hydrodynamic diameter increases from 54.33 to 461 nm and the corresponding PDI value of the solution increases from 0.393 to 0.645 (Figs. 4 & S4, Table S1) [69]. In case of ADDSi, increasing the fw from 20 to 90% dramatically increases the average size of molecular aggregates from 3.92 to 2868 nm and also the PDI value of the respective solution from 0.153 to 0.896 (Figs. 4, S4, Table S1). From Fig. 4 it is clear that the ADDSi forms larger molecular aggregates even at fw ∼ 40% relative to ADDPh of similar concentration. In ADDSi, the presence of extra hetero atom (oxygen) and three phenyl rings facilitates the molecule to involve in strong intermolecular interactions to form larger molecular aggregates. But in case of ADDPh, the lone phenyl ring cannot interact much effectively with the neighboring
Fig. 5. FE-SEM image of ADDPh a) In powder form b) A drop of 0.3 mM THF solution was drop casted on aluminum foil after evaporation the substrate was imaged c) In 90% water fraction. FE-SEM image of ADDSi d) In powder form e) A drop of 0.3 mM THF solution was drop casted on aluminum foil after evaporation the substrate was imaged. f) In 90% water fraction.
188
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
Fig. 6. Variation in the fluorescence lifetime of a) ADDPh and b) ADDSi upon addition of different fractions of water in THF.
molecules and hence it forms relatively smaller molecular aggregates. This is further supplemented by the steepness in the classical AIE curve of ADDSi, compared to ADDPh. These results have conclusively proven two important factors, (i) the observed enhancement in the emission intensity is not simply due to the increase in the solvent polarity but due to the aggregate formation. (ii) Stronger intermolecular interactions (as in ADDSi) facilitate the aggregate formation even at lower water fraction which in turn sharply raises the AIE curve. To have an account on the surface morphology of these molecular aggregates, we have intended to image them using field emission scanning electron microscopy (FE-SEM). For that we have dropcasted 0.3 mM solution (fw ∼ 80 & 90%) of ADDPh and ADDSi on an aluminum foil and allowed them to dry at room temperature. The dried sample was then imaged using FE-SEM technique and it is shown in Figs. 5 & S5. The images show that ADDPh forms spongy type molecular aggregates and ADDSi forms spherical molecular aggregates with the particle size of ∼1–3 m, which matches well with the average hydrodynamic diameter obtained using DLS studies. However, simple recrystallization during evaporation may sometimes result such images. To subdue such arguments, we have carried out similar investigation with the 0.3 mM solution of ADDPh & ADDSi in neat THF as well as for their powder form (solid state). The FESEM image of both ADDPh & ADDSi (Fig. 5b,e) dropcasted using their THF solution shows that the molecules are arranged in rod like structure i.e., crystalline, and the images look akin to the powdered sample images (Fig. 5a,d). Molecules that are isolated in THF, a low boiling solvent, undergo fast evaporation yet it forms ordered rod like structure analogous to the powder form (solid state). But the solution of ADDPh & ADDSi in THF:water mixture undergoes slow evaporation, the condition favorable for forming more ordered structure, yet they form spongy and spherical aggregates (Figs. 5c,f & S5). Hence, it can be concluded that the aggregates of ADDPh & ADDSi were preformed in the solution itself and it gets deposited on the aluminum foil after the evaporation of the solvent. Thus, the obtained SEM images of ADDPh & ADDSi in THF:water mixture indubitably establishes the aggregate formation in the mixed aqueous medium. Consequently, the formation of spongy like aggregates in ADDPh must be due to its weak intermolecular interaction, whereas for ADDSi, the strong intermolecular interactions result in the formation of spherical molecular aggregates. Thus the DLS and FESEM analyses complements well with one another.
2.3. Mechanism for AIE To further supplement the aggregation induced emission enhancement, time resolved fluorescence studies were carried out at different fw , using Time Correlated Single Photon Counting technique (TCSPC). The fluorescence lifetime decay of ADDPh in neat THF fits single exponential, with a lifetime value of 0.378 ns. This short fluorescence lifetime and low quantum yield (0.02) of ADDPh in THF implicates the involvement of strong non-radiative decay process (knr = 2.58 × 109 s−1 ) in depopulating the excited state. On adding water to this THF solution, the lifetime decay remains single exponential but there is a continuous enhancement in the lifetime value and it reaches 8.98 ns at fw ∼ 90% (Figs. 6 & S6, Table S2). The increase in the fluorescence lifetime must be due to the suppression of the non-radiative decay process that depopulates the excited state. The plot of non-radiative decay rate as a function of water percentage shows that there is a rapid decrease in the non-radiative decay rate upto fw ∼ 40%; it indicates that the isolated ADDPh molecules involves in aggregation which in turn blocks one of the vital non-radiative decay channel by restricting the intramolecular rotation (Fig. S7, Table S3). At fw > 40%, there is not much change in the non-radiative decay rate which accounts for the saturation in the classical AIE curve. Our DLS study already indicates that at fw > 50%, the aggregates of ADDPh begins to agglomerate to form larger molecular aggregates (multimodal distribution) and hence it doesn’t bring much change in the non-radiative decay rate, so do the quantum yield. The AIE amplification factor calculated using the fluorescence lifetime value of ADDPh is ∼23.74 which matches well with the amplification factor measured using the emission intensity (Figs. 6 & S6, Table S2). In case of ADDSi, the fluorescence lifetime decay in neat THF fits single exponential and the corresponding lifetime value is determined to be ∼1.51 ns. It is about ∼4 times higher than ADDPh under the same experimental condition and the corresponding non-radiative decay rate is estimated to be knr = 0.57 × 109 s−1 . Relatively slower non-radiative decay rate of ADDSi indicates that the bulkier silyl enol ether functionality at the top of the phenyl ring considerably decreases the intramolecular rotation and hinders the depopulation of the excited state (Fig. S7, Table S3). On adding water to this THF solution, there is a continuous enhancement in the fluorescence lifetime upto fw ∼ 70%, but after 70% there is a marginal decline in the lifetime value. The plot of non-radiative decay rate of ADDSi at different water fraction is analogous to
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
189
Fig. 7. Fluorescence image of LFMs developed by ADDPh (0.3 mM) aggregates on microscopic glass plate. a) Simple Arch type Fingerprint b) Loop type Fingerprint c) Concentric Whorl type Fingerprint. All the LFMs have been developed using 70% water fraction in THF and then visualized under 365 nm UV lamp.
ADDPh and the rapid decline in the non-radiative decay rate is observed at fw < 30% which is due to the relatively stronger intermolecular interaction furnished by the silyl enol ether functionality (Figs. 6 & S6, Table S2). At fw > 70%, the larger (from DLS) and spherical (from FESEM) molecular aggregates of ADDSi have strong intermolecular interactions, which opens other new non-radiative decay channels which depopulate the excited state and quenches the fluorescence lifetime [70]. These results indubitably establish that “Restriction of Intramolecular Rotation” is the active mechanism which accounts for the observed aggregation induced emission behavior in these ADD derivatives.
2.4. Enhancement and recognition of latent fingerprint marks Both ADDPh and ADDSi show typical AIE characteristics, and hence these dyes can be used as a fluorescent probe to enhance and visualize the LFMs using the wet method. Since this is the wet method, the visualization of the LFMs is possible only on the non-porous surface and not on the porous surface such as wood or paper. The strong fluorescence of these molecular aggregates has the advantage of low background noise even while imaging it using a mobile camera. We have used different concentration of ADDPh & ADDSi and several combinations of THF/water mixture to visualize the LFMs. Finally, it was optimized that 0.3 mM solutions of ADDPh
Fig. 8. Fluorescence image of LFMs developed by ADDPh (0.3 mM) aggregates on glass plate showing different secondary level information such as core, island, ending ridge, crossover, short ridge, bifurcation. The secondary level information’s are very clear even after digital magnification which was shown separately as a magnified image.
190
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
and ADDSi in 60% and 70% water fraction in THF/water are the combinations that work very well to enhance, visualize and lift the LFMs (Fig. S8). For this study, three volunteers donated sebaceous fingerprints by wiping their finger on the forehead and stamped the finger with nominal pressure on the non-porous substrates. The substrates with latent fingerprints were incubated for 2 min in THF/water mixture (2:3) containing 0.3 mM of ADDPh or ADDSi. The developed latent fingerprints were rinsed with distilled water, to wash of the excess and unwanted dye molecules. It was then dried using air drier for 1 min and photographed using mobile camera (Moto G, 2nd generation, 8 Mega Pixel camera) under 365 nm UV light (Handheld UV lamp DL01 with Radium F4T5/BLB, 4W G5 UV light). Depending on the quality of the LFMs, three levels of information can be attained. (1) Primary level information; pattern of LFMs (2) Secondary level information; describing minutiae points like core, delta, bifurcation, independent ridge, ridge termination, crossover, etc., (3) Final level information; pores and ridge contours. For recognizing and identifying the LFMs, information about papillary ridges are also important. Three basic types of papillary ridges viz., (a) Arch type (b) Loop type (c) Whorl type [5] are commonly present in human fingers. By using our current method, we have extracted the primary and secondary level information of LFMs and identified all three types of papillary ridge patterns and it is shown in Fig. 7. The secondary level information such as core, delta, bifurcation, independent ridge, and lake are clearly well resolved by this method (Fig. 8), which are considered to be an important tool in matching the fingerprint to solve the crime cases. We have also lifted the LFMs of their other fingers and are shown in Fig. S9, S10 & S11. In all these LFMs, only the papillary ridges are lit up by the UV light, the furrow areas (i.e., space between ridges) are remain black because of the preferential hydrophobic interaction of the probes with the fatty acid residues present in the finger print papillary ridges. The time and equipment needed to develop these LFMs are much better when compared to other reported AIE based wet methods [71,72]. In order to test the applicability of this wet method on different non-porous substrates we have developed the LFMs on the aluminum sheet and stainless steel plate which are shown in Fig. S12. In both the cases, the images are clearly lit up in the UV light and the corresponding primary and secondary level information can be easily extracted. When compared with microscopic glass plate and aluminum sheet, LFMs on the stainless steel plate shows a low resolution image. The solid state emission of the developed LFMs substrates were recorded to establish the preferential interaction of ADDPh/Si aggregates to the papillary ridges and the corresponding solid state emission spectrum is shown in Fig. S13. We have also developed the LFMs of the aged samples; the papillary ridges of the aged samples are clearly lit up in the UV light (Fig. S14). The primary and secondary level information are well resolved even for the aged sample.
3. Conclusion Aggregation induced emission behavior of two acridinedione derivatives were experimentally demonstrated using steady state and time resolved fluorescence studies, Dynamic light scattering and scanning electron microscopy studies. These studies complement each other and undeniably establish that the ‘Restriction in Intramolecular Rotation’ is the active mechanism which induces the emission during aggregation in both ADDPh & ADDSi. These easy to prepare ADD derivatives are the new addition to the AIE family. Strong hydrophobic interaction between these ADD aggregates and finger print residues were strategically exploited to enhance and visualize the latent finger print marks on a non-porous substrate. Using simple hand held UV lamp and mobile camera,
the primary and secondary level of information in the LFMs were easily decoded by this rapid, cheap, eco and user friendly method. These ADD dyes also exhibit bright blue luminescence in the solid state. The molecular arrangement and the intermolecular interaction which tunes the luminescence of ADD dye in the solid state are currently under investigation. Conflict of interest None. Author contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Acknowledgment RS and SKT thank CSIR (New Delhi) for the award of Senior Research Fellowship. Thanks are due to Prof. S. Balakumar, NCNST, University of Madras for extending the FE-SEM facility. We also thank Dr. K. J. Sriram, CSIR-CLRI,Chennai for extending the DLS facility. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.snb.2017.11.051. References [1] C. Champod, C. Lennard, P. Margot, M. Stoilovic, Fingerprints and Other Ridge Skin Impressions, CRC Press LLC, USA, 2004. [2] P. Hazarika, D.A. Russell, Advances in fingerprint analysis, Angew. Chem., Int. Ed. 51 (2012) 3524–3531. [3] L. Xu, Y. Li, S. Wu, X. Liu, B. Su, Imaging latent fingerprints by electrochemiluminescence, Angew. Chem., Int. Ed. 51 (2012) 8068–8072. [4] P. Komarinski, Automated Fingerprint Identification Systems, Elsevier Academic Press, USA, 2005. [5] R. Saferstein, An Introduction to Forensic Science, Ninth edition, Pearson Education, Inc., L, USA, 2007, pp. 426–457 (Chapter 14). [6] N. Jones, M. Stoilovic, C.J. Lennard, C. Roux, Vacuum metal deposition: factors affecting normal and reverse development of latent fingerprints on polyethylene substrates, Forensic Sci. Int. 115 (2001) 73–88. [7] S. Wiesner, E. Springer, Y. Sasson, J. Almog, Chemical development of latent fingerprints: 1 2-Indanedione has come of age, J. Forensic Sci. 46 (2001) 1082–1084. [8] A.A. Cantu, Silver physical developers for the visualization of latent prints on paper, Forensic Sci. Rev. 13 (2001) 29–64. [9] W. Song, Z. Mao, X. Liu, Y. Lu, Z. Li, B. Zhao, L. Lu, Detection of protein deposition within latent fingerprints by surface-enhanced Raman spectroscopy imaging, Nanoscale 4 (2012) 2333–2338. [10] M. Tahtouh, P. Despland, R. Shimmon, J.R. Kalman, B.J. Reedy, The application of infrared chemical imaging to the detection and enhancement of latent fingerprints: method optimization and further findings, J. Forensic Sci. 52 (2007) 1089–1096. [11] M. Bailey, M. Ismail, R. Webb, D. Everson, S. Bleay, N. Bright, M.L. Elad, Y. Cohen, J. Watts, M. de Puit, Enhanced imaging of developed fingerprints using mass spectrometry imaging, Analyst 138 (2013) 6246–6250. [12] M. Wang, M. Li, A. Yu, J. Wu, C. Mao, Rare earth fluorescent nanomaterials for enhanced development of latent fingerprints, ACS Appl. Mater. Interfaces 7 (2015) 28110–28115. [13] B.S. Kim, Y. Jin, M.A. Uddin, T. Sakaguchi, H.Y. Woo, G. Kwak, Surfactant chemistry for fluorescence imaging of latent fingerprints using conjugated polyelectrolyte nanoparticles, Chem. Commun. 51 (2015) 13634–13637. [14] Lee and Gaensslen’s, in: S. Robert Ramotowski (Ed.), Advances In Fingerprint Technology, third edition, CRC Press Taylor & Francis Group, Boca Raton, 2013. [15] Y. Li, L. Xu, B. Su, Aggregation induced emission for the recognition of latent fingerprints, Chem. Commun. 48 (2012) 4109–4111. [16] J.D. Luo, Z.L. Xie, J.W.Y. Lam, L. Cheng, H.Y. Chen, C.F. Qiu, H.S. Kwok, X.W. Zhan, Y.Q. Liu, D.B. Zhu, B.Z. Tang, Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole, Chem. Commun. 174 (2001) 1740–1741. [17] B.K. An, S.K. Kwon, S.D. Jung, S.Y. Park, Enhanced emission and its switching in fluorescent organic nanoparticles, J. Am. Chem. Soc. 124 (2002) 14410–14415.
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192 [18] J. Chen, C.C.W. Law, Y. Lam, S.M.F. Lo, I.D. Williams, D. Zhu, B.Z. Tang, Synthesis, light emission, nanoaggregation and restricted intramolecular rotation of 1,1-substituted 2,3,4,5-tetraphenylsiloles, Chem. Mater. 15 (2003) 1535–1546. [19] Y. Dong, J.W.Y. Lam, A. Qin, J. Sun, J. Liu, Z. Li, J. Sun, H.H.Y. Sung, I.D. Williams, H.S. Kwok, B.Z. Tang, Aggregation-induced and crystallization-enhanced emissions of 1,2-diphenyl-3,4-bis(diphenylmethylene)-1-cyclobutene, Chem. Commun. 325 (2007) 3255–3257. [20] J. Mei, N.L.C. Leung, R.T.K. Kwok, J.W.Y. Lam, B.Z. Tang, Aggregation-induced emission together we shine, united we soar, Chem. Rev. 115 (2015) 11718–11940. [21] B.Z. Tang, X.W. Zhan, G. Yu, P.P.S. Lee, Y.Q. Liu, D.B. Zhu, Efficient blue emission from siloles, J. Mater. Chem. 11 (2001) 2974–2978. [22] Z. Li, Y.Q. Dong, J.W.Y. Lam, J. Sun, A. Qin, M. Haüssler, Y.P. Dong, H.H.Y. Sung, I.D. Williams, H.S. Kwok, B.Z. Tang, Functionalized siloles: versatile synthesis, aggregation-Induced emission, and sensory and device applications, Adv. Funct. Mater. 19 (2009) 905–917. [23] L. Duan, L. Hou, T.W. Lee, J. Qiao, D. Zhang, G. Dong, L. Wang, Y. Qiu, Solution processable small molecules for organic light-emitting diodes, J. Mater. Chem. 20 (2010) 6392–6407. [24] T.P.I. Saragi, T. Spehr, A. Siebert, T. Fuhrmann-Lieker, J. Salbeck, Spiro compounds for organic optoelectronics, Chem. Rev. 107 (2007) 1011–1065. [25] R.J. Tseng, R.C. Chiechi, F. Wudl, Y. Yang, Highly efficient 7,8,10-triphenylfluoranthene-doped blue organic light-emitting diodes for display application, Appl. Phys. Lett. 88 (2006) 093512–093513. [26] K.T. Kamtekar, A.P. Monkman, M.R. Bryce, Recent advances in white organic light-Emitting materials and devices (WOLEDs), Adv. Mater. 22 (2010) 572–582. [27] J. Yang, J. Huang, Q. Li, Z. Li, Blue AIEgens: approaches to control the intramolecular conjugation and the optimized performance of OLED devices, J. Mater. Chem. C 4 (2016) 2663–2684. [28] Q. Li, Z. Li, The strong light-Emission materials in the aggregated state: what happens from a single molecule to the collective group, Adv. Sci. (2017) 1600484. [29] W. Li, L. Yao, H. Liu, Z. Wang, S. Zhang, S. Zhang, R. Xiao, H. Zhang, P. Lu, B. Yang, Y. Ma, Highly efficient deep-blue OLED with an extraordinarily narrow FHWM of 35 nm and a y coordinate <0. 05 based on a fully twisting donor?acceptor molecule, J. Mater. Chem. C 2 (2014) 4733–4736. [30] C. Chien, C. Chen, F. Hsu, C. Shu, P. Chou, C. Lai, Multifunctional deep-blue emitter comprising an anthracene core and terminal triphenylphosphine oxide groups, Adv. Funct. Mater. 19 (2009) 560–566. [31] K.V. Rao, K.K.R. Datta, M. Eswaramoorthy, S.J. George, Highly pure solid-state white-Light emission from solution-processable soft-hybrids, Adv. Mater. 25 (2013) 1713–1718. [32] J. Ye, C. Zheng, X. Ou, X. Zhang, M. Fung, C. Lee, Management of singlet and triplet excitons in a single emission layer: a simple approach for a high-efficiency fluorescence/phosphorescence hybrid white organic light-emitting device, Adv. Mater. 24 (2012) 3410–3414. [33] Y. Dong, J.W.Y. Lam, A. Qin, J. Liu, Z. Li, B.Z. Tang, J. Sun, H.S. Kwok, Aggregation-induced emissions of tetraphenylethene derivatives and their utilities as chemical vapor sensors and in organic light-emitting diodes, Appl. Phys. Lett. 91 (2007) 011111–011113. [34] G. Mu, W. Zhang, P. Xu, H. Wang, Y. Wang, L. Wang, S. Zhuang, X. Zhu, Constructing new n-Type ambipolar, and p-Type aggregation-induced blue luminogens by gradually tuning the proportion of tetrahphenylethene and diphenylphophine oxide, J. Phys. Chem. C 118 (2014) 8610–8616. [35] B. Xu, Z. Chi, H. Li, X. Zhang, X. Li, S. Liu, Y. Zhang, J. Xu, Synthesis and properties of aggregation-induced emission compounds containing triphenylethene and tetraphenylethene moieties, J. Phys. Chem. C 115 (2011) 17574–17581. [36] Y.T. Wu, M.Y. Kuo, Y.T. Chang, C.C. Shin, T.C. Wu, C.C. Tai, T.H. Cheng, W.S. Liu, Synthesis, structure, and photophysical properties of highly substituted 8, 8a-dihydrocyclopenta[a]indenes, Angew. Chem. Int. Ed. 47 (2008) 9891–9894. [37] C.J. Bhongale, C.W. Chang, C.S. Lee, E.W.G. Diau, C.S. Hsu, Relaxation dynamics and structural characterization of organic nanoparticles with enhanced emission, J. Phys. Chem. B 109 (2005) 13472–13482. [38] S. Kim, Q. Zheng, G.S. He, D.J. Bharali, H.E. Pudavar, A. Baev, P.N. Prasad, Aggregation-Enhanced fluorescence and two-photon absorption in nanoaggregates of a 9, 10-Bis[4 -(4 -aminostyryl)styryl]anthracene derivative, Adv. Funct. Mater. 16 (2006) 2317–2323. [39] J. He, B. Xu, F. Chen, H. Xia, K. Li, L. Ye, W. Tian, Aggregation-induced emission in the crystals of 9,10-distyrylanthracene derivatives: the essential role of restricted intramolecular torsion, J. Phys. Chem. C 113 (2009) 9892–9899. [40] Y. Wang, T. Liu, L. Bu, J. Li, C. Yang, X. Li, Y. Tao, W. Yang, Aqueous nanoaggregation-Enhanced one- and two-Photon fluorescence crystalline J-aggregation-induced red shift, and amplified spontaneous emission of 9,10-Bis(pdimethylaminostyryl) anthracene, J. Phys. Chem. C 116 (2012) 15576–15583. [41] Y.X. Li, Z. Chen, Y. Cui, G.M. Xia, X.F. Yang, Substitution position directing the molecular packing electronic structure, and aggregate emission property of bis[2-(9-anthracenyl)vinyl]benzene system, J. Phys. Chem. C 116 (2012) 6401–6408. [42] J.W. Chen, B. Xu, X.Y. Ouyang, B.Z. Tang, Y. Cao, Aggregation-induced emission of cis,cis-1,2,3,4-tetraphenylbutadiene from restricted intramolecular rotation, J. Phys. Chem. A 108 (2004) 7522–7526.
191
[43] H. Tong, Y. Dong, Y. Hong, M. Haeussler, J.W.Y. Lam, H.H.Y. Sung, X. Yu, J. Sun, I.D. Williams, H.S. Kwok, B.Z. Tang, Aggregation-induced emission effects of molecular structure, solid-state conformation, and morphological packing arrangement on light-emitting behaviors of diphenyldibenzofulvene derivatives, J. Phys. Chem. C 111 (2007) 2287–2294. [44] K. Shiraishi, T. Kashiwabara, T. Sanji, M. Tanaka, Aggregation-induced emission of dendritic phosphole oxides, New J. Chem. 33 (2009) 1680–1684. [45] H.C. Su, O. Fadhel, C.J. Yang, T.Y. Cho, C. Fave, M. Hissler, C.C. Wu, R. Reau, Toward functional -Conjugated organophosphorus materials: design of phosphole-Based oligomers for electroluminescent devices, J. Am. Chem. Soc. 128 (2006) 983–995. [46] Y. Ren, F. Biegger, T.J. Baumgartner, Molecular engineering of the physical properties of highly luminescent -conjugated phospholes, J. Phys. Chem. C 117 (2013) 4748–4758. [47] C.T. Lai, J.L. Hong, Aggregation-Induced emission in tetraphenylthiophene-derived organic molecules and vinyl polymer, J. Phys. Chem. B 114 (2010) 10302–10310. [48] J. Xu, L. Wen, W. Zhou, J. Lv, Y. Guo, M. Zhu, H. Liu, Y. Li, L. Jiang, Asymmetric and symmetric dipole-dipole interactions drive distinct aggregation and emission behavior of intramolecular charge-transfer molecules, J. Phys. Chem. C 113 (2009) 5924–5932. [49] R. Hu, E. Lager, A. Aguilar-Aguilar, J. Liu, J.W.Y. Lam, H.H.Y. Sung, I.D. Williams, Y. Zhong, K.S. Wong, E. Pen˜a-Cabrera, B.Z. Tang, Twisted intramolecular charge transfer and aggregation-induced emission of BODIPY derivatives, J. Phys. Chem. C 113 (2009) 15845–15853. [50] W. Jia, H. Wang, L. Yang, H. Lu, L. Kong, Y. Tian, X. Tao, J. Yang, Synthesis of two novel indolo[3,2-b]carbazole derivatives with aggregation-enhanced emission property, J. Mater. Chem. C 1 (2013) 7092–7101. [51] P. Shanmugasundaram, P. Murugan, V.T. Ramakrishnan, N. Srividya, P. Ramamurthy, Synthesis of acridinedione derivatives as laser dyes, Heteroatom Chem. 7 (1996) 17–22. [52] S. Singh, S. Chhina, V.K. Sharma, Cationic hydrogenation of benzyl alcohols and arylethylenes using acridane derivatives as hindered NADH models, J. Chem. Soc. (1982) 453–454. [53] C. Selvaraju, P. Ramamurthy, Excited-State behavior and photoionization of 1,8-acridinedione dyes in micelles–comparison with NADH oxidation, Chem. Eur. J. 10 (2004) 2253–2262. [54] V. Thiagarajan, D. Thirumalai, V.T. Ramakrishnan, P. Ramamurthy, A novel colorimetric and fluorescent chemosensor for anions involving PET and ICT pathways, Org. Lett. 7 (2005) 657–660. [55] R. Koteeswari, P. Ashokkumar, V.T. Ramakrishnan, E.J. Padma Malar, P. Ramamurthy, Unprecedented formation of an N-benzamidobisthiourea derivative and its role in the formation of a new CT state specific towards fluoride ion, Chem. Commun. 46 (2010) 3268–3270. [56] P. Ashokkumar, V.T. Ramakrishnan, P. Ramamurthy, Specific Ca2+ fluorescent sensor: signaling by conformationally induced PET suppression in a bichromophoric acridinedione, Eur. J. Org. Chem. (2009) 5941–5947. [57] R. Koteeswari, P. Ashokkumar, E.J. Padma Malar, V.T. Ramakrishnan, P. Ramamurthy, Highly selective, sensitive and quantitative detection of Hg2+ in aqueous medium under broad pH range, Chem. Commun. 47 (2011) 7695–7697. [58] P. Ashokkumar, V.T. Ramakrishnan, P. Ramamurthy, Photoinduced electron transfer (PET) based Zn2+ fluorescent probe: transformation of turn-on sensors into ratiometric ones with dual emission in acetonitrile, J. Phys. Chem. A 115 (2011) 14292–14299. [59] H.J. Timpe, S. Ulrich, S. Ali, Spin-trapping as a tool for quantum yield determinations in radical forming processes, J. Photochem. Photobiol. A: Chem. 61 (1991) 77–89. [60] H.J. Timpe, S. Ulrich, J.P. Fouassier, Photochemistry and use of decahydroacridine-1, 8-diones as photosensitizers for onium salt decomposition, J. Photochem. Photobiol. A: Chem. 73 (1993) 139–150. [61] S. Ulrich, H.J. Timpe, J.P. Fouassier, F. Morlet-Savary, Photoreduction of decahydroacridine-1, 8-diones by amines, J. Photochem. Photobiol A: Chem. 74 (1993) 165–170. [62] N. Srividya, P. Ramamurthy, V.T. Ramakrishnan, Solvent effects on the absorption and fluorescence spectra of some acridinedione dyes: determination of ground and excited state dipole moments, Spectrochimica Acta Part A 53 (1997) 1743–1753. [63] Z. Yang, Z. Chi, T. Yu, X. Zhang, M. Chen, B. Xu, S. Liu, Y. Zhang, J. Xu, Triphenylethylene carbazole derivatives as a new class of AIE materials with strong blue light emission and high glass transition temperature, J. Mater. Chem. 19 (2009) 5541–5546. [64] S. Dong, Z. Li, J. Qin, New carbazole-Based fluorophores: synthesis, characterization, and aggregation-Induced emission enhancement, J. Phys. Chem. B 113 (2009) 434–441. [65] C. Selvaraju, P. Ramamurthy, Excited-State behavior and photoionization of 1, 8-acridinedione dyes in micelles—comparison with NADH oxidation, Chem. Eur. J. 10 (2004) 2253–2262. [66] V. Thiagarajan, C. Selvaraju, P. Ramamurthy, Excited state behaviour of acridinedione dyes in PMMA matrix: inhomogeneous broadening and enhancement of triplet, J. Photochem. Photobiol. A 157 (2003) 23–31. [67] V.K. Indirapriyadharshini, P. Karunanithi, P. Ramamurthy, Inclusion of resorcinol-Based acridinedione dyes in Cyclodextrins: fluorescence enhancement, Langmuir 17 (2001) 4056–4060. [68] R. Kumaran, P. Ramamurthy, PET suppression of acridinedione dyes by urea derivatives in water and methanol, J. Phys. Chem. B 110 (2006) 23783–23789.
192
R. Suresh et al. / Sensors and Actuators B 258 (2018) 184–192
[69] L. Wang, Y. Shen, Q. Zhu, W. Xu, M. Yang, H. Zhou, J. Wu, Y. Tian, Systematic study and imaging application of aggregation-induced emission of ester-isophorone derivatives, J. Phys. Chem. C 118 (2014) 8531–8540. [70] S. Mukherjee, P. Thilagar, Fine-tuning solid-state luminescence in NPIs (1, 8-naphthalimides): impact of the molecular environment and cumulative interactions, Phys. Chem. Chem. Phys. 16 (2014) 20866–20877. [71] L. Xu, Y. Li, S. Li, R. Hu, A. Qin, B.Z. Tang, B. Su, Enhancing the visualization of latent fingerprints by aggregation induced emission of siloles, Analyst 139 (2014) 2332–2335. [72] P. Singh, H. Singh, R. Sharma, G. Bhargava, S. Kumar, Diphenylpyrimidinone–salicylideneamine – new ESIPT based AIEgens with applications in latent fingerprinting, J. Mater. Chem. C 4 (2016) 11180–11189.
Biographies Raghupathy Suresh received his M. Sc. Organic Chemistry from University of Madras, India in 2010. Currently he is pursuing Ph. D in chemistry at University of Madras. His research interests focused on synthesis of organic fluorophores, aggregation induced emission, solid state luminescence and fluorescent sensors.
Senthil Kumar Thiyagarajan received his M. Sc. Chemistry from Madras Christian College, Chennai, India in 2008. Currently he is pursuing Ph. D in chemistry at University of Madras. His research interests focused on photophysics and photochemistry of organic fluorophores, light induced excited state processes, and fluorescent sensors. Perumal Ramamurthy is a professor in University of Madras. He started his academic career as a lecturer in the department of Inorganic chemistry in 1987 and contributed significantly in the field of Ultrafast Spectroscopy and Photosciences not only through his scientific publications but also dedicating himself to establish the National Centre for Ultrafast Processes with state of art facilitites, which is unique of its kind among University researchers in our country. His major areas of research interest are ultrafast spectroscopy, nanomaterials, photophysics and photochemistry of organic molecules, fluorescent sensors.