Selective turn-on fluorescence for Zn2+ and Zn2+ + Cd2+ metal ions by single Schiff base chemosensor

Accepted Manuscript Title: Selective turn-on fluorescence for Zn2+ and Zn2+ +Cd2+ metal ions by single Schiff base chemosensor Author: P.S. Hariharan Savarimuthu Philip Anthony PII: DOI: Reference:

S0003-2670(14)00928-3 http://dx.doi.org/doi:10.1016/j.aca.2014.07.042 ACA 233397

To appear in:

Analytica Chimica Acta

Received date: Revised date: Accepted date:

30-4-2014 4-7-2014 30-7-2014

Please cite this article as: P.S.Hariharan, Savarimuthu Philip Anthony, Selective turn-on fluorescence for Zn2+ and Zn2++Cd2+ metal ions by single Schiff base chemosensor, Analytica Chimica Acta http://dx.doi.org/10.1016/j.aca.2014.07.042 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1 Selective turn-on fluorescence for Zn2+ and Zn2++Cd2+ metal ions by single Schiff base chemosensor P. S. Hariharan and Savarimuthu Philip Anthony* School of Chemical & Biotechnology, SASTRA University, Thanjavur-613401,

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Tamil Nadu, India. Fax: +914362264120; Tel: +914362264101; E-mail: [email protected]

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Highlights

Multiple metal ions sensor based on Schiff base chemosensor.

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Highly selective colorimetric detection of Mn2+ up to the level of 10-7 M.

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Selective turn-on fluorescence for Zn2+ ions (36 fold enhancement).

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Rare and strong second turn-on fluorescence (196 fold) for Cd2+ with 1-Zn2+.

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Distinguishable naked eye detectable colour for Mn2+, Zn2+ and Zn2+-Cd2+.

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Graphical abstract

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Turn-on and turn-on fluorescence: Single chemosensor for selective sensing of multiple metal ions

Schiff base based chemosensor 1 and 2 exhibited selective sensing of multiple metal ions, Mn2+, Zn2+ and Cd2+ via coloro/fluorometric changes including rare second turnon fluorescence in presence of bimetals.

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2 Abstract: Chemosensor based on Schiff base molecules (1, 2) were synthesized and demonstrated the selective fluoro/colorimetric sensing of multiple metal ions (Mn2+, Zn2+ and Cd2+) in acetonitrile-aqueous solution. Both 1 and 2 showed a highly selective naked-eye detectable colorimetric change for Mn2+ ions at 10-7 M.

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Fluorescence sensing studies of 1 and 2 exhibited a strong fluorescence enhancement (36 fold) selectively upon addition of Zn2+ (10-7 M, max = 488 nm). Fluorescence

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titration and single crystal X-ray analysis confirmed the formation of 1:1 molecular

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coordination complex between 1 and Zn2+. Interestingly, a rare phenomenon of strong second turn-on fluorescence (190 fold, max = 466 nm) was observed by the addition

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of Cd2+ (10-7 M) into 1+Zn2+ or Zn2+ (10-7 M) into 1+Cd2+. Importantly both 1 and 2

and Cd2+.

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exhibited different fluorescence  max with clearly distinguishable colour for both Zn2+

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Multiple metal ions sensor.

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Keywords: Chemosensor, Fluorescence sensor, Schiff base, Colorimetric sensor,

1. Introduction

Design of chemosensors that can selectively recognize and signal the presence of specific analytes through the naked eye and optical responses has received significant attention over the years because of their potential use in medicine, environment and biology [1-3]. Because of the simplicity, high sensitivity, selectivity and real-time analysis, both colorimetric and fluorescence based chemosensors become increasingly important in the analytical science [4-7]. In fact, a great number of chemosensor have been designed for monitoring heavy toxic metal ions [1-11]. Schiff bases, a particular class of chelating molecules that found applications in many research fields such as

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3 molecular optoelectronics, photochromism and medicine [12-18] have been widely used as chemical probes due to their facile synthesis and good photophysical properties [12-25]. Mn2+ is one of the essential trace elements for several endogenous anti-oxidant

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enzymes and plays an important role in the bone and other tissues formations, carbohydrate and lipid metabolism [26]. Mn2+ deficiency in human body is related to

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delayed blood coagulation and hypercholesterolaemia. However, uptake of high

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concentration of Mn2+ leads to severe psychiatric abnormalities, including hyperirritability, violent acts and hallucinations that end up in permanent crippling

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neurological disorder of the extrapyramidal system [27]. Similarly Zn2+ ion is the second most abundant transition metal ion in the human body and plays crucial roles

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in many important biological processes [28]. The imbalance of Zn2+ ion is linked to severe neurological disorders, including Alzheimer's and Parkinson's diseases [29].

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Whereas cadmium that has been widely used in many industrial processes that include

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electroplating, agriculture and military affairs, etc [30] is highly toxic. The exposure to high level of Cd2+ could cause some serious diseases such as renal dysfunction, calcium metabolism disorder and prostate cancer [31]. Hence chemosensor that selectively detects and distinguish of Zn2+ and Cd2+ ions has received a special interest because of their biological importance and potential health and environmental risk.

Several fluorescent chemosensor have been reported for selective sensing of

Zn2+ and Cd2+ ion individually [32-38]. However, interference between Zn2+ and Cd2+ was always observed during the sensing since both elements are in the same group of the periodic table that displayed very similar coordination function to the fluorescent sensors and cause similar spectral changes [39-44]. Therefore, developing

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4 chemosensor that can simultaneously detects and distinguish both Zn2+ and Cd2+ still a great challenge. To date, there are few chemosensor have shown selective sensing of Cd2+ ions in presence of Zn2+ ion [45-49]. However, in presence of both Zn2+ and Cd2+ ions, these sensors often showed strong preference towards Cd2+ and exhibited

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turn-on fluorescence corresponding to Cd2+ only. Hence, the presence of Zn2+ ions can not be differentiated from Cd2+.

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Herein, we report the triphenylamine based simple bis-Schiff base

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chemosensor that showed selective multiple metal ions, Zn2+, Cd2+ and Mn2+, sensing via fluoro/colorimetric changes (Scheme 1). An acetonitrile solution of 1 and 2

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exhibited selective turn-on fluorescence with strong enhancement (36 fold, max = 488 nm) by the addition Zn2+ ion (10-7 M). Cd2+ with 1 and 2 showed only four fold

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fluorescence enhancement. Interestingly, a rare phenomenon of strong second turn-on fluorescence enhancement (190 fold, max = 466 nm) was observed while adding Cd2+

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into 1 and 2 in presence of Zn2+ or Zn2+ into 1 and 2 in presence of Cd2+. Importantly,

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the fluorescence colour and  max of 1 or 2 with Zn2+ and Zn2+-Cd2+ together is clearly different and visually distinguishable. Further, 1 and 2 exhibited highly selective colorimetric changes upon addition of Mn2+ ions (10-7 M). Thus 1 and 2 exhibited multiple metal ions sensing including selective detection and distinguishing of Zn2+ and Cd2+ ions.

2. Experimental Section

3-Methoxytriphenylamine (97 %), (±)-trans-1,2-Diaminocyclohexane (99 %), BBr3 (1.0 M in DCM) and N, N’-dimethyl formamide (99 %) was obtained from sigmaAldrich. POCl3, ethylene diamine and solvents were obtained from Merck India. All chemicals are used as received. All the metal ion solutions used for the experiments were prepared by mixing the requisite amount in Milli-Q water. Absorption and

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5 fluorescence spectra were recorded using Perking Elmer Lambda 1050 and Jasco fluorescence spectrometer-FP-8200 instruments. Elemental analyses were measured with a Perkin-Elmer 2400 II CHN analyzer. 2.1. Synthesis of 1 and 2

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4-(diphenylamino)-2-hydroxybenzaldehyde was synthesized by introducing aldehyde functionality into 3-methoxytriphenylamine using Vilsmeier–Haack

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formylation [50]. Subsequently OMe was converted to OH by stirring with BBr3 in

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CH2Cl2 [51]. 1 and 2 was synthesized by refluxing 1:1 equivalents of aldehyde and diamine (cyclohexane diamine or ethylene diamine) in ethanol for 1 h. Then the

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reaction mixture was cooled to room temperature and the formed precipitate was

2.2. Optical sensor studies

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filtered off and washed with cold ethanol. The product was dried under vacuum.

An acetonitrile solution of 1 and 2 at 10-3 M was prepared and stored as stock

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solution. This solution was further diluted to 10-6 M for performing the sensor

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experiments. All the metal salts solution (10-3 M) were prepared by dissolving the appropriate amount of metal salt in milli-Q water and stored as stock solution. These solutions were diluted to 10-6 M/10-7 M for recording the colorimetric and fluorescence spectra. For checking the fluorescence sensing in real samples, different water sample solutions of Zn2+ and Cd2+ ions (10-6 M) were prepared. The fluorescence sensing experiments were performed by adding aqueous solution of metal ions (10-6 M/10-7 M) into acetonitrile solution of 1 or 2 (10-6 M). 2.3. Synthesis and single crystal growth of 1+Zn2+ Zn(CH3COO)2.2H2O (1 equivalent) and 1 (1 equivalent) were dissolved in 20 ml of hot ethanol separately. The mixing of both solutions at hot condition produced precipitate immediately and the solution was stirred at 60 C for further 30 min. Then

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6 the reaction mixture was cooled to room temperature and the precipitate was filtered, washed with ethanol and dried under vacuum. 100 mg of 1-Zn2+ was dissolved in DMF at hot condition and the solution was allowed to stand for few days at room temperature that yielded single crystals of 1-Zn2+.

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Crystal data: 1-Zn2+ (CCDC No: 980255): C44H40N4O3 Zn, M = 738.23, triclinic, P-1, a = 10.0447(8), b = 10.8901(9), c = 18. 2143(14) Å, a = 85.789(6), β = 76.516(7), r =

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70.002 (7), V = 1820.6(3) Å3, Z = 2, T = 298 K, 8281 reflections measured, 4210

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unique, Final R values: 0.0671, wR: 0.1232. 3. Results and Discussion

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1 and 2 was prepared by simple Schiff base condensation reaction between 4(diphenylamino)-2-hydroxybenzaldehyde and cyclohexane/ethylene diamine in

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ethanol (Scheme S1). The absorption spectrum of 1 and 2 in acetonitrile showed a strong absorption at 348 nm (intramolecular charge transfer (ICT) band) and a small

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hump at 300 nm (-* band). In order to study the sensor properties, various metal

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cations were added into 1 and 2 and monitored the optical (colorimetric and fluorescence) responses. Interestingly, both 1 and 2 exhibited a distinct colour change, colourless to orange, selectively for Mn2+. Fe3+, Co2+ and Cd2+ ions addition also produced coloured solution but only to light yellow colour. Absorption studies also showed the appearance of new peaks at longer wavelength (410 nm and 515 nm) selectively for Mn2+ along with 348 nm absorption of 1 and 2 (Fig. 1a, S1). The coordination of imino nitrogen of 1 and 2 with Mn2+ is expected to increase the electron withdrawing character that might lead to stronger ICT towards metal [52]. Fe3+, Cu2+ and Hg2+ with 1 and 2 showed a small red shift of absorption (348 to 358 nm). Other metal ions with 1 and 2 did not show any significant colour and absorption change. Absorption titration clearly showed the appearance of new absorption peaks

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7 at longer wavelength (410 nm and 515 nm) by the addition of aqueous solution of Mn2+ (10-6 M) into 1 (Fig. 1b). The concentration dependent studies further confirmed the formation of 1:1 coordination complex between Mn2+ and 1 (Fig. S2). The exact coordination complex structure of 1 with Mn2+ could not be established since the

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attempted single crystal growth was not successful. However, Jacobsen catalyst, a chiral Schiff base manganese complex is known to adopt square pyramidal structure

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[53]. Based on the above literature report, Mn2+ might have adopted similar square

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pyramidal coordination geometry with tetradendate 1 and 2 (Fig. S3). The interference studies demonstrated the high selectivity of 1 for Mn2+ in presence of different metal

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cations (Fig. S4).

Fluorescence studies of 1 with various metal ions showed highly selective

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turn-on fluorescence for Zn2+ ion (Fig. 2a). The very weak fluorescence of 1 in acetonitrile (max = 450 nm, ex = 360 nm) was strongly enhanced (36 fold, max = 488

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nm) by Zn2+ ion. Cd2+ addition showed only 4-fold enhancement of fluorescence (max = 458 nm). Fluorescence emission enhancement and red shift of max from 450 to 488 nm of 1 upon binding with Zn2+ is considered to be due to the formation of 1–Zn2+ coordination complex. The coordination of Zn2+ with 1 would inhibit the C=N isomerization [54,55] and excited-state proton transfer [56,57] that lead to chelationenhanced fluorescence [58-60]. The concentration dependent studies showed that fluorescence enhancement was completed by the addition of one equivalent of Zn2+ (10-6 M, Fig. S6). The interference studies of 1 indicate that other metal ions had very little influence on the Zn2+ selectivity (Fig. 2b). However, the presence of Hg2+, Pb2+ and Mn2+ reduced the fluorescence enhancement. 2 also showed similar strong fluorescence turn-on for Zn2+ only (Fig. S5a). But other cations especially presence of Cr3+, Fe3+, Co2+, Ni2+, Cu2+ and Hg2+ metal ions exhibited strong interference on the

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8 selectivity of Zn2+ by 2 (Fig. S5b). Thus the change of alicyclic semi-flexible diamine to flexible aliphatic diamine completely modified the coordination preference of Schiff base ligands. As a tetradendate N2O2 ligand, 1 is expected to form 1:1 coordination complex with Zn2+. The fluorescence titration also suggested the

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formation of 1:1 complex (Fig. S6). Single crystal X-ray structural analysis of 1-Zn2+ further unambiguously confirmed the formation of 1:1 square pyramidal Zn2+

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coordination complex (Fig. 3a, Table S1). Zn atom is coordinated with two nitrogen

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and oxygen from same ligand and the apical position was occupied by water molecule. In general, C2-symmetric cyclohexane diamine based Schiff base or other

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ligands are known to form coordination polymeric including helical supramolecular structure with metal ions [61-64]. However, 1-Zn2+ showed the formation molecular

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coordination complex that might be due to the bulky group of triphenylamine unit. The strong intermolecular hydrogen bonding interaction of water hydrogen with

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phenoxy oxygen leads to the formation of dimer in the crystal lattice. Further the

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dimers are interconnected along c-axis through C-H… interactions of triphenylamine in the crystal lattice of 1-Zn2+ (Fig. 3b). Interestingly, a rare phenomenon of selective second turn-on fluorescence was

observed in both 1 and 2 while adding Zn2+ into 1-Cd2+ or Cd2+ into 1-Zn2+ (Fig. 2b, S5b). Cd2+ alone showed weak fluorescence enhancement with 1 and 2 (4 fold, max = 458 nm). Addition of Zn2+ into 1-Cd2+ exhibited very strong fluorescence enhancement (190 fold, max = 466 nm, Fig. 2b). Similarly, Cd2+ addition into 1-Zn2+ also showed strong second turn-on fluorescence (Fig. 4b). 1-Zn2+ showed fluorescence max at 488 nm and 1-Cd2+ showed weak fluorescence at 458 nm. Addition of Zn2+ into 1-Cd2+ red shifts the fluorescence max from 458 to 466 nm whereas addition of Cd2+ into 1-Zn2+ blue shifts the max from 488 to 466 nm. A

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9 steady fluorescence enhancement with  max shifting was observed with the addition of Zn2+ (10-6 M) into 1-Cd2+ or Cd2+ (10-6 M) into 1-Zn2+ (Fig. 5). The fluorescence enhancement was saturated with the addition of 0.5 equivalents of Zn2+ or Cd2+. These results suggest that both Zn2+ and Cd2+ are important for the second turn-on

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florescence enhancement. The max shift further confirms that it is indeed different from 1-Zn2+ or 1-Cd2+.

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Absorption studies of 1 and 2 with Zn2+ and Cd2+ ions individually as well

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together were carried out to gain some insight on the structural changes (Fig. S7). The addition of Zn2+ and Cd2+ ions either separately or together into 1 and 2 showed small

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red shift of absorption max from 348 to 353 nm. A new small hump appeared at 380 nm for 1 and 2 with Zn2+ and Cd2+ ions due to metal coordination. Hence there is no

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difference in the max for 1 and 2 with Zn2+ and Cd2+ ions either separately or together. However, there is a small change in the absorption profiles. 1 and 2 with Zn2+

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exhibited more broadened absorption whereas Cd2+ addition showed less broadening with reduced absorbance. The addition of Zn2+ in 1/2-Cd2+ only increased the absorbance. Whereas addition of Cd2+ in 1/2-Zn2+ only reduced the absorption broadening. These results suggest that there is some structural change for 1 and 2 with Zn2+ and Cd2+ ions either separately or together. The influence of other metal ions on the second turn-on fluorescence intensity was investigated by adding different metal ions (mM) into 1-Zn2+- Cd2+ (μM based on 1). Other metal ions presence was found to be strongly affecting the second turn-on fluorescence intensity of 1-Zn2+-Cd2+ (Fig. S8). Instead of adding of Zn2+ and Cd2+ sequentially into 1, addition of both Zn2+ and Cd2+ together into 1 also showed similar fluorescence enhancement (Fig. S9). The strong fluorescence intensity of 1-Zn2+-Cd2+ was reduced by all metal ions. Particularly, Mn2+, Fe3+, Co2+, Ni2+, Hg2+ and Pb2+ showed nearly complete

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10 fluorescence quenching. Chemosensor 2-Zn2+/Cd2+ also showed a similar second-turn fluorescence enhancement by the addition of Cd2+/Zn2+ with shift in the max (Fig. S10). The strong fluorescence of chemosensors 1 and 2 with sky-blue colour (max =

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466 nm) with metal ions indicates that the solution contain both Zn2+ as well as Cd2+ ions. Whereas bluish-green colour of 1 and 2 (max = 488 nm) with metal ions

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indicates the presence of Zn2+ ions alone. It is noted that Cd2+ alone did not show any

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strong fluorescence enhancement with 1 and 2. Thus chemosensor 1 and 2 can selectively detect and distinguish Zn2+ and Cd2+ ions in aqueous solution. The

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selective fluorescence sensing of 1 and 2 with distinguishable fluorescence for Zn2+ and Cd2+ were also studied in different water samples such as tap, ground and pond

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water to demonstrate the real sample application of 1 and 2. To the acetonitrile solution of 1 or 2 (10-6 M), different water samples containing metal ions (10-6 M)

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were added separately as well as together. The fluorescence studies clearly showed

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strong fluorescence enhancement for Zn2+ and second turn-on fluorescence in presence of both Zn2+ and Cd2+ (Fig. S11). The fluorescence sensing of 1 for Zn2+ and Zn2++Cd2+ has also been investigated at wide pH range (2.0 to 12.0,). A moderate to strong fluorescence enhancement was observed at pH 8.0 and 10.0 (Fig. S12). Whereas, 1 showed small enhancement of fluorescence with Zn2+ and Zn2++Cd2+ at 4.0 and 6.0 pH. But addition of pH 2.0 and 12.0 Zn2+ or Zn2++Cd2+ solution did not show any fluorescence turn-on. The attempted effort to grow single crystals of 1 or 2 with Zn2+ and Cd2+ together to get the insight on the structural organization was not successful. Hence the reason for the strong second turn-on fluorescence upon the addition of Cd2+ to 1-Zn2+ or Zn2+ to 1-Cd2+ was not clear at present. It has been previously reported that

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11 metallodipyrrins coordination complex showed a strong fluorescence enhancement via increasing the fluorophore rigidity by the formation of multinuclear coordination complex [58]. The different max for 1-Zn2+, 1-Cd2+ and 1-Zn2+-Cd2+ exclude the simple transmetallation. Single crystal X-ray analysis of 1-Zn2+ showed the formation

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of discrete square pyramidal coordination complex (Fig. 3). However, Schiff base of cyclohexane/ethylene diamine with salicylaldehyde or C2-symmetric ligands were

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often produced extended helical supramolecular coordination polymers [61-64].

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Hence, it is speculated that the discrete square pyramidal structure might be converted into coordination polymeric network structure upon addition of Cd2+ into 1-Zn2+ and

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switch the fluorescence (Scheme S2). However, the structure by which both Zn2+ and

4. Conclusions

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Cd2+ atoms exist together is not clear and need further studies.

In conclusion, we have demonstrated multiple metal ions sensing including a

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rare second-turn on fluorescence enhancement using a simple triphenylamine based

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single Schiff base chemosensor. 1 and 2 with Zn2+ exhibited selective turn-on fluorescence (max = 488 nm, 36 fold) that was enhanced (190 fold) second time with blue shifting of max (466 nm) upon addition of Cd2+. Addition of Zn2+ into 1- or 2Cd2+ also showed similar fluorescence enhancement but with red shifted max. Interestingly, first and second turn-on fluorescence showed different max and distinguishable colour for Zn2+ and Zn2+ + Cd2+ together. Highly selective colorimetric sensing of Mn2+ (colourless to orange) with 1 and 2 has also been demonstrated. Thus, the triphenylamine based phenolic aldehyde provided a simple platform to fabricate multiple metal ions sensing chemosensor.

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12 Acknowledgements Financial supports from DST, New Delhi, India (DST Fast Track Scheme No. SR/FT/CS-03/2011 (G) and SR/FST/ETI-284/2011(c)) and CRF facility, SASTRA University are acknowledged with gratitude.

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References [1] A.P. de Silva, H.Q.N. Gunaratne, T. Gunnlaugsson, A.J.M. Huxley, C.P. McCoy,

us

[2] B. Valeur, I. Leray, Coord. Chem. Rev. 205 (2000) 3-40.

cr

J.T. Rademacher, T.E. Rice, Chem. Rev. 97 (1997) 1515-1566.

[3] S. P. Anthony, ChemPlusChem 77 (2012) 518-531.

an

[4] Y. Zhou, Z. Xu, J. Yoon, Chem. Soc. Rev. 40 (2011) 2222-2235. [5] S. K. Ghosh, T. Pal, Chem. Rev. 107 (2007) 4797-4862.

M

[6] J. Zhang, R.E. Campbell, A.Y. Ting, R.Y. Tisen, Nat. Rev. Mole. Cell Bio. 3 (2002) 906-918.

Ac ce pt e

8337.

d

[7] A.P. de Silva, J. Eilers, G. Zlokarnik, Proc. Nat. Aca. Sci. USA, 96 (1999) 8336-

[8] D. T. Quang, J. S. Kim, Chem. Rev. 110 (2010) 6280-6301. [9] E. Kimura, T. Koike, Chem. Soc. Rev. 27 (1998) 179-184. [10] S. P. Anthony, C. Delaney, S. Varughese, L. Wang, S. M. Draper, CrystEngComm 13 (2011) 6706-6711.

[11] D. Karthiga, S. P. Anthony, RSC Adv. 3 (2013) 16765-16774. [12] A. Perrier, F. Maurel, D. Jacquemin, Acc. Chem. Res. 45 (2012) 1173-1402. [13] M. Irie, Phochem. Photobiol. Sci. 9 (2010) 1535-1542. [14] Gust, D.; Moore, T. A.; Moore, A. L. Chem. Commun. (2006) 1169-1170. [15] T. He, F. Yanli, J. Mater. Chem. 18 (2008) 1617-1622.

Page 12 of 21

13 [16] W. R. Browne, M. M. Pollard, B. Lange, A. Meetsma, B. Feringa, J. Am. Chem. Soc. 128 (2006) 12412-12413. [17] M. Sliwa, S. Létard, I. Malfant, M. Nierlich, P. G. Lacroix, T. Asahi, H. Masuhara, P. Yu, K. Nakatani, Chem. Mater. 17 (2005) 4727-4735.

ip t

[18] D. A. Safin, M. G. Babashkina, Y. Garcia, Dalton Trans. 42 (2013) 1969-1972. [19] F. Faridbod, M. R. Ganjali, R. Dinarvand, P. Norouzi, S. Riahi, Sensors 8 (2008)

cr

1645-1703.

us

[20] Y. Xu, J. Meng, L. X. Meng, Y. Dong, Y. X. Cheng, C. J. Zhu, Chem. Eur. J. 6 (2010) 12898-12903.

an

[21] S. C. Wang, G. W. Men, L. Y. Zhao, Q. F. Hou, S. M. Jiang, Sens. Actuators B: Chem. 145 (2010) 826-831.

M

[22] D. Udhayakumari, S. Saravanamoorthy, M. Ashok, S. Velmathi, Tetrahedron Lett. 52 (2011) 4631-4634.

Ac ce pt e

4885-4901.

d

[23] Y. Feng, J. H. Cheng, L. Zhou, X. G. Zhou, H. F. Xiang, Analyst 137 (2012)

[24] L. Zhou, P. Y. Cai, Y. Feng, J. H. Cheng, H. F. Xiang, J. Liu, D. Wu, Anal. Chim. Acta 735 (2012) 96-106.

[25] L. Zhou, Y. Feng, J. H. Cheng, N. Sun, X. G. Zhou, H. F. Xiang, RSC Adv. 2 (2012) 10529-10536.

[26] J. R. Wispe, B. B. Warner, J. C. Clark, C. R. Dey, J. Neuman, S. W. Glasser, J. D. Crapo, L. Y. Chang, J. A. Whitsett, J. Biol. Inorg. Chem. 267 (1992) 23937-23941. [27] World Health Organization, Trace Elements in Human Nutrition and Health, (1996) 163–167, [28] L. C. Costello, C. C. Fenselau and R. B. J. Franklin, Inorg. Biochem. 105 (2011) 589-762.

Page 13 of 21

14 [29] C. J. Frederickon, J. Y. Koh, A. I. Bush, Nat. Rev. Neurosci. 6 (2005) 449-462. [30] R.L. Chaney, J.A. Ryan, Y.M. Li, S.L. Brown, in: M.J. McLaughlin, B.R. Singh (Eds.),Cadmiumin Soils and Plants, Kluwer Academic Publishers, Boston, (1999) pp.219–256.

ip t

[31] M. Waisberg, P. Joseph, B. Hale, D. Beyersmann, Toxicology 192 (2003) 95117.

cr

[32] H. N. Kim, W. X. Ren, J. S. Kim, J. Yoon, Chem. Soc. Rev. 41 (2012) 3210-

us

3244.

[33] E. M. Nolan, S. J. Lippard, Acc. Chem. Res. 42 (2008) 193-203.

an

[34] H.-Y. Lin, P.-Y. Cheng, C.-F. Wanb, A.-T. Wu, Analyst 137 (2012) 4415-4417. [35] K. Shen, X. Yang, Y. Cheng, C. Zhu, Tetrahedron 68 (2012) 5719-5723.

M

[36] J. Jia, Q.-C. Xu, R.-C. Li, X. Tang, Y.-F. He, M.-Y. Zhang, Y. Zhang, G.-W. Xing, Org. Biomol. Chem., 10 (2012) 6279-6286.

d

[37] K. Li, X. Wang, A. Tong, Anal. Chim. Acta 776 (2013) 69-73.

Ac ce pt e

[38] Q.-C. Xu, X.-H. Zhu, C. Jin, G.-W. Xing, Y. Zhang, RSC Adv. 4 (2014) 35913596.

[39] E. M. Nolan, J. W. Ryu, J. Jaworski, R. P. Feazell, M. Sheng, S. J. Lippard, J. Am. Chem. Soc. 128 (2006) 15517-15528. [40] Z. P. Liu, C. L. Zhang, W. J. He, Z. H. Yang, X. Gao, Z. J. Guo, Chem. Commun., 46 (2010) 6138-6140.

[41] Z. C. Xu, K.-H. Baek, H. N. Kim, J. N. Cui, X. H. Qian, D. R. Spring, I. Shin, J. Yoon, J. Am. Chem. Soc. 132 (2010) 601-610. [42] S. P. Anthony, Chem. Asian J. 7 (2012) 374-379. [43] X. J. Peng, J. J. Du, J. L. Fan, J. Y. Wang, Y. K. Wu, J. Z. Zhao, S. G. Sun , T. Xu, J. Am. Chem. Soc. 129 (2007) 1500-1501.

Page 14 of 21

15 [44] C. J. Chang, J. Jaworski, E. M. Nolan, M. Sheng, S. J. Lippard, Proc. Natl. Acad. Sci. U. S. A. 101 (2004) 1129-1134. [45] C. Lu, Z. Xu, J. Cui, R. Zhang, X. Qian, J. Org. Chem. 72 (2007) 3554-3557. [46] X. Zhou, P. Li, Z. Shi, X. Tang, C. Chen, W. Liu, Inorg. Chem. 51 (2012) 9226-

ip t

9231. [47] A. Jana, P. K. Sukul, S. K. Mandal, S. Konar,S. Ray, K. Das, J. A. Golen, A. L.

cr

Rheingold, S. Mondal, T. K. Mondal, A. R. Khuda-Bukhshc, S. K. Kar, Analyst 139

us

(2014) 495-504. [48] L. Xue, C. Liu, H. Jiang, Org. Lett. 11 (2009) 1655-1658.

an

[49] Y. Tan, J. Gao, J. Yu, Z. Wang, Y. Cui, Y. Yang, G. Qian, Dalton Trans. 42 (2013) 11465-11470.

Polymer Chem. 46 (2008) 3970-3984.

M

[50] Y. Li, L. Xue, H. Xia, B. Xu, S. Wen, W. Tian, J. of Polymer Sci: Part A:

Ac ce pt e

Cryst. 466 (2007) 85-100.

d

[51] A. Matoliukstyte, J. V. Grazulevicius, V. Jankauskas, Mol. Cryst. Liq.

[52] J. Bourson, J. Pouget, B. Valeur, J. Phys. Chem. 97 (1993) 4552-4557. [53] E. N. Jacobsen, M. H. Wu, in Comprehensive Asymmetric Catalysis (Eds: E. N. Jacobsen, A. Pfaltz, H. Yamamoto), Springer, Berlin, (1999) p. 649-677. [54] J. Wu, W. Liu, J. Ge, H. Zhang, P. Wang, Chem. Soc. Rev. 40 (2011) 3483-3495. [55] J.S. Wu, W.-M. Liu, X.Q. Zhuang, F. Wang, P.F. Wang, S.L. Tao, X.H. Zhang, S.K. Wu, S.T. Lee, Org. Lett. 9 (2007) 33-36. [56] Y. Zhou, Z.X. Li, S.Q. Zang, Y.Y. Zhu, H.Y. Zhang, H.W. Hou, T.C.W. Mak, Org. Lett. 14 (2012) 1214-1217. [57] X. Zhang, L. Guo, F.Y. Wu, Y.B. Jiang, Org. Lett. 5 (2003) 2667-2670.

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16 [58] Z. Liu, C. Zhang, Y. Li, Z. Wu, F. Qian, X. Yang, W. He, X. Gao, Z. Guo, Org. Lett. 11 (2009) 795-797. [59] L. Due, Q. Liu, H. Jiang, Org. Lett. 11 (2009) 3454-3457. [60] T.H. Ma, M. Dong, Y.M. Dong, Y.W. Wang, Y. Peng, Chem. Eur. J. 16 (2010)

ip t

10313-10318. [61] C. Piguet, G. Bernardinelli, G. Hopfgartner, Chem. Rev. 97 (1997) 2005-2062.

cr

[62] L. Han, M. Hong, Inorg. Chem. Commun. 8 (2005) 406-419.

us

[63] S. P. Anthony, T. P. Radhakrishnan, Chem. Commun. (2004) 1058-1059.

an

[64] L. Han, H. Valle, X. Bu, Inorg. Chem. 46 (2007) 1511-1513.

Figure Captions

Schematic diagram showing selective sensing of multiple metal ions by

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chemosensors 1 and 2.

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Scheme 1.

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17 Figure 1.

(a) Digital image and absorption spectra of 1 with different metal ions

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and (b) absorption of 1 (10-7 M) vs concentration of Mn2+ (10-7 M).

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18 Figure 2.

(a) Turn-on fluorescence of 1 (10-6 M) by Zn2+ (10-6 M) and (b) selectivity studies in presence of different metal ions (10-3 M, red =

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with Zn2+ (10-6 M).

Figure 3.

(a) Molecular structure and (b) crystal packing with supramolecular interactions in the crystal lattice of 1-Zn2+. H-bonds (broken line). dH…A distances (Å) are marked.

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Figure 4.

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Second turn-on fluorescence of (a) 1+Cd2+ vs Zn2+ (10-7 M) and (b)

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1+Zn2+ vs Cd2+ (10-7 M).

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Figure 5.

(a) Fluorescence intensity of 1-Cd2+ vs Zn2+ and (b) 1-Zn2+ vs Cd2+. 1 was taken in μM concentration and 1 equivalent of Zn2+/Cd2+ was added.

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