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Reversible electrochemical and chemical addressing of optical properties of ternary Os(II) polypyridyl complexes
Inorganic Chemistry Communications 13 (2010) 724–726
Contents lists available at ScienceDirect
Inorganic Chemistry Communications j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / i n o c h e
Reversible electrochemical and chemical addressing of optical properties of ternary Os(II) polypyridyl complexes Tarkeshwar Gupta ⁎ Department of Chemistry, University of Delhi, Delhi – 110 007, India
a r t i c l e
i n f o
Article history: Received 18 November 2009 Accepted 15 March 2010 Available online 27 March 2010 Keywords: Molecular switch Logic gate Sensor Ternary complexes Osmium
a b s t r a c t Electrochemical- and chemical-induced variation of the metal oxidation state of ternary Os(II) polypyridyl complexes triggers reversible changes in optical properties. This read/write process can be carried out conveniently and monitored with optical (UV/Vis or luminescence) spectrophotometers. An excellent sensitivity and reversibility may make it a suitable candidate for integration of molecular sensors and logic gate system. © 2010 Elsevier B.V. All rights reserved.
The development of molecular switches [1], sensors [2] and logic gates [3] is a stimulating prospect in modern inorganic/organic chemistry, where an understanding of the signal propagation processes in functional molecules constitutes a challenge for chemists, physicist and biologists. In this connection, designing of mixed-ligand metal complexes received vast attention during the last few years [4]. In particular, ternary metal polypyridyl complexes have been shown to be useful in various applications including molecular recognition [5], artificial nucleases [6], electro-chromic display [7], surface modification [8] and biological activity [9], as a result of their excellent photophysical and reversible electrochemical properties. By altering the electronic properties of the metal center and/or ligands it is possible to tune the optical properties of the system (Scheme 1). Inspired by the reversible redox behavior and incredible optical properties displayed by Os and Ru polypyridyl complexes, we performed and report here a complementary optical investigation using spectroelectrochemistry (SEC). This approach has allowed us to monitor the continuous change of the UV–Vis spectra in the λ = 200–800 nm regions as a function of molecular oxidation states (fully reduced Os2+ and fully oxidized Os3+ species). The experiments were accomplished by modulation of the redox potentials, in-situ in a SEC cell suitable for UV–Vis spectroscopy. To provide further support to our assignments and interpretations, modulation of optical properties (UV–Vis and fluorescence) as a function of molecular oxidation states by chemical means has also been performed in this studies.
⁎ Tel.: +91 11 27667794. E-mail address: [email protected]. 1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2010.03.029
Electrochemical measurements were performed to evaluate the redox activity (see Fig. S1) of the complex 1 (Scheme 1). Complex 1 show one electron redox process based on metal center in the range 0.5– 1.2 V. The half-wave redox potential, E1/2, is 0.88 V (vs Ag/AgCl) and 0.44 V (vs Ferrocene/Ferricenium, Fc/Fc+) and remains constant within scan rate, ν = 100–1300 mVs− 1. The peak-to-peak separation, ΔE, is ∼70 mV indicative of a one electron transfer process (see Supplementary data). Based on electrochemical data, a spectro-electrochemical study has been performed. The spectro-electrochemistry of complex 1 has been shown in Fig. 1. Upon oxidation of the Os(II) center, a number of spectroscopic changes have been observed. For example, the decrease of the bands centered at 508 nm (singlet state of metal-to-ligand charge-transfer, 1MLCT band) and 692 nm (triplet state of metal-toligand charge-transfer, 3MLCT band) have been observed upon oxidation of complex 1 by holding the potential at 1.0 V. Simultaneously a red shift of the band centered at 290 nm (ligand-to-metal chargetransfer band, LMCT) have also been observed on oxidation. On the other hand all the bands reappear upon holding the potential at 0.4 V. The oxidation and re-reduction process have been carried out three
Scheme 1. Molecular structure of complex 1 [10].
T. Gupta / Inorganic Chemistry Communications 13 (2010) 724–726
Fig. 1. Electrochemical switching of optical property of complex 1 (a) reduced state, (b) oxidized state. Inset show electrochemical oxidation (at 1.0 V) and subsequent rereduction (at 0.4 V) for three cycles at λ = 290 (♦), 313 (▼), 508 (●) and 692 (■) nm. Both reference and sample cuvettes were maintained with 2.0 mM solution of tBu4NPF6 in acetonitrile whereas sample cuvette contains 1.1 × 10− 2 mM solution of complex 1.
times using the same solution in order to know the reversibility/stability of complex 1. No hystereses were observed after three cycles of the redox process. Fig. 2 show the change in current upon oxidation and re-reduction of complex 1 vs time using 1.1 × 10− 2 mM solution of complex 1 in acetonitrile. Glassy carbon (with high surface area), Pt wire and Ag/ AgCl electrodes were used as working, counter and reference electrodes respectively, whereas tBu4NPF6 (2.0 mM) was used as supporting electrolyte. It has been noticed that any increase or decrease of applied potentials results in fast/slow oxidation and re-reduction of the complex 1. For instance, the saturation of the oxidation current was observed 10 min upon an increase of the voltage from 1.0 to 1.2 V. Similarly, saturation of the re-reduction current has been observed 5 min upon a decrease of the potential from 0.4 to 0.1 V. In order to determine the chemical reactivity, sensitivity and stability of complex 1 with various small molecules (at ppm level), different oxidizing (viz, NO+, Fe3+, Ag+ and Cr6+) and reducing agents (cobaltocene, and H2O) have been tested and the changes were monitored with UV–Vis spectroscopy. For instance, upon addition of NOBF4 (30 μL, 40 ppm stack solution in acetonitrile) to the acetonitrile solution of complex 1 (3.1 × 10− 6 M, 3 mL), the metal-to-ligand charge-transfer band at 508 nm and the pyridine centered π–π* transition band at 290 nm have been reduced along with the appearance of a new band at λ = 313 nm. Three isosbestic points at
Fig. 2. The change in current upon electrochemical oxidation (at 1.0 V) and subsequent re-reduction (at 0.4 V) of complex 1 (1.1 × 10− 2 mM in dry acetonitrile) vs time.
725
Fig. 3. Absorption spectra changes of complex 1 (3.1 × 10–6 M) with time upon chemical oxidation with NOBF4, ∼0.4 ppm, full oxidation were observed in 65 min. Inset show absorption changes at λ = 508 (■) R2 = 0.985 and λ = 290 nm (●) R2 = 0.958.
270, 300 and 405 nm have been observed (Fig. 3). Addition of 100 ppm of H2O (in dry acetonitrile) to the solution containing oxidized complex 1 (oxidized with NO+) resulted in re-appearance of all the bands. This read/write process has been carried out three times using the same solution and after no spectral changes (hysteresis) has been observed signifying the chemical reversibility/ stability of complex 1. The redox potential, E1/2, of NO+ (1.28 V) is larger [11] by 0.40 V than the redox potential of osmium(II) polypyridyl complexes. Therefore, it is expected that one-electron transfer occurs readily in the solution. It is noteworthy that there is much current interest in NOreleasing materials [12], including sol–gel matrices and dendritic systems. The reaction between NO+ and complex 1 was followed with UV–Vis spectrometry (Fig. 3, inset). Fig. 3 (inset) shows the linear fit of the logarithm value of absorption vs time which shows the pseudo first-order reaction kinetics between NO+ and complex 1. Similarly, an experiment has been performed using other analytes including FeCl3 (in dry acetonitrile solution), AgNO3 (in dichloromethane), K2Cr2O7 (in acidic aqueous solution) and all the reactions show first order kinetics with complex 1 at ppm level concentration (1–100 ppm). NOBF4 does not interfere in the range λ = 200–800 nm whereas for other analytes, the data were collected (not shown here) at particular wavelengths (e.g. λ = 692 and 508 nm) in order to minimize the interference by the analytes in the visible region. Interestingly, the chemical switching of optical properties can be described in terms of logic gate system [3]. For example, NO+ (represented as input 1) and H2O (represented as input 2) yield an IMP (implication) gate [13] at λ = 508 nm (assuming threshold value, ε (in M− 1 cm− 1) for output 1 = 22± 1 × 103 and for output 0 = 3 ± 1 × 103) and an INH (inhibit) logic gate [14] at λ = 313 nm (assuming threshold value, ε (in M− 1 cm− 1) for output 1 = 55± 2 × 103 and output 0 = 35 ± 2 × 103) (Fig. 4). Truth table for this Boolean Logic functions has been given in supporting information (Table S1).
Fig. 4. The output at λ = 313 nm equals the output of an INHIBIT (INH) gate while the output at λ = 516 nm equals the output of an implication (IMP) gate.
726
T. Gupta / Inorganic Chemistry Communications 13 (2010) 724–726
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2010.03.029.
References
Fig. 5. Emission spectra changes of complex 1 (3.1 × 10− 6 M in dry acetonitrile) upon addition of NOBF4, 1 ppm in acetonitrile, at 1 min interval time. Excitation wavelength λ = 470 nm.
In addition to UV–Vis spectral changes based on electron transfer process, further changes of emission spectra as a function of NOBF4 addition in acetonitrile solution of complex 1 (3.1 × 10− 6 M, 3 mL) has also been recorded (Fig. 5). Upon addition of NOBF4 (30 μL, 100 ppm in acetonitrile) at each 1 min time interval, emission intensity decreases and the emission maxima remain unchanged at λ = 746 nm. The ∼90% of the initial spectrum was re obtained after addition of H2O (30 μL, 100 ppm, in acetonitrile). Therefore complex 1 acted as an off-on switch with NOBF4 and H2O respectively. The loss of ∼ 10% recovery at each step could be due to the quenching of the emission in the presence of H2O. In summary, switching of optical properties (in λ = 200–800 nm region) of complex 1 has been demonstrated and chemical/electrochemical reversibility was verified via the complete recovery of the spectra in the reversed oxidation/re-reduction steps. High sensitivity of complex 1 with several analytes makes it a suitable platform for sensor integration based on electron transfer. It is noteworthy that sensing of analytes based on electron transfer process is relatively unexplored [15]. Complex 1 contains a pyridine pendant group, which can be further extended for the use of its axial coordination with other metal-based porphyrin system [16] (instead of methyl) leading to formation of donor–acceptor systems showing interesting optical, NLO and electronic properties. Innovation of this possibility is currently underway. Acknowledgments The author gratefully thanks Professor Milko E. van der Boom, Department of Organic Chemistry, Weizmann Institute of Science, Rehovot for laboratory facilities. Department of Science and Technology (DST) and University of Delhi, Delhi is thankfully acknowledged for financial support.
[1] (a) J.M. Spruell, W.F. Paxton, J.-C. Olsen, D. Benítez, E. Tkatchouk, C.L. Stern, A. Trabolsi, D.C. Friedman, W.A. Goddard, J.F. Stoddart, J. Am. Chem. Soc 131 (2009) 11571; (b) F. Cheng, N. Tang, Inorg. Chem. Commun. 11 (2008) 506; (c) Y.-L. Zhao, W.R. Dichtel, A. Trabolsi, S. Saha, I. Aprahamian, J.F. Stoddart, J. Am. Chem. Soc 130 (2008) 11294; (d) C.P. Collier, G. Mattersteig, E.W. Wong, Y. Luo, K. Beverly, J. Sampaio, F.M. Raymo, J.F. Stoddart, J.R. Heath, Science 289 (2000) 1172; (e) R.A. Bissell, E. Cordova, A.E. Kaifer, J.F. Stoddart, Nature 369 (1994) 133. [2] (a) V.S. Elanchezhian, M. Kandaswamy, Inorg. Chem. Commun. 12 (2009) 161; (b) C. McDonagh, C.S. Burke, B.D. MacCraith, Chem. Rev. 108 (2008) 400; (c) C. Jiang, S. Markutsya, Y. Pikus, V.V. Tsukruk, Nature Mater 3 (2004) 721; (d) J. Janata, M. Josowicz, Nature Mater. 2 (2003) 19; (f) R. Martínez-Máñez, F. Sancenón, Chem. Rev. 103 (2003) 4419; (g) A.P. De Silva, H.Q.N. Gunaratne, T. Gunnlangsson, A.J.M. Huxley, C.P. McCoy, J.T. Rademacher, T.E. Rice, Chem. Rev. 97 (1997) 1515. [3] (a) A.P. de Silva, Nature 454 (2008) 417; (b) A.P. de Silva, S. Uchiyama, T.P. Vance, B. Wannalerse, Coord. Chem. Rev. 251 (2007) 1623; (c) A.P. de Silva, S. Uchiyama, Nature Nanotechnol. 2 (2007) 399; (d) A.P. de Silva, M.R. James, B.O.F. McKinney, D.A. Pears, S.M. Weir, Nature Mater. 5 (2006) 787; (e) A.P. de Silva, N.D. McClenaghan, Chem. Eur. J 10 (2004) 574. [4] (a) S. Bai, Z. Fu, Inorg. Chim. Acta 362 (2009) 5163; (b) O.O.E. Onawumi, O.O.P. Faboya, O.A. Odunola, T.K. Prasad, M.V. Rajasekharan, Polyhedron 27 (2008) 113; (c) K. Szaciowski, W. Macyk, G. Stochel, Z. Stasicka, S. Sostero, O. Traverso, Coord. Chem. Rev. 208 (2000) 277; (d) S.A.A. Sajadi, B. Song, H. Sigel, Inorg. Chim. Acta 283 (1998) 193. [5] C.P. Da Costa, B. Song, F. Gregán, H. Sige, J. Chem. Soc., Dalton Trans. (2000) 899. [6] (a A.K. Patra, S. Roy, A.R. Chakravarty, Inorg. Chem. Acta 362 (2009) 1591; (b) S. Ramakrishnan, V. Rajendiran, M. Palaniandavar, V.S. Periasamy, B.S. Srinag, H. Krishnamurthy, M.A. Akbarsha, Inorg. Chem. 48 (2009) 1309; (c) T. Gupta, A.K. Patra, S. Dhar, M. Nethaji, A.R. Chakravarty, J. Chem. Sci. 117 (2005) 123. [7] (a) S. Ye, B. Sarkar, C. Duboc, J. Fiedler, W. Kaim, Inorg. Chem. 44 (2005) 2843; (b) R.C. Rocha, A.P. Shreve, Inorg. Chem. 43 (2004) 2231; (c) M.M. Richter, K.J. Brewer, Inorg. Chem. 31 (1992) 1594. [8] (a) A.D. Shukla, A. Das, M.E. van der Boom, Angew. Chem. Int. Ed 44 (2005) 3237; (b) R.J. Forster, D. Mulledy, D.A. Walsh, T.E. Keyes, Phys. Chem. Chem. Phys. 6 (2004) 3551; (c) R.J. Forster, L.R. Faulkner, Langmuir 11 (1995) 1014. [9] (a) C. Yuan, L. Lu, X. Gao, Y. Wu, M. Guo, Y. Li, X. Fu, M. Zhu, J. Biol. Inorg. Chem. 14 (2009) 841; (b) K.R. Rupesh, S. Deepalata, M. Krishnaveni, R. Venkatesan, S. Jayachandran, Eur. J. Med. Chem. 41 (2006) 1494. [10] T. Gupta, M. Altman, A.D. Shukla, D. Freeman, G. Leitus, M.E. van der Boom, Chem. Mater. 18 (2006) 1379 The purity of the Complex 1 has been assessed by comparison of their NMR, spectroscopic and electrochemical features with reported data. [11] (a) K.Y. Lee, D.J. Kuchynka, J.K. Kochi, Inorg. Chem. 29 (1990) 4196; (b) E.Z. Jandrasics, F.R. Keene, J. Chem. Soc. Dalton Trans. 2 (1997) 153. [12] (a) N.A. Stasko, M.H. Schoenfisch, J. Am. Chem. Soc. 128 (2006) 8265; (b) A.A. Eroy-Reveles, Y. Leung, P.K. Mascharak, J. Am. Chem. Soc. 128 (2006) 7166. [13] U. Pischel, B. Heller, New J. Chem. 32 (2008) 395. [14] Q. Da-Hui, J. Feng-Yuan, W. Qiao-Chun, T. He, Adv. Mater. 18 (2006) 2035. [15] (a) S. Tal, H. Salman, Y. Abraham, M. Botoshansky, Y. Eichen, Chem. Eur. J 12 (2006) 4858; (b) T.L. Lemmon, J.C. Westall, J.D. Ingle Jr., Anal. Chem. 68 (1996) 947. [16] D. Kim, E.J. Shin, Bull. Korean Chem. Soc. 24 (2004) 1490.
Contents lists available at ScienceDirect
Inorganic Chemistry Communications j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / i n o c h e
Reversible electrochemical and chemical addressing of optical properties of ternary Os(II) polypyridyl complexes Tarkeshwar Gupta ⁎ Department of Chemistry, University of Delhi, Delhi – 110 007, India
a r t i c l e
i n f o
Article history: Received 18 November 2009 Accepted 15 March 2010 Available online 27 March 2010 Keywords: Molecular switch Logic gate Sensor Ternary complexes Osmium
a b s t r a c t Electrochemical- and chemical-induced variation of the metal oxidation state of ternary Os(II) polypyridyl complexes triggers reversible changes in optical properties. This read/write process can be carried out conveniently and monitored with optical (UV/Vis or luminescence) spectrophotometers. An excellent sensitivity and reversibility may make it a suitable candidate for integration of molecular sensors and logic gate system. © 2010 Elsevier B.V. All rights reserved.
The development of molecular switches [1], sensors [2] and logic gates [3] is a stimulating prospect in modern inorganic/organic chemistry, where an understanding of the signal propagation processes in functional molecules constitutes a challenge for chemists, physicist and biologists. In this connection, designing of mixed-ligand metal complexes received vast attention during the last few years [4]. In particular, ternary metal polypyridyl complexes have been shown to be useful in various applications including molecular recognition [5], artificial nucleases [6], electro-chromic display [7], surface modification [8] and biological activity [9], as a result of their excellent photophysical and reversible electrochemical properties. By altering the electronic properties of the metal center and/or ligands it is possible to tune the optical properties of the system (Scheme 1). Inspired by the reversible redox behavior and incredible optical properties displayed by Os and Ru polypyridyl complexes, we performed and report here a complementary optical investigation using spectroelectrochemistry (SEC). This approach has allowed us to monitor the continuous change of the UV–Vis spectra in the λ = 200–800 nm regions as a function of molecular oxidation states (fully reduced Os2+ and fully oxidized Os3+ species). The experiments were accomplished by modulation of the redox potentials, in-situ in a SEC cell suitable for UV–Vis spectroscopy. To provide further support to our assignments and interpretations, modulation of optical properties (UV–Vis and fluorescence) as a function of molecular oxidation states by chemical means has also been performed in this studies.
⁎ Tel.: +91 11 27667794. E-mail address: [email protected]. 1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2010.03.029
Electrochemical measurements were performed to evaluate the redox activity (see Fig. S1) of the complex 1 (Scheme 1). Complex 1 show one electron redox process based on metal center in the range 0.5– 1.2 V. The half-wave redox potential, E1/2, is 0.88 V (vs Ag/AgCl) and 0.44 V (vs Ferrocene/Ferricenium, Fc/Fc+) and remains constant within scan rate, ν = 100–1300 mVs− 1. The peak-to-peak separation, ΔE, is ∼70 mV indicative of a one electron transfer process (see Supplementary data). Based on electrochemical data, a spectro-electrochemical study has been performed. The spectro-electrochemistry of complex 1 has been shown in Fig. 1. Upon oxidation of the Os(II) center, a number of spectroscopic changes have been observed. For example, the decrease of the bands centered at 508 nm (singlet state of metal-to-ligand charge-transfer, 1MLCT band) and 692 nm (triplet state of metal-toligand charge-transfer, 3MLCT band) have been observed upon oxidation of complex 1 by holding the potential at 1.0 V. Simultaneously a red shift of the band centered at 290 nm (ligand-to-metal chargetransfer band, LMCT) have also been observed on oxidation. On the other hand all the bands reappear upon holding the potential at 0.4 V. The oxidation and re-reduction process have been carried out three
Scheme 1. Molecular structure of complex 1 [10].
T. Gupta / Inorganic Chemistry Communications 13 (2010) 724–726
Fig. 1. Electrochemical switching of optical property of complex 1 (a) reduced state, (b) oxidized state. Inset show electrochemical oxidation (at 1.0 V) and subsequent rereduction (at 0.4 V) for three cycles at λ = 290 (♦), 313 (▼), 508 (●) and 692 (■) nm. Both reference and sample cuvettes were maintained with 2.0 mM solution of tBu4NPF6 in acetonitrile whereas sample cuvette contains 1.1 × 10− 2 mM solution of complex 1.
times using the same solution in order to know the reversibility/stability of complex 1. No hystereses were observed after three cycles of the redox process. Fig. 2 show the change in current upon oxidation and re-reduction of complex 1 vs time using 1.1 × 10− 2 mM solution of complex 1 in acetonitrile. Glassy carbon (with high surface area), Pt wire and Ag/ AgCl electrodes were used as working, counter and reference electrodes respectively, whereas tBu4NPF6 (2.0 mM) was used as supporting electrolyte. It has been noticed that any increase or decrease of applied potentials results in fast/slow oxidation and re-reduction of the complex 1. For instance, the saturation of the oxidation current was observed 10 min upon an increase of the voltage from 1.0 to 1.2 V. Similarly, saturation of the re-reduction current has been observed 5 min upon a decrease of the potential from 0.4 to 0.1 V. In order to determine the chemical reactivity, sensitivity and stability of complex 1 with various small molecules (at ppm level), different oxidizing (viz, NO+, Fe3+, Ag+ and Cr6+) and reducing agents (cobaltocene, and H2O) have been tested and the changes were monitored with UV–Vis spectroscopy. For instance, upon addition of NOBF4 (30 μL, 40 ppm stack solution in acetonitrile) to the acetonitrile solution of complex 1 (3.1 × 10− 6 M, 3 mL), the metal-to-ligand charge-transfer band at 508 nm and the pyridine centered π–π* transition band at 290 nm have been reduced along with the appearance of a new band at λ = 313 nm. Three isosbestic points at
Fig. 2. The change in current upon electrochemical oxidation (at 1.0 V) and subsequent re-reduction (at 0.4 V) of complex 1 (1.1 × 10− 2 mM in dry acetonitrile) vs time.
725
Fig. 3. Absorption spectra changes of complex 1 (3.1 × 10–6 M) with time upon chemical oxidation with NOBF4, ∼0.4 ppm, full oxidation were observed in 65 min. Inset show absorption changes at λ = 508 (■) R2 = 0.985 and λ = 290 nm (●) R2 = 0.958.
270, 300 and 405 nm have been observed (Fig. 3). Addition of 100 ppm of H2O (in dry acetonitrile) to the solution containing oxidized complex 1 (oxidized with NO+) resulted in re-appearance of all the bands. This read/write process has been carried out three times using the same solution and after no spectral changes (hysteresis) has been observed signifying the chemical reversibility/ stability of complex 1. The redox potential, E1/2, of NO+ (1.28 V) is larger [11] by 0.40 V than the redox potential of osmium(II) polypyridyl complexes. Therefore, it is expected that one-electron transfer occurs readily in the solution. It is noteworthy that there is much current interest in NOreleasing materials [12], including sol–gel matrices and dendritic systems. The reaction between NO+ and complex 1 was followed with UV–Vis spectrometry (Fig. 3, inset). Fig. 3 (inset) shows the linear fit of the logarithm value of absorption vs time which shows the pseudo first-order reaction kinetics between NO+ and complex 1. Similarly, an experiment has been performed using other analytes including FeCl3 (in dry acetonitrile solution), AgNO3 (in dichloromethane), K2Cr2O7 (in acidic aqueous solution) and all the reactions show first order kinetics with complex 1 at ppm level concentration (1–100 ppm). NOBF4 does not interfere in the range λ = 200–800 nm whereas for other analytes, the data were collected (not shown here) at particular wavelengths (e.g. λ = 692 and 508 nm) in order to minimize the interference by the analytes in the visible region. Interestingly, the chemical switching of optical properties can be described in terms of logic gate system [3]. For example, NO+ (represented as input 1) and H2O (represented as input 2) yield an IMP (implication) gate [13] at λ = 508 nm (assuming threshold value, ε (in M− 1 cm− 1) for output 1 = 22± 1 × 103 and for output 0 = 3 ± 1 × 103) and an INH (inhibit) logic gate [14] at λ = 313 nm (assuming threshold value, ε (in M− 1 cm− 1) for output 1 = 55± 2 × 103 and output 0 = 35 ± 2 × 103) (Fig. 4). Truth table for this Boolean Logic functions has been given in supporting information (Table S1).
Fig. 4. The output at λ = 313 nm equals the output of an INHIBIT (INH) gate while the output at λ = 516 nm equals the output of an implication (IMP) gate.
726
T. Gupta / Inorganic Chemistry Communications 13 (2010) 724–726
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2010.03.029.
References
Fig. 5. Emission spectra changes of complex 1 (3.1 × 10− 6 M in dry acetonitrile) upon addition of NOBF4, 1 ppm in acetonitrile, at 1 min interval time. Excitation wavelength λ = 470 nm.
In addition to UV–Vis spectral changes based on electron transfer process, further changes of emission spectra as a function of NOBF4 addition in acetonitrile solution of complex 1 (3.1 × 10− 6 M, 3 mL) has also been recorded (Fig. 5). Upon addition of NOBF4 (30 μL, 100 ppm in acetonitrile) at each 1 min time interval, emission intensity decreases and the emission maxima remain unchanged at λ = 746 nm. The ∼90% of the initial spectrum was re obtained after addition of H2O (30 μL, 100 ppm, in acetonitrile). Therefore complex 1 acted as an off-on switch with NOBF4 and H2O respectively. The loss of ∼ 10% recovery at each step could be due to the quenching of the emission in the presence of H2O. In summary, switching of optical properties (in λ = 200–800 nm region) of complex 1 has been demonstrated and chemical/electrochemical reversibility was verified via the complete recovery of the spectra in the reversed oxidation/re-reduction steps. High sensitivity of complex 1 with several analytes makes it a suitable platform for sensor integration based on electron transfer. It is noteworthy that sensing of analytes based on electron transfer process is relatively unexplored [15]. Complex 1 contains a pyridine pendant group, which can be further extended for the use of its axial coordination with other metal-based porphyrin system [16] (instead of methyl) leading to formation of donor–acceptor systems showing interesting optical, NLO and electronic properties. Innovation of this possibility is currently underway. Acknowledgments The author gratefully thanks Professor Milko E. van der Boom, Department of Organic Chemistry, Weizmann Institute of Science, Rehovot for laboratory facilities. Department of Science and Technology (DST) and University of Delhi, Delhi is thankfully acknowledged for financial support.
[1] (a) J.M. Spruell, W.F. Paxton, J.-C. Olsen, D. Benítez, E. Tkatchouk, C.L. Stern, A. Trabolsi, D.C. Friedman, W.A. Goddard, J.F. Stoddart, J. Am. Chem. Soc 131 (2009) 11571; (b) F. Cheng, N. Tang, Inorg. Chem. Commun. 11 (2008) 506; (c) Y.-L. Zhao, W.R. Dichtel, A. Trabolsi, S. Saha, I. Aprahamian, J.F. Stoddart, J. Am. Chem. Soc 130 (2008) 11294; (d) C.P. Collier, G. Mattersteig, E.W. Wong, Y. Luo, K. Beverly, J. Sampaio, F.M. Raymo, J.F. Stoddart, J.R. Heath, Science 289 (2000) 1172; (e) R.A. Bissell, E. Cordova, A.E. Kaifer, J.F. Stoddart, Nature 369 (1994) 133. [2] (a) V.S. Elanchezhian, M. Kandaswamy, Inorg. Chem. Commun. 12 (2009) 161; (b) C. McDonagh, C.S. Burke, B.D. MacCraith, Chem. Rev. 108 (2008) 400; (c) C. Jiang, S. Markutsya, Y. Pikus, V.V. Tsukruk, Nature Mater 3 (2004) 721; (d) J. Janata, M. Josowicz, Nature Mater. 2 (2003) 19; (f) R. Martínez-Máñez, F. Sancenón, Chem. Rev. 103 (2003) 4419; (g) A.P. De Silva, H.Q.N. Gunaratne, T. Gunnlangsson, A.J.M. Huxley, C.P. McCoy, J.T. Rademacher, T.E. Rice, Chem. Rev. 97 (1997) 1515. [3] (a) A.P. de Silva, Nature 454 (2008) 417; (b) A.P. de Silva, S. Uchiyama, T.P. Vance, B. Wannalerse, Coord. Chem. Rev. 251 (2007) 1623; (c) A.P. de Silva, S. Uchiyama, Nature Nanotechnol. 2 (2007) 399; (d) A.P. de Silva, M.R. James, B.O.F. McKinney, D.A. Pears, S.M. Weir, Nature Mater. 5 (2006) 787; (e) A.P. de Silva, N.D. McClenaghan, Chem. Eur. J 10 (2004) 574. [4] (a) S. Bai, Z. Fu, Inorg. Chim. Acta 362 (2009) 5163; (b) O.O.E. Onawumi, O.O.P. Faboya, O.A. Odunola, T.K. Prasad, M.V. Rajasekharan, Polyhedron 27 (2008) 113; (c) K. Szaciowski, W. Macyk, G. Stochel, Z. Stasicka, S. Sostero, O. Traverso, Coord. Chem. Rev. 208 (2000) 277; (d) S.A.A. Sajadi, B. Song, H. Sigel, Inorg. Chim. Acta 283 (1998) 193. [5] C.P. Da Costa, B. Song, F. Gregán, H. Sige, J. Chem. Soc., Dalton Trans. (2000) 899. [6] (a A.K. Patra, S. Roy, A.R. Chakravarty, Inorg. Chem. Acta 362 (2009) 1591; (b) S. Ramakrishnan, V. Rajendiran, M. Palaniandavar, V.S. Periasamy, B.S. Srinag, H. Krishnamurthy, M.A. Akbarsha, Inorg. Chem. 48 (2009) 1309; (c) T. Gupta, A.K. Patra, S. Dhar, M. Nethaji, A.R. Chakravarty, J. Chem. Sci. 117 (2005) 123. [7] (a) S. Ye, B. Sarkar, C. Duboc, J. Fiedler, W. Kaim, Inorg. Chem. 44 (2005) 2843; (b) R.C. Rocha, A.P. Shreve, Inorg. Chem. 43 (2004) 2231; (c) M.M. Richter, K.J. Brewer, Inorg. Chem. 31 (1992) 1594. [8] (a) A.D. Shukla, A. Das, M.E. van der Boom, Angew. Chem. Int. Ed 44 (2005) 3237; (b) R.J. Forster, D. Mulledy, D.A. Walsh, T.E. Keyes, Phys. Chem. Chem. Phys. 6 (2004) 3551; (c) R.J. Forster, L.R. Faulkner, Langmuir 11 (1995) 1014. [9] (a) C. Yuan, L. Lu, X. Gao, Y. Wu, M. Guo, Y. Li, X. Fu, M. Zhu, J. Biol. Inorg. Chem. 14 (2009) 841; (b) K.R. Rupesh, S. Deepalata, M. Krishnaveni, R. Venkatesan, S. Jayachandran, Eur. J. Med. Chem. 41 (2006) 1494. [10] T. Gupta, M. Altman, A.D. Shukla, D. Freeman, G. Leitus, M.E. van der Boom, Chem. Mater. 18 (2006) 1379 The purity of the Complex 1 has been assessed by comparison of their NMR, spectroscopic and electrochemical features with reported data. [11] (a) K.Y. Lee, D.J. Kuchynka, J.K. Kochi, Inorg. Chem. 29 (1990) 4196; (b) E.Z. Jandrasics, F.R. Keene, J. Chem. Soc. Dalton Trans. 2 (1997) 153. [12] (a) N.A. Stasko, M.H. Schoenfisch, J. Am. Chem. Soc. 128 (2006) 8265; (b) A.A. Eroy-Reveles, Y. Leung, P.K. Mascharak, J. Am. Chem. Soc. 128 (2006) 7166. [13] U. Pischel, B. Heller, New J. Chem. 32 (2008) 395. [14] Q. Da-Hui, J. Feng-Yuan, W. Qiao-Chun, T. He, Adv. Mater. 18 (2006) 2035. [15] (a) S. Tal, H. Salman, Y. Abraham, M. Botoshansky, Y. Eichen, Chem. Eur. J 12 (2006) 4858; (b) T.L. Lemmon, J.C. Westall, J.D. Ingle Jr., Anal. Chem. 68 (1996) 947. [16] D. Kim, E.J. Shin, Bull. Korean Chem. Soc. 24 (2004) 1490.