The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl2(L)2, where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl2 (Azpy)2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium’s selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru) π*(N1-N2) does correspond to t2g π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl2(Nazpy)2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.
KeywordsNatural Bond Orbital (NBO)HOMOLUMOAzopyridine LigandMLCTLLCT
Kooijman, H., Hostze, C.G., Caspers, S.E., Haasnoot, J.G., Reedijk, J. and Spek, A.L. (2004) α-Dichlorobis(2-phenylazo-4,6-dimethyl-pyridine)ruthenium(II) Chloroform Solvate, Metal-Organic Papers. Acta Crystallographica Section E, E60, m247-m249. https://doi.org/10.1107/S1600536804001618
Gowami, S., Chakravarty, A.R. and Chakrovorty, A. (1981) Chemistry of Ruthenium. 2. Synthesis, Structure, and Redox Properties of 2-(Arylazo) Pyridine Complexes. Inorganic Chemistry, 20, 2246-2250. https://doi.org/10.1021/ic50221a061
Jorna, A.J., Boelrijk, A.E.M., Hoorn, H.J. and Reedijk, J. (1996) Heterogenization of a Ruthenium Catalyst on Silica and Its Application in Alcohol Oxidation and Stilbene Epoxidation. Reactive & Functional Polymers, 29, 101-114. https://doi.org/10.1016/1381-5148(96)00005-3
Velders, A.H., Kooijman, H., Spek, A. L., Haasnoot, J.G., De Vos, D. and Reedijk, J. (2000) Strong Differences in the in Vitro Cytotoxicity of Three Isomeric Dichlorobis(2-phenyla-zopyridine)ruthenium(II) Complexes. Inorganic Chemistry, 39, 2966-2967. https://doi.org/10.1021/ic000167t
Affi, S.T., Bamba, K. and Ziao, N. (2015) Computational Characterization of Organometallic Ligands Coordinating Metal: Case of Azopyridine Ligands. Journal of Theoretical and Computational Chemistry, 14, Article ID: 1550006. https://doi.org/10.1142/s0219633615500066
Bamba, K., Leger, J.-M., Garnier, E., Bachmann, C., Servat, K. and Kokoh, K.B. (2005) Selective Electro-Oxidation of D-Glucose by RuCl2(azpy)2 Complexes as Electrochemical Mediators. Electrochimica Acta, 50, 3341-3346. https://doi.org/10.1016/j.electacta.2004.12.007
Chaitanya, K., Santhamma, C., Prasad, K.V. and Veeraiah, V. (2012) Molecular strucTure, Vibrational Spectroscopic (FT-IR, FT-Raman), First Order Hyperpolarizability, NBO Analysis, HOMO and LUMO Analysis, Thermodynamic Properties of 3,5-Dimethylben-zophenone by Ab Inito. Journal of Atomic and Molecular Sciences, 3, 1-22.
Ouattara, W.P., Bamba, K., Ziao, N. and N’guessan, K.N. (2016) Theoretical and Electrochemical Characterization of δ-RuCl2(Nazpy)2: Application to Oxidation of D-Glucose. American Journal of Analytical Chemistry, 7, 57-66. https://doi.org/10.4236/ajac.2016.71006
Foresman, J.B. and Frisch, A. (1996) Exploring Chemistry with Electronic Structure Methods. 2nd Edition, Gaussian Inc., Pittsburgh.
Schuchardt, K. L., Didier, B.T., Elsethagen, T., Sun, L., Gurumoorthi, V., Chase, J., Li, J. and Windus, T.L. (2007) Basis Set Exchange: A Community Database for Computational Sciences. Journal of Chemical Information and Modeling, 47, 1045-1052. https://doi.org/10.1021/ci600510j
Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., Petersson, G.A., Nakatsuji, H., Caricato, M., Li, X., Hratchian, H.P., Izmaylov, A.F., Bloino, J., Zheng, G., Sonnenberg, J.L., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa, J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Vreven, T., Montgomery, J.A.J., Peralta, J.E., Ogliaro, F., Bearpark, M., Heyd, J.J., Brothers, E., Kudin, K.N., Staroverov, V.N., Kobayashi, R., Normand, J., Raghavachari, K., Rendell, A., Burant, J.C., Iyengar, S.S., Tomasi, J., Cossi, M., Rega, N., Millam, J.M., Klene, M., Knox, J.E., Cross, J.B., Bakken, V., Adamo, C., Jaramillo, J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J.W., Martin, R.L., Morokuma, K., Zakrzewski, V.G., Voth, G.A., Salvador, P., Dannenberg, J.J., Dapprich, S., Daniels, A.D., Farkas, O., Foresman, J.B., Ortiz, J.V., Cioslowski, J. and Fox, D.J. (2009) Gaussian 09, Revision E.01. Gaussian, Inc., Wallingford.
Weinhold, F. and Landis, C.R. (2001) Natural Bond Orbitals and Extensions of Localized Bonding Concepts. Chemistry Education Research and Practice, 2, 91-104.
Reed, A.E., Curtiss, L.A. and Weinhold, F. (1988) Intermolecular Interactions from a Natural Bond Orbital, Donor-Acceptor Viewpoint. Chemical Reviews, 88, 899-926. https://doi.org/10.1021/cr00088a005
Sangeetha, C.C., Madivanane, R. and Pouchaname, V. (2014) The Vibrational Spectroscopic (FT-IR & FT Raman, NMR, UV) Study and HOMO & LUMO Analysis of Phthalazine by DFT and HF Studies. International Journal Of Engineering Research and General Science, 2, 222.
Bamba, K., Ouattara, W.P., N’Guessan, K.N. and Ziao, N. (2016) SARs Investigation of α-, β-, γ-, δ-, ε-RuCl2(Azpy)2 Complexes as Antitumor Drugs. Computational Chemistry, 4, 1-10. https://doi.org/10.4236/cc.2016.41001
Cramer, C.J. (2004) Essentials of Computational Chemistry, Theories and Models, Effective Core Potentials. 2nd Edition, Wiley, Hoboken, 179.
Oziminski, W.P. and Narbutt, J. (2010) Theoretical Investigations on the Structure and Bonding in Neutral Trinitrate Complexes of Americium(III) and Europium(III) with 6,6’-Bis-(5,6-Diethyl-1,2,4-Triazin-Yl)-2,2 Bipyridine in Solvent Extraction Systems. Institute of Nuclear Chemistry and Technology, Warszawa, 35.
Shriver, D.F. and Atkins, PW. (1999) Inorganic Chemistry. 3rd Edition, Oxford University Press, Oxford, 292.
N’Guessan, K.N., Bamba, K., Ziao, N. and Ouattara, W.P. (2015) Molecular Structure, Vibrational Spectra and NMR Analyses on Two Azopyridine Ruthenium Complexes Using Density Functional Theory Calculations. Journal of Chemical and Pharmaceutical Research, 7, 246.
Velders, A.H., van der Schilden, K., Hoste, A.C.G., Reedijk, J., Kooijman, H. and Speck, A.L. (2004) Dichlorobis(2-Phenylazopyridine)Ruthenium(II) Complexes: Characterization, Spectroscopic and Structural Properties of Four Isomers. Dalton Transactions, 3, 448-455, https://doi.org/10.1039/b313182c
Ghiasi, R. and Ebrahimi, M.E. (2012) Natural Bond Orbital (NBO) Population Analysis of Iridabenzene (C5H5Ir)(PH3)3. Journal of Applied Chemical Research, 20, 7-13.
Fan, W.-J., Cai, J.-W., Yang, G.-J., Chi, J.-W., Zhou, D., Tan, D.-Z. and Zhang, R.-Q. (2016) Aggregation of Metal-Free Organic Sensitizers on TiO2(101) Surface for Use in Dye-Sensitized Solar Cells: A Computational Investment. Computational and Theoretical Chemistry, 1093, 1-8. https://doi.org/10.1016/j.comptc.2016.08.006
Umer, M., Ibnelwaleed, A.H., Muhammad, D., Shakeel, A. and Khalil, H. (2015) Theoretical Study of Benzene/Thiophene Based Photosensitizers for Dye Sensitized Solar Cells (DSSCs). Dyes and Pigments, 118, 152-158.
Zhang, C.-R., Liu, Z.-J., Chen, Y.-H., et al. (2009) DFT and TDDFT Study on Organic Dye Sensitizers D5, DST and DSS for Solar Cells. Journal of Molecular Structure: THEOCHEM, 899, 86-93. https://doi.org/10.1016/j.theochem.2008.12.015