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Baryshnikov G.V.,Bohdan Khmelnitskii National University | Minaev B.F.,Bohdan Khmelnitskii National University | Minaeva V.A.,Bohdan Khmelnitskii National University | Podgornaya A.T.,Bohdan Khmelnitskii National University | Agren H.,KTH Royal Institute of Technology
Russian Journal of General Chemistry | Year: 2012

In the framework of Bader's atoms in molecules theory a complete analysis of the distribution function of electron density in molecules of complexes of Ca 2+ and Mg 2+ with methylidene rhodanine and its anion was carried out. The role of mutual polarization of the metal cation and the ligand in the formation of coordination bonds was demonstrated. The accumulation of electron density in the interatomic space of coordination bonds is assumed to be a consequence of the deformation of the ligand electron shell under the influence of the cation electric field. Based on the magnitude and sign of the Laplacian and the electron energy density at the critical points of coordination bonds the interactions were classified the in terms of the atoms in molecules theory. The energy of the coordination bonds was evaluated using the Espinoza's formula. The stability of metal-containing rings was considered basing on the values of the bond ellipticity. © Pleiades Publishing, Ltd., 2012. Source


Minaev B.,Bohdan Khmelnitskii National University | Minaeva V.,Bohdan Khmelnitskii National University | Baryshnikov G.,Bohdan Khmelnitskii National University | Girtu M.,Ovidius University | Agren H.,KTH Royal Institute of Technology
Molecular Simulation | Year: 2011

Harvesting energy directly from sunlight using photovoltaic technology is an essential component of the future global energy production programmes (A. Hagfeldt and M. Gratzel, Molecular photovoltaic, Acc. Chem. Res. 33 (2000), pp. 269-277). Photovoltaic devices, or solar cells, are based on the photoelectric effect, in which the incoming solar photons are absorbed in a sensitised semiconductor material releasing electric charges that are used to energise an external circuit (J.E. Monat, J.H. Rodriguez and J.K. McCusker, Ground- and excited-state electronic structures of the solar cell sensitiser bis(4,4'-dicarboxylato-2,2'-bipyridine)bis(isothiocyanato)ruthenium(II), J. Phys. Chem. A 106 (2002), pp. 7399-7406). The solar cells on the bases of nanocrystalline TiO2 are usually sensitised by metal-organic dyes such as Ru-complexes with phenylpyridine and bipyridine ligands. The incident photon-to-current conversion efficiency (IPCCE) in the wavelength region 400-600nm can be rather high (A. Hagfeldt and M. Gratzel, Molecular photovoltaic, Acc. Chem. Res. 33 (2000), pp. 269-277; J.E. Monat, J.H. Rodriguez and J.K. McCusker, Ground- and excited-state electronic structures of the solar cell sensitiser bis(4,4'-dicarboxylato-2,2'-bipyridine)bis(isothiocyanato) ruthenium(II), J. Phys. Chem. A 106 (2002), pp. 7399-7406). In order to improve the IPCCE value, the heavier metal ions can be tested. Sensitisers such as coumarin, porphyrins, chlorophyll derivatives, antenna-sensitiser polynuclear complexes and eosin have been studied and reported to be less efficient than the most effective Ru-based sensitising dyes, called the black dye (BD) and N3 dye (J.E. Monat, J.H. Rodriguez and J.K. McCusker, Ground- and excited-state electronic structures of the solar cell sensitiser bis(4,4'-dicarboxylato-2,2'- bipyridine)bis(isothiocyanato)ruthenium(II), J. Phys. Chem. A 106 (2002), pp. 7399-7406; B. Minaev, V. Minaeva and O. Vahtras, Electronic structure and spectra of dyes for sensitising nanocrystalline solar cells, Nano-Sol-Net International Symposium: Trends in Organic Electronics and Hybrid Photovoltaic's, Constana, Romania, 2008; F. Aiga and T. Tada, Molecular and electronic structures of BD; An efficient sensitising dye for nanocrystalline TiO2 solar cells, J. Mol. Struct. 658 (2003), pp. 25-32), used for nanocrystalline TiO2 solar cells. In this paper, we aim to understand the IPCCE of a new dye-sensitiser in order to predict a higher absorption efficiency of the solar spectrum and higher electron transfer rate from the redox systems to the oxidised dye. A simple Ru(II)(bpy)2(CN)2 complex is studied by the density functional method with optimised structure and vibrational analysis in order to predict the role of vibronic perturbations in the spectra and in the interface electron transfer rate. Intermolecular interactions with solvent and nanocrystalline surface are also discussed in terms of vibronic mixing of states. © 2011 Taylor & Francis. Source

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