Electronically Excited States in Model Complexes of Noble Metal Clusters with Carbon Nanodots

Russian Physics Journal - Theoretical calculations of excited states in the complexes of gold and silver three-atom nanoclusters with carbon quantum nanodots are performed using the M062X...     

Experimental and Theoretical Study of Spectroscopy of Binuclear Difluoroborate Dipyrromethene Complexes

Russian Physics Journal - The spectroscopic characteristics of mono and binuclear difluoroborate complexes of dipyrromethenes in various solvents and solid-state polymer media (films) are...     

Structure and electronic properties of hollow‐caged C60 fullerene‐derived (MN4)nC6(10 − n) (M = Zn,Mg, Fe,n = 1−6) complexes

Unique hollow‐caged (MN₄)_nC_{6(10 ? n)} (M = Zn, Mg, Fe, n = 1?6) complexes designed by introduction of n porphyrinoid fragments in C₆₀ fullerene structure were proposed and the atomic and electronic structures were calculated using LC‐DFT MPWB95 and M06 potentials and 6‐311G(d)/6‐31G(d) basis sets. The complexes were optimized using various symmetric configurations from the highest O_h to the lowest C₁ point groups in different spin states from S = 0 (singlet) to S = 7 (quindectet) for M = Fe to define energetically preferable atomic and electronic structures. Several metastable complexes were determined and the key role of the metal ions in stabilization of the atomic structure of the complexes was revealed. For Fe₆N₂₄C₂₄, the minimum energy was reported for C_2h, D_2h, and D_4h symmetry of pentet state S = 2, so the complex can be regarded as unique molecular magnet. It was found that the metal partial density of states determine the nature of HOMO and LUMO levels making the clusters promising catalysts. © 2014 Wiley Periodicals, Inc.     

Combined Quantum-Classical Simulation of Photoinduced Electronic Density Redistribution from Biopolymer Segments to Photochromic Probes

Russian Physics Journal - The mechanism of fluorescence quenching of the human serum albumin by transferring the energy of the photoinduced electronic excitation from the single tryptophan residue...     

Experimental and Theoretical Investigation of Optical Spectra of Methylene Green in Solutions

Russian Physics Journal - The hybrid multilevel approach based on molecular dynamics, quantum mechanics, and statistical theory has been applied to profiles of electronic absorption bands of a...     

Prediction of anisotropic transport in Nafion containing catalyst layers

Using dissipative particle dynamics we model phase separation within Nafion electrolytes of thickness between 5 and 10 nm containing 20 volume percent water, sandwiched between a carbon catalyst support (CCS) layer and air. The diffusion pathway for protons and water is probed by Monte Carlo trajectory calculations. While varying the interactions between CCS and water, diffusion parallel to the CCS is predicted to be highest and perpendicular diffusion to be lowest for a hydrophilic CCS. This is explained by variations in water density profiles along the perpendicular direction, which act as bottlenecks for diffusion. Increasing the hydrophobic character of the CCS lifts up these bottlenecks.     

Theoretic and Experimental Study of Photoprocesses in Substituted 4-Dicyanomethylene-4H-pyrans

The photoprocesses in substituted 4-dicyanomethylene-4H-pyran (DCM) derivatives were studied theoretically and experimentally. The experimental spectral and luminescent parameters of the molecules under study are in good agreement with the results of quantum-chemical calculations. Trends changes in the spectral and luminescent properties depending on the molecular structure were established. The appearance of the S₂ level near the S₁ level in the scheme of the energy states of symmetrically substituted DCM (bis-DCM) causes changes in photophysical processes and a drop in the fluorescence quantum yield.     

Photophysical Properties and Probability of Hydrogenation of C60

The photophysical properties of fullerene C₆₀ are studied by quantum chemistry. The calculated values are in good agreement with experiment. The probabilities of formation of hydrofullerenes with a varying number of attached hydrogen atoms are analyzed using the method of molecular electrostatic potential.     

T → S Energy Transfer in Some Molecular Complexes

Calculations on the bimolecular complexes of acetophenone or benzophenone with anthracene and its substituted derivatives were carried out using a standard quantum-chemical approach to molecular systems. The deactivation pathways for lower triplet excited states of acetophenone and benzophenone were established. The probability of energy transfer from the energy donor to acceptor in the complexes was considered. The analysis of calculation results showed that the T S transfer of electronic excitation energy in these complexes is feasible only in the case of a small distance between the molecules, and the efficiency of this transfer is higher in the acetophenone rather than benzophenone complexes.     

Predicting absorption spectra of silver-ligand complexes

The detailed structures of most of ligand-stabilized metal nanoclusters (NCs) remain unknown due to the absence of crystal structure data for them. In such a situation, quantum-chemical modeling is of particular interest. We compared the performance of different theoretical methods of geometry optimization and absorption spectra calculation for silver-thiolate complexes. We showed that the absorption spectra calculated with the ADC(2) method were consistent with the spectra obtained with CC2 method. Three DFT functionals (B3LYP, CAM-B3LYP, and M06-2X) failed to reproduce the CC2 absorption spectra of the silver-thiolate complexes.