Alexander A. Voityuk

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G-quadruplex nucleic acids represent a unique avenue for the building of electrically conductive wires. These four-stranded structures are formed through the stacking of multiple planar guanine assemblies termed G-tetrads. The diverse folding patterns of G-quadruplexes allow for several geometries to be adopted by stacked guanine bases within the core and(More)
Exciton delocalization and singlet excitation energy transfer have been systematically studied for the complete set of 16 DNA nucleobase dimers in their ideal, single-strand stacked B-DNA conformation, at the MS-CASPT2 level of theory. The extent of exciton delocalization in the two lowest (π,π(*)) states of the dimers is determined using the symmetrized(More)
CASSCF and CAS-PT2 calculations are performed for the ground and excited states of radical cations consisting of two and three nucleobases. The generalized Mulliken-Hush approach is employed for estimating electronic couplings for hole transfer in the pi-stacks. We compare the CASSCF results with data obtained within Koopmans' approximation. The(More)
We explore the relationship between the electronic-nuclear level structure, the electronic couplings, and the dynamics of hole hopping transport in DNA. We utilized the electronic coupling matrix elements for hole transfer between nearest-neighbor nucleobases in DNA [Voityuk, A. A.; Jortner, J.; Bixon, M.; Rösch, N. J. Chem. Phys. 2001, 114, 5614] to(More)
Molecular structures that direct charge transport in two or three dimensions possess some of the essential functionality of electrical switches and gates. We use theory, modeling, and simulation to explore the conformational dynamics of DNA three-way junctions (TWJs) that may control the flow of charge through these structures. Molecular dynamics(More)
Recently, Kurnikov et al. (J. Phys. Chem. B 2002, 106, 7) have shown that solvation of DNA duplexes destabilizes holes of sizes larger than three base pairs. In this paper, we consider the effects of solvation and internal reorganization on the hole charge distribution in sequences 5'-X-GG-Y-3'. Radical cation states in DNA are found to be localized to a(More)
The electron hole transfer (HT) properties of DNA are substantially affected by thermal fluctuations of the pi stack structure. Depending on the mutual position of neighboring nucleobases, electronic coupling V may change by several orders of magnitude. In the present paper, we report the results of systematic QM/molecular dynamic (MD) calculations of the(More)
We report a computational search for DNA π-stack structures exhibiting high electric conductance in the hopping regime, based on the INDO/S calculations of electronic coupling and the method of data analysis called k-means clustering. Using homogeneous poly(G)-poly(C) and poly(A)-poly(T) stacks as the simplest structural models, we identify the(More)
Electronic coupling is a key parameter that determines the rate of electron transfer reactions and electrical conductivity of molecular wires. To examine the performance of a two-state approach based on the orthogonal transformation of adiabatic states to diabatic states, we compare the effective donor-acceptor coupling V(DA) computed with three different(More)