Aromaticity of biphenylene networks.

Magnetically induced ring-currents and magnetic susceptibilities have been calculated for the series of biphenylene sheets and biphenylene nanoribbons with armchair and zigzag edges with hydrogen atoms, as well as with bromine and fluorine atoms. Calculations have been performed at the density functional level of theory. It has been shown that biphenylene sheets and nanoribbons are characterized by dominant paratropic ring current, resulting in antiaromatic character.

Insight into magnetically induced ring currents and photophysics of six-porphyrin nanorings.

The series of nanorings based on Zn-porphyrins and tetraoxa-isophlorins in different oxidation states ( = 0, 2+, 4+, 6+) have been studied studied computationally at density functional theory level (DFT) using BHandHLYP functional combined with def2-SVP basis sets. Magnetically induced ring currents of nanorings have been calculated using the GIMIC method and the Ampère-Maxwell integration scheme. Ring current calculations show that neutral nanorings sustain equal diatropic and paratropic currents of 8 nA T, resulting in zero net ring current strengths.

Calculating rate constants for intersystem crossing and internal conversion in the Franck-Condon and Herzberg-Teller approximations.

Effective and fast algorithms for calculating rate constants for internal conversion (IC) and intersystem crossing (ISC) in the Franck-Condon and Herzberg-Teller approximations have been developed and implemented. The methods have been employed for calculating IC and ISC rate constants for the pyrromethene-567 dye (PM567), hetero[8]circulene (4B) and free-base porphyrin (H2P). The fluorescence quantum yields obtained by comparing calculated rate constants for the radiative and non-radiative processes are in good agreement with experimental data.

A new look at acid catalyzed deacetylation of carbohydrates: A regioselective synthesis and reactivity of 2-O-acetyl aryl glycopyranosides.

In the present work we report that acetyl groups of per - acetylated aryl glycosides have different reactivity during the acidic deacetylation using HCl/EtOH in CHCl which leads to preferential deacetylation at O-3, O-4 and O-6. Thereby, the one-step preparation of 2-O-acetyl aryl glycosides with simple aglycon was accomplished for the first time. It was proved that the found reagent is to be general and unique for the preparation of series of 2-О-acetyl aryl glycosides.

Ab initio 3D potential energy and dipole moment surfaces for the CH4-Ar complex: Collision-induced intensity and dimer content.

We present new three-dimensional potential energy surface (PES) and dipole moment surfaces (DMSs) for the CH4-Ar van der Waals system. Ab initio calculations of the PES and DMS were carried out using the closed-shell single- and double-excitation coupled cluster approach with non-iterative perturbative treatment of triple excitations. The augmented correlation-consistent aug-cc-pVXZ (X = D,T,Q) basis sets were employed, and the energies obtained were then extrapolated to the complete basis set limit.

Static hyperpolarizability of the van der Waals complex CH(4)-N(2).

The static first hyperpolarizability of the van der Waals CH(4)-N(2) complex was calculated. The calculations were carried out in the approximation of the rigid interacting molecules for a broad range of intermolecular separations (R = 6-40 a(0)) and for six configurations at CCSD(T) level of theory using the correlation consistent aug-cc-pVTZ basis set with the basis set superposition error correction. It was shown that the long-range classical approximation, including the terms up to R(-6), is in a good agreement with ab initio calculations for R > 11 a(0).

Computational studies of photophysical properties of porphin, tetraphenylporphyrin and tetrabenzoporphyrin.

The molecular photonics of porphyrins are studied using a combination of first-principle and semi-empirical calculations. The applicability of the approach is demonstrated by calculations on free-base porphyrin, tetraphenylporphyrin, and tetrabenzoporphyrin. The method uses excitation energies and oscillator strengths calculated at the linear-response time-dependent density functional theory (TDDFT) or the corresponding values calculated at the linear-response approximate second-order coupled-cluster (CC2) levels.

Computational and experimental studies of the electronic excitation spectra of EDTA and DTPA substituted tetraphenylporphyrins and their Lu complexes.

Ethylendiaminetetraacetic acid (EDTA) substituted and diethylenetriaminopentaacetic acid (DTPA) substituted aminated free-base tetraphenylporphyrins (H2ATPP) and the corresponding lutetium(III) complexes have been studied computationally at the density functional theory (DFT) and second-order algebraic diagrammatic construction (ADC(2)) levels using triple-ξ basis sets augmented with polarization functions. The molecular structures were optimized using Becke's three-parameter hybrid functional (B3LYP). The electronic excitation spectra in the range of 400-700 nm were calculated using the ADC(2) and the linear-response time-dependent DFT methods.

Theoretical investigation of the ethylene dimer: interaction energy and dipole moment.

The interaction potential energy and the interaction-induced dipole moment surfaces of the van der Waals C(2)H(4)-C(2)H(4) complex has been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules. The calculations have been carried out using high-level ab initio theory with the aug-cc-pVTZ basis set and within the framework of the analytical description of long-range interactions between ethylene molecules. Binding energy for the most stable configuration of the C(2)H(4)-C(2)H(4) complex was calculated at the CCSD(T)/CBS level of theory.

Dipole moment surface of the van der Waals complex CH4-N2.

The interaction-induced dipole moment surface of the van der Waals CH(4)-N(2) complex has been calculated for a broad range of intermolecular separations R and configurations in the approximation of the rigid interacting molecules at the MP2 and CCSD(T) levels of theory using the correlation-consistent aug-cc-pVTZ basis set with the basis set superposition error correction. The simple model to account for the exchange effects in the range of small overlap of the electron shells of interacting molecules and the induction and dispersion interactions for large R has been suggested. This model allows describing the dipole moment of van der Waals complexes in analytical form both for large R, where induction and dispersion have the key role, and for smaller R including whole ranges of their potential wells, where the exchange effects are important.

Static polarizability surfaces of the van der Waals complex CH4-N2.

The static polarizability surfaces of the van der Waals complex CH(4)-N(2) have been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules. The calculations have been carried out at the CCSD(T) and MP2 levels of the theory using the aug-cc-pVTZ basis set with the BSSE correction and within the framework of the classical long-range multipolar induction and dispersion interactions. It was shown that the results of analytical polarizability calculations for the CH(4)-N(2) complex are in a good agreement with the ab initio polarizabilities in the outer part of the van der Waals well on the complex potential surface.

Theoretical investigation of the potential energy surface of the van der Waals complex CH4-N2.

The interaction potential energy surface of the van der Waals CH(4)-N(2) complex has been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules at the CCSD(T) and MP2 levels of theory using the correlation consistent aug-cc-pVTZ basis set. The BSSE correction was taken into account for all the calculations. The most stable configurations of the complex were found.