Robert W. Góra

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The photoinduced isomerization of diaminomaleonitrile (DAMN) to diaminofumaronitrile (DAFN) was suggested to play a key role in the prebiotically plausible formation of purine nucleobases and nucleotides. In this work we analyze two competitive photoisomerization mechanisms on the basis of state-of-the-art quantum-chemical calculations. Even though it was(More)
The potential energy surface (PES) of Ti@C(28) has been revisited, and the stationary points have been carefully characterized. In particular, the C(2v) symmetry structure considered previously turns out to be a transition state lying 2.3 kcal/mol above the ground state of C(3v) symmetry at the MP2/6-31G(d) level. A large binding energy of 181.3 kcal/mol is(More)
The hybrid variation -- perturbation many-body interaction energy decomposition scheme has been applied to analyze the physical nature of interactions in the ionic 3-pentenenitrile, 2-nitro-5-oxo, ion(-1), sodium crystal, which can be regarded as a model for a large group of aromatic quaternary nitrogen salts. In the crystal structure the sodium ions and(More)
Certain cyanine dye molecules have been observed to self-assemble in DNA templates to form large chiral aggregates, which exhibit induced circular dichroism. The structure and circular dichroism (CD) of one such system, aggregates of a cationic DiSC2(5) cyanine dye, are investigated using the time-dependent Kohn-Sham density functional theory (TD-DFT) and(More)
A new approach for the analysis of intermolecular interactions in a solution is proposed. The changes in the interaction energy components due to the solvent effects are estimated on the basis of the interaction energy calculated in the presence of the electric field induced in a polarizable medium, or in the field of the effective fragment potentials.(More)
The intermolecular hydrogen bonds in dimers of formic acid, acetic acid, and formamide were investigated. Additionally, three configurations of the pyrrole-2-carboxylic acid (PCA) dimer were studied to analyze how the pyrrole pi-electron system influences the carboxylic groups connected by double O-H...O hydrogen bonds. The ab initio calculations for the(More)
Newly developed method for characterisation and analysis of humic substances (HS) and humic-like substances (HULIS) in air dust particles was tested for potential interferences caused by abundant co-sampled pollens (common dandelion, common wormwood-absinth, apple tree). RP-HPLC using 10-step gradient of dimethylformamide (DMF) in a buffered aqueous mobile(More)
Twenty hydrogen-bonded complexes composed of nucleic acid base and amino acid side chain have been analyzed using ab initio quantum chemistry methods with the aim of gaining insights into the nature of molecular interactions in these systems. The intermolecular interaction energies were estimated using the second-order Møller-Plesset perturbation theory and(More)
The alternative nucleobase isocytosine has long been considered as a plausible component of hypothetical primordial informational polymers. To examine this hypothesis we investigated the excited-state dynamics of the two most abundant forms of isocytosine in the gas phase (keto and enol). Our surface-hopping nonadiabatic molecular dynamics simulations(More)
The origins of stabilization in the short strong hydrogen bonds commonly referred to as "resonance-assisted" (RAHB) have been revisited using the modern valence-bond theory, the hybrid variational-perturbational interaction energy decomposition scheme and atoms in molecules (AIM) analysis. Dimers of carboxylic acids and amides have been chosen as the model(More)