Comparative semiempirical and DFT study of styrylnaphthalenes and styrylquinolines and their photocyclization products

Abstract

Semiempirical molecular orbital (PM3, PM6, and RM1) and density functional theory (DFT) (B3LYP/6-31G*) studies are carried out for 1-and 2-styrylnaphthalenes and their aza-derivatives-2-and 4-styrylquinolines. Relative stabilities of three isomeric forms: E-and Z-isomers and the closed-ring dihydrocyclophotoproduct (derivative of dihydrophenanthrene) are calculated. Compared to PM3, PM6 and especially RM1 understate heats of formation; in some cases, PM6 and RM1 even place Z-isomer in energy below E-isomer. PM3 rather close to DFT predicts heats of isomerization reaction, whereas PM6 and especially RM1 underestimate these values. Semiempirical methods in comparison with DFT markedly underestimate heats of cyclization reaction; however, reproduce trends in relative stabilities of different isomers in dependence on the structure of styrylnaphthalenes and styrylquinolines. Qualitative correlation is found between calculated relative stabilities of the closed-ring forms (heats of cyclization reaction) and experimental data: cyclized products with low heats of cyclization are observed in steady-state photolysis and those with high heats of cyclization are not. In the latter case, the closed-ring compounds, if formed in the excited state, due to thermal instability decompose rapidly with ring opening in the ground state that prevents their observation.

Osteogenic response to BMP‐2 of hMSCs grown on apatite‐coated scaffolds

“…Comparison of different semiempirical methods − PM3, PM5, PM6, and RM1 – in calculations of diarylethylenes28, 29 showed that comparatively recently developed methods PM5, PM6, and RM1 overestimated relative stability of Z ‐isomers (underestimated heat of isomerization reaction), and in some cases even placed Z ‐isomers below E ‐isomers on the energy scale. Being in general clearly superior,30 as applied to calculation on diarylethylenes, the new parametric methods proved to be somewhat worse than PM3 31.…”

Tetrasubstituted Pyrrole Derivative Mimetics of Protein–Protein Interaction Hot-Spot Residues: A Promising Class of Anticancer Agents Targeting Melanoma Cells

“…In order to estimate the effect of the introduced structural modifications on the conformational properties of the new TSPs, the former lead 1 was included in the analysis. Indeed, the conformational space of the first series of TSPs was explored by applying in vacuum semi-empirical PM6 [ 16 ] calculations [ 11 ] while, in the present study, we performed density functional theory (DFT) [ 17 ] calculations and used the conductor-like polarizable continuum model (C-PCM) [ 18 ] to mimic an aqueous environment.…”

Photonics of styrylquinoline dyads

“…clization reaction of 2-styrylquinoline (in S 0 state) [30,31]. The closed-ring compounds (DHPs), if formed in the excited state, due to thermal instability decompose rapidly with ring opening in the ground state that prevents their observation in steady-state photolysis.…”