Two intramolecular interactions, i.e., (1) hydrogen bond and (2) substituent effect, were analyzed and compared. For this purpose, the geometry of 4- and 5-X-substituted salicylaldehyde derivatives (X = NO(2), H or OH) was optimized by means of B3LYP/6-311 + G(d,p) and MP2/aug-cc-pVDZ methods. The results obtained allowed us to show that substituents (NO(2) or OH) in the para or meta position w...

After nitrogen, fluorine is probably the next most favorite hetero-atom for incorporation into small molecules in life science-oriented research. This review focuses on a particular fluorinated substituent, the trifluoromethoxy group, which is finding increased utility as a substituent in bioactives, but it is still perhaps the least well understood fluorine substituent in currency. The present...

The Cu(I) complexes having phenanthroline derivatives as ligands are known to exhibit photo-induced 'flattening' structural change in the metal-to-ligand charge transfer (MLCT) excited state. Our recent ultrafast spectroscopic studies of [Cu(dmphen)2](+) (dmphen = 2,9-dimethyl-1,10-phenanthroline) showed that the photo-induced structural change predominantly occurs in the S1 state on a subpicos...

Ab initio calculations of the spin-spin coupling constants have been carried out for methanand ethanimine, methanaland ethanaloxime at the level of the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes (SOPPA(CCSD)) using the aug-cc-pVTZ-J basis sets. Previously we have shown that this method can reproduce quantitatively the coupling constant...

Motivated by the need for chemical strategies designed to tune peptide fragmentation to selective cleavage reactions, benzyl ring substituent influence on the relative formation of carbocation elimination (CCE) products from peptides with benzylamine-derivatized lysyl residues has been examined using collision-induced dissociation (CID) tandem mass spectrometry. Unsubstituted benzylamine-deriva...

Abstract Simple polycyclic aromatic hydrocarbons, substituted by strongly electron-donating (NH 2 ) and withdrawing (NO groups, are studied employing density functional theory (DFT) calculations. A new approach to a description of the substituent effect, energy substituent, E (X), is proposed evaluated. It defined as (X) = (R-X)? (R), where R unsubstituted system; X NH , NO . Changes in substit...