Exacting control over conformation in response to an external stimulus is the central focus of molecular switching. Here we describe the synthesis of a series of diphenylacetylene-based molecular switches, and examine their response to covalent modification and deprotonation at remote phenolic positions. A complex interplay between multiple intramolecular hydrogen bond donors and acceptors dete...

In the centrosymmetric title compound, C(30)H(28)N(6)O(2), the dihedral angles between the anti-pyrine ring and the terminal phenyl and central benzene rings are 50.55 (10) and 14.62 (9)°, respectively. Some short inter-molecular C-H⋯O inter-actions may help to establish the packing. An intramolecular C-H⋯O hydrogen bond is also present.

Nucleosides spin-labelled with isoindoline-derived benzimidazole ((Im)U) and benzoxazole ((Ox)U) moieties were synthesized and incorporated into DNA oligonucleotides. Both labels display limited mobility in duplex DNA but (Im)U was less mobile, which was attributed to an intramolecular hydrogen bond between the N-H of the imidazole and O4 of the uracil nucleobase.

The diastereotopy of the methylene protons at positions 2 and 6 in 1,4-dihydropiridine derivatives with various substituents has been investigated. NMR spectroscopy and quantum chemistry calculations show that the CH···O intramolecular hydrogen bond is one of the factors amplifying the chemical shift differences in the 1H-NMR spectra.

the potential function of lippincott and schroeder for linear hydrogen bond has been re-examined and extended to nonlinear hydrogen bond. the parameters originally introduced to the potential function by lippincott and schroeder have been determined from the structural parameters such as 0.. .odistance 0-h bond distance, h.. .o distance and hoo angle. thevalidity of harmonic oscillator approxim...

In the title compound, C(15)H(14)ClNO(4)S, the benzene rings are oriented at a dihedral angle of 85.42 (1)°. An intra-molecular N-H⋯O hydrogen bond results in the formation of a five-membered ring and an intramolecular C-H⋯O inter-action also occurs.

has been synthesized as a conformational model for disulfide loops of limited ring size. 'H-nmr studies a t 270 MHz establish the presence of three intramolecular hydrogen bonds involving the Leu, Val, and methylamide NH groups in CDCl,. Evidence for peptide aggregation in CDCl, is also presented. A structural transition involving loosening of the hydrogen bond formed by the Val NH group is obs...

A combination of molecular modeling, DFT calculations, and advanced solid-state NMR experiments is used to elucidate the supramolecular structure of a series of benzoxazine oligomers. Intramolecular hydrogen bonds are characterized and identified as the driving forces for ring-shape and helical conformations of trimeric and tetrameric units. In fast MAS (1)H NMR spectra, the resonances of the p...