In the title structure, C21H20O5·C2H5OH, the curcumine-type mol-ecule has a double E conformation for the two benzyl-idene double bonds [C=C = 1.342 (4) and 1.349 (4) Å] and is nearly planar with respect to the non-H atoms (r.m.s. deviation from planarity = 0.069 Å). The two phenolic OH groups form bifurcated hydrogen bonds with intra-molecular branches to adjacent meth-oxy O atoms and inter-mo...

Crystal structures of Schiff bases containing pyridoxal (PL), N-(pyridoxylidene)-tolylamine, C(15)H(16)N(2)O(2) (I), N-(pyridoxylidene)-methylamine, C(9)H(12)N(2)O(2) (III), and their 1:1 adduct with 2-nitrobenzoic acid, (I)(+) C(7)H(4)NO_4;- (II), and 4-nitrobenzoic acid, (III)(+) C(7)H(4)NO_4;- (IV), serve as models for the coenzyme pyridoxal-5'-phosphate (PLP) in its PLP-dependent enzymes. T...

Theoretical calculations at the MP2 level, NBO and AIM analysis, and matrix-isolation infrared spectroscopy have been used to investigate the structure of the isolated molecule of 1,4-butanediol (1,4-BDO). Sixty-five structures were found to be minima on the potential energy surface, and the three most stable forms are characterized by a folded backbone conformation leading to the formation of ...

Acid-base catalyzed glycosyl donor and then glycosyl acceptor activation with phenylboron difluoride or diphenylboron fluoride permits hydrogen bond mediated intramolecular S(N)2-type glycosidation in generally high anomeric selectivity.

The title compound, C(13)H(12)N(2)O(3), has an E configuration with respect to the C=N bond: the conformation is stabilized by an intramolecular O-H⋯N hydrogen bond. In the crystal, an N-H⋯O interaction links the molecules into a C(4) chain along [100].

Infrared-ultraviolet double resonance spectroscopy has been applied to study the infrared spectra of the supersonically cooled gas phase complexes of formic acid, acetic acid, propionic acid, formamide, and water with 9-hydroxy-9-fluorenecarboxylic acid (9HFCA), an analog of glycolic acid. In these complexes each binding partner to 9HFCA can function as both proton donor and acceptor. Relative ...

The title compound, C(17)H(21)N(3)O(3), has a Z configuration about the N=N double bond. The molecular conformation is stabilized by intramolecular N-H⋯O and O-H⋯N hydrogen bonds.

In the title compound, C(12)H(15)NO(3), all C, N and O atoms lie in a mirror plane. An intramolecular C-H⋯O hydrogen bond is present.

Molecules of the title compound, C12H12N6, contain both a diimine linkage and an N-N bond, and assume a planar structure. The compound lies about an inversion centre and there are three intramolecular C-H...N hydrogen bonds.

A detailed NMR study of the thiopeptide amythiamicin D establishes its solution conformation and the presence of a single intramolecular hydrogen bond involving NH13 and O28, and also provides the first evidence for self-association of thiopeptides in solution.