The planarity of the polyene chain of the retinal chromophore in bacteriorhodopsin is studied using molecular dynamics simulation techniques and applying different force-field parameters and starting crystal structures. The largest deviations from a planar structure are observed for the C(13)==C(14) and C(15)==N(16) double bonds in the retinal Schiff base structure. The other dihedral angles al...

In the title compound, C(15)H(15)N(3)O(3)·H(2)O, the hydazide Schiff base mol-ecule shows an E conformation around the C=N bond. An intra-molecular O-H⋯N hydrogen bond makes an S(6) ring motif. The dihedral angle between the substituted phenyl rings is 23.40 (11)°. The water mol-ecule mediates linking of neighbouring mol-ecules through O-H⋯(O,O) hydrogen bonds into infinite chains along the a a...

The crystal structure of the title salt, [Cu(ClO4)(C8H20N4)]ClO4, is reported. The CuII ion exhibits a square-pyramidal geometry and is coordinated by the four N atoms of the neutral 1,4,7,10-tetra-aza-cyclo-dodecane (cyclen) ligand and an O atom from one perchlorate anion, with the second perchlorate ion hydrogen-bonded to one of the amine N atoms of the cyclen ligand. Additional N-H⋯O hydroge...

Thiol esters and boronic acids react to produce ketones under aerobic conditions in the presence of catalytic quantities of a CuI or CuII salt. The reaction occurs at reasonable rates between room temperature and 50 degrees C at neutral pH using thiol esters derived from bulky 2 degrees amides of thiosalicylamides such as those based on N-tert-butyl-2-mercaptobenzamide. In this mechanistically ...

In the centrosymmetric tetra-nuclear title complex, [Ni(4)(C(12)H(15)NO(3))(2)(CH(3)COO)(2)(N(3))(2)(CH(3)OH)(2)]·2CH(3)OH, the asymmetric unit comprises half of a complex mol-ecule and a methanol solvent mol-ecule. The Ni(II) ions display two different coordination environments: (i) two O atoms from the Schiff base ligand, two O atoms from symmetry-related methanol mol-ecules and an O atom fro...

In each of the two independent mol-ecules in the asymmetric unit of the title compound, [Cu(C(13)H(15)NO(3))(C(3)H(4)N(2))], the Cu(II) atom is four-coordinated by two O atoms and the N atom of the tridentate Schiff base ligand and one N atom from the imidazole ligand in a distorted square-planar geometry. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O hydrogen bonds.

The crystal structure of title compound, [Eu(NO(3))(3)(C(15)H(15)NO(2))(2)], contains two Schiff base 6-meth-oxy-2-[(4-methyl-phen-yl)imino-meth-yl]phenolate (L) ligands and three independent nitrate ions that chelate to the europium(III) ion via the O atoms. The coordination number of the Eu(III) ion is ten. The L ligands chelate with a strong Eu-O(deprotonated phenolate) bond and a weak Eu-O(...

By exploiting dynamic nuclear polarization (DNP) at 90 K, we observe the first NMR spectrum of the K intermediate in the ion-motive photocycle of bacteriorhodopsin. The intermediate is identified by its reversion to the resting state of the protein in red light and by its thermal decay to the L intermediate. The (15)N chemical shift of the Schiff base in K indicates that contact has been lost w...

The tetra-nuclear title complex, [Zn4(C19H20N2O4)2(CH3COO)4], is formed from two dinuclear motifs related by an inversion centre. The two crystallographically independent Zn(II) ions in the asymmetric unit are in different coordination environments. One is square-based pyramidal with one O atom of an acetate group occupying the axial position and two N and O atoms of one bmspd [H2bmspd = N,N'-b...

The title compound, C(15)H(13)BrClNO, is a Schiff base derived from the condensation of equimolar quanti-ties of 3-bromo-5-chloro-salicylaldehyde and 1-phenyl-ethanamine. The structure displays a trans configuration with respect to the imine C=N double bond. The N atom is also involved in an intra-molecular O-H-N hydrogen bond, which stabilizes the configuration of the compound.