Biomedical subjects

Duan-Jun Xu

Publications and source records attributed to Duan-Jun Xu.

9 recordsLinked to original sources

PubMed2005

Diaqua(2,2'-diamino-4,4'-bi-1,3-thiazole)oxosulfatovanadium(IV) tetrahydrate.

The title compound, [VO(SO(4))(C(6)H(6)N(4)S(2))(H(2)O)(2)].4H(2)O, displays a distorted octahedral coordination geometry. The 2,2'-diamino-4,4'-bithiazole ligand is present in the usual chelating bidentate mode. The sulfate ligand coordinates in a monodentate fashion to the V atom. A large displacement of the V atom from the equatorial plane towards the oxo group correlates with the strong V=O double bond. In the crystal structure, a three-dimensional supramolecular network is formed by hydrogen bonds.

Journal Article↗

PubMed2005

catena-Poly[[aquabis(1H-benzimidazole-kappa N3)manganese(II)]-mu-adipato].

In the title polymeric complex, [Mn(C6H8O4)(C7H6N2)2(H2O)]n, the MnII atom is surrounded by two adipate dianions, two benzimidazole molecules and one coordinated water molecule. The Mn atoms and coordinated water molecule are located on a twofold axis, and the bridging adipate ligand is located on an inversion center. The adipate dianions bridge neighboring MnII atoms to form polymeric chains. Each MnII atom is seven-coordinate, the longest Mn-O bond length being 2.5356 (16) A.

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PubMed2004

catena-Poly[[bis(1H-benzimidazole-kappaN3)(salicylato-kappaO)copper(II)]-mu-salicylato-O,O':O''].

The title compound, [Cu(C7H5O3)2(C7H6N2)2]n, is a one-dimensional polymeric complex bridged by salicylate anions. The Cu(II) atom is surrounded by three salicylate and two benzimidazole ligands, with a tetragonally elongated octahedral coordination geometry. The Cu-O bond distances in the axial directions are 2.6092 (16) and 2.6834 (17) A. pi-pi stacking interactions exist between the benzimidazole rings of neighboring polymeric complex chains.

Benzimidazoles↗

PubMed2004

Poly[[bis(1H-benzimidazole-kappaN3)cadmium(II)]-mu-aqua-mu-succinato-kappa2O1:O4].

The title compound, [Cd(C(4)H(4)O(4))(C(7)H(6)N(2))(2)(H(2)O)](n), is a three-dimensional polymeric complex. The Cd(II) atom is located on an inversion centre and assumes an elongated octahedral coordination geometry, with a long Cd-O distance of 2.5381 (5) A to the coordinated bridging water molecule. The succinate dianion, located on another inversion centre, bridges adjacent Cd atoms to form succinate-bridged polymeric chains. The coordinated water molecule is located on a twofold axis and links adjacent succinate-bridged chains to form a water-bridged polymeric chain.

Journal Article↗

PubMed2003

Bis(di-2-pyridylphosphinato-kappa3N,O,N')copper(II) dichloromethane disolvate.

The solid-state structure of the first reported homoleptic copper di-2-pyridylphosphinate complex shows an extremely large 'z-out' tetragonal distortion, with an axial Cu.O distance of 2.430 (2) A. The title complex, [Cu(C(10)H(8)N(2)O(2)P)(2)].2CH(2)Cl(2) or Cu[py(2)P(O)O](2).2CH(2)Cl(2), comprises two di-2-pyridylphosphinate ligands coordinated to the central copper(II) ion, which sits on an inversion center. The pyridyl rings of one ligand are trans to the pyridyl rings of their symmetry-related counterpart. The two trans py-Cu-py moieties are coplanar, as required by the inversion symmetry. A disordered dichloromethane solvent molecule is cocrystallized in the asymmetric unit cell.

Journal Article↗

PubMed2003

Helical catena-poly[[tris(1H-benzimidazole-kappaN(3))cobalt(II)]-micro-maleato-kappa(3)O,O':O"].

The crystal structure of the title compound, [Co(C(4)H(2)O(4))(C(7)H(6)N(2))(3)](n), consists of polymeric chains of the Co(II) complex. Two maleate dianions and three benzimidazole ligands coordinate to the Co(II) atom with a distorted octahedral geometry. The maleate dianions bridge neighbouring Co(II) atoms via both terminal carboxylic acid groups, one of which is monodentate and the other bidentate, to form a helical structure of alternating maleate dianions and Co(II) atoms, with a pitch height of 9.2667 (17) A. The absolute structure has been determined, and the crystal contains only right-handed helices. Intrahelical N-H...O hydrogen bonds stabilize the helical structure, while interhelical N-H...O hydrogen bonds link neighbouring helices to form the supramolecular structure.

Journal Article↗

PubMed2003

Benzaldehyde 2,4-dinitrophenylhydrazone.

Crystals of the title compound, C(13)H(10)N(4)O(4), were obtained from a condensation reaction of benzaldehyde and 2,4-dinitrophenylhydrazine. The molecule assumes an approximately planar E configuration. Within the dinitrophenyl moiety, the average distance for the aromatic C-C bonds close to the imino group [1.417 (3) A] is appreciably longer than the average distance for the other aromatic C-C bonds in the same phenyl ring [1.373 (3) A]. This increased distance may be a result of the overlap of the non-bonding orbital of the imino N atom with the pi orbitals of the arene. It is likely that pi-pi stacking exists in the crystal structure.

Journal Article↗

PubMed2002

(R)-mandelic acid (S)-alanine hemihydrate.

Crystals of the title complex, C(3)H(7)NO(2).C(8)H(8)O(3).0.5H(2)O, were obtained from an aqueous solution containing racemic mandelic acid and (S)-alanine. The unit cell includes two independent molecular complexes and one water molecule. The structure formed by (R)-mandelic acid and (S)-alanine in a 1:1 molar ratio shows the successful optical separation of racemic mandelic acid. Strong hydrogen bonding, with a rather short O...O separation of 2.494 (3) A, is observed between the carboxyl and carboxylate groups. A structural comparison suggests that the strong hydrogen bonding affects the neighbouring covalent bond.

Journal Article↗

PubMed2002

(1R,3S)-Camphoramic acid.

The title chiral compound, 3-aminocarbonyl-1,2,2-trimethylcyclopentane-1-carboxylic acid, C(10)H(17)NO(3), was prepared from (1R,3S)-camphoric acid. The five-membered ring adopts a conformation which is intermediate between a twist and an envelope. Elongations of the C-C bonds and contractions of the C-C-C bond angles are observed within the five-membered ring. A (1)H NMR spectrum was recorded to assist in distinguishing the amide group from the carboxyl group.

Journal Article↗