Xian-He Bu

Synthesis, crystal structure, antitumor activity and DNA-binding study on the Mn(II) complex of 2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline.

The complex [Mn(L)(NO(3))(2)(H(2)O)(2)] (1) (L=2H-5-hydroxy-1,2,5-oxadiazo[3,4-f]1,10-phenanthroline) was synthesized and characterized by elemental analysis, IR and UV. The crystal and molecular structure of 1 was determined by single-crystal X-ray diffraction; crystal data: light yellow, monoclinic, space group P2(1)/n, Z=4, a=7.432(2) A, b=9.582(3) A, c=23.445(7) A, beta=90.519(5) degrees. The Mn atom in 1 is hexa-coordinated in a distorted octahedral arrangement by two N atoms of the ligand L and four O atoms of two water molecules and two nitrate anions. Biological tests in vitro showed that 1 has significant antitumor activity against HL-60, KB, Hela and BGC-823 cells. The interaction of 1 with calf thymus DNA was investigated by absorption titration, thermal denaturation and viscosity measurements. The results suggest that 1 binds with DNA by intercalating via the ligand L.

Novel Diazamesocyclic Ligands Functionalized with Pyridyl Donor Group(s) − Synthesis, Crystal Structures, and Properties of Their Copper(II) Complexes

Two novel diazamesocyclic ligands based on l,5-diazacyclooctane (DACO) and functionalized with additional pyridyl donor groups, namely 1,5-bis(2-pyridylmethyl)-1,5-diazacyclooctane (L1) and 1-(2-pyridylmethyl)-1,5-diazacyclooctane (L2), have been synthesized and characterized, as have their CuII complexes. Crystal structure analyses revealed that with Cu(ClO4)2L1 forms a five-coordinate mononuclear complex [CuIIL1Cl]ClO4 (1), whereas L2 forms a µ-Cl−-bridged dinuclear complex [CuII(L2)Cl]2(ClO4)2 (2). Furthermore, it has been found that the apical chloride anion of 1 may be easily exchanged by azide anion, forming the mononuclear complex [CuIIL1(N3)]ClO4 (3). There is a notable difference between 3 and 1 in that 3 forms a quasi-two-dimensional network through intermolecular C−H···O hydrogen bonds and π−π stacking interactions. Each CuII center in the three complexes is pentacoordinated in a distorted square-pyramidal environment and the DACO ring of each ligand adopts a boat-chair configuration in all the complexes. In the mononuclear complexes 1 and 3, the Cl− or N3− anions occupy the apical sites, whereas in the dinuclear complex 2 the two bridging Cl− anions occupy both axial positions as well as one equatorial position, leading to an intramolecular Cu···Cu separation of 3.396 A. Variable-temperature magnetic susceptibility measurements on 2 in the range 4−300xa0K indicate a weak intramolecular ferromagnetic coupling between adjacent CuII centers with 2J = 2.28 cm−1; the magneto-structural correlations are discussed in detail. The solution behavior of the complexes has been further studied by UV/vis and ESR techniques.

Manganese(II) complex of 6,7-dicycanodipyridoquinoxaline with antitumor activities: synthesis, crystal structure and binding with DNA.

A new Mn(II) complex with the planar ligand 6,7-dicycanodipyrido[2,2-D:2,3-f]quinoxaline (L) [MnL(NO(3))(H(2)O)(3)]NO(3).CH(3)OH (1) has been synthesized and characterized by elemental analysis, IR, TG-DTA and molar conductance. Its crystal structure was determined by X-ray diffraction, crystal data: yellow, triclinic, space group P1;, Z=2, a=7.3743(8) A, b=11.2487(15) A, c=14.1655(15) A, alpha=79.412(2) degrees, beta=83.208(2) degrees, gamma=80.466(2) degrees. The Mn atom was hexa-coordinated to form a distorted octahedral geometry by two nitrogen atoms of L and four oxygen atoms of three H(2)O and NO(3)(-) in the complex. The binding mode of the complex with calf thymus DNA has also been investigated with spectrophotometric methods, viscosity and thermal denaturation measurements. The experimental results indicate that the complex intercalated into DNA base pairs via the ligand L. The intrinsic binding constant K(b) values for 1 (5.00 x 10(5) M(-1)) and L (1.65 x 10(5) M(-1)) were determined by absorption titration and calculated with the model of McGhee and Von Hippel. Biological tests against four different cell lines (HL-60, KB, Hela and BGC-823) in vitro showed that the complex had significant antitumor properties since the 50% inhibition concentrations (IC(50)) of the complex were within a microM range similar to those of antitumor drug 5-fluorouracil.

Three-dimensional frameworks built from hydrogen bonds and π–π stacking interactions: structural and spectral study on Co(II) complexes of 1,5-diazacyclooctane (DACO) functionalized by heterocyclic pendants

Abstract A series of penta-coordinated Co(II) complexes of 1,5-diazacyclooctane (DACO) functionalized by additional imidazole or pyridine donor pendants, [CoL1Cl](ClO4)·H2O (1), [CoL2Cl](ClO4) (2) and [CoL3Cl](ClO4) (3), where L1=1,5-bis(imidazole-4-ylmethyl)-DACO, L2=1,5-bis(N-1-methylimidazol-2-ylmethyl)-DACO and L3=1,5-bis(pyridyl-2-ylmethyl)-DACO, have been synthesized and characterized by IR spectra, elemental analyses, conductance, thermal analyses and UV–Vis techniques. The structures of complexes 1 and 2 have been determined by X-ray crystallography. In all the mononuclear complexes, each Co(II) center is penta-coordinated due to the boat/chair configuration of the DACO rings and quite stable to oxidation. The most striking feature of complexes 1 and 2 is the formation of different 3D networks with channels through hydrogen-bonding and π–π stacking interaction. The solution behaviors of all the complexes have been further analyzed in detail.

Frequency-upconverted organic crystal.

The fluorescent characteristics of Trogers base have been investigated experimentally. A one-photon-induced fluorescent spectrum was observed, and the peak wavelength was at 337 nm with a full width at half-maximum of ~85nm . The violet radiation of the Trogers base crystal could result from the pi(*) -pi transition of the benzenoid pi bond. Two-photon-pumped frequency-upconverted fluorescence was obtained, which is a wideband emission with the main peak wavelength at 337 nm and a subordinate peak. Donor groups and acceptor groups of electrons in the aromatic rings strengthen the two-photon-pumped frequency-upconverted fluorescence.

Novel nickel(II) complexes with diazamesocyclic ligands functionalized by additional phenol donor pendant(s): synthesis, characterization, crystal structures and magnetic properties

The formation of two unique μ-phenoxo-bridged nickel(II) complexes with l,5-diazacyclooctane (DACO) ligands functionalized by additional phenol donor pendants has been achieved and the complexes have been characterized by IR, elemental analyses, conductivity, thermal analysis, and UV-Vis techniques. Single-crystal X-ray diffraction analyses reveal that HL111 forms a phenoxo-bridged binuclear complex (in the presence of N3− anions) [NiL111(N3)]2·0.5H2O 1, H22L22 a phenoxo-bridged edge-sharing linear trinuclear complex [Ni3(L22)2(C2H5OH)2Cl2] 2, where HL111xa0= 1-(2-hydroxybenzyl)-1,5-diazacyclooctane and H22L22xa0=xa01,5-bis(2-hydroxybenzyl)-1,5-diazacyclooctane. In 1 the two NiII are in five-coordinated distorted square-pyramidal environments with a intramolecular Niu2006⋯u2006Ni distance of 3.1232(13) A. However in 2 the two terminal NiII are in nearly ideal square-pyramidal coordination environments and the central NiII takes an octahedral configuration by axial coordination of two ethanol molecules, the adjacent intramolecular Niu2006⋯u2006Ni distance being 3.132(2) A. Such a trinuclear nickel(II) complex with square-pyramidal/octahedral/square-pyramidal coordination is unprecedented. These results also indicate that the coordination chemistry of the nickel(II) complexes with DACO ligands can be controlled by altering the pendant donors. Variable-temperature magnetic data show that both complexes display modest intramolecular antiferromagnetic coupling between adjacent nickel(II) centers, which is unusual for such linear trinuclear nickel(II) complexes. The magneto-structural correlation has been investigated for both complexes, and a rough correlation between the exchange coupling and the Ni–O–Ni angle of phenoxo-bridged binuclear nickel(II) complexes obtained and discussed. np

Novel organic crystals as candidates for frequency up-converted materials: syntheses and crystal structures of two Tröger's bases

The syntheses and crystal structures of two novel Trögers bases as candidates for frequency up-coverted organic materials are reported.

Novel copper(II) complexes with diazamesocyclic ligands functionalized by additional donor group(s): syntheses, crystal structures and magnetic properties

Copper(II) complexes with three diazamesocyclic ligands based on l,5-diazacyclooctane (DACO) bearing additional imidazole or phenol functional donor groups, 1,5-bis(imidazol-4-ylmethyl)- (L111), 1-(imidazol-4-ylmethyl)- (L222), and 1-(2-hydroxybenzyl)-1,5-diazacyclooctane (HL333), have been newly synthesized and characterized, and their structures determined by X-ray diffraction analyses. It has been revealed that with Cu(ClO4)2·6H2O L111 forms a mononuclear complex [CuL111Cl]ClO4·H2O 1, L222 forms a μ-Cl− bridged binuclear complex [CuL222Cl]2[ClO4]22, whereas HL333 forms a phenoxo-bridged binuclear complex [CuL33(H2O)]2[ClO4]23. Each CuII in the three complexes is five-coordinated in a distorted square-pyramidal environment. For the mononuclear complex 1 the Cl− anion is at the apical site, whereas for the μ-Cl−-bridged binuclear complex 2 the two bridging Cl− anions occupy both the axial and one equatorial position with Cu–Cl–Cu angle 88.81(5)° and intramolecular Cuu2006⋯u2006Cu separation 3.494(8) A. In the phenoxo-bridged binuclear complex 3 the Cu–O–Cu bridging angle is 100.80(12)° and the intramolecular Cuu2006⋯u2006Cu distance is 3.0324(9) A. Variable-temperature magnetic susceptibility measurements on the two binuclear complexes 2 and 3 in the range 4.2–300 K indicate a quite different magnetic intramolecular coupling between the binuclear copper(II) centers, from a weak ferromagnetic to a very strong antiferromagnetic coupling, with 2Jxa0=xa01.16 (for 2) vs. −574 cm−1 (for 3), and the magneto-structural correlations are discussed in detail. The solution behaviors of the complexes have been further studied by UV/Vis and ESR techniques.

A large delocalized π-electron system: diquinoxalino­[2,3-a:2′,3′-c]­phenazine chloro­form solvate

The title compound, C24H12N6·CHCl3, crystallizes in the monoclinic system in space group P21/c. The structure consists of one molxadecule of diquinoxalinoxad[2,3-a:2′,3′-c]xadphenazine (Dqpz), which is a large delocalized π-electron system, and a chloroxadform solvent molxadecule. There exist weak intermolecular C—H⋯N and π–π interactions between adjacent Dqpz molxadecules.

A novel heptacoordinated cobalt(II) complex of 6,7-di­cyano­dipyridoquinoxaline (dcdpq): [Co(NO3)2(CH3CN)(dcdpq)]

The title complex, (acetoxadnitrile)(6,7-dixadcyanoxaddipyridoxad[3,2-f;2,3-h]xadquinoxine)xaddixadnitroxadcobalt(II), [Co(NO3)2(C2H3N)(C16H6N6)], crystallizes in the monoclinic system with space group P21. The CoII center is heptacoordinated by two N atoms of the pyridine moieties, four O atoms of two nitrate anions and one N atom of a CH3CN molxadecule. The crystal structure reveals that the CoN3O4 coordination sphere has a distorted pentagonal-bipyramid geometry.