Qin-Hui Luo

Synthesis, characterization and scavenger effects of OH• and O−•2 radicals of lanthanide(III) complexes with pyruvic acid semicarbazone

Abstract Complexes of lanthanide chlorides with pyruvic acid semicarbazone (PASH), having the general formula Ln(PAS)3·nH2O (where Ln = La−Nd,Sm-Dy, Er, Yb; n = 1−3), have been synthesized and characterized on the basis of elemental analyses, IR spectra and thermal analyses. It has been found that the ligand and its complexes possess scavenger effects on OH• and O−•2 radicals.

A study on the structure and properties of a new model compound of Cu(II)Zn(II)-superoxide dismutase

[N,N′-butylenebis(2-acetylpyridineiminato)] copper(II) diperchlorate, a new model compound of CuZn-SOD (Cu(II)Zn(II)-superoxide dismutase) was synthesized and studied. Its spectral properties and crystal structure showed that it has planar square configuration distorted toward tetrahedron, being very similar to the active center of Cu(II)Zn(II)-SOD. Its activity is 10% of CuZn-SOD and twenty-eight times that of Na2 [Cu(salicylate)2].

Synthesis, structure and electrochemical behaviour of cobalt(II) complexes with 2,6-bis(benzimidazol-2′-yl) pyridine

SummaryThe complexes Co(BBP)Cl2, Co(BBP)2SO4·H2O, Co(BBP)2(NO3)2·H2O, Co(BBP)2(ClO4)2 and Co(BBP−H)2· 2H2O, where BBP is 2,6-bis(benzimidazol-2′-yl) pyridine, were prepared and characterized by elemental analysis, electrical conductance, i.r. and electronic spectra. The electrochemical behaviour of the complexes was recorded and the X-ray crystal structure of Co(BBP)Cl2(MeOH)2 was determined. The geometry about cobalt is a distorted octahedron.

Heterodinuclear Cryptates [EuML(dmf)](ClO4)2 (M=Ca, Cd, Ni, Zn): Tuning the Luminescence of Europium(III) through the Selection of the Second Metal Ion

Four heterodinuclear cryptates [EuML(dmf)](ClO(4))(2) (M=Ca, Cd, Ni, Zn) were synthesized by a two-step method (L denotes deprotonated anionic cryptand synthesized by condensation of tris(2-aminoethyl)amine with 2,6-diformyl-4-chlorophenol). The ES-MS spectra of the four cryptates and the crystal structure of [EuNiL(dmf)](ClO(4))(2) x MeCN confirm that a strict dinuclear Eu(III)-M(II) entity exits in the cryptates. The cyclic voltammetry and luminescence spectral investigations indicate that the introduction of second metal ions into the mononuclear Eu(III) cryptate result in a negative shift of the redox potential of Eu(III) and a change in luminescence intensity of Eu(III). The cryptate [EuML(dmf)](ClO(4))(2) was shown to quench the emission of Eu(III) when M=Ni and to enhance the emission of Eu(III) when M=Ca, Cd, and Zn in the sequence: mononuclear

The synthesis and crystal structure of imidazolate-bridged [Cu(tern)(im)Zn(tren)](ClO4)3·MeOH (tren = tris(2-aminoethyl)amine; im = imidazolate]

The reaction of [Cu(tren)](ClO4)2[tren = tris(2-aminoethyl)amine] with [Zn(tren)](ClO4)2 and imidazole in alkaline MeOH–H2O solution gives imidazolate-bridged [Cu(tren)(im)Zn(tren)](ClO4)3·MeOH (im = imidazolate) which is similar to the active centre of superoxide dismutase as shown by X-ray crystallography.

A study on the mimics of Cu–Zn superoxide dismutase with high activity and stability: two copper(II) complexes of 1,4,7-triazacyclononane with benzimidazole groups

Two copper(II) complexes [CuL(1)Cl]ClO(4) and [CuL(2)MeCN](ClO(4))(2)xH(2)O were synthesized (L(1)= 1-(benzimidazole-2-ylmethyl)-1,4,7-triazacyclononane, L(2)= 1,4-bis(benzimidazole-2-ylmethyl)-1,4,7-triazacyclonone). The benzimidazole groups were N-substituents of tacn, and the complexes are more stable than their parents. They are able to catalyse the dismutation of superoxide anion in aqueous solutions at physiological pH and in bovine serum albumin solution (0.5 mg ml(-1)). X-ray structure analysis and EPR and electronic spectra show that the structure of complex is more similar to the Cu(II) centre of Cu(2)Zn(2)SOD than that. Comparing with other Cu(II) complexes, the complex possesses both high SOD activity and highly thermodynamic stability.

Synthesis, characterization and luminescence properties of lanthanide(III) complexes with 2,6-bis(benzimidazol-2'-YL)pyridine

Abstract New complexes of hydrated lanthanide(III) nitrates with 2,6-bis(benzimidazol-2′-yl)pyridine (BBP) having the formulae [Ln(BBP) 2 (NO 3 ) 2 ]NO 3 · n H 2 O (where Ln = La-Nd, Sm-Tb, n = 1,2), [Ln(BBP)(BBPH)(NO 3 )(OH 2 )]NO 3 · n H 2 O (where Ln = Dy, Er, n = 3, 4) and [Ln(BBPH)(NO 3 ) 2 (OH 2 )] · 2H 2 O (where Ln = Lu) have been prepared and characterized by elemental analyses, IR and electronic spectra, molar conductance, thermal analyses and X-ray powder diffraction patterns. The emission spectra of all the complexes have also been examined. It has been found that all the complexes show the luminescence of the ligand. The Sm, Eu and Tb complexes also show the corresponding metal ion luminescence.

Synthesis, structure and 1H NMR spectra of cadmium complexes with 2,6-bis(benzimidazol-2′-yl)pyridine

Abstract The cadmium complexes with the formulae CdLX 2 · n H 2 O (X = Cl − , n = 1; X = NO − 3 , n = 0.5), Cd(L-H)LX (X = ClO − 4 , BF − 4 ) and Cd(L-H)Ac, where L is 2,6-bis(benzimidazol-2′-yl)pyridine, were obtained by reactions of L with different cadmium salts in methanol and characterized by elemental analysis, electrical conductance, IR and 1 H NMR spectra. It has been found also that in the perchlorate, acetate and tetrafluoroborate complexes the ligand loses an N-proton on the benzimidazole ring of the ligand, acting as a singly negative ligand. The neutral complex (Cd(L-H) 2 was also first structurally characterized. The geometry about cadmium is a distorted octahedron with six nitrogen atoms from two singly negative tridentate ligands.

Synthesis, crystal structure and properties of a new dinuclear manganese(III) complex: a mimic for catalase

A new dinuclear manganese (III) complex [(ac)Mn(bbml)(2)Mn(ac)] x (BF(4))(2) x 3.5H(2)O (Hbbml=[bis(2-benzimidazolylmethyl)amino]ethanol, Hac=acetic acid) was synthesized and characterized by several physical methods. X-ray structure analysis shows that the complex has a dimeric unit and the two Mn(III) atoms are bridged by the oxygen atoms of the two ligands, forming a bis (micro-alkoxo)dimanganese core. The Mn-Mn distance is 3.2103 A. Electrospray mass spectrometry (ES-MS) experiment shows that the complex cation may easily have lost one or two ac(-) and leave unoccupied coordination site which would favor the coordination and activation of hydrogen peroxide. Furthermore, its catalytic activity for the disproportionation of hydrogen peroxide and the effect of added heterocyclic base were also investigated. The complex has some similarities to manganese catalase in structure and activity.

A dioxotetraamine fluorenyl ligand and its nickel(II) complex — crystal structure and fluorescent sensing properties in aqueous solution

Abstract A new ligand consisting of fluorenyl and dioxotetraaza units, namely, 2,10-diamino-6-(9H-fluoren-9-yl)-4,8-diazaundecane-5,7-dione (L), and its nickel(II) complex were synthesized. The crystal structure of [Ni(H−2L)] showed that Ni(II) is in a square planar coordination environment. Studies of solution chemistry of the ligand and its nickel(II) complex indicate that the ligand can form a stable complex with Ni2+ ions and fluorescence quenching of the ligand is accompanied by the coordination of the metal ion to the dioxotetraaza unit and electron transfer from the Ni(II) center to fluorenyl in aqueous solution.