Search

Three novel mononuclear 4‐vinylpyridine‐based Fe(III) complexes [FeL(4‐VP)]BPh4 (4‐VP=4‐vinylpyridine; H2L=bis(salicylicdeneaminopropyl)amine, H2salten, 1; H2L=bis(salicylicdeneaminopropyl)methylamine, H2saltenMe, 2; H2L=bis(3‐methoxysalicylideneaminopropyl)methylamine, 3‐OMeH2saltenMe, 3) were synthesized and characterized. Single‐crystal X‐ray diffraction analyses revealed that 1–3 both present the mononuclear structure based on 4‐VP coordinated with bis(salicylicdeneaminopropyl)amine and its derivatives, which give 2D architectures by various interactions among cations and counter‐ions. Magnetic studies showed that both 1 and 2 exhibit one‐step complete spin‐crossover (SCO) behaviours with critical transition temperatures (T1/2) of 178 and 87 K respectively, while 3 exhibits one‐step incomplete spin crossover behaviour (T1/2,3=93 K). The introduction of methyl groups on the amine nitrogen of the Schiff base ligands in 2 and 3 give the bigger repulsive effect, further decrease the cooperation of spin centres, resulting in their spin transition occurring at lower temperatures. In addition, the presence of C−H⋯O weak interactions in 1 and 3 with synergistic effect, led to their spin transition temperatures being higher than that of 2. [ABSTRACT FROM AUTHOR]

Three novel transition metal coordination polymers, [Ni(CHNO)·2CHOH] ( 1), [Zn(CHNO)·4CHOH] ( 2) and [Cd(CHNO)·2CHOH] ( 3) (CHNO=2-acetylpyridine- d-tryptophan) were synthesized and characterized by elemental analysis, IR, UV, H NMR and X-ray diffraction single crystal analysis. The analyses of the structures indicate that all three materials crystallize in the tetragonal crystal system, space group P422. They have similar structures; i.e., the Schiff base coordinates in its deprotonated form and behaves as a hexadentate (4N+2O) coordinated ligand to form a distorted octahedron geometry. On the other hand, as a result of the alternate arrangement of chains through N-H···O intermolecular hydrogen bonds interactions, 2-D layers are formed for the three complexes. Furthermore, the luminescent properties and thermal stabilities of the three complexes were investigated. [ABSTRACT FROM AUTHOR]

A pair of stereoisomers of magnesium Schiff base complexes, [Mg(C18H16N3O2)2·2CH3OH]n(1) (C18H16N3O2: 2-acetylpyridine-l-tryptophan) and [Mg(C18H16N3O2)2·2CH3OH]n(2) (C18H16N3O2: 2-acetylpyridine-d-tryptophan), was synthesized and characterized by IR, UV, elemental analysis,1H NMR, and X-ray diffraction single crystal analysis. The analyses of the structures indicate that they all crystallize in the tetragonal crystal system, space groupP43212andP41212, respectively. The two magnesium complexes have similar crystal structures. Mg(II) is six-coordinate with two nitrogens from C=N, two nitrogens from pyridine, and two carboxylic oxygens in different ligands forming a distorted octahedral geometry. Through N–H···O intermolecular hydrogen bonds a 2-D layer structure was formed. The interaction between1and calf thymus DNA was also investigated by UV absorption spectra, fluorescence emission spectra and viscometry. The results indicate that1interacts with DNA very strongly (Kb = 2.01 × 107 L mol−1andKsq = 0.195). The nature of the binding seems to be mainly an electrostatic interaction between DNA and the magnesium complex. Other binding modes, such as hydrogen bonds, may also exist. [ABSTRACT FROM AUTHOR]

Abstract: Three novel transition metal coordination complexes, Cu(C18H16N3O2)2·2CH3OH (1), Zn(C18H16N3O2)2·2CH3CH2OH (2) and Cd(C18H16N3O2)2·2CH3OH (3) (C18H16N3O2: 2-acetylpyridine-L-tryptophan) have been synthesized and characterized by IR, UV, elemental analysis, 1H NMR and X-ray diffraction single crystal analysis. The three crystals crystallize in the tetragonal crystal system, space group P43212. They are all six-coordinated by two nitrogen atoms from C=N, two nitrogen atoms from pyridine rings and two carboxylic oxygen atoms in different ligands, forming a distorted octahedron geometry. Each ligand serves as a bridging ligand to link metal ions through carboxylic oxygen atoms, leading to a three-dimensional coordination polymer. The anticancer activities of these three complexes on MDA-MB-231 breast cancer cells were also investigated. The results indicate that all of the three complexes can inhibit the cellular proliferation. Furthermore, Cd(C18H16N3O2)2·2CH3OH (3) has the highest anti-proliferative activity among the three complexes. In addition, Cd(C18H16N3O2)2·2CH3OH (3) can inhibit proteasomal chymotrypsin-like activity and also can induce apoptosis on human breast cancer MDA-MB-231 cells. [Copyright &y& Elsevier]

Abstract: The chiral Schiff base coordination polymer [Ce(H2L)3(NO3)3Ce(H2L)3(NO3)3(H2O)] n [H2L: trans-N,N′-bis-(2-hydroxy-1-naphthalidehy-dene)-(1R,2R)-cyclohexanediamine] was synthesized and characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. X-ray crystallography shows that the Ce(III) coordinates with three neutral Schiff base ligands and three nitrates. One Ce(III) is nine-coordinated by three oxygen atoms from three different Schiff base ligands and six oxygen atoms from three nitrates, the other Ce(III) is ten-coordinated because of the coordination of an additional water molecule. Each Schiff base ligand serves as a bridging ligand to link Ce(III) ions through oxygen atoms, leading to a coordination polymer. The Ce(III) coordination polymer displays two dimensional plane grid network structure. The antiproliferation activities of the ligand H2L and its Ce(III) coordination polymer on MDA-MB-231 breast cancer cells were also studied by MTT (3-[4,5-dimethyltiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) method. The results indicate that H2L and [Ce(H2L)3(NO3)3Ce(H2L)3(NO3)3(H2O)] n can inhibit the cellularproliferation. Moreover, the coordination polymer had higher antiproliferative activity than that of the ligand. [Copyright &y& Elsevier]

The ternary copper(II) complex with 1,10-phenanthroline and Schiff base derived from 2-amino-4-fluorobenzoic acid and salicylaldehyde, was synthesized and characterized by IR and 1 H NMR spectroscopy, elemental analysis, and single crystal X-ray diffraction. X-ray crystallography shows that the copper atom adopts square pyramidal geometry and is five coordinated by the nitrogen atom from C N , two nitrogen atoms from 1,10-phenanthroline, the hydroxyl oxygen atom and the carboxylate oxygen atom. Our studies on the anticancer activity of the complex indicate that the complex can inhibit the cellular proliferation in human breast cancer MDA-MB-231 cells. In addition, it has proteasome-inhibitory activity in human breast cancer MDA-MB-231 cells. The inhibition of the tumor proteasomal activity results in the accumulation of ubiquitinated proteins and ubiquitinated form of IκB-α, a natural proteasome substrate, followed by induction of apoptosis. The results suggest that the title complex, as a potent proteasome inhibitor, has potential to be developed into a novel anticancer drug. [ABSTRACT FROM AUTHOR]

Abstract: A Schiff base compound (L) was synthesized using o-vanillin and 4, 4′-diaminodiphenylmethane and characterized by elemental analysis, 1H NMR, 13C NMR, IR, electronic absorption spectra and X-ray diffraction single crystal analysis. The title compound(L) has no fluorescence intensity in a range of 450–650nm, but its fluorescence spectrum shows enhancement in the intensity of the signal at 372nm on binding with the Zn(II) cation from pH=6 to 14. No such significant change was observed for other metal ions. Fluorescence intensity was linear with concentration of Zn (II) cation in a range from 1×10−7 mol·L−1 to 1.2×10−5 mol·L−1. This Schiff base compound is a promising system for the development of new fluorescent probes for the detection of Zn (II) cation. [Copyright &y& Elsevier]