Qi-Mao Huang

Synthesis, crystal structure, electrochemical and magnetic properties of dinuclear complexes with strong electron-drawing groups in the diphenoxo-tetraaza macrocyclic ligand

Three symmetrical macrocyclic dinuclear complexes [M2L(H2O) n ](ClO4)2 (M2+ = Cu2+, Ni2+, Mn2+ and n = 0, 2) have been synthesized by cyclocondensation between 2,6-diformyl-4-fluorophenol and 1,4-diaminobutane in the presence of M2+ cations. The crystal structure of [Cu2L](ClO4)2 was determined by X-ray diffraction techniques. The electronic and magnetic properties of the complexes were studied by cyclic voltammetry and magnetic susceptibility. The results confirm that the complexes obtain electrons easily and there are very strong antiferromagnetic couplings between two copper(II) ions in [Cu2L](ClO4)2. The strong electron-drawing groups of fluorine attached to the phenyl ring of a macrocyclic complex enhances the antiferromagnetic exchange of the complex and makes it more easily reduced than its analogs.

Hexamine copper(II) coordination polymers: synthesis, structure and magnetic properties

Four new one-dimensional (1D) polymeric complexes, {[Cu4(L1)2(µ-Br)2(µ4-CO3)]Br(ClO4)3·3H2O}n (1), {[Cu2L2(µ-Cl)Cl2] (ClO4)2·H2O}n (2), {[Cu2L3(µ-Cl)2](ClO4)2}n (3), and {[Cu2L4(µ-Cl)2](ClO4)2}n (4), have been synthesized and characterized, where L1 = N,N,N′,N′-tetrakis(3′-aminopropyl)-1,3-propylenediamine, L2 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1,3-propylenediamine, L3 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1,4-butylenediamine, L4 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1, 6-hexylenediamine. X-Ray structure analysis revealed that the polymeric complexes, created by the bridging groups which are exhibited in the formula, present different 1D coordination motifs: double-stranded chains with voids of 43.5 A2 for 1, sigmoid chains for 2, zigzag chains for 3 and 4 with different coordination polyhedra. Various hydrogen bonding interactions such as N–H⋯Cl, N–H⋯O, C–H⋯Cl, N–H⋯Br and O–H⋯Br join the polymeric chains to generate two-dimensional networks with bigger voids. Magnetic susceptibility data were fitted according to the molecular structures using Hamiltonians: H = −2J1(S2S3 + S1S4) − 2J2(S2S1) − 2J3(S1S3 + S2S4) − 2J4(S3S4), which corresponds to a rectangular array of spins for 1, and H = −2JS1S2 corresponds to a dinuclear array of spins for 2, 3 and 4. It was found that the coupling constants of 1 are −60, −113, −54 and −11 cm−1, and those of 2, 3, and 4 are −2.46, −1.56 and −0.15 cm−1, respectively.

Two dinuclear Schiff-base complexes: synthesis, characterization, and biological activity

Two complexes, [Zn2L(µ-OAc)](ClO4) (1) and [Mn2L(OAc)2] · 4H2O (2), were synthesized by [2 + 2] cyclo-condensation between 2,6-diformyl-4-fluorophenol and 1,3-propyldiamine in the presence of metal ions M(II) (M = Zn and Mn), and were characterized by chemical analyses, IR spectra, electrospray mass spectra, and X-ray determinations. The results show that 1 forms dimers through hydrogen bonding. In 2, lattice waters, forming a 1-D water chain, function as glue to form a 3-D supramolecular network through extended hydrogen bonding. pBR322 plasmid DNA can be transformed to nicked form in air by 1 or nicked and linear forms in air by 2. Moreover, their antibacterial activities against S. aureus were investigated using penicillin as reference system.

Coordination polymers of polyamine and macrocycles controlled by pyridine-containing arms

N,N′-bis(3-aminopropyl)-3-pyridylmethylamine (bapa) has been synthesized as a building block for coordination polymers, and its coordination polymer {[Cu(bapa)(MeCN)][Cu(bapa)(ClO4)] (ClO4)3·MeCN}∞ (1) was obtained by reacting it with Cu(ClO4)2·6H2O in MeCN solution. In addition, three macrocyclic coordination polymers, {[CuL1](H2O)2}∞ (2), {[MnL1](H2O)2}∞ (3) and {[CuL2]CH3CN·H2O·ClO4}∞ (4), were obtained by the condensation between bapa and N,N′-bis(3-formyl-5-methylsalicylimine)-1, 2-propylenediimine for 2 and 3, and N,N′-bis(3-formyl-5-methylsalicylidene)-1,2-ethylenediimine for 4 in the presence of Cu(II), Mn(II) and Cu(II), respectively. These polymers have the common feature that the 3-methylaminopyridine group in one ligand coordinates to the metal ion in the neighboring coordination unit, leading to the formation of a one-dimensional infinite chain. There are abundant hydrogen bonds in each of the complexes, involving water clusters and perchlorate anions.

Bis[N-(2-furylmeth­yl)ethane-1,2-di­amine]­bis­(perchlorato)copper(II)

In the title complex, [Cu(ClO4)2(C7H12N2O)2], the Cu(II) ion lies on a crystallographic inversion centre. The coordination sphere around Cu(II) ion can be described as tetragonally distorted octahedral with two perchlorate O atoms occupying the apical positions and four N atoms from two N 1-(2-furylmethyl)ethane-1,2-diamine ligands in the basal plane.

A tetranuclear copper(II) complex: crystal structure, assembly, EPR, electrochemistry and magnetism

A tetranuclear copper(II) complex, [Cu2L]2(ClO4)2 · 4H2O (1), where H3L = N,N′-bis(4-(3′-formyl-5′-chlorosalicyclidene)iminoethyl)-4-chloro-2,6-bimethyliminophenol, has been synthesized and structurally characterized by ES-MS, IR and X-ray crystallography. The complex is a dimer of two dinuclear copper(II) acylic enantiomorph subunits ([Cu2L]ClO4 · 2H2O), held together by π–π, coordination and hydrogen bond interactions. The Cu–Cu separation in each subunit, bridged by one phenoxide, is 3.228 Å, and the shortest distance of Cu–Cu between the two subunits is 3.252 Å. There are two crystallographically unique copper(II) environments, one (Cu1) is square-based pyramidal with O3N2 donor set, another (Cu2) square planar with O2N2 donor set. The cyclic voltammogram of the complex shows that it undergoes two stepwise reduction processes, E pc = −0.707 and −0.850 V, respectively. Magnetic measurements in the 2–300 K range indicate strong antiferromagnetic interactions between Cu(II) ions in each subunit with the exchange constant J = −211(2) cm−1. The observation has been rationalized on the basis of the effective magnetic pathway.