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In this work, the effects of a chitosan-based derivative (CSA), DOPO and CSA-DOPO additives on the flammable properties of EP composites were systematically studied, where CSA was synthesized by a facile condensation between chitosan (CS) and 9-anthralaldehyde and. DOPO was 9, 10-dihydro-9-oxa-10- phosphaphenanthreene-10-oxide. The mass ratio of CS and 9-anthralaldehyde in CSA was determined by elemental analysis and theoretical calculation, which matched well with each other. Under the 8% addition in EP, EP/2.66%/5.34%DOPO sample was the only one, which passed the UL-94 rating and exhibited the highest LOI value of 36.4%. Compared with EP, the cone calorimeter test (CC) showed that the total smoke emission value and the peak heat release rate of the CSA and DOPO modified EP decreased 36.0% and 61.9%, respectively, and the residual char amount increased by 151%. The possible flame retardant mechanism of CSA/DOPO towards EP was proposed according to the results of the real time FTIR spectra at different pyrolysis temperatures, cone calorimeter and Py-GC/MS analysis for EP and EP/2.66%CSA/5.34%DOPO samples, and Raman spectra and XPS for their char residues. Moreover, the incorporation of CSA/DOPO effectively improved the mechanical properties, especially, the flexural strength was increased by 52.3%. It was proposed that CSA/DOPO plays roles in both vapor and condensed phases, and the synergistic effect of CSA and DOPO significantly improve the flame retardancy and mechanical strength of EP.

Two unsymmetrical complexes, [NiL1]ClO4 (1) and [NiL2]ClO4 (2) have been synthesized and characterized by IR, UV, ES-MS and single crystal X-ray diffraction, where HL1 and HL2 are, respectively, the [1+1] condensation products of 2,6-diformyl-4-X-phenol (X = F or CH3) with N 1-(2-aminoethyl)-N 2-(4-nitrobenzyl) ethane-1,2-diamine. The coordination geometry of the metal in both complexes can be approximately described as square planar with a mean plane deviation of 0.032 A in complex 1 and 0.027 A in complex 2, respectively. The binding activities of the complexes toward calf-thymus DNA have been analyzed by spectroscopy and viscosity methods. The binding constants of 1 and 2 obtained from UV spectroscopic studies are 5.43 × 105 and 1.83 × 105 M−1, respectively, while the linear Stern–Volmer quenching constants obtained from fluorescence spectroscopic studies are 0.83 × 103 and 0.71 × 103 M−1, respectively. The cyclic voltammograms of the complexes show a pseudo-reversible electrochemical process.

Two symmetrical macrocyclic dinuclear complexes, [Cu2L1(ClO4)2(H2O)2][Cu2L1(H2O)2] (ClO4)2 (1) and [Cu2L2(ClO4)2] (2), (where H2L1 and H2L2 are the [2 + 2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-flurophenol, respectively), have been synthesized and characterized. The electronic and magnetic properties of the complexes were studied by cyclic voltammetry and magnetic susceptibility. There are strong antiferromagnetic couplings between the two copper(II) centers in both complexes. The strongly electron-withdrawing fluorine groups in H2L2 weaken the antiferromagnetic exchange, but make the metal centers more easily reduced than its analog H2L1. The interactions of the complexes with calf thymus DNA were studied by UV–Vis and CD spectroscopic techniques.

An asymmetrical bis-pyridine pendant-armed macrocyclic heterobinuclear complex, [ZnNiL](ClO4)2·CH3CN (H2L was derived from the condensation between 3,3′-((ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))bis(methylene))bis(2-hydroxy-5-methylbenzaldehyde) and 1.3-diaminopropane), has been synthesized and characterized by physico-chemical and spectroscopic methods. The asymmetric unit contains two complete macrocyclic complexes that are nevertheless quite similar to one another. The Zn–Ni separations, bridged by the two phenoxides, are 3.107 and 3.141 Ǻ, respectively. The phosphate hydrolysis catalyzed by the complex was investigated using bis(4-nitrophenyl)phosphate (BNPP) as the substrate. The catalytic rate constant (k cat) is 1.64 × 10−3 s−1 at pH 7.4 and 25 °C, which is 108-fold higher than that of the corresponding uncatalyzed reaction. The interaction between the complex and calf thymus (CT) DNA was investigated by UV–vis absorption, viscosity experiments, and cyclic voltammetry. The complex shows good binding propensity to calf thymus DNA via intercalation with a binding constant of 5 × 104 M−1. The agarose gel electrophoresis studies show that the complex has a concentration-dependent DNA cleavage activity.

A new Ni(II) complex, namely [Ni2(OAc)L]·ClO4·H2O, was synthesized by [2 + 2] cyclo-condensation between 2,6-diformyl-4-methylphenol and N,N-bis(3-aminopropyl)-4-methoxybenzylamine (amba) in the presence of nickel(II) and characterized by spectroscopy, elemental analysis, and X-ray single crystal diffraction. The interactions of the complex with DNA have been measured by spectroscopy and viscosity measurements. Absorption spectroscopic investigation reveals intercalative binding of the Ni(II) complex with DNA, with a binding constant of 2.6 × 104 M−1. Fluorescence spectroscopy shows that the Ni(II) complex can displace ethidium bromide and bind to DNA, with a quenching constant of 7.57 × 103 M−1. The appearance of increased CD bands near 245 and 275 nm gives evidence for effective complex DNA binding. The agarose gel electrophoresis studies show that the complex displays effective DNA cleavage activity in the absence of any external agents.

A new mononuclear nickel(II) complex, [NiL2] (HL = ((2-(5-fluoro-2-hydroxybenzyl)(2-(imidazole-2-yl)ethyl))imine), has been synthesized and characterized by IR, UV–vis and X-ray diffraction technique. The X-ray crystal structure of the complex shows that the coordination environment around Ni(II) ion is an approximate octahedron. Each molecule connects with four adjacent neighbors through strong hydrogen bonding interactions (N–H···O, d(N–O) = 2.687 A and ∠N–H···O = 158.3(1)°), forming a supramolecular network. The interaction of the complex with DNA was monitored using agarose gel electrophoresis. The results show that the complex has DNA cleavage activity. The cyclic voltammogram shows one pair of anodic and cathodic peaks with E1/2 = −1.06 V, assigned to the Ni(II)/Ni(I) couple.

A novel linear trinuclear copper(II) complex bridged by phenoxy and benzyloxy oxygen atoms ([Cu3L2](ClO4)2 · (CH3CN)2, L = C11H13BrN2O2 2−) was synthesized and the crystal structure of the complex was determined by X-ray diffraction technique. The crystal structure of the complex contains a linear trinuclear array of copper(II) ions in which the central copper(II) ion is in an octahedron coordination sphere and lies on an inversion center of the molecule, the terminal ones are in an identical square pyramid structure. Variable-temperature magnetic data indicate that the complex displays a strong antiferromagnetic coupling with J = −270(8) cm−1 between the metal ions.

A new binuclear copper complex [CuLCl2]2, [L = 1-(p-tolylsulfonyl)-1,4,7- triazacyclononane], has been synthesized and structured as well as magnetically characterized. In the complex, each copper(II) atom is located in the center of a distorted square pyramidal configuration of five coordinating atoms (two nitrogen atom and three chlorine atom). Two copper(II) atoms were bridged by two chlorine anions (Cl1 and Cl1a). The distance between two copper(II) atoms is 3.483 A. An antiferromagnetic exchange coupling effect exists in the complex.

Two macrocyclic dinuclear complexes, [Cu2L1](PF6)2 and [Cu2L2](ClO4)2, were synthesized by cyclo-condensation between N,N′-bis(3-formyl-5-methylsalicylidene)ethylenediimine or N,N′- bis(3-formyl-5-n-butylsalicylidene)ethylenediimine and ethylenediamine in the presence of Cu2+ ions. The crystal structures of the complexes were studied. The variable-temperature magnetic susceptibilities and cyclic voltammograms of the complexes were measured. The magnetic and electrochemical properties of the complexes were discussed. The results show that the complexes display very strong antiferromagnetic exchanges and that all copper(II) complexes undergo a one-electron transfer process.