Kinetics on Thermal Decomposition of Iron(III) Complexes of 1,2-Bis(Imino-4’-Antipyrinyl)Ethane with Varying Counter Anions

A comparative thermal decomposition kinetic investigation on Fe(III) complexes of a antipyrine Schiff base ligand, 1,2-Bis(imino-4’-antipyrinyl)ethane (GA)), with varying counter anions viz. CIO4-, NO3-, SCN-, Cl-, and Br-, has been done by thermogravimetric analysis by using Coats-Redfern equation. The kinetic parameters like activation energy (E), pre-exponential factor (A) and entropy of activation (ΔS) were quantified. On comparing the various kinetic parameters, lower activation energy was observed in second stage as compared to first thermal decomposition stage. The same trend has been observed for pre-exponential factor (A) and entropy of activation (ΔS). The present results show that the starting materials having higher activation energy (E), are more stable than the intermediate products, however;the intermediate products possess well-ordered chemical structure due to their highly negative entropy of activation (ΔS) values. The present investigation proves that the counter anions play an important role on the thermal decomposition kinetics of the complexes.

Catalytic Kinetic on the Thermal Decomposition of Ammonium Perchlorate with a New Energetic Complex Based on 3,5-Bis(3-pyridyl)-1H-1,2,4-triazole

A new energetic complex,[Co（3,3？-Hbpt）（Htm）]·H_2O（1,3,3？-Hbpt = 3,5-bis（3-pyridyl）-1H-1,2,4-triazole and H_3tm = trimesic acid）,has been synthesized by hydrothermal reactions and characterized by single-crystal X-ray diffraction,elementary analysis,IR spectroscopy,thermogravimetric analysis and X-ray powder diffraction. Single-crystal X-ray diffraction indicates that the complex belongs to triclinic system,space group P 1 with a = 10.0911（1）,b = 10.2573（1）,c = 10.6393（1） ？,α = 103.793（2）,β = 101.041（2）,γ = 107.918（3）o,V = 974.9（2） ？~3,Z = 2,D_c = 1.732 g·cm-3,μ = 0.941 mm^（-1）,M_r = 508.31,F（000） = 518,the final R = 0.0523 and wR = 0.0935 with I 〉 2σ（I）. In the title complex,Co（Ⅱ） ions are connected by Htm2-anions generating 1D ladder-like chains which are linked by 3,3？-Hbpt to form 1D cages. In addition,the thermal decomposition of ammonium perchlorate（AP） with complex 1 was explored by differential scanning calorimetry（DSC）. AP is completely decomposed in a shorter time in the presence of complex 1,and the decomposition heat of the mixture is 2.531 kJ·g^（-1）,significantly higher than that of pure AP. By Kissinger＇s method,the ratio of Ea/ln（A） is 11.05 for the mixture,which indicates that complex 1 shows good catalytic activity toward the AP decomposition.

One-dimensional Zigzag Chain Composed of HgI_2 Unit and 2,5-Bis(4-pyridyl)-1,3,4-thiadiazole:[HgI_2(C_(12)H_8N_4S)]

The title compound, [HgI2（C12H8N4S）], has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/n with a = 14.086（2）, b = 6.0365（6）, c = 20.286（2）°A,β= 108.818（5）°, V = 1632.7（3）°A^3, Mr = 694.67, Z = 4, D, = 2.826 g/cm^3,μ= 13.331 mm^-1, F（000） = 1240, S = 1.108, the final R = 0.0438 and wR = 0.0934 for 3085 observed reflections （I〉 2σ（I））. The Hg（Ⅱ） atom is coordinated by two 2,5-bis（4-pyridyl）-1,3,4-thiadiazole （L） molecules and two iodine anions in a distorted tetrahedral coordination geometry. Mercury atoms are linked by the organic ligands to form a one-dimensional zigzag chain. It is noteworthy that such 1D zigzag chains are extended into a two-dimensional double layer framework through I…I interactions

Comparative Studies of 1,4-Bis[2-(4-Pyridyl)ethenyl]-benzene Using Density Functional Theory

The optimized molecular structure and harmonic vibrational frequencies of a 1,4-bis [ 2-（4-pyridyl）ethenyl]- benzene（BPENB） molecule were calculated via five popular density functional theory（DFI＇） methods. On the basis of the comparison between calculated and experimental results, it is concluded that the B3PW91 and B3LYP methods are superior to the others in optimizing structures, and the BPW91 method reproduces the observed fundamental fre-quencies most satisfactorily.

Synthesis,Spectra,X-ray Diffraction and Thermal Studies of New Zn(Ⅱ) Compounds Based on Dibenzoylmethane

Two new zinc（Ⅱ） compounds with dibenzoylmethane and N-donor ancillary ligands,[Zn（μ-pyz）（dbm）_2]_n（1） and [Zn（dbm）_2（μ-bpe）Zn（dbm）_2]（2）（Hdbm = dibenzoylmethane,pyz = pyrazine and bpe = 1,2-bis（4-pyridyl）ethane）,have been prepared and characterized using elemental analysis,IR,~1H NMR and 13 C NMR spectroscopy,and studied by thermal gravimetric analysis as well as single-crystal X-ray diffraction. The crystal and molecular structures of 1 and 2 have been solved by X-ray diffraction and they turned out to be a one-dimensional coordination polymer with linear dispositions of metal atoms and binuclear compound,respectively. These one-dimensional polymers are further connected to form a 3D supramolecular network by C–H···O（only in 2） and π-π interactions.

Syntheses,Structures and Luminescent Properties of Cd(Ⅱ)/Zn(Ⅱ) Coordination Polymers Based on the Flexible 4-Substituted Bis(1,2,4-triazole) Ligand

Two new cadmium（II） and zinc（II） coordination polymers, {[Cd（btre）0.5- （mip）（H2O）2]·H2O}n （1） and [Zn（btre）（mip）]n （2）, were synthesized at room temperature condition and characterized by IR spectra, elemental analyses, single-crystal and powder X-ray diffractions （btre = 1,2-bis（1,2,4-triazol-4-yl）ethane, H2mip = 5-methyl-1,3-benzenedicarboxylic acid）. Complex 1 belongs to the triclinic system, P space group, with a = 8.9830（6）, b = 10.0579（6）, c = 10.2479（9） , α = 98.837（6）, β = 115.975（8）, γ = 106.370（6）°, V = 756.30（11） 3 and Z = 2; complex 2 crystallizes in monoclinic, space group P21/c, with a = 7.0332（3）, b = 14.9947（7）, c = 15.9689（7） ？, β = 97.1170（10）°, V = 1671.12（13） ？3 and Z = 4. Compounds 1 and 2 based on the same N/O-donor ligands show different structures. The one-dimensional chains of 1 are further linked by hydrogen bonding and π-π interactions to yield a three-dimensional supramolecular structure. The two-dimensional （6,3） networks of 2 are further extended into a 3D framework via π-π interactions. Thermal stabilities and luminescence of 1 and 2 were investigated.

Oxidation reactivity of 1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE)by CompoundⅠmodel of cytochrome P450s

Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is needed.We have previously proved that density functional theory（DFT） is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis（2,4,6-tribromophenoxy）ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis（2,4,6-tribromophenoxy）ethanol, which may undergo hydrolysis yielding2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.

Synthesis and Crystal Structure of Cobalt(II) Complex [Co(H_2O)_2(bpe)(OAc)_2]·4,4'-dpdo

The reaction of Co(OAc)2 with bpe and 4,4?-dpdo in an aqueous-alcohol solution affords the formation of red crystals of [Co(H2O)2(bpe)(OAc)2]?4,4?-dpdo (bpe = trans-1,2-bis(4- pyridyl)ethylene, 4,4?-dpdo = 4,4?-dipyridyl N,N?-oxide). The molecular and crystal structures were determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P1 with a = 7.6146(9), b = 8.6691(11), c = 10.3440(11) ?, α = 88.311(3), β = 76.992(3), γ = 75.809(3)°, V = 644.76(13) ?3, Z = 1, C26H28CoN4O8, Mr = 583.45, Dc = 1.503 g/cm3, μ = 0.724 mm-1, F(000) = 303, T = 223(2) K, the final R = 0.0477 and wR = 0.1177 for 3199 observed reflections with I > 2σ(I). In the crystal the cobalt atom is six-coordinated by oxygen atoms from two carboxylic molecules, two nitrogen atoms from the bpe ligands and two water molecules, completing an octahedral geometry. The structure of the title complex consists of neutral chains containing cobalt(II) ions bridged by mutually trans bpe molecules. The adjacent chains are connected through weak hydrogen bonds to form a two-dimensional structure.

Catalyst-free 2+2 Photodimerization of l,4-Bis[2-(4-pyridyl)ethenyl]-benzene in Solution Under Low Power UV Irradiation

Two different kinds of configurations of 1,4-bis[2-(4-pyridyl)etheny 1]-benzene(trans-bpeb and c/5-bpeb)were achieved,and a bpeb dimer was synthesized in dimethyl sulfoxide(DMSO).Compared with the previous work that synthesized the bpeb dimer or polymer in crystal with a template agent needed,the reaction occurred in a solu・tion phase in the present method.A hand-held ultraviolet lamp(365 nm)with the power of 12 W and the Watt density of 0.35 mW/cm2 can realize the photodimerization of bpeb,instead of the high-power mercury lamp in most previous studies.Unlike other 2+2 cycloaddition in liquid state using catalysts even noble metals,no catalysts were required here,which is cost-saving.Only the trans-pbeb can start the cycloaddition and the formation of the close J-aggregations of Zra≪5-pbeb in DMSO is a precondition for explaining the 2+2 photodimerization.The productivity for the 2+2 cycloaddition product was achieved as 55.6%.

Synthesis and Crystal Structure of One New Coordination Polymer: [Ni(qptc)_(0.5)(bpp)( H_2O)]_n

Solvothermal reaction of aromatic terphenyl-2,5,2＇,5＇-tetracarboxylic acid （H4qptc） ligand and the transitional metal cation of Nin in the presence of 1,3-bi（4-pyri- dyl）propane （bpp） affords one new coordination polymer, [Ni（qptc）0.5（bpp）（H2O）], （1）. The structure has been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR, TGA, and magnetism. The qptc4- acts as a H-shaped ligand linking the NiⅡ centers together to form a 2D polymeric [Ni（qptc）0.5], layer consisting of alternately arranged left- and right-handed helical chains. Each 2D polymeric [Ni（qptc）0.5], layer is further linked through the bridging bpp ligands, thus resulting in a unique （3,4）- connected network with the （62.8）（62. 84） topology. The crystal of 1 crystallizes in monoclinic, space group C2/c with a = 16.088（5）, b = 14.913（5）, c = 18.849（6） A, β= 100.982（4）, V= 4439（2） A3, Z= 8, C24H21N2NiO5, Mr = 476.14, Dc = 1.425 g/cm3, F（000） = 1976 and μ（MoKa） = 0.912 mm-1. The final R = 0.0584 and wR = 0.1131 for 3894 observed reflections with Ⅰ 〉 20（I） and R = 0.1224 and wR = 0.1279 for all data.

A New Co(Ⅱ)Coordination Compound Constructed by Tripyridyltriazole and Pyromellitic Acid:Synthesis,Crystal Structure and Antifungal Activity

A new coordination compound, [Co（L223）2（H2O）2]·H2pm（1, L223 = 3,4-bis（2-pyridyl）-5-（3-pyridyl）-1,2,4-triazole and H4 pm = pyromellitic acid）, has been synthesized. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis reveals that complex 1 belongs to the triclinic system, space group P1 with a = 10.2470（8）, b = 10.2879（9）, c = 10.2951（11） ？, α = 109.398（2）, β = 97.6590（10）, γ = 95.3260（10）°, V = 1003.60（16） ？3, Z = 1, Dc = 1.565 g/cm^3, μ = 0.508 mm%^-1, Mr = 945.73, F（000） = 485, the final R = 0.0562 and w R = 0.0783 with I 〉 2σ（I）. Two L223 as chelating ligands link one Co（II） ion to form a 0D motif. Furthermore, the 0D motifs are linked into a 2D coordination pattern with hydrogen bonds. In addition, the antifungal effects of the ligand and the complex were evaluated by the disc diffusion method against Colletotrichum gloeosporioides Penz. 1 represents antifungal activity with high levels of inhibitory potency which is larger than the corresponding ligand.

Syntheses, Crystal Structures, and Fluorescence Properties of Two 2D→2D Coordination Polymers Based on the Flexible 4-Substituted Bis(1,2,4-triazole) Ligand

Two new 2 D → 2 D zinc(II) coordination polymers, [Zn(btre)0.5(nbdc)(H2 O)]n(1) and {[Zn(btre)0.5(Me Oip)(H2 O)2]·H2 O}n(2)(btre = 1,2-bis(1,2,4-triazol-4-yl)ethane, nbdc=3-nitro-1, 2-benzenedicarboxylate, Me Oip=4-methoxybenzene-1, 3-dicarboxylate) were synthesized at room temperature condition and characterized by IR spectra, elemental analyses, single-crystal and powder X-ray diffractions. Three sets of equivalent 2 D(6, 3) networks parallel polycatenated with each other to give a 2 D → 2 D network in 1 and 2. There are strong π-π interactions and hydrogen bonding interactions between adjacent parallel polycatenated 2 D(6, 3) network in 1. Only hydrogen bonding interactions exist in 2. Thermal stabilities and luminescence of 1 and 2 were investigated.

Syntheses,Structures and Photocurrent Response Properties of Two Crystals Based on Tetrathiafulvalene Derivatives

In this paper,two compounds[Zn_(2)^(2+)(2,6-bis(4΄-pyridyl)-TTF)(TPA)_(2)^(2-)](1)and[Cd^(2+)(2,6(7)-bis(4΄-pyridyl)-TTF)(TPA)2-(H_(2)O)_(2)](TTF=tetrathiafulvalene,TPA=terephthalic acid)(2)were synthesized by using solvothermal method and characterized by single-crystal X-ray.The purity of the two compounds was confirmed by their PXRD data.We also tested the photocurrent responses of these two compounds,and found they could generate photocurrent signal when exposed to light,but the photocurrent intensity of compound 2 is significantly greater than that of 1.From the crystal structure analysis,the possible reason for this phenomenon is that 2 has a more compact ligand arrangement than 1,leading to a higher carrier density and easier excitation.