查看更多>>摘要：Lead hydrogen arsenate PbHAsO4 and lead hydrogen phosphate PbHPO4, which can form a continuous solid solution series, have been extensively studied owing to their ferroelectric properties. PbHAsO4 has also been found to occur in weathered As-and Pb-rich outcrops and historically contaminated soils as a schultenite mineral. Although most ferroelectric studies were of substantial interest more than 30 years ago, the contamination of the Earth's surface with toxic Pb and As remains a major concern for environmentalists. In this study, six compounds of PbHAsO4-PbHPO4 solid solution series were synthesized from aqueous solutions at ambient conditions. They were subsequently analyzed using Raman and Fourier transform infrared spectroscopy to describe their vibrational characteristics, which should help identify the series members in natural or synthetic samples in further environmental and mineralogical studies. Additionally, powder X-ray diffraction analyses were conducted to investigate the variations in the unit cell parameters along the series. The results showed linear variations in the band positions in both Raman and infrared spectra, which depend on the extent of the isomorphic substitution of (PO4)(3-) for (AsO4)(3-). However, the bands become broader or split as a result of phosphate substitution, making it difficult to correlate the band positions with the molecular composition of an unknown phase. The X-ray diffraction data revealed linear variations of all lattice constants as a function of P. Moreover, a relevant finding of this study is the systematic deviation in the chemical compositions of the synthetic phases from the composition of aqueous solutions from which they precipitated, caused by the preferential incorporation of (AsO4)(3-) with respect to (PO4)(3-) into the structure.
Al-Noaimi, MousaAwwadi, Firas F.Mansi, Iman A.Sawwan, Mohammad...
11页
查看更多>>摘要：Two polymorphs based on a new Pd(II) complex, [Pd(Y)] {H2Y = (2-SR)C6H4NHN = C(COCH3)-NHC9H6N; R = C6H5}, have been characterized by FTIR, UV/Vis, elemental analysis and 1HNMR. Quantum theory of atoms in molecules was used to analyse the bonding in the two polymorphs. The formation of different polymorphs of [Pd(Y)] was rationalized based on the chirality of the complex. The molecular structures of the two polymorphs are stabilized by C-H.O hydrogen bonding interactions. The UV/Vis spectra were calculated using time-dependent density functional theory (TD-DFT). The cytotoxic activity of the ligand and its complex were evaluated against seven cancer cell lines and one normal skin fibroblast cell line. The complex is more active against DU145, MCF7, MDA231 and HCT116 cell lines, with IC50 values in the range 0.14-0.58 mu M, whereas it is less active against A375, A549 and PanC-1 cell lines, with IC50 values in the range 7.05-10.2 mu M. Except for PanC-1, the ligand is also active against six cell lines, with higher IC50 values that range from 57.3 to 866.5 mu M. The potencies of the [Pd(Y)] complex against DU145, MCF7, MDA231, and HCT116 cell lines ranged from two to elevenfold more than the potent chemotherapeutic control doxorubicin but are comparative or less for the other cell lines. The complex has shown high safety against normal cell lines compared to doxorubicin.
查看更多>>摘要：This work is directed toward the synthesis, structural characterization and NLO properties investigation of the novel copper(I) nitrate pi,sigma-coordination compound [Cu(Anor)(CH3CN)](NO3) (1) based on 1-allyl-3-norbornanthiourea (Anor). In the crystal structure of both Anor and 1, the organic part is disordered because of the superposition of (2S)-exo and (2R)-exo enantiomers. The Anor ligand in 1 acts as a bridging ligand, connecting Cu (I) ions into the cationic coordination polymer {[Cu(Anor)(CH3CN)]+}(n) through eta(2)-allyl group and the thiourea S atom. The H atoms of the -NH- groups in the Anor structure participate in N-H center dot center dot center dot S hydrogen bonding and form an infinite hydrogen-bonded layer, while the same ligand groups in the organometallic chain of 1 are linked by bifurcated N-H center dot center dot center dot O bonds to the two O atoms of the same NO3- anion. The second-order nonlinear optical properties for Anor and coordination compound 1 were studied at 1064 nm generated by a nanosecond pulsed Nd:YAG laser. The corresponding values of the average first-order NLO hyperpolarizabilities calculated by the DFT method and the B3LYP functional for the Anor ligand molecule and the cation fragment confirm the experimentally determined much higher second-harmonic generation efficiency for compound 1.
查看更多>>摘要：A new metal-organic framework (MOF), namely [Cd-3(tp)(3)(bmi)(2)] (SUSE-1, SUSE = Sichuan University of Science & Engineering) (H(2)tp = 1,4-dicarboxybenzene acid and bmi = 1,3-bis(2-methylimidazolyl)pentane), has been synthesized. It exhibits a typical 8-connected bcu-type network with [Cd-3(COO)(6)(bmi)(4)] nodes. SUSE-1 showed effective photocatalytic performance for the disintegration of the dyes Rhodamine B (Rh B), methyl orange (MO) and methylene blue (MB). In addition, a plausible mechanism for the degradation of MB was suggested from the results of the trapping method and LC-MS studies.
查看更多>>摘要：The rational synthesis of well-defined clusters requires further understanding of the fundamental aspects related to the stabilization of preferred isomers over other possible species. Atomically-precise gold superatoms offer useful templates to evaluate the role of the characteristics of the ligand shell in the resulting structure. Herein, we explore the the role of different diphenyl ligands in the determining a compact Au-11 core, or extended Au-9 + 2Au core, provided experimentally by [Au-11(dppp)(5)](3+) and [Au-11(dppe)(6)](3+) clusters, with variable bridging chain length. Our findings highlight the contribution from ligand-ligand and core-ligand interactions, and the core rearrangement, which favors the experimentally characterized compact [Au-11(dppp)(5)](3+) cluster, by 34.4 kcal.mol(-1) in comparison to the hypothetical [Au-11(dppe)(5)](3+) owing to the decrease in the bridge from -(CH2)(3)- to -(CH2)(2)-, increasing the steric crowding within the cluster. For the extended Au-9 + 2Au core, the contrary case is found, where the experimentally characterized [Au-11(dppe)(6)](3+) cluster is favored by 49.2 kcal.mol(-1) in comparison to the hypothetical [Au-11(dppp)(6)](3+) species. The obtained optical characteristics, denotes a similar visible absorption profile for the compact core species, which contrast to the extended Au-9 + 2Au core, which is more sensible to the ligand, as accounted by the calculated optical profile. Thus, the overall structure is determined mainly by the contribution from the ligand shell characteristics and the resulting core-ligand, underlying designing aspects towards tunable clusters for building blocks of nano-structured materials.
查看更多>>摘要：A variety of polynuclear cobalt complexes with H2salen type Schiff bases and their reduced analogues have been synthesized and their structures and properties have been reported in literature. This review represents an overview on the synthetic strategies, structures, magnetic properties and biological activities of these complexes. It is worthy to mention here that only those complexes are considered in this review whose X-ray structures are available. The complexes may grossly be divided into three major sub classes; Cobalt(II), cobalt(III) and mixed valence cobalt(III)/cobalt(II) complexes. Different synthetic strategies have been applied for their preparation. In most of the cases, mixed valence complexes have been synthesized by the in situ partial (aerial) oxidation of cobalt(II) to cobalt(III). However, reduction of cobalt(III) precursors has also been identified as another synthetic route. Trinuclear cobalt(II)-cobalt(II)-cobalt(II) complexes were usually synthesised from cobalt(II) precursors in anaerobic condition. Different methods of synthesising di and polynuclear complexes are also discussed. The less explored areas of potential applications of these complexes are also discussed.
查看更多>>摘要：Herein, the coordination behaviour of a hexapodal building block, 2,2,4,4,6,6-hexakis((6-methylpyridin-3-yl) oxy) cyclotriphosphazene (MeHPCP), towards divalent metal ions (Mn, Co and Ni) is described. Three new coordination compounds, namely the molecular complex [Mn(MeHPCP)(Cl)(2)(H2O)(2)] (1) and the onedimensional (1D) zig-zag chain coordination polymers {Co-2(MeHPCP)(Cl)(4)(H2O)(2)](MeCN)(H2O)(3)} n (2) and {[Ni(MeHPCP)(Cl)(2)(H2O)]} n (3), were structurally characterized by FT-IR spectroscopy and single crystal X-ray diffraction analysis. Thermogravimetric analyses show that all the compounds have high thermal stability (>350 degrees C). The magnetic properties of 2 and 3 were analyzed by electron spin resonance (ESR) and the physical properties measurement system (PPMS) technique and these complexes exhibited paramagnetic behavior.
查看更多>>摘要：The ring strain, pi-sigma hyperconjugation and ring-opening reaction of silicon-substituted cyclobutenes (monosilacyclobutenes, disilacyclobutadienes, trisilacyclobutenes and tetrasilacyclobutene) are systemically studied at the level of B3LYP/6-311 + G(d,p). The strengths of the ring strains are characterized by the bond angle deviation from the normal angle of hybrid orbitals of the silicon and carbon atoms. A reasonable correlation is found between the strain energy and the departure of the bond path length from a linear geometrical bond. The positions of strongly-bent sigma bonds are regarded as an important factor that causes different strains in silacyclobutenes. The pi-sigma hyperconjugation is directly estimated using the second order perturbation energy from the NBO analysis and we found that hyperconjugation is responsible for relaxing the ring strain in silacyclobutenes. The thermal ring opening reactions of silacyclobutenes are predicted to possess a symmetry-allowed conrotatory mechanism. The contribution of the bond energy is the main factor that dictates the ring-opening process to be either endothermic or exothermic.
查看更多>>摘要：Three pyridine-based macrocyclic ligands, two containing one pyridine pendant arm (L-1 and L-2) and one containing piperazine rings in the macrocyclic scaffold (L-3), with an increasing size of the macrocycle from 12-, 14- to 30-membered ring for L-1-L-3 were synthesized and characterized. A series of Ni(II) complexes with all these ligands, with molecular formulas [NiL1(CH3OH)](ClO4)(2) (1), [NiL2(CH3CN)](ClO4)(2) (2), and [Ni2L3(DMF)(2)(CH3CN)(2)](ClO4)(4) (3) (DMF = N,N-dimethylformamide), was prepared and thoroughly characterized. Single crystal X-ray structural analysis confirmed that all the complexes have a coordination number of six and their geometries are close to octahedral. In the case of the mononuclear complexes 1 and 2, all the nitrogen atoms of the macrocycle are coordinated, however, in the dinuclear complex 3 with the piperazine-based ligand L-3, two nitrogen donor atoms (of the total number of ten) are uncoordinated. The first coordination spheres of all the complexes are completed by solvent molecules. The values of effective magnetic moments, determined by the Evans method in solution, are 3.12, 3.19 and 4.36 mu(B) for complexes 1, 2 and 3, respectively, which correspond well to the theoretical spin-only values.
查看更多>>摘要：This study explored the thermochromic behavior of [(mu 2-6-methyl-2-pyridinemethanolate)2{Cu(6-methyl-2pyridinemethanol)}2](PF6)2. The complexes show no significant variation between 296 K and 100 K according to a single-crystal X-ray crystallographic investigation. The occupancy of the triplet at 300 K and 100 K is 55% and 16.9%, respectively based on magnetic susceptibility. Photographs of the complex at different temperatures and quantum calculation exhibit that the thermochromic behavior is induced by the alteration of spin state between triplet and singlet.
NSTL
Elsevier