查看更多>>摘要：The multinuclear Co(II) and Zn(II) salamo-based complexes [{Co2(L)(mu-OMe)}8]center dot 11CH3OH center dot 2H2O (1) and [Zn2(L) (mu-OEt)]center dot CHCl3 (2) have been successfully isolated by the solvent evaporation method and characterized structurally by elemental analyses, IR spectra and UV-Vis spectra. Complex 1 consists of four closely related neutral dinuclear units, 1A, 1B, 1C and 1D, while complex 2 consists of three closely related neutral dinuclear units 2A, 2B and 2C. Complexes 1 and 2 are unique examples of crystallographically independent but chemically identical molecules with unique ti5 parameters. For complex 1, all the Co(II) atoms possess extremely distorted trigonal bipyramidal geometries, except the for Co4 atom, with the Co(II) atoms lying out of the plane of the equatorial donor atoms. For complex 2, except for the Zn5 atom, the Zn(II) atoms possess extremely distorted trigonal bipyramidal geometries and square-based pyramidal geometries. Significantly, the geometries about the Co4 and Zn5 atoms show ti5 values very close to 0.500 and there are few such examples like those. Complex 2 has an obvious fluorescence enhancement, which may be caused by intramolecular charge transfer (ICT) and blocks the ligand to the metal charge transfer transition (LMCT) process. The intermolecular interactions were quantitatively analyzed by Hirshfeld surface analyses.
查看更多>>摘要：The importance of structural speciation in the control of chemical reactivity in Ni(II) binary-ternary systems, involving (O,O,N)-containing substrates (1,1 '-iminodi-2-propanol), and aromatic chelators (2,2 '-bipyridine, 1,10-phenanthroline), prompted the systematic synthesis of new crystalline materials characterized by elemental analysis, FT-IR, UV-Visible, Luminescence, magnetic susceptibility, and X-ray crystallography. The structures contain mononuclear octahedral assemblies, the lattice architecture of which exemplifies reaction conditions under which conformational variants and solvent-associated lattice-imposed complexes are assembled. Transformations between complex species denote their association with reactivity pathways, suggesting alternate synthetic methodologies for their isolation. Theoretical work (Hirshfeld, Electrostatic Potential, DFT) signifies the impact of crystal structure on energy profiles of the generated species. The arisen physicochemical profiles of all compounds portray a well-configured interwoven network of pathways, projecting strong connection between structural speciation and Ni(II) reactivity patterns in organic-solvent media. The collective results provide welldefined parameterized profiles, poised to influence the synthesis of new Ni(II)-iminodialcohol materials with specified structural-magneto-optical properties.
查看更多>>摘要：In the present work are calculated, for the first time, the lattice energies (kJmol(-1)) for mercury and silver fulminates (by using the Glasser-Jenkins equations): Hg(CNO)(2) = 1399.1, Ag(CNO), orthorhombic = 389.5 and Ag (CNO), rhombohedral = 305.1 (assuming the following charges: Hg: +2, Ag: +1 and CNO:-1). By using SE-PM6 molecular modelling, the "real " charges were calculated, and the "corrected " U-POT values (kJmol(-1)) are: Hg (CNO)(2) = 777.0, Ag(CNO), orthorhombic = 107.2 and Ag(CNO), rhombohedral = 83.97. By using absolute chemical hardness values, the specific impulse (I-s) values are 217.05 s and 178.41 s, for Hg(CNO)(2) and Ag(CNO), respectively. The following empirical equation was derived: D = 10 I-s n (where D is the detonation velocity (ms(-1), Is is the specific impulse and n is the number of CNO- per formulae). The gas phase explosion enthalpies (kJmol(-1)) are: Hg(CNO)(2) =-420.6 and Ag(CNO) =-164.4. The sublimation enthalpy for mercury fulminate was calculated as 51.9 kJmol(-1). Others relationship between thermochemical data to mercury and silver fulminates were also established.
Ansari, Kamal UddinRasamsetty, AmaleswariKumar, PardeepShukla, Pragya...
9页
查看更多>>摘要：The reaction of Ln(NO3)3.nH2O (where Ln = Gd, Tb, Dy or Yb) in the presence of sodium acetate led us to isolate a family of structurally analogous dinuclear lanthanide complexes with the general molecular formula of [Ln2(CH3COO)4(NO3)2(H2O)4]. 2H2O (where Ln = Gd (1) or Tb (2) or Dy (3) or Yb (4)), which are characterized by single-crystal X-ray diffraction. The dc magnetic susceptibility measurements were performed on 1 reveal the presence of a weak ferromagnetic exchange between the Gd(III) center (J = +0.01 cm- 1; -2JS1.S2 Hamiltonian). This weak exchange interaction in 1 is presumably overcome by the external magnetic field, and therefore, the Xband EPR spectral features of 1 were simulated by considering the single-ion spin Hamiltonian parameter (g = 1.98, D = 0.03 cm- 1, and divide E/D divide = 0.004). In contrast to 1, complexes 2-4 exhibit a weak antiferromagnetic exchange between the Ln(III) centers. The magnetization relaxation dynamics studies performed on the anisotropic complexes (2-4) show slow relaxation of magnetization in the presence of an optimum external magnetic field. The spin-lattice relaxation predominantly follows the Direct and Raman mechanism exclusively, and the Orbach process was found to be non-existent. By employing ab initio calculations, the electronic structure and the mechanism of magnetization relaxation dynamics of 2-4 have been investigated. The magnetocaloric effect parameter for 1 shows a change in magnetic entropy (-dSm) value of 39 J Kg-1 K-1 at 2.0 K (dH = 70 kOe), which is one of the largest -dSm value registered among the various discrete molecular coolants reported in the literature..
查看更多>>摘要：Three coordination polymers (CPs), namely {[Co(L)(dpa)].H2O}n (1), {[Zn(L)2(dpb)]}n (2) and {[Zn(L)(dpe)]}n (3), have been assembled through a dual-ligand strategy of a semi-rigid dicarboxylic acid (H2L = 1,4-bis(4phenoxy)benzenedicarboxylic acid) with the help of different N-donor co-ligands (dpa = di(pyridin-4-yl)amine, dpb = 1,4-di(pyridin-4-yl)benzene), dpe = trans-1,2-di(4-pyridyl)ethylene). Single crystal X-ray diffraction analyses reveals that compound 1 is a 4-fold interpenetrating 2D sql network and compound 2 is a 2-fold interpenetrating 2D sql network, although the final structures are different because of various inter-layer stacking modes. Compound 3 is a 8-fold interpenetrating 3D dia framework containing an octahedral cage. A photoluminescence investigation shows that compounds 2 and 3 exhibit strong fluorescence originating from the intraligand charge transfer transitions. Benefiting from its chemical stability and luminescent properties, compound 2 possesses multi-functional fluorescent responses toward the Fe3+ ion, the Cr2O72- ion and the NZF antibiotic in aqueous medium. The KSV values of compound 2 are 4.68 x 104 M-1 for the Fe3+ ion, 7.23 x 104 M-1 for the Cr2O72- anion, and 1.03 x 104 M-1 for the NZF antibiotic. Additionally, the possible mechanism for the luminescence quenching has been investigated.
查看更多>>摘要：Starting from phloroglucinol, a multidentate Schiff base ligand, H3L [N, N'-((1E, 1'E)-(5-acetyl-2,4,6-trihydroxy-1,3-phenylene)bis(ethan-1-yl-1-ylidene)bis(2-hydroxy-2-phenylacetohydrazide)], decorated with multiple coordination sites has been designed. A dinuclear dysprosium complex, [{Dy(L)(H2O)(2)}(2)]center dot 4CH(3)OH center dot 3H(2)O (1), was synthesized by employing this ligand and characterized by elemental analysis, spectroscopic and structural investigations. Single crystal X-ray diffraction analysis reveals that 1 is a dinuclear Dy(III) complex with a large (DyDy)-Dy-center dot center dot center dot distance. Magnetic investigation shows the absence of slow relaxation of the magnetization in 1 owing to the lack of an axial crystal-field.
Babailov, S. P.Zapolotsky, E. N.Kokovkin, V. V.Shakirova, O. G....
9页
查看更多>>摘要：The processes of spin-crossover (SCO) transition in the solid phase and in the solution for complexes of [Fe(HC(Pz)(3))(2)](CF3SO3)(2) and [Fe(HC(Pz)(3))(2)]SiF6 were studied by UV-vis-spectrometry and NMR methods. According to NMR, the both complexes in solution showed the monotonic decrease in the fraction of the low-spin (LS) state and the increase in the fraction of the high-spin (HS) state when the temperature increases from 295 to 360 K. The observed chemical shifts and signal half-widths change significantly on temperature, despite the fact that the fraction of the HS form increases with rising temperature not so sharp as in the solid phase. The increased in temperature sensitivity of the observed chemical shifts in comparison with the temperature sensitivity of the "pure" HS and LS forms is caused by a growth in the relative population of the HS form with temperature rising. The significant temperature dependences of the observed chemical shifts and signal half-widths are suggested to use for temperature control in liquid media using NMR and MRI.
查看更多>>摘要：This manuscript describes the synthesis, structural analysis, antioxidant evaluation, cytotoxicity, interaction with DNA, and molecular docking modeling of copper(II) complexes derived from aromatic aldehydes and amines containing furyl and thiophene fragments (C1-C5). All compounds were tested as catalytic mimetics of super -oxide dismutase (SOD) using the NBT photoreduction method in a pH 7.8 buffer solution, and structural analysis revealed that all complexes had a quadratic geometry. However, there were important differences in the eval-uations with CT-DNA interaction, antioxidant activity, and cytotoxic characteristics. The main interest was to correlate the structure obtained by X-ray diffraction with the tested activities, adding relevant information for future and even deeper applications.
Devdass, AnthonyTalukdar, KallolZeller, MatthiasFortenberry, Ryan C....
11页
查看更多>>摘要：A series of tetradentate mixed-donor ligands has been synthesized containing an amine, thioether, or phosphine donor at the 8-position of a 2-(1,1-di(pyridin-2-yl)ethyl)quinoline backbone. Upon metalation with CuCl2, the preorganized N-4, N3P, and N3S donor ligands enforce distorted trigonal bipyramidal coordination environments around the copper metal center, in which a chlorido donor occupies the remaining axial coordination site. The complexes were characterized by elemental analysis, high-resolution mass spectrometry, and X-ray crystallography. The non-pyridyl equatorial donor was the sole difference from among the tetradentate ligands, and is responsible for the structural and electronic variations across the series. Indeed, more intermediate geometries between the ideal trigonal bipyramidal and square pyramidal extremes are observed with the larger phosphorus and sulfur donors. Relative to the N-4 derivative, the N3P and N3S systems have greater chemical stability upon redox cycling as observed in spectroelectrochemical experiments and lower inner-sphere reorganization energies for the Cu-II/I redox couples based on density functional theory calculations.
Faihan, Ahmed S.Al-Jibori, Subhi A.Hatshan, Mohammad R.Al-Janabi, Ahmed S....
5页
查看更多>>摘要：Treatment of one molar equivalent of [PtCl2(diphos)] (diphos = dppe, dppp, dppb or dppf) or [PtCl2(PPh3)(2)] with one molar equivalent of (H2CPPT) in the presence of Et3N afforded the new heterocyclic thiourea dianion complexes [Pt(kappa(2)-CPPT)(diphos)] and [Pt(kappa(2)-CPPT)(PPh3)(2)] (1-5). The synthesized complexes were characterized by FT-IR, H-1 NMR and P-31-{H-1} NMR spectroscopy. Moreover, X-ray single crystal structure determination for complexes [Pt(kappa(2)-CPPT)(dppe)] (1) and [Pt(kappa(2)-CPPT)(dppb)] (3) showed a four membered ring structure with the Pt(II) ion being central and adopting a slightly distorted square planar geometry. Furthermore, the X-ray structures showed that the sulfur atom is trans to the phosphine ligand with the shortest Pt-P bond, compared to the nitrogen atom that is trans to the other Pt-P bond. Interestingly, the obtained complexes, apart from previously synthesized ones, showed one isomer formation only. This behavior is probably due to the inductive effect for both of the heteroatoms and the chlorine atom on the pyridyl group. Generally, the prepared complexes showed similar behavior to their analogous non-substituted thiourea dianion complexes, with no observable effect of the heteroatom on the overall structure. Furthermore, antibacterial activities were tested against three pathogenic bacterial species; among the four tested complexes, complexes 4 and 2 showed high activity values.
NSTL
Elsevier