Heterobimetallic Bi(III)-Ti(IV) coordination complexes: synthesis and solid-state structures of BiTi4(sal)6(mu-OiPr)3(OiPr)4, and the cyclic isomers Bi4Ti4(sal)10(mu-OiPr)4(OiPr)4 and Bi8Ti8(sal)20(mu-OiPr)8(OiPr)8

The reaction of a 1:2 mixture of bismuth(III) salicylate with titanium(IV) isopropoxide in refluxing toluene has been investigated and found to proceed with ligand exchange to produce the new heterobimetallic complexes BiTi(4)(sal)(6)(mu-O(i)Pr)(3)(O(i)Pr)(4) (1), Bi(4)Ti(4)(sal)(10)(mu-O(i)Pr)(4)(O(i)Pr)(4) (2), and Bi(8)Ti(8)(sal)(20)(mu-O(i)Pr)(8)(O(i)Pr)(8) (3). Complex 1 is the major product, while 2 and 3 were identified as minor products from the reaction. Compound 1 is produced pure and in high yield by employing stoichiometric amounts of reagents; its crystal structure consists of a [Ti(4)(sal)(6)(O(i)Pr)(7)](3)(-) ion capped by a Bi(3+) ion. Complexes 2 and 3 exhibit cyclic ring structures of bismuth and titanium atoms showing crystallographically imposed inversion symmetry. Both structures occlude large quantities of lattice solvent. The compositional and structural parameters from the single crystal studies indicate that complexes 2 and 3 may represent sequential steps in a ligand exchange process between the two metal species, while the reactivity patterns that were observed provide clues about the solution state structure of bismuth(III) salicylate itself. The 2D COSY (1)H NMR spectrum of 1 indicates retention of the asymmetric structure in solution as evidenced by the presence of 14 diastereotopic isopropoxide methyl resonances.     

Crystal structures, electronic properties, and pressure-induced superconductivity of the tetrahedral cluster compounds GaNb(4)S(8), GaNb(4)Se(8), and GaTa(4)Se(8)

The crystal structures of the tetrahedral cluster compounds GaNb(4)S(8) and GaTa(4)Se(8) were determined by single-crystal X-ray diffraction. They crystallize in the cubic GaMo(4)S(8) structure type (F3m), which can be derived from the spinel type by shifting the metal atoms off the centers of the chalcogen octahedra along [111]. Electrical resistivity and magnetic susceptibility measurements show that the electronic conduction originates from hopping of localized unpaired electrons (S = (1)/(2)) among widely separated Nb(4) or Ta(4) clusters, and thus these materials represent a new class of Mott insulators. Under high pressure we find that GaNb(4)S(8) undergoes a transition from the Mott insulating to a superconducting state with T(C) up to 4 K at 23 GPa, similar to GaNb(4)Se(8) and GaTa(4)Se(8). High-pressure single-crystal X-ray studies of GaTa(4)Se(8) reveal that the superconducting transition is connected with a gradual decrease of the octahedral distortion with increasing pressure. DFT band structure calculations show that weakly coupled cluster orbitals are responsible for a high density of states at the Fermi level. The correct insulating magnetic ground state for GaNb(4)S(8) with mu(eff) = 1.73 mu(B) is for the first time achieved by the LDA+U method using U = 6 eV and rhombohedral symmetry.     

A new cyclic borazine species B(8)(NH)(4)(NMe(2))(8) containing a twelve-membered B(8)N(4) ring

The reaction between B(2)(NMe(2))(4) and two equivalents of [NH(4)][PF(6)] in thf at room temperature affords the new cyclic borazine B(8)(NH)(4)(NMe(2))(8) containing a non-planar twelve-membered ring with alternating B(2)(NMe(2))(2) and NH units.     

New routes to manganese higher-nuclearity topologies: synthesis of the cluster [Mn8(mu4-O)4(phpz)8(thf)4

Reaction of Mn(ClO4)2.6H2O with 3(5)-methyl-5(3)-(2-hydroxyphenyl)pyrazole (H2phpz) affords a highly asymmetric octanuclear manganese(III) cluster resulting from the different bridging coordination modes of the ligand H2phpz.     

Synthesis and crystal structure of a novel three-dimensional inorganic open-framework: Cd8(OH)8(SO4)4

The title compound Cd₈(OH)₈(SO₄)₄ (1) obtained under hydrothermal conditions by reacting Cd(OH)₂ with 4-aminobenzenesulfonic acid in an aqueous ethanol solution was confirmed by single-crystal X-ray diffraction. Crystal data: P2₁/c with a?=?6.8984(4), b?=?7.5640(4), c?=?11.3919(5)?Å, β?=?119.763(2)°, V?=?516.01(5)?ų, H₈Cd₈O₂₄S₄, M _r ?=?1419.50, Z?=?1, D _c ?=?4.568?Mg?m^?3, μ?=?8.595?mm^?1, F(000)?=?648, R?=?0.023, wR?=?0.060 for 1208 observed reflections [I?>?2σ(I?)]. The crystal structure of complex 1 forms a three-dimensional (3-D) framework.     

Zn8(SiO4)(C8H4O4)6]n: the firstborn of a metallosilicate-organic hybrid material family (C8H4O4 = isophthalate)

[Zn8(SiO4)(C8H4O4)6]n (C8H4O4 = isophthalate), synthesized by hydrothermal reaction, possesses a diamondoid framework structure constructed from hexahedron-like Zn8(SiO4) cores and C8H4O4 linkers and remains stable up to 500 degrees C in air, representing the first member of a new class of metallosilicate-organic hybrid materials.     

Discovery and synthesis of new UV-induced intrastrand C(4-8)G and G(8-4)C photolesions

UV irradiation of cellular DNA leads to the formation of a number of defined mutagenic DNA lesions. Here we report the discovery of new intrastrand C(4-8)G and G(8-4)C cross-link lesions in which the C(4) amino group of the cytosine base is covalently linked to the C(8) position of an adjacent dG base. The structure of the novel lesions was clarified by HPLC-MS/MS data for UV-irradiated DNA in combination with chemical synthesis and direct comparison of the synthetic material with irradiated DNA. We also report the ability to generate the lesions directly in DNA with the help of a photoactive precursor that was site-specifically incorporated into DNA. This should enable detailed chemical and biochemical investigations of these lesions.     

光学纯的(4S, 8R)-和(4S, 8S)-1- 烯-8, 9-二醇的改进合成法

本文提出了一个改进的合成两个光学异构纯的94S)-1- 烯-8, 9-二醇的方法,其优点是简便、有效, 适于克量级制备。     

Electron scattering from perfluorocyclobutane (c-C4F8)

We report experimental results for electron scattering from perfluorocyclobutane, c-C(4)F(8), obtained from measurements in our two laboratories. A set of differential, integral, and momentum transfer cross sections is provided for elastic scattering for incident electron energies from 1.5 to 100 eV. Inelastic scattering (vibrational excitation) cross sections have been measured for incident electron energies of 1.5, 2, 5, 6, and 7 eV. In order to investigate the role of intermediate negative ions (resonances) in the scattering process we have also measured an excitation function for elastic scattering and vibrational excitation of the ground electronic state of C(4)F(8) for incident energies between 0.6 and 20 eV. These results are compared with the limited amount of data available in the literature for scattering from this molecule.     

X-Ray Structure of 8-Quinolinolato Lanthanide Complex: (8-Quinolinolato)bis(2,6-di-tert-butyl-4-methylphenoxo)samarium

Ｉｎｔｒｏｄｕｃｔｉｏｎ8 Ｈｙｄｒｏｘｙｑｕｉｎｏｌｉｎｅｉｓａｃｌａｓｓｉｃａｌｃｈｅｌａｔｉｎｇａｇｅｎｔｆｏｒｔｒａｎｓｉｔｉｏｎｍｅｔａｌｓａｎｄｌａｎｔｈａｎｉｄｅｓ .Ｒｅｃｅｎｔｌｙｍｅｔａｌｃｏｍ ｐｌｅｘｅｓｉｎｃｏｒｐｏｒａｔｉｎｇ 8 ｑｕｉｎｏｌｉｎｏｌａｔｏｌｉｇａｎｄｓｈａｖｅｒｅｃｅｉｖｅｄｍｏｒｅａｎｄｍｏｒｅａｔｔｅｎｔｉｏｎ .Ｔｈｅｒｅｓｅａｒｃｈｉｎｔｅｒｅｓｔｐｒｏｂａｂｌｙａｒｉｓｅｓｆｒｏｍｔｗｏａｓｐｅｃｔｓ .Ｆｉｒｓｔ,8 ｑｕｉｎｏｌｉｎｏｌａｔｏｍｅｔ…     

稀土钬及铒钇丙氨酸配合物的量热与热分析研究

合成了两种固态稀土丙氨酸配合物[Ho2(Ala)4(H2O)8]Cl6和[ErY(Ala)4(H2O)8](ClO4)6 (Ala为丙氨酸),用量热和热分析方法研究了这两种配合物的热力学性质.用全自动高精密绝热量热计测定了在78～377 K温区内的低温热容.对于[Ho2(Ala)4(H2O)8]Cl6,在214～255 K温区内发现一固-固相变,其相变温度为235.09 K.对于[ErY(Ala)4(H2O)8](ClO4)6,在99～121 K温区内也发现一固-固相变,其相变温度为115.78 K. [Ho2(Ala)4(H2O)8]Cl6固-固相变焓为3.02 kJ• mol－1,相变熵为12.83 J•K－1•mol－1； [ErY(Ala)4(H2O)8](ClO4)6 固-固相变焓为1.96 kJ•mol－1,相变熵为16.90 J•K－1•mol－1.同时,用TG技术在40～800 ℃温区研究了两配合物的热稳定性.由TG/DTG曲线分析可知, [Ho2(Ala)4(H2O)8]Cl6从80 ℃到479 ℃热分解分两步完成, [ErY(Ala)4(H2O)8](ClO4)6从120 ℃到430 ℃热分解分三步完成.