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131.
Dr. Robert J. Wilson Dr. Lies Broeckaert M. Sc. Fabian Spitzer Priv.‐Doz. Dr. Florian Weigend Prof. Dr. Stefanie Dehnen 《Angewandte Chemie (International ed. in English)》2016,55(39):11775-11780
Reaction of the binary Zintl anion (Sn2Sb2)2? with the β‐diketiminato complex [LCu(NCMe)] (L=nacnac=[(N(C6H3iPr2‐2,6)C(Me))2CH]?) in ethylenediamine or DMF affords the ternary cluster dimer {[CuSn5Sb3]2?}2 ( 1 ) as its [K(crypt‐222)]+ salt. The chemical formulation of 1 is supported by energy‐dispersive X‐ray spectroscopy (EDX) and quantum chemical calculations. Each monomeric part of the dimer represents a trimetallic “[CuSn5Sb3]2?” cluster, with an architecture in between a tricapped trigonal prism and a capped square antiprism. As shown by quantum chemical investigations, the presence of Sb atoms and, in particular, of Cu atoms in the cluster skeleton makes the monomeric unit behave like an inhomogeneous superatom, which clearly prefers to dimerize, thereby producing a relatively short, yet virtually non‐bonding Cu???Cu distance. 相似文献
132.
133.
Stefan Liebig Heinrich Billetter Tim Wallraff Stefanie Busch Stefan Müller Uwe Ruschewitz 《无机化学与普通化学杂志》2016,642(1):66-72
Three alkali metal acetylides, namely KNaC2, KRbC2, and NaRbC2, were synthesized and characterized by means of X‐ray powder diffraction. KNaC2 and KRbC2 crystallize as a variant of the anti‐PbCl2‐type structure (Pnma, Z = 4), whereas NaRbC2 crystallizes as a variant of the anti‐PbFCl‐type structure (Pmmn, Z = 2). Based on a simple systematic approach developed by Sabrowsky et al. for inter‐alkali metal chalcogenides all known inter‐alkali metal acetylides can be classified into two classes: variants of the anti‐PbCl2 type structure and variants of the anti‐PbFCl type structure. Acetylides with Q(ABC2) ≤ 1.45 crystallize in the anti‐PbCl2‐type structure, whereas for Q(ABC2) > 1.45 the anti‐PbFCl‐type structure is found (Q(ABC2) = Vm(A2C2)/Vm(B2C2) with Vm(A2C2) > Vm(B2C2); Vm: molar volume, A, B = alkali metals). 相似文献
134.
The visible-light irradiation of 9-mesityl-10-methylacridinium perchlorate 1 in the presence of monoalkenes and molecular oxygen leads to typical products of singlet oxygen addition (type II photooxygenation). The molecular probes 1-methylcyclohexene and limonene, respectively, result in hydroperoxide mixtures with a characteristic product pattern. A switch in the oxidative mechanism (electron-transfer photooxygenation) is observed for naphthalene derivatives as electron-rich acceptor molecules, revealing that the 9-mesityl-10-methylacridinium cation serves as a dual sensitizer with the capacity of efficient singlet oxygen formation and electron-transfer reaction. [reaction: see text]. 相似文献
135.
The loading module of mycosubtilin: an adenylation domain with fatty acid selectivity 总被引:1,自引:0,他引:1
Hansen DB Bumpus SB Aron ZD Kelleher NL Walsh CT 《Journal of the American Chemical Society》2007,129(20):6366-6367
136.
137.
King BT Körbe S Schreiber PJ Clayton J Nemcova A Havlas Z Vyakaranam K Fete MG Zharov I Ceremuga J Michl J 《Journal of the American Chemical Society》2007,129(43):12960-12980
The 15 symmetrically methylated derivatives of the CB11H12(-) anion (1a) have been synthesized and found to vary greatly in ease of oxidation. Cyclic voltammetry in liquid SO2 yielded fully reversible oxidation potentials for five of those that have no adjacent unsubstituted vertices in positions 7-12; three others showed some indication of reversibility. The anions 1a-16a and the Jahn-Teller distorted neutral radicals 1r-16r have been characterized by ab initio and density functional theory calculations. In the state average CASSCF(13,12)/6-31+G* approximation, the ground state potential energy surface of 1r contains five symmetry-related pairs of minima. The computational results account for the reversible redox potentials very well when the solvent is included explicitly (RI-DFT(BP)/TZVP, COSMO). For display and for a semiquantitative understanding of methyl substituent effects in terms of perturbation theory, the molecular orbitals of 1a have been expressed in the symmetry-adapted cluster basis. The results serve as an underpinning for a set of additive empirical increments for redox potential prediction. Relative to the usual hydrogen standard, a single methyl group facilitates oxidation by approximately 50, 70, 70, and 10 mV in positions 1, 2, 7, and 12, respectively. This electron donor effect on the redox potential is due to a contribution, whereas those of (inductive and direct field) type are negligible. 相似文献
138.
Lord SJ Lu Z Wang H Willets KA Schuck PJ Lee HL Nishimura SY Twieg RJ Moerner WE 《The journal of physical chemistry. A》2007,111(37):8934-8941
We report the solvatochromic, viscosity-sensitive, and single-molecule photophysics of the fluorophores DCDHF-N-6 and DCDHF-A-6. These molecules are members of the dicyanomethylenedihydrofuran (DCDHF) class of single-molecule emitters that contain an amine electron donor and a DCDHF acceptor linked by a conjugated unit; DCDHF-N-6 and DCDHF-A-6 have naphthalene- and anthracene-conjugated linkers, respectively. These molecules maintain the beneficial photophysics of the phenylene-linked DCDHF (i.e., photostability, emission wavelength dependence on solvent polarity, and quantum yield sensitivity to solvent viscosity), yet offer absorption and emission at longer wavelengths that are more appropriate for cellular imaging. We demonstrate that these new fluorophores are less photolabile in an aqueous environment than several other commonly used dyes (rhodamine 6G, Texas Red, and fluorescein). Finally, we image single copies of the acene DCDHFs diffusing in the plasma membrane of living cells. 相似文献
139.
Lutter S Tiersch B Koetz J Boschetti-de-Fierro A Abetz V 《Journal of colloid and interface science》2007,311(2):447-455
This paper is focused on the influence of polystyrene (PS)-poly(1,4-butadiene) (PB)-poly(ethylene oxide) (PEO) triblock terpolymers on the w/o microemulsion of the pseudo-ternary system water/sodium dodecylsulfate (SDS)/xylene-pentanol. Despite the insolubility of the copolymer in water as well as in the xylene-pentanol mixture, it can be incorporated into the w/o microemulsion and interactions between the triblock terpolymer molecules and the anionic surfactant headgroups can be detected by differential scanning calorimetry (DSC) measurements. Furthermore, dynamic light scattering measurements were used to determine the aggregate diameter of the modified microemulsions. For lower polymer concentrations large aggregates between 100 and 500 nm can be observed. Surprisingly, at a higher terpolymer concentration of 5 wt%, significant smaller aggregate diameters can be identified by dynamic light scattering and Cryo-SEM. One can conclude that the copolymers are incorporated in the inverse microemulsion droplets, where the PB blocks cover the water droplets. The thermally induced radical cross-linking of the butadiene units in the presence of azobisisobutyronitrile (AIBN) leads then to covalently closed nanocapsules with an average size of 10 nm. 相似文献
140.
Surup F Wagner O von Frieling J Schleicher M Oess S Müller P Grond S 《The Journal of organic chemistry》2007,72(14):5085-5090
The iromycins A-D are members of a new family of rare alpha-pyridone metabolites. The isolation and structure elucidation of these microbial secondary metabolites from Streptomyces sp. Dra 17 revealed a N-heterocyclic core structure with two unusual side chains. Iromycins act as inhibitors of nitric oxide synthases (NOS), a protein family, which produces the crucial second messenger nitric oxide (NO). Importantly, these compounds inhibit selectively endothelial NOS rather than neuronal NOS and thus set prospects for both medical therapy and basic research. Feeding experiments with 13C- and 15N -labeled precursors indicated an uncommon type of polyketide biosynthesis and clearly ruled out an isoprenoid origin. A detoxification pathway of a particular secondary metabolite in the host strain is a rare observation and here we demonstrate it with the iromycin family. 相似文献