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301.
302.
A survey of the quantum chemical results obtained for several MLCT complexes studied in Amsterdam is presented in order to illustrate the progress made in this field from the beginning of the 1980s when excited states properties were analyzed in terms of bonding and antibonding molecular orbitals (MO). Nowadays the photoactive states and the main features of the absorption spectra can be determined without any ambiguity. The time scales of elementary processes such as direct ultra-fast dissociations or intersystem crossing processes, are also readily available. 相似文献
303.
A new carotenoid, Sidnyaxanthin, was isolated from the Tunicate: Sidnyum argus. The structure was elucidated by spectral analysis and chemical transformation 相似文献
304.
Bertrand Marrot Chantal Brouca-Cabarrecq Alain Mosset 《Journal of chemical crystallography》1998,28(6):447-452
The synthesis and crystal structure of a new EDTA complex, [CaSb2(EDTA)2(H2O)8]n, are reported. This compound crystallizes in the monoclinic space group P21/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb2O6. 相似文献
305.
Nadine Leygue Aritz Perez e Iñiguez De Heredia Chantal Galaup Eric Benoist Laurent Lamarque Claude Picard 《Tetrahedron》2018,74(31):4272-4287
A series of four new 18-membered hexaaza macrocyclic ligands bearing three endocyclic pyridine units and acetate or methylenephosphonate pendant arms has been prepared. The new synthetic procedure is based on the use of amine and diamine precursors incorporating masked carboxylate or phosphonate functions and on an efficient sodium template effect which controls the crucial macrocyclization step (yields of macrocyclization reactions: 62–88%). This procedure appears as a suitable alternative compared to the classical Richman-Atkins methodology generally used for the preparation of this class of macrocycles. As demonstrated with the EuIII and TbIII complexes derived from two ligands, these tripyridinophane chelators form luminescent and stable mononuclear LnIII complexes in aqueous solution at physiological pH. In such a medium, TbIII complexes exhibit a brightness of 1700 (λexc?=?279?nm) and 3000 (λexc?=?268?nm)?M?1?cm?1. 相似文献
306.
Hassan Srour Olivier Ratel Mathieu Leocmach Emma A. Adams Sandrine Denis‐Quanquin Vinukrishnan Appukuttan Nicolas Taberlet Sbastien Manneville Jean‐Charles Majest Christian Carrot Chantal Andraud Cyrille Monnereau 《Macromolecular rapid communications》2015,36(1):55-59
Tuning the chain‐end functionality of a short‐chain cationic homopolymer, owing to the nature of the initiator used in the atom transfer radical polymerization (ATRP) polymerization step, can be used to mediate the formation of a gel of this poly(electrolyte) in water. While a neutral end group gives a solution of low viscosity, a highly homogeneous gel is obtained with a phosphonate anionic moiety, as characterized by rheometry and diffusion nuclear magnetic resonance (NMR). This novel type of supramolecular control over poly(electrolytic) gel formation could find potential use in a variety of applications in the field of electro‐active materials.
307.
Maulucci N Chini MG Micco SD Izzo I Cafaro E Russo A Gallinari P Paolini C Nardi MC Casapullo A Riccio R Bifulco G Riccardis FD 《Journal of the American Chemical Society》2007,129(10):3007-3012
Azumamide E, a cyclotetrapeptide isolated from the sponge Mycale izuensis, is the most powerful carboxylic acid containing natural histone deacetylase (HDAC) inhibitor known to date. In this paper, we describe design and synthesis of two stereochemical variants of the natural product. These compounds have allowed us to clarify the influence of side chain topology on the HDAC-inhibitory activity. The present contribution also reveals the identity of the recognition pattern between azumamides and the histone deacetylase-like protein (HDLP) model receptor and reports the azumamide E unprecedented isoform selectivity on histone deacetylases class subtypes. From the present studies, a plausible model for the interaction of azumamides with the receptor binding pocket is derived, providing a framework for the rational design of new cyclotetrapeptide-based HDAC inhibitors as antitumor agents. 相似文献
308.
Villaume S Strich A Ndoye CA Daniel C Perera SA Bartlett RJ 《The Journal of chemical physics》2007,126(15):154318
State of the art coupled cluster (CC) methods are applied to accurately characterize the ground state electronic structure and photoelectron spectra of transition metal carbene ions MCH(2) (+) (M=Fe, Co, and Ni). The geometries and energies of the lowest energy quartet, triplet, and doublet electronic states as well as several low-lying vertical excitation energies of FeCH(2) (+), CoCH(2) (+), and NiCH(2) (+) are reported. The excitation energies are computed using the equation-of-motion CC and for states of different symmetries, by the energy differences of single reference ground and excited states (Delta-CC). The latter employ several reference states; the unrestricted Hartree-Fock, restricted open shell Hartree-Fock, and unrestricted Kohn-Sham. We conclude that the (2)A(1) electronic ground state of NiCH(2) (+) is separated by about 30.0 kJ/mol from the next highest state, and the lowest (4)B(1) and (4)B(2) states of FeCH(2) (+) as well as the (3)A(2) and (3)A(1) states of CoCH(2) (+) are nearly degenerate. The presence of metal-pi*(MCH(2)) charge transfer states with significant oscillator strengths in the visible/near-UV energy domain of the theoretical spectra of FeCH(2) (+) and CoCH(2) (+) are at the origin of the photofragmentation of these compounds observed after irradiation between 310 and 360 nm. 相似文献
309.
Valeriani C Allen RJ Morelli MJ Frenkel D Rein ten Wolde P 《The Journal of chemical physics》2007,127(11):114109
We present a method for computing stationary distributions for activated processes in equilibrium and nonequilibrium systems using forward flux sampling. In this method, the stationary distributions are obtained directly from the rate constant calculations for the forward and backward reactions; there is no need to perform separate calculations for the stationary distribution and the rate constant. We apply the method to the nonequilibrium rare event problem proposed by Maier and Stein, to nucleation in a 2-dimensional Ising system, and to the flipping of a genetic switch. 相似文献
310.
The synthesis, spectroscopic properties, and TD-DFT calculations of new aza-Boron-dipyromethene dyes featuring pendant nitrofluorenylethynyl substituents are described. This functionalization allows for moving the luminescence in the NIR, conserving a good quantum yield efficiency. 相似文献