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41.
A luminescent Zn(II) complex, [Zn(bpy)(aba)2] (1) {bpy = 2,2'-bipyridyl and aba = 4-dimethylaminobenzoate} has been synthesized as a white solid. Complex 1 shows unusually high selectivity toward nitrobenzene in the presence of other organic guests in solution, as well as in the vapor phase, resulting in both a dramatic color change and a concomitant quenching of luminescence. When crystallized from nitrobenzene, 1 affords deep red crystals with the composition [Zn(bpy)(aba)2] x C6H5NO2 (2) as a hydrogen-bonded channel structure via unusual intermolecular C-H...C(sp3) and H...H interactions. Inside the channels, nitrobenzene molecules form infinite polar linear tapes through strong C-H...O interactions in a head-to-tail fashion. The desorption and resorption of nitrobenzene can be achieved in a thermally reversible manner that can be monitored by X-ray powder diffraction patterns. 相似文献
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SK Ghorai SK Samanta M Mukherjee S Ghosh 《The journal of physical chemistry. A》2012,116(32):8303-8312
A ternary system consisting of a protein, catechin (either + or - epimer), and Tb(III) in suitable aqueous buffer medium at physiological pH (= 6.8) has been shown to exhibit highly efficient "antenna effect". Steady state and time-resolved emission studies of each component in the binary complexes (protein with Tb(III) and (+)- or (-)-catechin with Tb(III)) and the ternary systems along with the molecular docking studies reveal that the efficient sensitization could be ascribed to the effective shielding of microenvironment of Tb(III) from O-H oscillator and increased Tb-C (+/-) interaction in the ternary systems in aqueous medium. The ternary system exhibits protein-mediated efficient antenna effect in D(2)O medium due to synergistic ET from both the lowest ππ* triplet state of Trp residue in protein and that of catechin apart from protection of the Tb(III) environment from matrix vibration. The simple system consisting of (+)- or (-)-catechin and Tb(III) in D(2)O buffer at pH 6.8 has been prescribed to be a useful biosensor. 相似文献
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We study several classes of non-Hermitian Hamiltonian systems, which can be expressed in terms of bilinear combinations of Euclidean–Lie algebraic generators. The classes are distinguished by different versions of antilinear (PT)-symmetries exhibiting various types of qualitative behaviour. On the basis of explicitly computed non-perturbative Dyson maps we construct metric operators, isospectral Hermitian counterparts for which we solve the corresponding time-independent Schrödinger equation for specific choices of the coupling constants. In these cases general analytical expressions for the solutions are obtained in the form of Mathieu functions, which we analyze numerically to obtain the corresponding energy spectra. We identify regions in the parameter space for which the corresponding spectra are entirely real and also domains where the PT symmetry is spontaneously broken and sometimes also regained at exceptional points. In some cases it is shown explicitly how the threshold region from real to complex spectra is characterized by the breakdown of the Dyson maps or the metric operator. We establish the explicit relationship to models currently under investigation in the context of beam dynamics in optical lattices. 相似文献
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Gogoi Sanjib Banerjee Sanjib Bhowmick Sumit 《Journal of Thermal Analysis and Calorimetry》2022,147(22):12437-12453
Journal of Thermal Analysis and Calorimetry - 2219Al alloys microalloyed with varying Cd contents were processed by casting technique. Differential scanning calorimetry (DSC) was performed from 323... 相似文献
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Moumita Majumdar Arup Sinha Tapas Ghatak Sanjib K. Patra Nabanita Sadhukhan S. M. Wahidur Rahaman Jitendra K. Bera Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(8):2574-2585
The complete sequence of reactions in the base‐promoted reduction of [{RuII(CO)3Cl2}2] to [RuI2(CO)4]2+ has been unraveled. Several μ‐OH, μ:κ2‐CO2H‐bridged diruthenium(II) complexes have been synthesized; they are the direct results of the nucleophilic activation of metal‐coordinated carbonyls by hydroxides. The isolated compounds are [Ru2(CO)4(μ:κ2‐C,O‐CO2H)2(μ‐OH)(NPF‐Am)2][PF6] ( 1 ; NPF‐Am=2‐amino‐5,7‐trifluoromethyl‐1,8‐naphthyridine) and [Ru2(CO)4(μ:κ2‐C,O‐CO2H)(μ‐OH)(NP‐Me2)2][BF4]2 ( 2 ), secured by the applications of naphthyridine derivatives. In the absence of any capping ligand, a tetranuclear complex [Ru4(CO)8(H2O)2(μ3‐OH)2(μ:κ2‐C,O‐CO2H)4][CF3SO3]2 ( 3 ) is isolated. The bridging hydroxido ligand in 1 is readily replaced by a π‐donor chlorido ligand, which results in [Ru2(CO)4(μ:κ2‐C,O‐CO2H)2(μ‐Cl)(NP‐PhOMe)2][BF4] ( 4 ). The production of [Ru2(CO)4]2+ has been attributed to the thermally induced decarboxylation of a bis(hydroxycarbonyl)–diruthenium(II) complex to a dihydrido–diruthenium(II) species, followed by dinuclear reductive elimination of molecular hydrogen with the concomitant formation of the RuI? RuI single bond. This work was originally instituted to find a reliable synthetic protocol for the [Ru2(CO)4(CH3CN)6]2+ precursor. It is herein prescribed that at least four equivalents of base, complete removal of chlorido ligands by TlI salts, and heating at reflux in acetonitrile for a period of four hours are the conditions for the optimal conversion. Premature quenching of the reaction resulted in the isolation of a trinuclear RuI2RuII complex [{Ru(NP‐Am)2(CO)}{Ru2(NP‐Am)2(CO)2(μ‐CO)2}(μ3:κ3‐C,O,O′‐CO2)][BF4]2 ( 6 ). These unprecedented diruthenium compounds are the dinuclear congeners of the water–gas shift (WGS) intermediates. The possibility of a dinuclear pathway eliminates the inherent contradiction of pH demands in the WGS catalytic cycle in an alkaline medium. A cooperative binuclear elimination could be a viable route for hydrogen production in WGS chemistry. 相似文献