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用密度泛含方法研究了LaC5n(n=-1,0,+1)分子簇的结构和稳定性及振动光谱,对这个六原子体系提出了三种可能构型,点群结构为C2v对称性.第一个构型为La接在弯曲的C5链上,第二个是La通过二个键与C5环相连第三个是La通过一个键与C5环相连;结果表明,第一个构型即当La接在弯曲的C5链上时能量最低.振动光谱分析指出,当n=-1时,第二个构型为局域极小值;当n=+1时,第一个和第二个构型为局域极小值;对n=0,局域极小值没有找到.  相似文献   
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用密度泛函方法研究了LaC3n(n=-1,0,+1)分子簇的结构和稳定性,对这个四原子体系,提出了5种可能构型,其中3种具有C2v对称性,2种为C∞v对称性.在C2v对称性结构中,其中1个为La接在弯曲的C3链上,第2个是La通过2个键与C3环相链,第3个是La通过1个键与C3环相连;在C∞v对称性中,第1个La接在C3链的一端,而在第2个构型中,La被插入在C3链中.结果表明,环状结构当La接在弯曲的C3链上的是局域极小值并且最稳定  相似文献   
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The use of a strongly donating “(bis‐dialkylphosphine)Ni” fragment promotes the catalytic coupling of a large range of ArCl and ArZnCl derivatives under mild conditions. Stoichiometric mechanistic investigations and DFT calculations prove that a Ni0/NiII cycle is operative in this system.  相似文献   
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We use second order Moller Plesset perturbation theory and several density functional theory methods to calculate the counterpoise corrected electronic interaction energies between benzene and a series of polyaromatic molecules. These systems serve as a simple model for DNA intercalation. We show that addition of nitrogen atoms to the polyaromatic molecules always increases sandwich‐type interactions, and that, of the density functional theory methods studied, only SVWN can mimic the interaction energies and optimal separations obtained with perturbation theory. SVWN reproduces the optimal molecular distances obtained with perturbation theory very well, and often comes within less than 10% of the interaction energy. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008  相似文献   
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A novel fluorescent sensor based on tetraphenylethene (TPE) modified with 2,6‐pyridinedicarboxylic acid (PDA) that shows aggregation‐induced emission (AIE) characteristics for thorium recognition with remarkable fluoresence enhancement response has been synthesized. This sensor is capable of visually distinguishing Th4+ among lanthanides, transition metals, and alkali metals under UV light. Th4+ can be detected by the naked eye at ppb levels owing to the AIE phenomenon. The sensor showed high selectivity for Th4+ compared to all other metals tested, and this recognition displayed good anti‐interference qualities. This study represents the first application of a AIE fluorescence sensor in actinide metal recognition and it has potential applications in environmental systems for thorium ion detection.  相似文献   
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