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In this work, we designed Li‐ and Na‐doped homo‐ and heterodinuclear helical molecules, that is, Li2‐sexipy with two Li atoms, LiNa‐sexipy with Li and Na atoms, and Na2‐sexipy with two Na atoms. LiNa‐sexipy exhibited shorter Li‐L length compared with Li2‐sexipy; longer Na‐L length compared with Na2‐sexipy; and more charge polarization, especially along the vertical direction. Thus, the largest βtot value of LiNa‐sexipy among three molecules was observed. However, the loss of conjugation did not attenuate nonlinear optics (NLO) response. In addition, the maximum absorptions for the three helicates were all at the ultraviolet region, which suggested the performance of their transparency. These results indicated the advantages of heterodinuclear helix in this work and provided a new strategy of alkali metal doping to solve the conflict between transparency and NLO properties and enhance the NLO response of materials. [ABSTRACT FROM AUTHOR]

The hydrosilylation of terminal alkyne is the most straightforward and atom‐economy method to generate α‐vinylsilane. In the present paper, the acetylene and phenylacetylene hydrosilylation reactions were firstly studied by imposing external electric field (EEF) as a catalyst at the level of ωB97XD/TZVP. The results demonstrated that the oriented negative FY direction is the optimal direction, which mostly reduced the reaction barriers. Further computations indicated that the larger the EEF, the lower the barrier. When the EEF was increased to 180 (10−4) au, the barrier height of acetylene hydrosilylation (path Q) reduced almost 20 kcal/mol. To be surprised, as the phenyl substitute used, the hydrosilylation reaction (path FQ) was largely accelerated with the barrier height lowered to 13.2 kcal/mol, which decreased about 37 kcal/mol. Hopefully, this theoretical study would provide a guide for the experiment of the hydrosilylation of alkyne as much as possible. [ABSTRACT FROM AUTHOR]

In our previous work, new alkalides Li+(calix [4]pyrrole)M− with cup‐like complexant have been reported for the large static first hyperpolarizabilities (β0) (Chen et al., J Am Chem Soc 2006, 128, 1072). In this work, new inorganic alkalides are found by using a more flexible complexant, methylamine (NH2CH3)4. The structures with all real frequencies and β0 values of the inorganic alkalides Li+(cage [4]methylamine)M− (M = Li, Na, and K) are obtained at MP2 level. The result shows that these inorganic alkalides have more considerable β0 values to be 18,825 (M = Li) < 27,942 (M = Na) < 81,094 au (M = K), which are more than two times larger than those (10,969 ∼ 35,934 au) of the reported alkalides Li+(calix [4]pyrrole)M−. To understand this structure–property relationship, two cup‐like Li+(NH2CH3)4M− (M = Li, Na, and K) models are designed to compare their β0 values. By comparing the β0 values among the cup‐like alkalides Li+(calix [4]pyrrole)M−, Li+(NH2CH3)4M−, and cage‐like alkalides Li+(cage [4]methylamine)M− (M = Li, Na, and K), the complexant shape effect of alkalides has been revealed. It is found that the complexant shape is an important factor in large β0 values. Moreover, the monotonic dependences of β0 on the Li–M distance and the NBO charges of cation (Li+) and anions (M−) in inorganic alkalides Li+(cage [4]methylamine)M− have been shown. In this work, the frequency dependent first (hyper)polarizabilities are also determined. It is found that both the frequency dispersion and the effects of the electron correlation are strong. Moreover, the dependence of both the static and frequency dependent β on the atomic number of alkali metal anions is similar. This work provides a new way to understand the nature of high‐performance nonlinear optical (NLO) materials, and it is helpful to design new NLO materials. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011. [ABSTRACT FROM AUTHOR]