Halide Ion Complexes of Decaborane (B10H14) and Their Derivatives: Noncovalent Charge Transfer Effect on Second-Order Nonlinear Optical Properties

详细信息    查看全文

• 作者：Shabbir Muhammad ; Takuya Minami ; Hitoshi Fukui ; Kyohei Yoneda ; Ryohei Kishi ; Yasuteru Shigeta ; Masayoshi Nakano
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：February 9, 2012
• 年：2012
• 卷：116
• 期：5
• 页码：1417-1424
• 全文大小：372K
• 年卷期：v.116,no.5(February 9, 2012)
• ISSN：1520-5215

文摘

Quantum molecular engineering has been performed to determine the second-order nonlinear optical (NLO) properties in different halo complexes of decaborane (B₁₀H₁₄) and their derivatives using the density functional theory (DFT) method. These decaborane halo complexes of X^{鈥?/sup>@B₁₀H₁₄ (X = F, Cl, Br, and I) are found to possess noncovalent charge transfer interactions. The static polarizability (伪₀) and first hyperpolarizability (尾₀) among these complexes increase by moving down the group from F to I, partly due to the increase in size of their anionic radii and the decrease in their electron affinities. A two-level approximation has been employed to investigate the origin of 尾₀ values in these halo complexes, which show very consistent results with those by the finite-field method. Furthermore, in the same line, two experimentally existing complexes, I鈥?/sup>@B₁₀H₁₄ and I鈥?/sup>@2,4-I₂B₁₀H₁₂, are found to have considerably large 尾₀ values of 2859 and 3092 a.u., respectively, which are about three times larger than a prototypical second-order NLO molecule of p-nitroaniline, as reported by Soscun et al. [Int. J. Quantum Chem.2006, 106, 1130鈥?137]. Besides this, the special effects of solvent, counterion, and bottom substitutions have also been investigated. Interestingly, 2,4-alkali metal-substituted decaborane iodide complexes show remarkably large second-order NLO response with 尾₀ amplitude as large as 62436 a.u. for I鈥?/sup>@2,4-K₂B₁₀H₁₂ complex, which are explained in terms of their transition energies, frontier molecular orbitals and electron density difference plots. Thus, the present investigation provides several new comparative insights into the second-order NLO properties of halo complexes of decaborane, which possess not only large first hyperpolarizabilities, but also high tunability to get a robustly large second-order NLO response by alkali metal substitution effects.}