摘要
对2-(4-取代苯基)乙烯基吡啶系列用密度泛函法(DFT),在B3LYP/6-31+G**冰平上全优化几何构型,探讨苯环对位上不同取代基对分子电荷的转移、前线轨道能量等性质的影响规律。结果,电子由苯环向乙烯链移动,并通过乙烯链再向吡啶环移动;前线轨道能量随着取代基吸电子能力的增加而降低,随着供电子能力的增强而升高。在此基础上采用含时密度泛函(TD-DFT)计算分子第一激发态的电子跃迁能,得到最大吸收波长λ_(max)。计算结果,6个化合物的最强跃迁都由于基态到单重激发态分子的HOMO→LUMO跃迁,由轨道对称性可知为π→π*跃迁。引入上述5种取代基,均导致最大吸收波长红移。
Theoretical studies on a series of 2-（4-substitutional-phenyl） vinylpyridine were carried out using Density Functional Theory （DFT） at B3LYP/6-31 ＋ G＊＊ level to obtain optimized equilibrium structure. The effects of p-substituting groups （F, Cl, Br, CH3, OCH3 ） on the molecular charge transfer and energies of frontier molecular orbital have been investigated. The results showed that the electron transfer from benzene ring to vinyl, then to pyridine ring. The energies of frontier molecular orbitals become lower with the electron-attracting groups increasing, and become higher with the electron-donor groups increasing. On this basis, the first excited state electronic transition energy has been calculated using time-dependent density functional theory, and Aw was obtain. The computed results indicate that the electronic absorption of all compounds is mainly from π→π transition. The introduction of those substituting groups leads to bathochromic shift of maximal absorption wavelength. The predicted conclusion quite accorded with the available experimental ones.
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2008年第11期1409-1411,共3页
Computers and Applied Chemistry
基金
湖南省自然科学基金(06JJ2015).
