烷基取代对罗丹明的电子结构与光谱的影响  

Effect of Alkyl Substitution on the Electronic Structure and Spectrum of Rhodamine

作　　者：雷永林[1] 霍冀川[1] 

机构地区：[1]西南科技大学材料科学与工程学院,四川绵阳621010

出　　处：《物理化学学报》2010年第2期447-452,共6页Acta Physico-Chimica Sinica

基　　金：四川省教育厅重点项目(2005A139)资助~~

摘　　要：在密度泛函理论(DFT)的B3LYP水平对不同烷基在不同位置取代形成的8种罗丹明化合物进行结构优化,并在此基础上应用含时密度泛函理论(TD-DFT)和单激发组态相互作用(CIS)方法分析了取代基对罗丹明的电子结构、前线分子轨道及电子光谱的影响.计算结果表明,前线分子轨道主要分布在罗丹明分子的氧杂蒽环上,罗丹明分子中两个N端的H各只有1个H被烷基取代时,最高占据轨道(HOMO)在主要共轭环分布最多,且HOMO和最低未占据轨道(LUMO)分布比例相差最小,两个N端4个H同时被甲基取代时,能隙最窄,对气相最大吸收波长红移程度最大,两个N端4个H同时被乙基取代时,气相荧光最大,发射波长最长.The structures of eight kinds of rhodamine compounds, substituted by different alkyls at different positions, were optimized using the density functional theory （DPT） at the B3LYP level. On the basis of these optimized structures, the influence of the substituting group on the electronic structures and spectral properties as well as frontier molecular orbitals of rhodamine were analyzed using the singlet configuration interaction （CIS） method and time dependent density functional theory （TD-DFT）. Results indicate that the frontier molecular orbitals are mainly distributed in the xanthene ring of rhodamine when only one H atom of the two N-ends in the rhodamine molecule is substituted by alkyls. The distribution of the highest occupied molecular orbital （HOMO） is the greatest in the main conjugate ring and the difference in the distribution ratio between the HOMO and the the lowest unoccupied molecular orbital （LUMO） is small. When the four H atoms of the two N-ends in the rhodamine molecules are substituted by methyl, the bandgap is found to be the narrowest and the red shift in the gas maximum absorption wavelength is the largest. When the four H atoms of the two N-ends in rhodamine molecules are substituted by ethyl, the gas fluorescence maximum emission wavelength is the longest.

关 键 词：密度泛函理论 罗丹明 烷基取代 前线分子轨道 电子光谱 

分 类 号：O641.1[理学—物理化学]