Tuck Patrick Owen, Mawhinney Robert Christopher, Rappon Manit
Department of Chemistry, Lakehead University, 955 Oliver Rd. Thunder Bay ON, Canada P7B 5E1.
Phys Chem Chem Phys. 2009 Jun 14;11(22):4471-80. doi: 10.1039/b902528f. Epub 2009 Apr 3.
A CIS and TD-DFT study using a polarizable continuum solvent model has been conducted to assess non-specific solvent effects on the spectral shifts in Nile Red (NR). The results in this paper show that the electronic band shifts of Nile Red are a consequence of both a field effect on the transition energy and an effect due to a solvent induced geometry change. The S0-->S1 transition experiences a large red-shift with increasing solvent polarity but is relatively insensitive to geometric change. The TD-B3LYP assessment of the S0-->S2 transition yields a blue shift with increasing solvent polarity but a red shift due to the solvent induced geometry change. Ground state dipole moments and polarizabilities are also shown to increase with solvent polarity. CIS optimization of the first excited state of NR is reported, but the solvent effects suggest a locally excited state may have been obtained. Further studies are needed to assess the role of a TICT state.
使用可极化连续介质溶剂模型进行了含时耦合微扰密度泛函理论（CIS和TD-DFT）研究，以评估非特异性溶剂对尼罗红（NR）光谱位移的影响。本文结果表明，尼罗红的电子能带位移是跃迁能量的场效应以及溶剂诱导几何变化效应共同作用的结果。随着溶剂极性增加，S0→S1跃迁经历大幅红移，但对几何变化相对不敏感。对S0→S2跃迁的TD-B3LYP评估显示，随着溶剂极性增加产生蓝移，但由于溶剂诱导几何变化产生红移。基态偶极矩和极化率也随溶剂极性增加而增大。报道了NR第一激发态的CIS优化，但溶剂效应表明可能得到的是局域激发态。需要进一步研究来评估扭转内电荷转移（TICT）态的作用。
