Department of Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
J Phys Chem A. 2009 Nov 5;113(44):12179-86. doi: 10.1021/jp903014s.
The circular dichroism (CD) spectra of (1,8,15,22-tetraalkoxylphthalocyaninato)lead complexes Pb[Pc(alpha-OCH3)4] (1), Pb[Pc(alpha-OC2H5)4] (2), and Pb[Pc(alpha-OC5H11)4] (3) (OC5H11 = 3-pentyloxy) together with the monoanion of heteroleptic (phthalocyaninato)(1,8,15,22-tetramethoxylphthalocyaninato)yttrium double-decker {Y(Pc)[Pc(alpha-OCH3)4]}- (4) were investigated by time-dependent density functional theory calculations. The calculation results reveal that 1 and 2 show similar CD spectra, which however are quite different from that of 3 despite the very similar electronic absorption spectra for 1-3 due to their similar electronic structure. The difference in the calculated structural parameter of the phthalocyanine macrocyclic ligand for 1-3 is negligible. In contrast, the orientation of alkoxyl substituents relative to the isoindole segments on which the substituents are attached for 1 and 2 is almost the same but significantly different from that for 3. These results suggest that the relative orientation of alkoxyl substituents determines the CD spectrum of chiral phthalocyaninatolead complexes with C(4) molecular symmetry. Further support comes from the change in the calculated CD spectrum of 1 depending on the orientation angle of the methoxyl groups. The calculation result on the CD spectrum of the yttrium double-decker compound 4 indicates the transfer of chiral information from the (1,8,15,22-tetramethoxylphthalocyaninato)yttrium fraction to the unsubstituted phthalocyanine fraction and the in turn significant contribution of the unsubstituted phthalocyanine ring to the CD spectrum of the double-decker molecule. The present work, clarifying the structural factor influencing the CD spectroscopic properties of chiral phthalocyaninatometal complexes with nonplanar molecular structure, will be helpful for clearly understanding the relationship between the chiroptical property and molecular structure.
（1,8,15,22-四烷氧基酞菁基）铅配合物 Pb[Pc（α-OCH3）4]（1）、Pb[Pc（α-OC2H5）4]（2）和 Pb[Pc（α-OC5H11）4]（3）（OC5H11 = 3-戊氧基）以及异核（酞菁基）（1,8,15,22-四甲氧基酞菁基）钇双层{Y（Pc）[Pc（α-OCH3）4]} -（4）的单阴离子的圆二色性（CD）光谱通过时间相关密度泛函理论计算进行了研究。计算结果表明，尽管 1-3 的电子吸收光谱非常相似，由于它们具有相似的电子结构，因此 1 和 2 表现出相似的 CD 光谱，但与 3 的 CD 光谱却截然不同。1-3 的酞菁大环配体的计算结构参数差异可以忽略不计。相比之下，1 和 2 中烷氧基取代基相对于取代基所连接的异吲哚片段的取向几乎相同，但与 3 的取向明显不同。这些结果表明，烷氧基取代基的相对取向决定了具有 C（4）分子对称性的手性酞菁基铅配合物的 CD 光谱。进一步的支持来自于根据甲氧基基团的取向角改变计算的 1 的 CD 光谱。对钇双层化合物 4 的 CD 光谱的计算结果表明，手性信息从（1,8,15,22-四甲氧基酞菁基）钇部分转移到未取代的酞菁部分，并且未取代的酞菁环对双层分子的 CD 光谱有显著贡献。本工作阐明了影响非平面分子结构的手性酞菁基金属配合物的 CD 光谱性质的结构因素，有助于清楚地理解手性光学性质与分子结构之间的关系。
