Department of Chemistry, The University of Burdwan, Golapbag, Burdwan - 713 104, India.
J Phys Chem A. 2011 Sep 8;115(35):9929-40. doi: 10.1021/jp204924z. Epub 2011 Aug 17.
The present article reports, for the first time, the photophysical aspects of noncovalent interaction of a fullerene derivative, namely, C(60) pyrrolidine tris-acid ethyl ester (PyC(60)) with a series of zincphthalocyanines, for example, underivatized zincphthalocyanine (1), zinc-1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (2), and zinc-2,3,9,10,16,17,23,24-octakis-(octyloxy)-29H,31H-phthalocyanine (3) in toluene. Ground state electronic interaction of PyC(60) with 1, 2 and 3 has been evidenced from the observation of well-defined charge transfer (CT) absorption bands in the visible region. Utilizing the CT transition energy, vertical electron affinity (E(A)(v)) of PyC(60) is determined. Steady state fluorescence experiment enables us to determine the value of binding constant (K) in the magnitude of 2.60 × 10(4) dm(3)·mol(-1), 2.20 × 10(4) dm(3)·mol(-1), and 1.27 × 10(4) dm(3)·mol(-1) for the noncovalent complexes of PyC(60) with 1, 2, and 3, respectively. K values of PyC(60)-ZnPc complexes suggest that PyC(60) is incapable of discriminating between 1, 2, and 3 in solution. Lifetime experiment signifies the importance of static quenching phenomenon for our presently investigated supramolecules and it yields larger magnitude of charge separated rate constant for the PyC(60)-1 species in toluene. Photoinduced energy transfer between PyC(60) and ZnPc derivatives, namely, 1, 2, and 3, in toluene, has been evidenced with nanosecond laser photolysis method by observing the transient absorption bands in the visible region; transient absorption studies establish that energy transfer from (T)PyC(60)* to the ZnPc occurs predominantly, as confirmed by the consecutive appearance of the triplet states of PyC(60). Theoretical calculations at semiempirical level (PM3) evoke the single projection geometric structures for the PyC(60)-ZnPc systems in vacuo, which also proves that interaction between PyC(60) and ZnPc is governed by the electrostatic mechanism rather than dispersive forces associated with π-π interaction.
本文首次报道了富勒烯衍生物 C(60) 吡咯烷三酸乙酯（PyC(60)）与一系列锌酞菁的非共价相互作用的光物理方面，例如，未取代的锌酞菁（1）、锌-1,4,8,11,15,18,22,25-八丁氧基-29H,31H-酞菁（2）和锌-2,3,9,10,16,17,23,24-八（辛氧基）-29H,31H-酞菁（3）在甲苯中的情况。从可见区域中观察到明确的电荷转移（CT）吸收带，可以证明 PyC(60) 与 1、2 和 3 的基态电子相互作用。利用 CT 跃迁能量，确定了 PyC(60) 的垂直电子亲和力（E(A)(v)）。稳态荧光实验使我们能够确定 PyC(60) 与 1、2 和 3 的非共价配合物的结合常数（K）值分别为 2.60×10(4) dm(3)·mol(-1)、2.20×10(4) dm(3)·mol(-1)和 1.27×10(4) dm(3)·mol(-1)。PyC(60)-ZnPc 配合物的 K 值表明，PyC(60) 在溶液中无法区分 1、2 和 3。寿命实验表明，对于我们目前研究的超分子，静态猝灭现象非常重要，并且在甲苯中，PyC(60)-1 物种的电荷分离速率常数更大。通过观察可见区域中的瞬态吸收带，纳米秒激光光解法证实了 PyC(60) 和 ZnPc 衍生物（即 1、2 和 3）之间在甲苯中的光诱导能量转移；瞬态吸收研究表明，能量从（T）PyC(60)*转移到 ZnPc 主要发生，这正如 PyC(60) 的三重态的连续出现所证实的那样。在半经验水平（PM3）的理论计算中，在真空中为 PyC(60)-ZnPc 体系引出了单一投影几何结构，这也证明了 PyC(60) 和 ZnPc 之间的相互作用受静电机制而非与π-π相互作用相关的分散力控制。
