Center for Photochemical Sciences and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, USA.
Inorg Chem. 2011 Feb 7;50(3):1135-49. doi: 10.1021/ic102209q. Epub 2010 Dec 28.
The structural, optical, and photophysical properties of 1,4,8,11,15,18,22,25-octabutoxyphthalocyaninato-palladium(II), PdPc(OBu)(8), and the newly synthesized platinum analogue PtPc(OBu)(8) are investigated combining X-ray crystallography, static and transient absorption spectroscopy, and relativistic zeroth-order regular approximation (ZORA) Density Functional Theory (DFT)/Time Dependent DFT (TDDFT) calculations where spin-orbit coupling (SOC) effects are explicitly considered. The results are compared to those previously reported for NiPc(OBu)(8) (J. Phys. Chem. A 2005, 109, 2078) in an effort to highlight the effect of the central metal on the structural and photophysical properties of the group 10 transition metal octabutoxyphthalocyanines. Different from the nickel analogue, PdPc(OBu)(8) and PtPc(OBu)(8) show a modest and irregular saddling distortion of the macrocycle, but share with the first member of the group similar UV-vis spectra, with the deep red and intense Q-band absorption experiencing a blue shift down the group, as observed in virtually all tetrapyrrolic complexes of this triad. The blue shift of the Q-band along the MPc(OBu)(8) (M = Ni, Pd, Pt) series is interpreted on the basis of the metal-induced electronic structure changes. Besides the intense deep red absorption, the title complexes exhibit a distinct near-infrared (NIR) absorption due to a transition to the double-group 1E (π,π*) state, which is dominated by the lowest single-group (3)E (π,π*) state. Unlike NiPc(OBu)(8), which is nonluminescent, PdPc(OBu)(8) and PtPc(OBu)(8) show both deep red fluorescence emission and NIR phosphorescence emission. Transient absorption experiments and relativistic spin-orbit TDDFT calculations consistently indicate that fluorescence and phosphorescence emissions occur from the S(1)(π,π*) and T(1)(π,π*) states, respectively, the latter being directly populated from the former, and the triplet state decays directly to the S(0) surface (the triplet lifetime in deaerated benzene solution was 3.04 μs for Pd and 0.55 μs for Pt). Owing to their triplet properties, PdPc(OBu)(8) and PtPc(OBu)(8) have potential for use in photodynamic therapy (PDT) and are potential candidates for NIR light emitting diodes or NIR emitting probes.
1,4,8,11,15,18,22,25-辛氧基酞菁钯（II），PdPc（OBu）（8）和新合成的铂类似物 PtPc（OBu）（8）的结构，光学和光物理性质通过 X 射线晶体学，静态和瞬态吸收光谱以及相对论零阶正则逼近（ZORA）密度泛函理论（DFT）/时间相关 DFT（TDDFT）计算进行了研究，其中明确考虑了自旋轨道耦合（SOC）效应。将结果与先前报道的 NiPc（OBu）（8）（J. Phys. Chem. A 2005，109，2078）进行了比较，以突出中心金属对 10 族过渡金属辛氧基酞菁的结构和光物理性质的影响。与镍类似物不同，PdPc（OBu）（8）和 PtPc（OBu）（8）显示出大环的适度和不规则的鞍形扭曲，但与该组的第一个成员具有相似的紫外可见光谱，深红光和强 Q 带吸收沿组向下移动发生蓝移，几乎所有四吡咯配合物均观察到这种三联体。MPc（OBu）（8）（M = Ni，Pd，Pt）系列中 Q 带的蓝移基于金属诱导的电子结构变化进行了解释。除了强烈的深红光吸收外，标题配合物还由于跃迁到双组 1E（π，π*）态而表现出明显的近红外（NIR）吸收，该吸收主要由最低的单组（3）E（π，π*）态主导。与非发光的 NiPc（OBu）（8）不同，PdPc（OBu）（8）和 PtPc（OBu）（8）均显示深红光荧光发射和 NIR 磷光发射。瞬态吸收实验和相对论自旋轨道 TDDFT 计算一致表明，荧光和磷光发射分别来自 S（1）（π，π*）和 T（1）（π，π*）态，后者直接从前者产生，三重态直接衰减到 S（0）表面（在去氧苯溶液中 Pd 的三重态寿命为 3.04μs，Pt 为 0.55μs）。由于其三重态性质，PdPc（OBu）（8）和 PtPc（OBu）（8）可用于光动力疗法（PDT），并且是近红外发光二极管或近红外发射探针的潜在候选者。
