A series of a rigid meso–meso directly linked chlorin–chlorin, chlorin–bacteriochlorin, and bacteriochlorin–bacteriochlorin dyads, including free bases as well as Zn(II), Pd(II), and Cu(II) complexes, has been synthesized, and their absorption, emission, singlet oxygen (¹O₂) photosensitization, and electronic properties have been examined. Marked bathochromic shifts of the long-wavelength Q_y absorption band and increase in fluorescence quantum yields in dyads, in comparison to the corresponding monomers, are observed. Nonsymmetrical dyads (except bacteriochlorin–bacteriochlorin) show two distinctive Q_y bands, corresponding to the absorption of each dyad component. A nearly quantitative S₁–S₁ energy transfer between hydroporphyrins in dyads, leading to an almost exclusive emission of hydroporphyrin with a lower S₁ energy, has been determined. Several symmetrical and all nonsymmetrical dyads exhibit a significant reduction in fluorescence quantum yields in solvents of high dielectric constants; this is attributed to the photoinduced electron transfer. The complexation of one macrocycle by Cu(II) or Pd(II) enhances intersystem crossing in the adjacent, free base dyad component, which is manifested by a significant reduction in fluorescence and increase in quantum yield of ¹O₂ photosensitization.

中文翻译：

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对称和非对称的介观介观的直接连接的卟啉二联体：合成和光化学性质

已经合成了一系列刚性的中观-内观介导的二氢卟酚-二氢卟酚，二氢卟酚-二氯和细菌二氯-细菌二氯双联体，包括游离碱以及Zn（II），Pd（II）和Cu（II）配合物。 ，并对其吸收，发射，单线态氧（¹ O ₂）光敏化和电子性能进行了研究。与相应的单体相比，观察到了长波长Q _y吸收带的显着红移和二元组中荧光量子产率的增加。非对称的二元组（除细菌绿素-细菌绿素外）显示两个独特的Q _y带，分别对应于每个二元组组分的吸收。几乎定量的S ₁ -S ₁已经确定了二倍体中水卟啉之间的能量转移，导致具有较低S ₁能量的水卟啉几乎排他地发射。在高介电常数的溶剂中，几种对称和所有非对称二元组的荧光量子产率均显着降低。这归因于光致电子转移。一个大环与Cu（II）或Pd（II）的络合作用增强了相邻的游离碱基二元组组分之间的系统间交叉，这通过荧光的显着降低和¹ O ₂光敏化的量子产率的提高得以体现。