Effects of Structural Deformations on Optical Properties of Tetrabenzoporphyrins: Free-Bases and Pd Complexes

摘要: A recently developed method of synthesis π-extended porphyrins made it possible to prepare a series tetrabenzoporphyrins (TBP) with different numbers meso-aryl substituents. The photophysical parameters free-bases and Pd complexes meso-unsubstituted TBP’s, 5,15-diaryl-TBP’s (Ar2TBP’s) 5,10,15,20-tetraaryl-TBP’s (Ar4TBP’s) were measured. For comparison, similarly meso-arylsubstituted fused nonaromatic cyclohexeno-rings, i.e. Arn-tetracyclohexenoporphyrins (ArnTCHP’s, n = 0, 2, 4), also synthesized studied. Structural information was obtained by ab initio (DFT) calculations X-ray crystallography. It found that: 1) Free-base Ar4TBP’s are strongly distorted out-of-plane (saddled), possess broadened, red-shifted spectra, short excited-state lifetimes low fluorescence quantum yields (τfl 2−3 ns, ϕfl 0.02−0.03). These features characteristic other nonplanar free-base porphyrins, including Ar4TCHP’s. 2) Ar2TBP completely planar ...