Synthesis and photophysical properties of a3b-type unsymmetrically substituted anthracene-based zinc(II)phthalocyanine

A novel unsymmetrical zinc(II) phthalocyanine (ZnPc) (3) with an alkynyl functional group was prepared by an efficient mixed statistical condensation of 4-((4-ethynylbenzyl)oxy)phthalonitrile (1) and 4-(4-tertbutylphenoxy)phthalonitrile (2). FTIR, 1H NMR, UV-Vis, elemental analysis, and MALDI-TOF were used to characterize this new compound. Working with different concentrations, the compound’s aggregation properties were investigated and concluded that no aggregation tendency has been observed in the studied concentration range (1.0 x 10-6 M to 1.2 x10-5 M). Fluorescent quantum yields and lifetimes of the compound were studied and found to be 0.09 and 0.57 ns, respectively. As a fluorescent quencher, 1,4-benzoquinone was used in the experiments at differing concentrations in tetrahydrofuran. The kq values showed a close follow-up to the diffusion control limits, around 1011 s-1 and they seem to agree with Einstein-Smoluchowski’s approximation for bimolecular, diffusion-control-including, interactions. For the new compound, the KSV value was calculated as 27.55, which is lower than that of unsubstituted ZnPc. The fluorescence of the studied compound 3 was effectively quenched by 1,4-benzoquinone.