Synthesis and characterization of phthalocyanines with direct Si-Si linkages

Several cofacial phthalocyanines (Pcs) with an Si-Si linkage were obtained by one-step condensation of 1H-isoindole-1,3(2H)-diimine with hexachlorodisilane as template in quinoline. They were characterized by gel-permeation chromatography, IR, NMR spectroscopy, and mass spectrometry, and cyclic voltammetry. The results strongly suggest that we indeed obtained Pc dimers directly linked by an Si-Si bond using this novel concept of utilizing a compound/salt with an element-element bond as a template. The cofacial dimer structures are reasonably supported by X-ray absorption near-edge structure (XANES), electronic absorption and magnetic circular dichroism (MCD) spectra, and molecular orbital (MO) calculations. Interestingly, they show an electronic absorption spectrum very similar to that of silicon tetrabenztriazacorrole (SiTBC).