Electrochemical studies on stacked-ring silicon phthalocyanines

Voltammetric and spectroscopic data on monomeric, dimeric, and trimeric t-butyldimethylsilyl silicon phthalocyanines (SiPc) are compared. These phthalocyanines are bonded through axial OSiO linkages with an interplanar spacing of about 0.34 nm. The through-space orbital interactions which result from the cofacial orientation of the SiPc rings causes a large stabilization of the one-electron oxidation product of the dimer and trimer SiPc compared to the monomer SiPc and a slight destabilization of their one-electron reduction products. The electrochemical reactions have significance in correlation with the conductivity, photoconductivity, and solid-state orientation of phthalocyanines which aggregate or polymerize.