Synthesis, electrochemical and photophysical properties of phthalocyaninato oxotitanium(IV) complexes tetra-substituted at the alpha and beta positions with arylthio groups.

The synthesis, electrochemical and photophysical properties of the following tetra-substituted thiol oxotitanium phthalocyanines are reported for the first time: 1,(4)-(tetraphenylthiophthalocyaninato)titanium(IV)oxide (); 1,(4)-(tetrabenzylthiophthalocyaninato)titanium(IV)oxide (); 2,(3)-(tetraphenylthiophthalocyaninato)titanium(IV)oxide () and 2,(3)-(benzylthiophthalocyaninato)titanium(IV)oxide (). Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples each involving a one electron transfer process. The first two reductions were confirmed by spectroelectrochemistry to be metal-based reductions due to TiIVPc-2/TiIIIPc-2 and TiIIIPc-2/TiIIPc-2 redox processes, while the last reduction was confirmed to be a ring-based reduction due to TiIIPc-2/TiIIPc-3. Low fluorescence quantum yields (0.05-0.14), relatively long triplet lifetimes (150-210 micros) and triplet yields (0.31 to 0.82) were observed.