Novel peripherally and non-peripherally hydrobenzoin substituted optically active phthalocyanines: Synthesis, characterization, aggregation, electrochemical properties and catalytic applications

Abstract

The novel optically active two zinc(II)phthalocyanines and two cobalt(II)phthalocyanines with four chiral hydrobenzoin moieties at the non-peripheral (4 and 5) and peripheral positions (6 and 7) of the phthalocyanine ring have been synthesized. The structures of the synthesized compounds are characterized by 1H NMR, IR, UV–Vis, circular dichroism (CD) and MALDI-TOF MS spectral data. The comparative studies of the spectral, aggregation properties, voltammetry and catalytic applications of novel zinc(II) and cobalt(II)phthalocyanines, tetra-substituted with hydrobenzoin at peripheral and non-peripheral positions, were investigated. All synthesized phthalocyanines are highly soluble in most common organic solvents. In the enantioselective addition of diethylzinc to aldehydes, the best catalytic activity was obtained with 3-methoxybenzaldehyde in the presence of non-peripherally hydrobenzoin substituted zinc(II)phthalocyanine 4 and afforded the corresponding chiral secondary alcohol with the yield of 38% and the enantiomeric excess of 33%. In the oxidation of benzyl alcohol, the highest conversion of benzyl alcohol to benzaldehyde was obtained with non-peripherally substituted cobalt(II)phthalocyanine 5 as 91% with the highest selectivity of 83%.