Preparation of Unsymmetric Phthalocyanines with Benzylchalcogeno and Butoxy Groups

A mixture of 4,5-dibenzylchalcogeno-3,6-diethylphthalonitrile and 4,5-dibutoxyphthalonitrile was treated with lithium in n-pentanol at 110 °C to give unsymmetric phthalocyanines.Optical and electrochemical properties of them were examined by UV-vis spectroscopy and cyclic voltammetry.3][4] We recently reported the preparation of octakis(benzylchalcogeno)phthalocyanines [PcSBn and PcSeBn] and their related compounds.5aIn the UV-vis spectra of PcSBn and PcSeBn, the difference of their wavelengths of the Q-band absorption is small (Δ λ max = 2 nm) although the peripheral chalcogen atoms are different each other.It is likely that the π-electronic system of symmetric phthalocyanines is not strongly affected by the peripheral benzylthio and benzylseleno groups.To estimate the influence of different chalcogen atoms, phthalocyanines with the butoxy, benzylthio, and benzylseleno groups at the β-positions were prepared, and their absorption spectra and electrochemical properties were examined by UV-vis spectroscopy and cyclic voltammetry.Typically, phthalonitriles (1) and (2a) were mixed in a 1:1 ratio and treated with lithium in n-pentanol at 110 °C for 1 h (Scheme 1 and Table 1). 5he blue-green precipitate was purified by column chromatography to produce six phthalocyanines; 3 (16%), 4a (20%), 5a (12%), 6a (trace), 7a (trace), and PcSBn (5%).Compounds (4a), (5a), and (7a) easily dissolved in CHCl 3 , respectively, while the solubility of 6a was low in the solvent.By the similar reaction at 100 °C, the products were obtained in the following distribution; 3 (21%), 4a (17%), 5a (12%), 6a (8%), and 7a (14%).When the reaction