Discotic liquid crystals of transition metal complexes, 53: synthesis and mesomorphism of phthalocyanines substituted by m-alkoxyphenylthio groups

We have successfully synthesized a series of novel octakis(m-alkoxyphenylthio) phthalocyaninato copper(II) complexes, (m-CnOPhS)(8)PcCu (n = 2, 4, 6, 8, 10, 12, 14, 16: 1b similar to 1i), by our developed method to reveal their mesomorphism. The phase transition behavior and mesophase structures have been established by using a polarizing optical microscope, a differential scanning calorimeter, and a temperature-dependent small angle X-ray diffractometer. Interestingly, the very short chain-substituted derivatives, (m-C1OPhS)(8)PcCu (1a) and (m-C2OPhS)(8)PCu (1b), show a hexagonal ordered columnar (Col(ho)) mesophase, whereas each of the other longer-chain-substituted derivatives, (m-CnOPhS)(8)PcCu (n = 4 similar to 16: 1c similar to 1i), shows only rectangular ordered columnar (Col(ro)) mesophase(s). In contrast to the present longer-chain-substituted phenylthio derivatives, each of the previous longer-chain-substituted phenoxy derivatives, (m-CnOPhO)(8)PcCu (n = 10-20), shows a different columnar mesophase of Colho. We discuss this difference of mesomorphism from the viewpoint of the different steric hindrance originated by the peripheral substituents, PhO and PhS groups. Moreover, we could estimate the optical band gaps of (m-C10OPhO)(8)PcCu and (m-C10OPhS)(8)PcCu (1f) from absorption edge of the Q-bands to be 1.79 eV and 1.70 eV, respectively. Therefore, the phenylthio-substituted derivative gave a narrower band gap by ca. 0.1 eV in comparison with the phenoxy-substituted derivative.ArticleJOURNAL OF PORPHYRINS AND PHTHALOCYANINES. 21(3):159-178 (2017)journal articl