Discotic Liquid Crystals of Transition metal Complexes 23: Synthesis and Mesomorphism of Tetrakis(3,4-di-n-alkylphenyl)porphyrin Derivatives and Their Metal Complexes

Five novel long-chain-substituted porphyrin derivatives, tetrakis(3,4-dialkylphenyl)porphyrins (abbreviated as (Cn)8 TPPH 2 (n = 8, 12, 18), ( C 18)8 TPPCu and ( C 18)8 TPPNi ), were synthesized and their mesomorphism was investigated. It was found that the (Cn)8 TPPH 2 (n = 8, 12), derivatives are isotropic liquids at room temperature and that each of the ( C 18)8 TPPM ( M ≡ H 2, Cu , Ni ) derivatives has two liquid crystal phases M1 and M2 and two unidentified phases X1 and X2. It was revealed by X-ray studies that the M2 phase is a discotic lamellar (DL) phase. Interestingly, these porphyrin derivatives exhibit not a columnar but a lamellar mesophase, even though they have a disk-like central core with eight alkyl chains in the surroundings.