Discotic Liquid Crystals of Transition Metal Complexes, 2: The Effect of Alkyl Chain Length on Discotic Mesomorphism in Bis[1,3-di(p-n-alkylphenyl)propane-1,3-dionato]copper(II)

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Abstract
A Series of disk-like complexes, bis[l,3-di(p-n-alkylphenyl)propane-l,3-dionatolcopper(II) (n-alkyl: R-CnH2m+1 n=o−12; Cn-Cu(II)), have been synthesized in fousing our interest on the effect of the alkyl chain lenght for the discotic mesomorphism. It was found that each of the cooper(II) complexes substituted by R[dbnd]C4H9-C12H25(C4-Cu(II)-C12-Cu(II)) is a discogen, and that each of teh complexes from C7-Cu(II) to C9-Cu(II) has plural discotic mesophases. C9-Cu(II) has three discotic mesophases which is the first example in transition metal complexes. Each of the complexes, Cn-Cu(II) (n=5−7,9−11), has two solid polymorphs with different m.p.s. in monotropic relationship. Eaxh o the ligands substituted by R[dbnd]C7H15-C12H25(C7-Ligand - C12-Ligand) is a smetogen. It became to be clear that teh discotic mesogen complexes can be otained eve when the non-mesomorphic ligands (n=4-6) are used.