Discotic liquid crystals of transition metal complexes 29: mesomorphism and charge transport properties of alkylthio-substituted phthalocyanine rare-earth metal sandwich complexes

A series of bis[octakis(alkylthio)phthalocyaninato]rare-earth-metal(iii) di scotic compounds, [(CnS)(8)Pc](2)M (M = Eu(iii), Tb(iii), Lu(iii); n = 8, 1 0, 12, 14, 16, 18), has been synthesized. The mesomorphic and supramolecula r structures have been investigated by using differential scanning calorime try, polarization microscopy and temperature-dependent X-ray diffraction te chniques. From the X-ray diffraction and spectroscopic results, it was reve aled that in each of the rare-earth compound classes, [(CnS)(8)Pc](2)Eu (n = 10, 12), [(CnS)(8)Pc](2)Tb (n = 10, 12, 14) and [(CnS)(8)Pc](2)Lu (n = 10 , 12), derivatives were found which displayed a novel unique pseudo-hexagon al mesophase. The temperature dependence of the one-dimensional intracolumnar charge carr ier mobilities, Sigma mu (1D), has been measured for [(C12S)(8)Pc](2)Lu and [(C18S)(8)Pc](2)Lu using the PR-TRMC (pulse-radiolysis time-resolved micro wave conductivity) technique. The mobility values in both the K and D phase s are more than an order of magnitude larger than found previously for [(C1 2O)(8)Pc](2)Lu and are close to the maximum values ever found for discotic materials. The lack of a decrease in Sigma mu (1D) at the mesophase to isot ropic liquid transition suggests that these compounds may represent the fir st liquid phase organic semiconducting materials.