ABSTRACT:We have synthesized novel liquid crystallinePc-C 60 dyads (C n S) 6 PcCu-C 60 (n=14,16,18: 1a~c) by using our developed synthetic method in order to investigate the mesomorphism and alignment behaviour. Each of the (C n S) 6 PcCu-C 60 dyads shows perfect homeotropic alignment in the Col ho mesophase between two glass plates for n = 14, 16, 18 and also on a glass plate for n = 14, although none of the parent Pc compounds (C n S) 8 PcCu and the Pc precursors (C n S) 6 PcCu-OH and (C n S) 6 PcCu-OFBA shows homeotropic alignment. It may be attributed to the strong affinity between fullerene and glass surface. Although the reason is not so clear at the present time, this is very useful guideline for the molecular design to prepare homeotropic alignment-showing discotic liquid crystals. Very interestingly, the spherical C 60 parts form a helical structure around the column formed by the disk-like Pc parts. This supramolecular structure very resembles spiranthes. The spiranthes-like supramolecular structure is compatible with one-dimensional nano-array expecting the high conversion efficiency of solar cells.

ABSTRACT:In our previous work, we could successfully synthesize the 1:1 phthalocyanine-fullerene (Pc-C 60 ) dyads, (OFbaC 60 )PcCu(OCH 3 ) 2, in very high yields (81~96%) by using Prato reaction. In this study, we have Moreover, it is noteworthy that 3c and 3d show only one Col tet.o mesophase having ordered stacking distance with perfect homeotropic alignment. Such simple phase transition can contribute to maintain stable performance in wide temperature range, when they will be applied to organic thin film solar cells.

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A homologous series of the phthalocyanine-fullerene dyads, (CnS)6PcCu-Cm-C60 (4a~g) [(n, m) = (14, 8) (a); (14, 10) (b); (14, 12) (c); (16, 8) (d); (16, 10) (e); (16, 12) (f); (18, 10) (g)], have been synthesized with changing both the chain length of the peripheral alkylthio group (n) and the spacer length (m) between Pc and C60 in order to find out the homologues showing perfect homeotropic alignment at rt. As a result, each of the dyads 4a~g shows perfect homeotropic alignment in their hexagonal ordered columnar (Colho) mesophases and the homologues 4a~c having shorter alylthio chains (n = 14) show perfect homeotropic alignment at rt. Very interestingly, the spherical C60 parts form a helical structure around the column formed by the disk-like Pc parts. This supramolecular structure very resembles spiranthes flower. The spiranthes-like supramolecular structure is compatible with one-dimensional nano-array expecting the high conversion efficiency of solar cells.

Preparation of cyclic polyphenylene array 2, which corresponds to a complete carbon array of a zigzag-type CNT segment with (18,0)-structure, has been established by a Diels-Alder reaction of cyclic biphenylylene-acetylene derivative 1 with tetraphenylcyclopentadienone. The reaction of 2 with excess FeCl3 realized a presumed cyclodehydrogenation reaction and elimination of the alkyl chains that were introduced as a measure to counter the low solubility problem, but this resulted in the formation of a complicated mixture that included the mass region of a presumed zigzag-type CNT segment with (18,0)-structure. The rather efficient blue emission of cyclic compounds 1 and 2 was discussed utilizing fluorescence (FL) quantum efficiencies (Φ(FL)) and lifetimes (τ(FL)) in their crystalline state along with those in dichloromethane solution. Thermal analyses of these compounds revealed their characteristic phase transition behavior. The synthesis of a novel cyclic polyphenylene array by utilizing a Diels-Alder reaction of cyclic phenylene-acetylene compounds with tetraphenylcyclopentadienone should afford an attractive pathway to a novel belt-shaped CNT segment.