Complementary Shapes in Columnar Liquid Crystals: Structural Control in Homo- and Heteronuclear Bimetallic Assemblies.

TitleComplementary Shapes in Columnar Liquid Crystals: Structural Control in Homo- and Heteronuclear Bimetallic Assemblies.
Publication TypeJournal Article
Year of Publication1994
AuthorsSerrette, AG, Lai, CK, Swager, TM
JournalChemistry of Materials
Keywordsbimetallic triketone tetraketonate liq crystal structure, complementary shape columnar liq crystal

A comprehensive study of the liq.-cryst. properties of 51 bimetallic compds. based upon 1,3,5-triketonate and 1,3,5,7-tetraketonate ligands is reported. These materials are liq. cryst. when six or more side chains are appended to the mesogenic core, and only columnar phases were obsd. Most of the liq. crystals were homonuclear dicopper complexes. Schiff-base derivs. of some of the triketones allowed for the synthesis of heteronuclear bimetallic liq. crystals. The NiCu and NiPd Schiff-base complexes are the 1st heteronuclear liq. crystals with proximate (strongly interacting) metal centers. Other heteronuclear complexes studied were not liq. cryst. due to the tendency to retain coordinated solvent or to form strongly assocd. structures in the absence of axial ligands. The use of complementary shapes was demonstrated as a means to generate av. relative organizations (correlations) between the complexes. The presence of these correlated structures was shown through comparisons of the structures, phase behavior, and the immiscibility between materials having the same phase but different shapes. Correlated structures were shown which produce av. rotations of 90° and 180° between nearest-neighbor mols. A crystal structure of one compd. confirmed that a similar superstructure was exhibited in the solid state. The correlated structures exhibit relatively short (3.29 \AA) correlations between the mesogens, thereby allowing for strong intermol. interactions. The ability to control the orientation and relative position of transition metal centers in liq. crystals has applications in the design of new liq.-cryst. materials with useful magnetic and electronic properties. [on SciFinder(R)]