A comprehensive study of the liquid-crystalline properties of 51 bimetallic compounds based upon 1,3,5-triketonate and 1,3,5,7-tetraketonate ligands is reported. These materials are liquid crystalline when six or more side chains are appended to the mesogenic core, and only columnar phases were observed. Most of the liquid crystals were homonuclear dicopper complexes. Schiff-base derivatives of some of the triketones allowed for the synthesis of heteronuclear bimetallic liquid crystals. The NiCu and NiPd Schiff-base complexes are the first heteronuclear liquid crystals with proximate (strongly interacting) metal centers. Other heteronuclear complexes investigated were not liquid crystalline due to the tendency to retain coordinated solvent or to form strongly associated structures in the absence of axial ligands. The use of complementary shapes was demonstrated as a means to generate average 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 average rotations of 90°and 180°between nearestneighbor molecules. A crystal structure of one compound confirmed that a similar superstructure was exhibited in the solid state. In addition, it was found that the correlated structures exhibit relatively short (3.29 A) correlations between the mesogens, thereby allowing for strong intermolecular interactions. The ability to control the orientation and relative position of transition metal centers in liquid crystals has applications in the design of new liquid-crystalline materials with useful magnetic and electronic properties.
for analytical support. The authors thank D. R. Langley and N. Zein for helpful discussions. Supplementary Material Available: Tables of 13C and NMR chemical shifts and NMR NOE data and summaries of MS and IR data for kedarcidin chromophore (Figure 1), tables of 13C and NMR data for methyl -L-mycaroside (1), the methyl a-and /3-glycosides of kedarosamine (2), and the 2'-chloroazatyrosyl naphthoamide fragment (3), computer-generated drawing of the X-ray structure of the 3-p-bromobenzoate derivative of the methyl /3-glycoside of kedarosamine with atom numbering scheme, and crystallographic parameters (19 pages). Ordering information is given on any current masthead page.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.