Ring mesogenic properties

Neither polyimides based on pyromellitic dianhydride nor on biphenyltet-racarboxylic anhydride with aliphatic spacers have yielded LC polyimides [77-79]. The need for an extra ring to obtain mesogenic properties was evident. Employment of a terphenyl tetracarboxylic anhydride has been reported to produce a LC polyimide free of other functional groups (19). 

Finally, 4-pentyl-4 -cyanobiphenyl (CB), a compound with mesogenic properties, has been co-condensed with europium and samarium atoms. On the basis of matrix IR spectra and DFT calculations at the B3LYP level, it has been proposed that at low temperatures (below 30 K) mononuclear sandwich complexes [(CB)2Eu] and [(CB)2Sm] were obtained while with higher concentration of metal and at higher temperatures bimetallic sandwich complexes [(CB)2Eu2] and [(CB)2Sm2] were present, in which both phenyl rings of CB are coordinated to Eu or Sm (Vlasov et al., 2005). 

Januszko, A. Glab, K. L. Kaszynski, R Patel, K. Lewis, R. A. Mehl, G. H. Wand, M. D. The Effect of carborane, bicyclo[2.2.2]octane and benzene on mesogenic and dielectric properties of laterally fluori-nated three-ring mesogens, J. Mater. Chem. 2006,16, 3183-3192. 

Piecek, W. Kaufman, J. M. Kaszynski, P. A Comparison of mesogenic properties of one- and two-ring dipentyl derivatives ofp-carboranes, bicyclo[2.2.2]octane, and benzene, Liq. Cryst. 2003, 30, 39-48. 

Douglass, A. G. Both, B. Kaszynski, P. Mesogenic properties of single ring compounds dipentyl derivatives of p-carboranes and bicyclo[2.2.2]octane, J. Mater. Chem. 1999, 9, 683-686. 

Nagamine, T. Januszko, A. Ohta, K. Kaszynski, P. Endo, Y. The effect of the linking group on mesogenic properties of three-ring derivatives of p-carborane and biphenyl, Liq. Cryst. 2008, 35, 865-884. 

Dirhodium tetraphosphine, for hydroformylations, 7, 252 Discodermolide, via ring-closing diene metathesis, 11, 218 Discotic mesogens mesophases, properties, 12, 202 properties, 12, 202 Diselenides... 

Recently much effort has been made to induce liquid crystallinity in polyimides. Kricheldorf et al., Chen et al., and Sato et al. have suggested that an aromatic im-ide ring may be an excellent mesogen through their studies on thermotropic liquid-crystalline polyimide-esters [41-54] and polyimide-carbonates [55, 56]. Some thermotropic properties of aromatic polyether-imides have also been reported by Asanuma et al. [57]. 

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