Synthesis and Mesomorphic Properties of 4,4'-Di-n-alkyl-bibicyclo[2.2.2]octanes

Abstract

The homologous series of di-alkyl-bibicyclo[2.2.2]octanes (methyl to octyl) was prepared. All homologues with the exception of the methyl compound show broad smectic phase ranges. For the pentyl homologue the smectic phase exists between 46 °C and 247 °C. X-ray investigations show a novel type of diffraction pattern.

Carborane-Containing Liquid Crystals: Synthesis and Structural, Conformational, Thermal, and Spectroscopic Characterization of Diheptyl and Diheptynyl Derivatives of p-Carboranes

“…On the other hand, a significant barrier to intramolecular rotation around the heptyl-bridgehead carbon in bicyclo[2.2.2]octane derivative 3[2]a (Table ) results in conformational rigidity and a high dynamic aspect ratio for 3[2]a in the condensed phase. This coincides with a high clearing temperature of 226 °C observed for 3[2]a (Table ). These observations are consistent with findings for other compounds and a suggestion that increased conformational mobility and substituent flexibility is detrimental to the mesophase stability…”

Bicyclo[1.1.1]pentanes, [n]Staffanes, [1.1.1]Propellanes, and Tricyclo[2.1.0.02,5]pentanes

“…Relatively high phase stabilities have been observed for mesogens with all aliphatic rings either connected directly (e.g., [4]93 , [3]94 , and [3]95 , Chart ) 337 or through an ester link (e.g., 341 and 342 ). , These compounds exhibit highly ordered smectic phases, except that the dithiolester [3]95 surprisingly displays a nematic phase following the S G phase . [ n ]Staffanes exhibiting liquid-crystalline phases have a minimum of n = 3 bicyclo[1.1.1]pentane rings, , while even single ring bicyclo[2.2.2]octanes exhibit nematic properties and the two-ring systems, bisbicyclo[2.2.2]octanes, are smectics with high clearing temperatures …”

Nitro substitution in achiral calamitic liquid crystals

“…(1) For two-ring nitro derivatives, only one density wave with a characteristic period d is observed (compounds where h 5 3e*/(2e*1 1), e* 5 (e d 1 2e ) )/3; Da 5 (a d Õ a ) ) is the polarizability anisotropy; F is the cavity reaction 2-1, 2-7, 2-9 table 2 and [75,81,83,92,[279][280][281][282]), with the ratio d/L > 1 recorded in their smectic A phases. eld; m is the dipole moment; b is the angle between the molecular long axis and the dipole moment; N is the Replacement of the terminal nitro group by the cyano group in liquid crystalline compounds results in increasing number of molecules per unit volume and S is the order parameter.…”

“…SmA, N (a) A 5 CH 5 N, B 5 single bond [92,93] Z 5 CN n 5 6 SmB, N Z 5 NO 2 n 5 1-3 phase N n 5 8 N n 5 4 SmB, N n 5 9 N re , SmA, N n 5 5-9 SmE, SmB, N Z 5 CN n 5 5 SmE, SmB These results illustrate that the reentrant nematic Z 5 NO 2 n 5 7 N phase is more evident in the octyloxy substituted nitro …”