The influence of the second core and the trifluoromethy terminal on the properties of multi-arm chenodeoxycholic acid-derived liquid crystals

Abstract

ABSTRACT A series of multi-arm liquid crystals (2T series) containing trifluoromethyl terminal group were synthesised, with chenodeoxycholic acid (CDCA) as the first core; 10-oxo-10-(4’-((4-(trifluoromethyl)benzoyl)oxy)-[11’−biphenyl]-4-yl)oxy)decanoic acid (TA) as the liquid crystal arms; and (R,S)-1,2-propanediol (PD), 44’-biphenyldiol (BD), isosorbide (IB) and p-dihydroxybenzene (DHB) as the second cores, respectively. CDCA2TA is the intermediate product obtained by introducing liquid crystal arm TA into CDCA. 2T-PD, 2T-IB, 2T-DHB and 2T-BD are multi-armed liquid crystals obtained by introducing CDCA2TA into the second cores PD, IB, DHB and BD, respectively. The IR results of CDCA2TA in solid and CCl4 solutions indicate the presence of hydrogen bonds involving C-F, OH, C=O and Ar-H in the CDCA2TA molecules. When CDCA2TA of chiral smectic A (SmA*) phase is introduced into the second cores, the multi-arm LCs show different LC phases under the influence of the second cores. 2T-PD shows the SmX* phase. 2T-DHB shows cholesteric (Ch) and nematic (N) phases. 2T-BD and 2T-IB show Ch phase. The rigidity of the second cores plays an important role in displaying cholesteric phase for the multi-arm LCs. The second cores also play an important influence on the thermal performance by influencing the conformation of the multi-arm LCs.