STRUCTURES AND LIQUID-CRYSTALLINE PROPERT IES OF MONOARMED CROWN-ETHERS

With the aid of CPK molecular model, three monoarmed alicyclic crown e ther containing 15-crown-5 unit liquid crystals (1-3) were first synth esized. The transition temperatures were T-KSc.-7.5 T-Sc.(N) 18.2 T-NI 23.6 for 1, T-KI 91.1 T-IN 82.6 T-NSd. 70.4 T-Sc.(K) 50.3 for 2 and T -KC 33.8 T-CN 46.7 T-NI 64.4 for 3. The relationship between structure s and properties was investigated, which revealed that monoarmed crown ether liquid crystals could possess mesomorphism not only when the ra tio of molecular length to diameter was larger than 3, but also the mo lecular plarity was required, By inserting chiral group, chiral smetic phases were resulted. It is worth mentioning that the synthesis of cr own ether liquid crystals with chirality is hitherto also a new attemp t.