Self-assembly of enantiopure and racemic 2,2′,6,6′-tetrasubstituted biaryl tectons into hydrogen bonded chiral squares and infinite chiral square layers

Both chiral and achiral hydrogen bonding o-,o-,o'-,o'-tetrasubstituted biaryls often exhibit unique self-assembling properties giving rise to chiral square cyclotetramers. The individual chiral squares self-assemble further with the formation of infinite layers which are either achiral or are chiral (homochiral). A priori analysis reveals various hydrogen bonding modes which may take part in the self-assembly, differing each from the other by structure and symmetry of the resulting squares and layers. Results of the theoretical analysis are compared with the experimental findings obtained from X-ray crystallographic analysis of three novel and two already known isosteric biaryl tectons, (S)-2a, (RS)-2a, 3a, (S)-5 and (RS)-5, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.