Chiral ( 3b ) and achiral ( 3a ) C 3 -symmetrical nitrogen centered amide disks were investigated with optical polarizing microscopy, differential scanning calorimetry and UV-Vis/circular dichroism spectroscopy. Similar to the carbonyl centered amide disks 1a / b , only achiral compound 3a shows order in the liquid crystalline phase. Using the same techniques, two asymmetrical mono amide bisurea disks were investigated, one containing 6 "chiral urea" groups ( 4 ) and the other containing 3 "chiral amide" centers ( 5 ). These compounds do show supramolecular aggregation in dilute apolar solutions, featuring hysteresis in experiments investigating thermoreversibility; similar to C 3 -symmetrical trisurea compounds 2a / b .
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Gorp et al. (2003) studied this question.