| Abstract
| - A series of 10 didodecanoylamides of α,ω-alkylidenediamines bridged by a straight carbon chainvarying in length from 0 to 9 carbons was examined as possible gelator molecules of organic liquids togain information on the relationships between the spacial arrangement of two amide groups in a moleculeand their effects on the microscopic structures of the gel. The structural characteristics of these amidesare parallel and antiparallel arrangements of two amide carbonyl groups, which depend on the even andodd numbers of a bridging zigzag carbon chain. The linear alkyl chain moieties and a center carbon chainof diamides intermolecularly interact with each other within the van der Waals contact. Two amide moietiesof an even number carbon chain diamide intermolecularly interact with each other by using two pairs ofhydrogen bonds with two other molecules in a plane, which formed ribbonlike self-complementarilyassembled aggregates. On the other hand, a diamide of an odd number carbon chain forms four independenthydrogen bonds with four other molecules not in a plane, which assembled into woven aggregates.Asymmetric introduction of a methyl group at the α-position of the amide groups successfully twists thetwo side chain van der Waals cores of the chiral diamides in the fixed direction, giving helically twistedribbon and coiled coil aggregates. The helically twisted ribbon and coiled coil aggregates of these chiraldiamides were directly observed by CD, SEM, and TEM, providing a basis for the design of a sophisticatedsmall molecular gelator of a tailor-made shape.
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