Bisurea gelators

Scheme 22 Synthesis of bisurea gelators 152-157 (a) dichloromethane, room temp. (top). Ribbonlike organization of aU-trflns-155 by intermolecular hydrogen bonding involving both urea units (bottom)...

The achiral bisurea derivatives 152-154 possessing terminal benzyl groups and 155-157 with terminal alkyl chains of variable lengths were studied by van Esch and Feringa (Scheme 22) [106,107]. The compounds exhibited efficient gelation of 1- and 2-octanol, toluene, tetralin, -butyl acetate, cyclohexanone, and hexadecane. Gelators were prepared in high yields by reaction of alkyl or benzyl isocyanates with the respective amines. 

Fig. 31 Some selected structures of monourea 177 and bisurea 178 types of gelators of sc CO2...

Scheme 26 Synthesis of polymerizable monourea L-Ser gelator 179 (a) EDCl, DMAP (b) H2, Pd/C (c) methacr)do)d chloride (d) TEA, CH2CI2, and bisurea l-G1u derivatives 180 and 181 (e) TEA, CH3(CH2)5NCO and bisurea l-G1u derivatives 180 and 181 (f) HO(CH2)xOCOC(CH3) = GHz (g) OCN(CH2)i2NCO...

Mono- and bisurea derivatives containing L-Ser and l-G1u alkyl and alkyl methacrylate ester groups were designed as polymerizable organo-gelators [120]. The L-Ser derivative 179, and l-G1u derivatives 180 and 181, (Scheme 26) exhibited efficient gelation of ethylene glycol, hexane, ethyl ac-... 

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