Effect of Alkyl Chain Length of N‐Alkyl‐N′‐(2‐benzylphenyl)ureas on Gelation

Abstract

Urea derivatives that were substituted with a 2‐benzylphenyl group and an alkyl group functioned as low molecular weight gelators for various organic solvents and ionic liquids. Urea derivatives with long alkyl chains were effective for the gelation of polar solvents. However, they were not suitable for the gelation of non‐polar solvents, whereas urea derivatives with short alkyl chains were effective. Ionic liquids were similar to polar solvents in that urea derivatives with long alkyl chains were the most effective gelators. The physical properties of the formed supramolecular gels were analyzed by dynamic viscoelasticity measurements using a rheometer.

On-demand gelation of ionic liquids using photoresponsive organometallic gelators

“…The gelation capability could be modulated by changing the ligand species. In addition to gelator L , there are many similar gelators with different gelation properties; 44 hence, appropriate gelators can be chosen. For example, gelator L is insoluble in a 70% ethanol aqueous solution and does not form a gel.…”

“…C 6 H 5 NHCONHC 12 H 25 ( L ), 45 o -C 6 H 4 (CH 2 Ph)(NHCONHC 12 H 25 ) ( L′ ), 44 [C 3 CNmIm][FSA], 54 and [BmIm][B(CN) 4 ] 55 were synthesized according to previously reported methods. [C 6 CNEt 3 N][Tf 2 N] was synthesized by using a standard method (ESI†), and [BmIm][PF 6 ] was purchased from Kokusan Chemical Co., Ltd (Japan).…”

“…For example, gelator L is insoluble in a 70% ethanol aqueous solution and does not form a gel. However, gelator L 0 (= o-C 6 H 4 (CH 2 Ph)(NHCONHC 12 H 25 )) containing a benzyl group can gelate the liquid, 44 and photogelation was possible by using an L 0 -coordinated complex (2-B(CN) 4 , Fig. 6d).…”

“…There are several LMWGs that are useful for the gelation of ILs, which are typically benzene derivatives with urea substituents. 44,45 Therefore, we aimed to develop a unique, versatile method for the on-demand photogelation of ILs using such LMWGs. For this purpose, we developed organometallic compounds that release LMWGs upon photoirradiation in ILs.…”

Chain length effect of spiro-ringN-alkylation on photophysical signalling parameters in Fe(iii) selective rhodamine probes

“…Similarly, alkyl substituents with variable chain lengths are known 19 to modulate the chain-flexibility, hindrance assisted rotation, dynamics and tacticity in derivatized poly-( n -alkyl acrylate) and poly-( n -alkyl methacrylate) materials. In recent examples of alkylation driven physico-chemical modulation, variations in chain lengths were shown to control effectively (a) the solvent driven gelation 20 in N -alkyl- N′ -(2-benzylphenyl)-urea derivatives and (b) binding efficiencies 21 of imidazolium-based ionic liquids with proteins (BSA). In a recent report 22 on n -alkyl derivatized rhodamine B hydrazide based probes for selective metal ion detection, the effect of n -alkyl-substituents at the donor hydrazide end was shown to fine-tune the photophysical signalling parameters in correlation with the alkyl chain length.…”