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.

Conformationally flexible hexakis-urea 1 was synthesized efficiently by condensing hexakis(aminomethyl)benzene with 4-nitrophenyl-(3,5-di-tert-butylphenyl)carbamate. The hexakis-urea 1 is unexpectedly soluble in organic solvents of low polarity duet oi ntramolecular hydrogen bonding. The hexakis-urea 1 recognizes chloride, bromide, and acetate in a1 :2 host-guest ratio and in a positive allosteric manner in CDCl 3 .T he ability of 1 to recognize dihydrogen phosphate is au nique outcome, and the structure of the associated complex, which contains four dihydrogen phosphate ions, was clarified by singlecrystal X-ray structurala nalysis. However,i ns olution, a complex with three dihydrogen phosphate ions was identified. The dihydrogen phosphate association in CDCl 3 proceeds in an amphoteric allostericm anner;i napositive allosteric manner (K 1 < K 2 )i nt he first step andanegative allosteric manner (K 2 > K 3 )i nt he subsequent step.

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