Dipartimento di Scienze Chimiche e Geologiche SS 554 Bivio per Sestu, Università degli Studi di Cagliari, 09042 Monserrato, CA, Italy.
Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, UK.
Molecules. 2022 Feb 13;27(4):1257. doi: 10.3390/molecules27041257.
Three novel bis-urea fluorescent low-molecular-weight gelators (LMWGs) based on the tetraethyl diphenylmethane spacer-namely, , , and , bearing indole, dansyl, and quinoline units as fluorogenic fragments, respectively, are able to form gel in different solvents. and gel in apolar solvents such as chlorobenzene and nitrobenzene. Gelator is able to gel in the polar solvent mixture DMSO/HO (HO 15% /). This allowed the study of gel formation in the presence of anions as a third component. An interesting anion-dependent gel formation was observed with fluoride and benzoate inhibiting the gelation process and HPO, thus causing a delay of 24 h in the gel formation. The interaction of with the anions in solution was clarified by H-NMR titrations and the differences in the cooperativity of the two types of NH H-bond donor groups (one indole NH and two urea NHs) on when binding BzO or HPO were taken into account to explain the inhibition of the gelation in the presence of BzO. DFT calculations corroborate this hypothesis and, more importantly, demonstrate considering a trimeric model of the gel that BzO favours its disruption into monomers inhibiting the gel formation.
三种新型双脲荧光低分子量凝胶剂（LMWGs）基于四乙基二苯甲烷间隔基，分别为、、和，带有吲哚、丹磺酰基和喹啉单元作为荧光片段，能够在不同溶剂中形成凝胶。和在非极性溶剂如氯苯和硝基苯中形成凝胶。凝胶剂能够在极性溶剂混合物 DMSO/H2O（H2O 15%/）中形成凝胶。这允许研究阴离子作为第三组分存在下的凝胶形成。观察到有趣的阴离子依赖性凝胶形成，氟化物和苯甲酸盐抑制凝胶化过程，而 HPO4 则导致凝胶形成延迟 24 小时。通过 H-NMR 滴定澄清了与溶液中阴离子的相互作用，并考虑了两种类型的 NH H-键供体基团（一个吲哚 NH 和两个脲基 NHs）在与 BzO 或 HPO4 结合时的协同作用的差异，以解释在存在 BzO 时凝胶化的抑制。DFT 计算证实了这一假设，更重要的是，考虑到的三聚体模型凝胶，BzO 有利于其分解成单体，从而抑制凝胶形成。
