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Three novel bis-urea fluorescent low-molecular-weight gelators (LMWGs) based on the tetraethyl diphenylmethane spacer—namely, <b>L1</b>, <b>L2</b>, and <b>L3</b>, bearing indole, dansyl, and quinoline units as fluorogenic fragments, respectively, are able to form gel in different solvents. <b>L2</b> and <b>L3</b> gel in apolar solvents such as chlorobenzene and nitrobenzene. Gelator <b>L1</b> is able to gel in the polar solvent mixture DMSO/H₂O (H₂O 15% <i>v</i>/<i>v</i>). 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 H₂PO₄⁻, thus causing a delay of 24 h in the gel formation. The interaction of <b>L1</b> with the anions in solution was clarified by ¹H-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 <b>L1</b> when binding BzO⁻ or H₂PO₄⁻ 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 <b>L1</b> gel that BzO⁻ favours its disruption into monomers inhibiting the gel formation.