Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

We describe herein the two-component charge-transfer (CT) interaction induced organogel formation with 18 beta-glycyrrhetinic acid appended pyrene (GA-pyrene, 3) as the donor, and 2,4,7-trinitrofluorenone (TNF, 4) as the acceptor. The use of TNF (4) as a versatile electron acceptor in the formation of CT gels is demonstrated through the formation of gels in a variety of solvents. Thermal stability, stoichiometry, scanning electron microscopy (SEM), optical micrographs, and circular dichroism (CD) are performed on these CT gels to investigate their thermal and assembly properties. UV-vis, fluorescence, mass spectrometric as well as variable-temperature H-1 NMR experiments on these gels suggest that the CT interaction is one of the major driving forces for the formation of these organogels.