Reversible gelation in cyclohexane of pyrene substituted by dialkyl l-glutamide: photophysics of the self-assembled fibrillar network

Abstract

l-Glutamic acid-derived compound with pyrenyl group was able to form organic gels in benzene, cyclohexane, and so on. The gels were produced through the formation of highly oriented aggregates and a remarkable development of their fibrous polymer networks. Our scopes of this study are to present the salient features of the photophysics of pyrene in the highly oriented fibrillar network in cyclohexane and to describe spectroscopic measurements used either to detect pyrene association prior to excitation or to confirm the absence of aggregated pyrenes. The concentration and the temperature affected the gel-formation. The sol in the concentration below critical gel concentration includes nanoassemblies with highly oriented aggregates of the compound. Functionalization of l-glutamide derivative with different head groups using electron accepting pyrene and electron-donating N, N-dimethylaniline (DMA) chromophores was also performed to detect the exciplex formation as the mimicry of the photoinduced electron transfer process in the photosynthesis. Upon cooling from 60 to 10 °C, red shifted fluorescence from 446 to 456 nm ascribed to the charge transfer from DMA to pyrene was observed in the mixed system of pyrene- and DMA-containing l-glutamide derivatives in cyclohexane.