Strong Fluorescence Film of Dicyano Oligo(P-Phenylenevinylene) Supramolecular Gel for Aromatic Amine Vapors Detection

Based on quantum chemical calculation, two cyano groups were introduced to an oligo(p-phenylenevinylene) unit to obtain a fluorophore with a low highest-occupied molecular orbital (HOMO) energy level and a strong emissive efficiency in an aggregate state. An alkyl-substituted phenylalaninamide moiety was linked to this fluorophore to produce a new gelator as a sensing material for the detection of organic amine vapors. Results revealed that the wet gels and xerogel nanofiber film generated strong emission. The fluorescence of the xerogel film could be rapidly and efficiently quenched by aromatic amine vapors at low concentrations. The detection limits for aniline, N-methylaniline, and N,N-dimethylaniline were as low as 21, 5, and 11 ppb, respectively. By contrast, the xerogel film emission was poorly sensitive to aliphatic amines because the gelator fluorophore possessed an appropriate HOMO energy level located between aromatic amines and aliphatic amines. Consequently, the sensing film became highly selective for aromatic amines.