Quenching of tryptophan and 4,4′-diaminostilbene fluorescence by dinitrophenyl ethers: Use of 1-allyloxy-2,4-dinitrobenzene, as a quencher

The nitrophenol derivatives have multiple biological effects and their behaviour in environment is of interest. The fluorescence quenching property can be taken into consideration to understand dinitrophenyl ether toxicity. This study employs fluorescence spectroscopy to characterize the interaction of a model compound for dinitrophenyl ethers, namely 1-allyoxy-2,4-dinitrobenzene with two fluorophores, tryptophan and 4,4'-diaminostilbene. The results show that 1-allyoxy-2,4dinitrobenzene quenches the fluorescence of both compounds. The Stern-Volmer plots evidence deviations from linearity and this fact reveals that in both cases static quenching occurs. Quenching of tryptophan fluorescence was studied to some detail and the results suggest that the basis of the static quenching is a bond formation between the fluorophore and the quencher. In the case of 4,4′-diaminostilbene, 1allyoxy-2,4-dinitrobenzene acts as a moderate quenching agent.