Hydrazine functionalized probes for chromogenic and fluorescent ratiometric sensing of pH and F: experimental and DFT studies

Two novel hydrazine based sensors, BPPIH ( N 1 , N 3 -bis(perfluorophenyl)isophthalohydrazide) and BPBIH ( N 1′ , N 3′ -bis(perfluorobenzylidene)isophthalohydrazide), are presented here. BPPIH is found to be a highly sensitive pH sensor in the pH range 5.0 to 10.0 in a DMSO-water solvent mixture with a p K a value of 9.22. Interesting optical responses have been observed for BPPIH in the above mentioned pH range. BPBIH on the other hand turns out to be a less effective pH sensor in the above mentioned pH range. The increase in fluorescence intensity at a lower pH for BPPIH was explained by using density functional theory. The ability of BPPIH to monitor the pH changes inside cancer cells is a useful application of the sensor as a functional material. In addition fluoride (F − ) selectivity studies of these two chemosensors have been performed and show that between them, BPBIH shows greater selectivity towards F . The interaction energy calculated from the DFT-D3 supports the experimental findings. The pH sensor ( BPPIH ) can be further interfaced with suitable circuitry interfaced with desired programming for ease of access and enhancement of practical applications. Two novel hydrazine based sensors, BPPIH ( N 1 , N 3 -bis(perfluorophenyl)isophthalohydrazide) and BPBIH ( N 1′ , N 3′ -bis(perfluorobenzylidene)isophthalohydrazide), are presented here.