Detection of Al3+ and Fe3+ ions by nitrobenzoxadiazole bearing pyridine-2,6-dicarboxamide based chemosensors: effect of solvents on detection†
Abstract
Hybrid chemosensors, L1 and L2, based on a pyridine-2,6-dicarboxamide fragment while containing a 4-nitrobenzoxadiazole group, have been designed and investigated for the sensing of Al3+ and Fe3+ ions. Detection was found to be significantly controlled by the selection of a solvent, CH3OH (protic), THF (non-protic) or H2O (HEPES buffer). While only Al3+ ions were detected in CH3OH, only Fe3+ ions were sensed in H2O (HEPES buffer). Interestingly, both Al3+ and Fe3+ ions were detected in THF. UV-visible as well as fluorescence spectral studies, binding constants and detection limits illustrated the notable sensing abilities of two closely related chemosensors. Both chemosensors were found to bind one equivalent of an M3+ ion as confirmed by Job's plot that was further supported by binding parameters as well as FTIR, NMR and mass spectral studies. The reversibility was achieved for both the chemosensors by using pyrophosphate ion (PPi).