A Simple Red Emitting “Turn-On” Optical Relay Detector for Al3+ and CN−. Application in the Real Sample and RAW264.7 Cell Imaging

A quantitative and qualitative fluorogenic molecular probe (R) has been designed and synthesized using Rhodamine-B hydrazide and 3,5-dibromo salicylaldehyde. The probe R has been applied for detection of ionic species and probe R turned out to be a prominent distinguisher among divalent and trivalent cations Al3+, Cr3+ and Fe3+ via the fluorometric response in acetonitrile medium. Colorimetric changes were observed for trivalent cations and Cu2+. Among all trivalent cations, Al3+ is possessing relay recognition for CN− even in the presence of other interfering anions with optimum precision. The association constant and the detection limit for R-Al3+ are 4.5 × 106 M−1 and 17.9 nM respectively. On the other hand, R + Al3++CN− exhibits an association constant and detection limit of 5.77 × 105 M−1 and 4.6 nM respectively. The stoichiometry of Al3+ binding with R is found to be 1:1. Quantum efficiency of probe R, R + Al3+ and R + Al3++CN− are found to be 0.2, 0.88 and 0.04 respectively. The receptor showed excellent real-time applicability for commercially available antiperspirant and apple seeds extract. The efficiency of the receptor further extended for fluorescent imaging of Al3+ and CN− in RAW264.7 cells.