Fluorescence Chemosensor for HSO4 − Ion Based on Pyrrole-Substituted Salicylimine Zn2+ Complex: Nanomolar Detection

Abstract

A novel pyrrole-substituted salicylimine zinc (II) ion complex has been synthesized and evaluated its anion binding affinity. The probe 4 has high selectivity for HSO4 (-) over other anions in CH3OH:H2O (70:30, v/v) solvent system. The emission intensity of 4 was quenched upon addition of HSO4 (-). The probe 4 is highly selective for HSO4 (-) with a detection limit of 40 nm. Photoinduced electron transfer (PET) is responsible for observed change. The binding affinity of 4 for HSO4 (-) was further authenticated through ratiometric change in absorbance profile.

Sequential Recognition of Bisulfate and Acetate by a Ruthenium(II) Complex: Experimental and Theoretical Studies

“…Although, research in recent years has produced relevant advances in the development of optical HSO 4 − and AcO − chemosensors based on different strategies, such as organic compounds containing amide, amine, phenol, hydrazone, pyrrole, urea, imidazole, flavone, triazole, indole and thiourea together with positively charged subunits (imidazolium, guanidinium, pyridinium) that are capable of providing H‐bond donors to recognize anions, these available organic chemosensors have some limitations such as low hydro‐stability, low water solubility, and insufficient selectivity or sensitivity [19–56] . Another strategy is based on the design of metal complex chemosensors, since the presence of the metal ion not only provides additional binding sites for the guest anion but also structurally pre‐organizes the binding sites for optimal anion‐binding via hydrogen bonding and metal ion coordination, resulting in a strong affinity when are compared to purely organic chemosensors [57–68] . Among all metal complexes, ruthenium complexes‐based luminophores are being considered due to their strong MLCT transitions for sensing applications besides they exhibit, nontoxicity, and interesting photophysical properties [69–73] .…”

“…Another strategy is based on the design of metal complex chemosensors, since the presence of the metal ion not only provides additional binding sites for the guest anion but also structurally pre-organizes the binding sites for optimal anionbinding via hydrogen bonding and metal ion coordination, resulting in a strong affinity when are compared to purely organic chemosensors. [57][58][59][60][61][62][63][64][65][66][67][68] Among all metal complexes, ruthe-nium complexes-based luminophores are being considered due to their strong MLCT transitions for sensing applications besides they exhibit, nontoxicity, and interesting photophysical properties. [69][70][71][72][73] Consequently, several Ru(II) complex based chemosensors have been developed for the detection of anions and small biomolecules in recent years.…”