Highly Sensitive Ratiometric Chemosensor for Selective ′Naked‐Eye′ Nanomolar Detection of Co²⁺ in Semi‐Aqueous Media

Abstract

An easy-to-prepare chemosensor, (E)-1-(phthalazine-4-yl)-2-(1-(pyridine-2-yl)ethylidene) hydrazine (3), structurally characterized by single X-ray crystallography, is developed for the selective and sensitive detection of Co(2+) in aqueous media. Chemosensor 3 shows both absorption and fluorescence responses to Co(2+) by forming a 1:1 complex (among the surveyed metal ions) with a detection limit down to 50 nM. It can also be used as a 'naked-eye' sensor due to the outstanding visible and emission color changes from yellow to red and blue to orange, respectively.

A phthalazine-based two-in-one chromogenic receptor for detecting Co2+and Cu2+in an aqueous environment

“…In contrast, colorimetric methods can conveniently and easily monitor target ions with the naked eye. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Compared with the many known colorimetric organic molecule sensors for Zn 2+ , Cu 2+ and Hg 2+ , there are a few colorimetric chemosensors for Co 2+ . [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Compared with the many known colorimetric organic molecule sensors for Zn 2+ , Cu 2+ and Hg 2+ , there are a few colorimetric chemosensors for Co 2+ .…”

A Fluorescent and Colorimetric Sensor for Nanomolar Detection of Co2+ in Water

“…[18] The fluorescence spectra of the receptor were recorded in DMSO. As shown in Figures S2 and 4, the addition of 10 equiv of Hg 2 + , Pb 2 + , Mn 2 + , Ni 2 + , Al 3 + , Cu 2 + , Zn 2 + , Fe 2 + , Fe 3 + and Cd 2 + had no obvious influence on the fluorescence emission.…”

“…The observed phenomena are explained on the basis of metal-toligand charge transfer (MLCT) and coordination to a paramagnetic Co 2 + center. [18] The fluorescence spectra of the receptor were recorded in DMSO. A binding study of the receptor with Co 2 + was also carried out in DMSO.…”

Studies on UV–vis and fluorescence changements in Co2+ and Cu2+ recognition by a new benzimidazole–benzothiadiazole derivative

“…The detection limits of benzimidazole type ligands for Cu 2+ were reported to be around 3-4 × 10 −7 M [60][61][62]. Also, Co 2+ recognition by different type of ligands was given in the literature with limit of detection 0.5-6 × 10 −7 M [63,64].…”