Boronic acid-linked fluorescent and colorimetric probes for copper ions

Abstract

The first examples of boronic acid-linked fluorescent and colorimetric chemosensors for copper ions are reported; the monoboronic acid-conjugated rhodamine probe displays a highly selective fluorescent enhancement with Cu2+ among the various metal ions whereas the fluorescence of the bisboronic acid-conjugated fluorescein probe is selectively quenched by Cu2+, probably by way of a PET mechanism.

A new rhodamine B based fluorometric chemodosimeter for Cu2+ ion in aqueous and cellular media

“…Due to the presence of reactive phenyl hydrazide group the probe exhibits above said silent features like specific irreversible "turn-on" absorbance/fluorescence changes with Cu 2 þ ions in the pH range 1-6 and the absorbance/emission wave lengths (550/580 nm) are longer compared to some of the reported probes [34][35][36]. The probe also has higher quantum yields compare to the reported rhodamine probes [30][31][32][33][34][35][36][37][38][39]. Due to its less cell toxicity, water solubility and cell permeability it has been utilized for the fluorescence imaging of Cu 2 þ ions in cellular media and for determination of copper in biological various biological fluids.…”

“…An reversible fluorescence "turn-on" monoboronic acid-conjugated rhodamine based probe have proposed for Cu 2 þ with high selectivity, and they successfully applied it to image Cu 2 þ in living cells and organisms. However, it shows moderate sensitivity which might limit its application in detection of Cu 2 þ in aqueous samples with very low concentrations [30]. Then 2-picolyl functionalized coumarin based fluorogenic probe for imaging Cu 2 þ in living cells was reported but however, it showed a "turn-off" fluorescence signal with incubation of Cu 2 þ [31].…”

A Novel Chemosensor Based on Rhodamine Derivative for Colorimetric and Fluorometric Detection of Cu2+ in Aqueous Solution

“…Besides, rhodamine derivatives are well-known for their spirolactam (fluorescence "off") to ring-opened amide (fluorescence "on") equilibrium, during which significant fluorescence enhancement as well as color changes will take place, and based on this mechanism, a variety of rhodamine-based spirolactam derivatives have been designed as probes for the recognition of different metal ions such as Pb 2+ [16,17], Hg 2+ [18][19][20], Cu 2+ [21][22][23][24], Fe 3+ [25][26][27], Cr 3+ [28,29].…”

Fluorescence Chemosensory Determination of Cu2+ Using a New Rhodamine–Morpholine Conjugate

“…K a can also be estimated by the ratio intercept/slope of the Benesi-Hildebrand plot's linear regression. The obtained K a strongly supported RECM-Cu 2+ 1:1 binding stoichiometry and showed a strong probe in comparison with some recently-reported work on Cu 2+ fluorescent and colorimetric probes [5,16,46]. Most of the various Cu 2+ -rhodamine-based chemosensors have already been developed and involve a coordination mode with 1:1 stoichiometry, which is the most possible binding mode of rhodamine-based chemosensors and Cu 2+ [5,24,25,32].…”