Phenol- and Catechol-Based Ruthenium(II) Polypyridyl Complexes as Colorimetric Sensors for Fluoride Ions

Abstract

We report two ruthenium(II) polypyridyl complexes with pendant phenol/catechol functionality that act as colorimetric sensors for fluoride ions. Experiments have revealed that hydrogen bond formation occurs with a slight excess of fluoride ion. However, in higher [F-], deprotonation of the O-H functionality resulted. Time-dependent (TD-DFT) calculations at the B3LYP/LANL2DZ level have shown that new bands appear at longer wavelengths upon complexation with fluoride ions. These are of mixed character, MLCT (dpi(Ru)-->pi*(L1/bpy)), and intra- and interligand [pi(L1)-->pi*(bpy) and pi(L1)-->pi*(L1)] transitions. These complexes also act as sensors for fluoride ions in solvent-water mixtures.

Interfacial Electron Transfer Dynamics of Two Newly Synthesized Catecholate Bound RuII Polypyridyl‐Based Sensitizers on TiO2 Nanoparticle Surface – A Femtosecond Pump Probe Spectroscopic Study

“…[37] [38] in 5 and that for phenol in 6 (λ max at ca. 270 nm, ε = 2340) [39] are masked due to strong intra-and/or interligand π-π* transitions at 288 nm (ε ≈ 10 5 ), [40,41] and the band at 245 nm along with the shoulder at 253 nm are assigned to higher energy MLCT d-π* transitions. [41] The absorption bands at 354 and 322 nm for 5 and 6, respectively, can be attributed to interligand charge transfer transitions from π bpy to π* bpy-tyr and from π bpy to π* bpy-phenol .…”

Fluoride Sensing by Catechol‐Based π‐Electron Systems

“…The fact that the response saturates at a concentration of TBAF twice that of 3 strongly supports the 1:2 adduct (one catechol and two fluorides) proposed for the sensing mechanism (Figure 1 b). From the absorption titration (Supporting Information, Figure S4), [17,19] the association constant (K) of 3 with fluoride was determined to be 1.5 10 5 m À1 , which is higher than that of 1 (7.6 10 4 m À1 ) and 2 (9.7 ) [20] and boron (2.9 10 5 m À1 ) [8] sensing materials although the sensing conditions used were a little different. The decrease in association constant from 3 through to 1 follows the relative acidities of the materials.…”

“…For example, we are only aware of a single report on a catechol-based dye that has been used to sense fluoride. [17] At the heart of the dye was a ruthenium complex and while the dye did sense fluoride in a polar aprotic solvent it was not a good choice of chromophore as such complexes are generally poorly luminescent and subject to oxygen quenching. We have therefore developed a series of fluorescent dyes (Figure 1 a) that contain a catechol 'moiety' for interacting with fluoride, which differ in the conjugation length of the chromophore with the difference controlled by the number of thiophene units.…”

Dihydrogen Phosphate Selective Anion Receptor Based on Acylhydrazone

“…The design and synthesis of receptors capable of binding and sensing biologically important anions selectively have drawn considerable attention because anions play a major role in biological, medical, environmental, and chemical sciences [1][2][3][4][5][6][7][8][9][10][11][12][13] Recently, many chemical sensor research groups focus the study on recognition of phosphate, as Phosphate is an essential component of chemotherapeutic and antiviral drugs.…”