Electropolymerisable ruthenium(ii) phenanthrolines carrying azacrown ether receptors: metal ion recognition in thin film redox sensors

Abstract

The tris(1,10-phenanthroline)ruthenium(II) complexes 1-3 (with 0, 4 and 2 appended azacrown ether units, respectively) linked via alkyl chains to 4H-cyclopenta[2,1-b:3,4-b9]dithiophene (CPDT) were synthesised, characterised and immobilised on Pt and ITO electrodes through electropolymerisation. The electrochemical, UV-vis absorption and metal ion recognition properties of the thus modified electrodes were investigated in detail. Immobilisation of 2 on electrodes was only feasible in a copolymerisation with the parent CPDT. The copolymer film poly(2 + CPDT) exhibited sensitivity for Ba 2+ and Pb 2+ in cyclic voltammetry investigations. At milli-and micromolar concentrations of Ba 2+ and Pb 2+ , respectively, a redox potential shift of more than 200 mV was found in MeCN. 3 was electropolymerised on electrodes directly and the resulting thin film of poly(3) showed similar redox potential shifts for Ba 2+ and Pb 2+ (around 150 mV) with a higher sensitivity for Pb 2+ than Ba 2+ .

Addressing of multiple-metal ions on a single platform

“…Schmittel et al [40] utilized electropolymerization to immobilize crown ether appended Ru(II) phenanthroline complexes, 13 and 14, on Pt and ITO (indium tin oxide) electrodes. The stable thin films thus formed, were exploited for the detection of Ba 2+ and Pb 2+ ions.…”

“…Structure of compounds 13 and 14 capable of forming electropolymerised thin films which could detect Pb 2+ and Ba 2+ ions via electrochemical shifts[40].…”

A Miniaturized Therapeutic Chromophore for Multiple Metal Pollutant Sensing, Pathological Metal Diagnosis and Logical Computing

“…The results presented show how effective a unimolecular receptor/sensor system can be when used in combination with chemometric tools. Hence, therapeutic chromophore 1 competes efficiently with multiple-dye integrated sensors or devices, multichannel sensors and array based sensors, and takes analytical device miniaturization6789101112131415161718192021222324252627282930313233343536373848495051525354555657585960 a step further with easy accessibility and diversification using an already existing concept of pattern generation and chemometric analysis. The multi-metal receptive nature of the unimolecular therapeutic device 1 further increases its potential for the construction of a next generation complex logic gate device at the molecular level123456789101112.…”

“…To date, miniaturization to a single-molecule sensor has been achieved using, e.g., multichannel sensing to detect different metal ions2930313233, shape shifting molecules to detect saccharides3435 or chromophoric sensors363738 to detect metal ions3738. Their potential was demonstrated by the detection of multianalytes in solution.…”

“…Likewise, Eric T. Kool and coworkers developed a very elegant concept of tetramer-length oligodeoxy-fluoroside (ODF) sensor sequences attached to microbeads, each of which contains four different dye units for the detection of various metal ions484950. These examples1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950 demonstrate that modern approaches aimed at high analytical capacity and easy applicability have markedly advanced multi-analyte detection and molecular computation. Still, there is scope for an alternative sensor to both concepts of (1) a multi-dye integrated sensor that involve tedious synthetic assembling or (2) a single-molecule driven multichannel sensor, based on diverse measuring parameters.…”