Probing Förster and Dexter Energy-Transfer Mechanisms in Fluorescent Conjugated Polymer Chemosensors

Abstract

Fluorescence quenching in solutions of a pendant-functionalized conjugated polymer chemosensor (ttp-PPETE) has been evaluated in the presence of a variety of transition metal cations, including Ni2+, Co2+, Cu2+, Fe2+, and Cr6+. Photophysical analysis of the emission quenching revealed a static quenching mechanism that demonstrated strong positive deviations from predicted linear behavior. The enhanced emission quenching mechanism was found to correlate closely with the relative loading of the cationic analytes on the polymer chemosensor. This behavior has been attributed to rapid energy transfer along the polymer backbone. A modified Stern−Volmer static quenching model has been successfully applied that incorporates an energy-transfer term that takes into account different energy-transfer mechanisms. Both Förster and Dexter energy-transfer enhancements were observed for ttp-PPETE quenching depending upon the identity of the quencher analyte involved. Stern−Volmer constants in all cases were on the order of 105 M-1 for the transition metals reported. Photophysical characterization for ttp-PPETE includes absorbance, emission, and single-photon counting lifetimes in the absence and presence of varying concentrations of the analytes.

Multi‐spectroscopic Study on the Interaction between CdTe Quantum Dots and Bovine Serum Albumin

“…19,20 The modified Stern-Volmer plots are showed in Figure 3 and the corresponding quenching constants K a at different temperatures were given in Table 1. The decreasing trend of K a with increasing temperature suggested that the quenching is not initiated by dynamic collision but by the formation of a complex, that is to say, the quenching is a static process.…”

Imaging Cerebral Gene Transcripts in Live Animals

“…Second, the hippocampus contains the hippocampal fissure, where SPION may be detected before its uptake/distribution. We selected the contralateral somatosensory cortices (SSCs) as our ROI for analysis because it is distant from the ventricle and the air-surface interface of the trachea (Murphy et al, 2004;Li et al, 2005).…”

A Fluorescent Chemosensor for Transition‐Metal Ions Based on Optically Active Polybinaphthyl and 2,2′‐Bipyridine

“…As is evident from Figure 5 and 6, an effective fluorescence quenching can be detected upon the addition of Cd 2þ , Zn 2þ , Fe 2þ , Mn 2þ , and Co 2þ ions at the ratio of 1:10, whereas there is a nearly-complete fluorescence quenching of Cu 2þ and Ni 2þ to the polymer, which can be attributed to the energy or electron-transfer between the polymer backbones and binding metal complexes in the conjugated polymer backbone. [10,15,18,20,75] According to Table 3, and Figure 6, the chiral polymer can still show fluorescence upon the addition of the Cd 2þ , Zn 2þ , Fe 2þ , Mn 2þ , and Co 2þ ions, even at a high concentration of 20:1 molar ratio, but the intensity of the fluorescence spectra of the Cu 2þ and Ni 2þ -chelating polymers is very weak. It was also found that there is no obvious difference between the emission wavelengths of all of the metal-polymer complexes and the metal-free polymer.…”

“…Conjugated polymers incorporating molecular-recognition moieties can use the conjugated polymer's high sensitivity to external structural perturbations and to electron density changes within its main-chain backbone and at the same time they can interact and form complexes with transition-metal ions. [12][13][14][15][16][17][18][19] Sensitive detection methods employed for sensing metal ions involve the design of ''turn-on'' fluorescent chemosensors based on the photoinduced electron transfer and energymigration mechanism in the conjugated polymer backbone. [10,11,[20][21][22] Functional polymers bearing chiral moieties and the extended conjugated p-system have attracted considerable interest over the past decade.…”