Fluorogenic Zn(II) and Chromogenic Fe(II) Sensors Based on Terpyridine-Substituted Tetraphenylethenes with Aggregation-Induced Emission Characteristics

Abstract

Terpyridine-containing tetraphenylethenes (TPEs) are synthesized and their optical and metal sensing properties are investigated. They are practically nonluminescent in the solution state but become highly emissive as nanoparticle suspensions in poor solvents or thin films in the solid state, demonstrating a novel phenomenon of aggregation-induced emission (AIE). The emission of the nanoaggregates of TPEs is pH-sensitive: it is decreased and eventually quenched upon protonation of their terpyridine units because of their AIE nature. The TPEs can work as "turn-off" fluorescent chemosensors for metal ions and display different fluorescence responses to various metal ions. A characteristic red shift in the emission spectra is observed in the presence of Zn(2+), which facilitates the discrimination of Zn(2+) from other metal ions. Because of the metal-to-ligand-charge-transfer process, terpyridine-substituted TPEs display an obvious magenta color upon selectively binding with Fe(2+), allowing a rapid identification of Fe(2+) in the aqueous media by naked eyes.

Addressing of multiple-metal ions on a single platform

“…Hong et al [75] synthesized terpyridine functionalized tetraphenylethene (TPE) 46 which could selectivily sense Zn 2+ via fluorescence and Fe 2+ via color change. The nanoaggregates of 46 in aqueous medium displayed a bathochromic shift ( v = 1900 cm −1 ) in the emission band on addition of Zn 2+ ion, ascribed to ICT mechanism.…”

Highly Fluorescent and Photostable Probe for Long‐Term Bacterial Viability Assay Based on Aggregation‐Induced Emission

“…[ 28 ] Our initiate purpose was to use TPE-2BA to image bacteria given that the polysaccharide cell walls of bacteria may have interaction with the boronic acid moieties of the dye. The results, however, disappointed us: neither Gram-positive (e.g., Staphylococcus epidermidis and Bacillus subtilis ) nor Gram-negative (e.g., Escherichia coli ) bacteria can be stained by TPE-2BA ( Figure 1 B, F, and J).…”

New Chemo-/Biosensors with Silole and Tetraphenylethene Molecules Based on the Aggregation and Deaggregation Mechanism

“…Moreover, the interferences from other metallic cations can be neglected. Similarly, fluorescence enhancement was detected for terpyridine-functionalized TPE (3, Scheme 8.2) after mixing with Zn 2þ [10]. Compound 4, bearing two imidazole moieties, was potentially useful for sensing Fe 3þ as its fluorescence increased in the presence of Fe 3þ [11].…”