Ruthenium(II) Polypyridine Complex-Based Aggregation-Induced Emission Luminogen for Rapid and Selective Detection of Phosgene in Solution and in the Gas Phase

Abstract

A bis-heteroleptic ruthenium­(II) complex, Ru-1, of 4,7-bis­(2-aminoethylamino)-1,10-phenanthroline for selective “turn-on” detection of highly toxic chemical warfare agent phosgene is presented. Probe Ru-1 exhibits aggregation-induced emission (AIE), and the restricted intramolecular motion is responsible for the AIE activity. In a CHCl3/CH3CN [95:5 (v/v)] solvent mixture, a unique self-assembled vesicular structure was formed after aggregation, which was supported by transmission electron microscopy, field emission scanning electron microscopy, and atmoic force microscopy studies. Probe Ru-1 showed a rapid and highly selective luminescence turn-on response for phosgene over other competitive chemical warfare agents with a low detection limit (13.9 nM) in CH3CN. The 2-aminoethylamino groups in Ru-1 act as a reacting site for nucleophilic addition to the carbonyl center of phosgene and undergo intramolecular cyclization. The final product of the phosgene-mediated reaction, Ru-1-Phos, contains 2-imidazolidinone groups, which has been confirmed by electrospray ionization mass spectometry and 1H nuclear magnetic resonance (NMR) spectroscopy. 1H NMR titration of Ru-1 with phosgene supported the reaction mechanism and also pointed to the simultaneous reaction of phosgene at two 2-aminoethylamino sites. For the first time, the crystal structure of the phosgene reaction product, Ru-1-Phos, containing the cyclized 2-imidazolidinone group was confirmed by single-crystal X-ray diffraction, which indubitably validates the reaction mechanism. Triplet state time-dependent density functional theory calculations showed that the weak luminescence of Ru-1 was mostly due to the population of the non-emissive 3MC state. The cyclization reaction with phosgene and the corresponding 2-imidazolidinone product formation populated the emissive 3MLCT state in Ru-1-Phos and is the key reason for the enhanced luminescence. Furthermore, a low-cost portable test paper strip has been fabricated with Ru-1 for the real-time selective monitoring of phosgene gas at the nanomolar level.

An aggregation induced emission active bis-heteroleptic ruthenium(ii) complex for luminescence light-up detection of pyrophosphate ions

“…This result is comparable to our previously reported ruthenium( ii ) complex-based AIEgens. 52,59–61 1[PF 6 ] 2 is highly soluble in common organic solvents, such as CH 3 CN, CH 2 Cl 2 , CH 3 COCH 3 , CH 3 OH and DMSO, whereas it is sparingly soluble in water. The AIE properties of 1[PF 6 ] 2 were investigated in binary solvent systems viz CH 3 CN–H 2 O and CH 3 CN–PEG solution with different water and PEG fractions.…”

Robust Fluorescent Self-Assembly System for Sensing of Phosgene, Thionyl Chloride, and Oxalyl Chloride

“…The sensor exhibited sensitive detection performances toward phosgene, diethyl chlorophosphate, and other acyl chlorides. , Khatua designed a bis-heteroleptic ruthenium­(II) complex for the selective “turn-on” detection of phosgene (LOD: 13.9 nM) in CH 3 CN. The sensor was fabricated by conducting a cyclization reaction between phosgene and the 2-aminoethylamino group . However, the detection limits and the response rates were unsatisfactory, and the complex procedures were difficult to execute.…”

“…16,17 Khatua designed a bis-heteroleptic ruthenium(II) complex for the selective "turn-on" detection of phosgene (LOD: 13.9 nM) in CH 3 fabricated by conducting a cyclization reaction between phosgene and the 2-aminoethylamino group. 18 However, the detection limits and the response rates were unsatisfactory, and the complex procedures were difficult to execute. These sensors cannot efficiently detect toxic acyl chlorides or thionyl chloride.…”

Aggregation-Induced Ignition of Near-Infrared Phosphorescence of Non-Symmetric [Pt(C^N*N’^C’)] Complex in Poly(caprolactone)-based Block Copolymer Micelles: Evaluating the Alternative Design of Near-Infrared Oxygen Biosensors

“…Because the very essence of AIE lies in the rigidification of the emitters’ microenvironment that restricts intramolecular motions and thus suppresses the rotovibrational relaxation of excited states [ 2 , 3 , 4 ], one can expect that organometallic compounds, in line with “classical” organic AIEgens, are also prone to exert AIE and related phenomena. Indeed, recent reports reviewed in [ 8 ] demonstrated that various (iridium(III) [ 9 , 10 ], ruthenium(II) [ 11 , 12 ], rhenium(I) [ 13 , 14 , 15 ], gold(I) [ 16 ], etc.) organometallic complexes also demonstrate AIE or related photophysical (e.g., increase in two-photon emission cross-sections [ 10 ]) and photochemical (e.g., enhancement of singlet oxygen generation [ 9 , 10 ]) behavior.…”