Organophosphate inhibitors of acetylcholine esterase (including phosphinates and phosphonates) are used as pesticides and as chemical warfare agents. [1][2][3][4][5][6][7] As such, their detection over a range of concentrations and conditions is required and has attracted considerable attention. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Several detection methods rely on an immobilized acetylcholine esterase detector coupled to a transducer (i.e., pH electrodes, 5,9,[11][12][13]15,16,22 fiber optics, 10,21 and piezoelectric crystals 14 ). Although the immobilized enzymes are sensitive and detect a broad spectrum of acetylcholine esterase inhibitors, they lack selectivity and are prone to false positives when exposed to choline mimics. 15,23,24 The rapid detection of volatile fluoro and cyano phosphates is of particular interest since these are major constituents in the chemical warfare arsenal. Reported is a new selective method for the rapid detection of these esters. The method uses a new platinum 1,2-enedithiolate complex with an appended alcohol that upon exposure to selected phosphate esters is converted to a roomtemperature lumiphore. 25 Complex, 1, was prepared by the literature procedure (eq 1). 26a,dThe chemical conversion of 1 to [(dppe)Pt{S 2 C 2 (CH 2 CH 2 -N-2-pyridinium)}] + , 2, by activated phosphate esters (eq 2) can be monitored by the emissions from 2 which have been assigned to a thiolate to heterocycle π* intraligand charger-transfer singlet, 1 ILCT*, and triplet, 3 ILCT*. While 1, and 1H + , are nonemissive (φ < 0.00001), 2 is emissive in room-temperature solution ( 1 φ ) 0.002, 3 φ ) 0.01, DMSO) and when immobilized in cellulose acetate/triethylcitrate films ( 1 φ ≈ 0.01, 3 φ ≈ 0.2). 26 Neutral pyridine-substituted complexes such as (dppe)Pt{S 2 C 2 -(2-pyridyl)(R)} R ) H, and CH 2 CH 2 OH, are not emissive due to a lowest lying d to d transition which leads to rapid nonradiative decay of emissive excited states. 26 However, the emissive properties of 2 are similar to those of [(dppe)Pt{S 2 C 2 (2-pyridinium)(H)}] + suggesting that either the steric bulk or solution dynamics of the [(dppe)Pt{S 2 C 2 (2-pyridinium)(CH 2 CH 2 OH)}] + side-chain increases the nonradiative decay rate. The gross differences in the photophysical properties of 2 and [(dppe)Pt-{S 2 C 2 (2-pyridinium)(H)}] + from those of 1H + could arise from the necessity for the 1,2-enedithiolate and heterocycle to be coplanar for emission from the ILCT excited states. 26d Whereas in 2 the 1,2-enedithiolate and heterocycle are held coplanar in the ground state, 26d the ability of the 1,2-enedithiolate and heterocycle to be coplanar in the [(dppe)Pt{S 2 C 2 (2-pyridinium)(R)}] + complexes depends on the bulk of the R group, and this could account for the emission from R ) H and not R ) CH 2 CH 2 OH.Given the chemical reactivity of 1 and combined photophysical properties of 1 and 2, activated phosphate esters serve to turn on the emission in this family of complexes. The reaction of 1 with phosphate, thiophosphate...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.