Complexation between the fungicide tebuconazole and copper(II) probed by electrospray ionization mass spectrometry

Abstract

Electrospray ionization mass spectrometry (ESI-MS) is used to probe the complex formation between tebuconazole (1) and copper(II) salts, which both are commonly used fungicides in agriculture. Experiments with model solutions containing 1 and CuCl(2) reveal the initial formation of the copper(II) species [(1)CuCl](+) and [(1)(2)CuCl](+) which undergo reduction to the corresponding copper(I) ions [(1)Cu](+) and [(1)(2)Cu](+) under more drastic ionization conditions in the ESI source. In additional experiments, copper/tebuconazole complexes were also detected in samples made from soil solutions of various origin and different amount of mineralization. The direct sampling of such solutions via ESI-MS is thus potentially useful for understanding of the interactions between copper(II) salts and tebuconazole in environmental samples.

Electrospray ionization mass spectrometric investigations of the complexation behavior of macrocyclic thiacrown ethers with bivalent transitional metals (Cu, Co, Ni and Zn)

“…(ii) Alternatively, the reduction could take place upon coordination of Cu II to 1 in the course of the ESI process and thus the redox reaction would have occurred in the gas phase rather than in solution. We have previously observed such reductions of copper taking place in the gas phase, [33,39,[45][46][47] but the Cu I /Cu II system is also one of the most frequently observed redox couples in solution. Therefore, instead of speculating about the most probable moment of reduction, we have more directly addressed the probability of the reduction to copper(I) having already occurred in solution.…”

Mimicking of cyproconazole behavior in the presence of Cu and Zn

“…First, the steric protection of Cu(II), which can be provided by at least four small (e.g. tebuconazole, cyproconazole) neutral ligands 8,19 or by a relatively large ligand (e.g. lecithin), which covers Cu(II).…”

“…200 kJ mol −1 ) complexes. [8][9][10] The pK a values of the majority of triazoles are below 2. 11 This predetermines that triazoles, namely Cyp (pK a = 1.73 ± 0.01), will be in the neutral form in most environmental systems.…”

“…The oxidation state of copper strongly influences its reaction and complexing abilities. Three possible ways of Cu reduction are expected: (i) in the solution by a ligand, e.g., by tebuconazole; 8 (ii) during the spraying process when Cu(II) is not sterically protected by large ligands (e.g. lecithin 18 ) or by at least four small ligands 19 or Cu(II) is not stabilized by a negative charge on a ligand or a counter ion (e.g.…”

Cation–π interaction of Ag+ with [6]helicene: An experimental and theoretical study

“…Diluted solution of [6]helicene with AgCF 3 SO 3 (both ~ 2.5 mg L -1 ) in acetonitrile/chloroform (1:1) were introduced into the ESI source via a fused-silica capillary at a flow rate of 0.6 mL h -1 . In order to evaluate the appearance energy (AE) [25] of the resulting complex [Ag(C 26 H 16 )] + , the collision-induced dissociation (CID) method was applied, similarly as in previous papers [25][26][27][28][29]. The mentioned AE of [Ag(C 26 H 16 )] + was determined by the standard procedure [25] from the corresponding energy-dependences depicted in Figure 2 [30,31], employing the Gaussian 03 suite of programs [32].…”