AI Article Synopsis
- The study explores how hydrogen bonding competes with proton transfer in systems created from electrogenerated dianions from dinitrobenzene isomers and certain urea derivatives.
- An ErCrCi mechanism was used to relate the voltammetric responses to both hydrogen bonding and proton transfer, revealing that increasing the urea concentration shifts the responses from being diffusion-controlled to irreversible due to proton transfer effects.
- Results showed that among the dinitrobenzene isomers, 1,3-dinitrobenzene had the highest proton transfer rate (∼25 M(-1) s(-1)), followed by 1,2-dinitrobenzene (∼5 M(-1) s(-1
Article Abstract
Competition between hydrogen bonding and proton transfer reactions was studied for systems composed of electrogenerated dianionic species from dinitrobenzene isomers and substituted dihomooxacalix[4]arene bidentate urea derivatives. To analyze this competition, a second-order ErCrCi mechanism was considered where the binding process is succeeded by proton transfer and the voltammetric responses depend on two dimensionless parameters: the first related to hydrogen bonding reactions, and the second one to proton transfer processes. Experimental results indicated that, upon an increase in the concentration of phenyl-substituted dihomooxacalix[4]arene bidentate urea, voltammetric responses evolve from diffusion-controlled waves (where the binding process is at chemical equilibrium) into irreversible kinetic responses associated with proton transfer. In particular, the 1,3-dinitrobenzene isomer showed a higher proton transfer rate constant (∼25 M(-1) s(-1)) compared to that of the 1,2-dinitrobenzene (∼5 M(-1) s(-1)), whereas the 1,4-dinitrobenzene did not show any proton transfer effect in the experimental conditions employed.
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