Comparison of diffusivities data of streptocyanine dyes by electrochemical and NMR-DOSY methods

Christiane André-Barrès (1) , Fadia Najjar (1, 2) , Marie-Pierre Maether (1) , Corinne Payrastre (1) , Pierre Lavedan (3) , Théodore Tzedakis (4)

1 SPCMIB - Synthèse et Physico-Chimie de Molécules d'Intérêt Biologique
2 LU / ULB - الجامعة اللبنانية [بيروت] = Lebanese University [Beirut] = Université libanaise [Beyrouth]
3 Service commun de Résonance Magnétique Nucléaire - RMN (Toulouse, France)
4 LGC - Laboratoire de Génie Chimique

Diffusivity data of streptocyanine dyes in acetonitrile were investigated using both transient voltammetric techniques and NMR-DOSY. Results of voltammetric measurements allow determination of the diffusion coefficient D values in the range of 1.2-1.6 x 10-9 m² s-1 for the target dyes. Deuterated acetonitrile solvent was used for NMR-DOSY experiments and diffusivities of streptocyanines are given after calibration of acetonitrile on its tracer diffusion value of D∗ACN of 4.37 x 10-⁹. The results for the two methods appear to be in good agreement allowing use of the convenient NMR-DOSY method to measure diffusivity of streptocyanine dyes at low concentrations and so giving a direct access to the number of exchanged electrons using limiting current electrochemical techniques. This last method affords a great advantage of obtaining diffusion coefficients by non-electrochemical method.

Mots clés: Diffusion coefficient; Self-diffusion; Mutual diffusion; Convolution potential sweep voltammetry; NMR-DOSY

Domaines: Génie chimique; Biochimie, Biologie Moléculaire; Génie des procédés

Christiane André-Barrès, Fadia Najjar, Marie-Pierre Maether, Corinne Payrastre, Pierre Lavedan, et al.. Comparison of diffusivities data of streptocyanine dyes by electrochemical and NMR-DOSY methods. Journal of electroanalytical chemistry and interfacial electrochemistry, 2012, vol. 686, pp. 54-57. ⟨10.1016/j.jelechem.2012.09.030⟩. ⟨hal-00878483⟩