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Determination of pKa values for (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes in dimethyl sulfoxide: Cyclic voltammetry and density functional theory calculations |
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| Authors: | Forouzan Zonouzi Alireza Shayesteh Taher Alizadeh Hamid Dezhampanah Bahram Ghalami-Choobar Afsaneh Zonouzi |
| Institution: | 1. Department of Chemistry, University campus 2, University of Guilan, Rasht, Iran;2. School of Chemistry, College of Science, University of Tehran, Tehran, Iran;3. Department of Chemistry, University campus 2, University of Guilan, Rasht, Iran
Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran;4. School of Chemistry, College of Science, University of Tehran, Tehran, Iran Pharmaceutical and Cosmetic Research Center (PCRC), University of Tehran, Tehran, Iran |
| Abstract: | The (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes (azo dyes 1–4 ) were synthesized in high purity. As they are insoluble in water, the usual analytical methods cannot be utilized to determine their pKa values. Cyclic voltammetry was experimentally used to determine their pKa values in DMSO solvent. In addition, computational methods and a conductor-like screening model (COSMO) were used to calculate the solvent effect.  ,  , Kexchange, and pKa values were estimated for the azo dyes being studied using the BP86, TPSS, B3LYP, PBE0, TPSSh, and PW6B95 density functionals in def2-TZVP basis sets. The obtained mean absolute deviations (MADs) indicate that the results of BP86, PBE0, and PW6B95 functionals are in good agreement with experimental values. |
| Keywords: | azo dyes cyclic voltammetry DFT calculations dimethyl sulfoxide pKa |