Bromocresol purple in the processes of cation-anionic interactions in aqueous solutions: UV–Vis spectroscopy and computer simulation of dissimilar association

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2022-03, Vol.269, p.120741, Article 120741
• Main Author: Shapovalov, Serghey A.
• Format: Article
• Language: English
• Subjects: Bromocresol purple; Dissimilar association; Enthalpy of formation; Semiempirical method; UV–Vis spectroscopy
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2021.120741

[Display omitted] •The interaction between anions of bromocresol purple (BP) and cyanine cations has been investigated.•Energy diagrams and structures of associates have been determined by semiempirical method PM7.•Semiempirical calculations are in agreement with the UV–Vis spectroscopy data.•Association of dye into an associate is accompanied by a significant gain in energy.•The non-obvious nature of the destruction of the dissimilar associate BP with quinaldine blue was revealed under acetone. The formation of associates between single- or double-charged anions of bromocresol purple (3,3′-dimethyl-5,5′-dibromophenolsulfonephthalein) and single-charged cations of cyanines (quinaldine blue, quinaldine red) has been investigated. The equilibrium constants of the association have been determined on the basis of UV–Vis spectroscopy data. The energy of the cation-anion interaction (the standard enthalpy of formation of ions and associates), as well as the probable structure of associates, were established using the PM7 semiempirical method. The presented results can be useful in the development of new spectroscopic methods for the detection of organic additives in water (e.g. acetone) due to the spectral properties of dissimilar associates.