Jump to main content
Jump to site search

Issue 28, 2021
Previous Article Next Article

The dependence of the spectroscopic properties of orcein dyes on solvent proticity: insights from theory and experiments

Author affiliations

Abstract

The electronic spectral properties of α-hydroxy-orcein (α-HO), one of the main components of the orcein dye, have been extensively investigated in solvents of different proticity through UV-Vis spectrophotometry combined with DFT and TDDFT calculations. The results highlight the occurrence of an acid–base equilibrium between the neutral (absorption maximum at 475 nm) and the monoanionic (absorption maximum at 578 nm) forms of the molecule. The position of this equilibrium was found to be sensitively dependent on solvent proticity, solution concentration and pH. Quantum mechanical calculations support the rationalization of the experimental data, confirming the key role of the protic solvent in shifting the acid–base equilibrium, through the establishment of hydrogen bond interactions on specific functional groups of the dye. Both deprotonation and dye coordination with protic solvent molecules determine the reduction of the HOMO–LUMO energy gap (0.71 eV), that can be related with the bathochromic effect envisaged both experimentally (0.59 eV) and theoretically (0.50 eV).

Graphical abstract: The dependence of the spectroscopic properties of orcein dyes on solvent proticity: insights from theory and experiments

Back to tab navigation

Supplementary files

Article information


Submitted
08 Apr 2021
Accepted
22 Jun 2021
First published
23 Jun 2021

Phys. Chem. Chem. Phys., 2021,23, 15329-15337
Article type
Paper

The dependence of the spectroscopic properties of orcein dyes on solvent proticity: insights from theory and experiments

C. Clementi, A. Romani, F. Elisei, F. De Angelis, F. Daus and F. Nunzi, Phys. Chem. Chem. Phys., 2021, 23, 15329 DOI: 10.1039/D1CP01535D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements