1. Photoinduced degradation of indigo carmine: insights from a computational investigation
- Author
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Mônica H. M. T. Assumpção, Sebastião C. da Silva, Flaviana S Candeias, Fernando Campanhã Vicentini, Alex Brown, Antonio H da S Filho, and Gabriel L. C. de Souza
- Subjects
Physics ,010304 chemical physics ,Organic Chemistry ,Photodissociation ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Quantum chemistry ,Catalysis ,0104 chemical sciences ,Computer Science Applications ,Inorganic Chemistry ,Photoexcitation ,chemistry.chemical_compound ,Computational Theory and Mathematics ,Indigo carmine ,chemistry ,Excited state ,0103 physical sciences ,Density functional theory ,Singlet state ,Physical and Theoretical Chemistry ,Ground state - Abstract
In this work, we present a computational investigation on the photoexcitation of indigo carmine (IC). Physical insights regarding IC photoexcitation and photolysis were obtained from a fundamental perspective through quantum chemistry computations. Density functional theory (DFT) was used to investigate the ground state while its time-dependent formalism (TD-DFT) was used for probing excited state properties, such as vertical excitation energies, generalized oscillator strengths (GOS), and structures. All the computations were undertaken using two different approaches: M06-2X/6-311+G(d,p) and CAM-B3LYP/6-311+G(d,p), in water. Results determined using both methods are in systematic agreement. For instance, the first singlet excited state was found at 2.28 eV (with GOS = 0.4730) and 2.19 eV (GOS = 0.4695) at the TD-DFT/CAM-B3LYP/6-311+G(d,p) and TD-DFT/M06-2X/6-311+G(d,p) levels of theory, respectively. Excellent agreement was observed between the computed and the corresponding experimental UV-Vis spectra. Moreover, results suggest IC undergoes photodecomposition through excited state chemical reaction rather than via a direct photolysis path. To the best of our knowledge, this work is the first to tackle the photoexcitation, and its potential connections to photodegradation, of IC from a fundamental chemical perspective, being presented with expectations to motivate further studies.
- Published
- 2020
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