Origin of the Absorption Band of Bromophenol Blue in Acidic and Basic pH: Insight from a Combined Molecular Dynamics and TD-DFT/MM Study
2016 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 120, no 36, 7175-7182 p.Article in journal (Refereed) Published
We study the linear and nonlinear optical properties of a well-known acid base indicator, bromophenol blue (BPB), in aqueous solution by employing static and integrated approaches. In the static approach, optical properties have been calculated using time-dependent density functional theory (TD-DFT) on the fully relaxed geometries of the neutral and different unprotonated forms of BPB. Moreover, both closed and open forms of BPB were considered. In the integrated approach, the optical properties have been computed over many snapshots extracted from molecular dynamics simulation using a hybrid time-dependent density functional theory/molecular mechanics approach. The static approach suggests closed neutral double right arrow anionic interconversion as the dominant mechanism for the red shift in the absorption spectra of BPB due to a change from acidic to basic pH. It is found by employing an integrated approach that the two interconversions, namely open neutral double right arrow anionic and open neutral double right arrow dianionic, can contribute to the pH- dependent shift in the absorption spectra of BPB. Even though both static and integrated approaches reproduce the pH-dependent red shift in the absorption spectra of BPB, the latter one is suitable to determine both the spectra and spectral broadening. Finally, the computed static first hyperpolarizability for various protonated and deprotonated forms of BPB reveals that this molecule can be used as a nonlinear optical probe for pH sensing in addition to its highly exploited use as an optical probe.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016. Vol. 120, no 36, 7175-7182 p.
Absorption spectra, Doppler effect, Dyes, Electromagnetic wave absorption, Integrated control, Molecular dynamics, Nonlinear optics, Optical properties, Probes, Solutions, Acid-base indicators, First hyperpolarizabilities, Integrated approach, Linear and nonlinear optical properties, Molecular dynamics simulations, Non-linear optical, Spectral broadening, Time dependent density functional theory
IdentifiersURN: urn:nbn:se:kth:diva-193993DOI: 10.1021/acs.jpca.6b07660ISI: 000383641600016PubMedID: 27556901ScopusID: 2-s2.0-84987876579OAI: oai:DiVA.org:kth-193993DiVA: diva2:1038630
FunderSwedish Foundation for Strategic Research Swedish National Infrastructure for Computing (SNIC)Swedish e‐Science Research Center
QC 201610192016-10-192016-10-142016-10-19Bibliographically approved