Information of the electronic structure origin of the photophysical properties
is of paramount importance to understand the intricate physical/chemical
transformations a molecule undergoes in the process of light absorption. Moreover,
experimental analysis of excited states involved in the photophysical phenomenon is
often difficult for their transiency, and hence quantum chemical information of the
excited state emerges as the only tool for an in-depth understanding of the
photoexcitation mechanism. Exploration of the ground (S0
) and excited electronic states
of molecules and subsequent estimation of absorption/emission wavelength need
rigorous standardization of computational methodology. Hence, the chapter offers a
general description of the state-of-the-art methodologies to explore the photophysical
properties of the molecules, which are promising candidates for important applications.
This bridging would ultimately aid in understanding the complex excited state
phenomena occurring in different materials with much clarity fostering their
development in varied verticals like medicine, biotechnology, energy, etc. Fluorescent
active molecules and their subsequent structure-activity correlation would be the prime
focus of the present piece thus rendering a suitable explanation of their excited state
properties through theoretical modelling and explanation at the level of electronic
structure. Application of the standardized methodology on a few chosen molecules of
probable industrial importance such as the smallest known Green Fluorescent Protein
(GFP), 3-hydroxy-4-pyridine carboxaldehyde (HINA), 2-hydroxy-3-naphthaldehyde
semicarbazone (2H3NS), etc. would provide ample scope to validate the computational
data through comparison with the already available experimental dataset. The
theoretical interpretations of photo-responsiveness of future industrially important
molecules through standardized computational methodology are likely to be a colossal
accrue of the current book chapter.
Keywords: Computation, Density functional theory, Excited state, Fluorescence, Photophysics.
