Emission from CT State and J-aggregates in a Model Coumarin-Paraben Conjugate: A Spectroscopic Study.

Designing of fluorophores for multifarious optical applications is a fascinating area of research. We report the photophysical behaviour of a synthesized coumarin based probe (E)-N'-(1-(7-(diethylamino)-2-oxo-2 H-chromen-3-yl)ethylidene)-4-hydroxybenzohydrazide (CP) and its utility as a cell-imaging agent. CP exhibits emission from monomers and J-aggregates in solution. The spectrodynamics in the solid-state, on the other hand, was dictated by contributions from H- and J-aggregates along with the monomers. CP showed good emission aptitude in aqueous solutions at pH value 7.0, which is close to the biological pH (7.35-7.45). The emission aptitude of CP in water was utilized to use CP as a cell imaging agent. To our delight, CP can successfully image human peripheral blood mononuclear cells (PBMC) with the cell matrix showing prominent green and red emission at the respective channels observable under a fluorescence microscope. Furthermore, we probed the binding nature of CP to PBMC cells by the aid of molecular dynamics simulations.