This work presents the determination of acidic strengths at the electronic ground and excited states (pK and ) of three flavonol derivatives using electronic absorption and fluorescence emission spectroscopy. The differences of the pK and values were successfully correlated with the molecular structures according to the substitution pattern at the flavonol structure (hydrogen, diethylamino or fluoro moieties). In order to obtain more information about the observed photoacidity of these superacids, geometry optimizations and excitation energy calculations were performed at the CAM-B3LYP/6-311++G(d,p) level for their neutral, protonated and deprotonated species.

This review summarizes diverse synthetic methodologies to prepare a wide range of heptamethine cyanine dyes, including symmetrical, unsymmetrical, and meso‐substituted derivatives, and their photophysical properties and uses. Their sensing applications are also discussed, considering the nature of their electronic structures and photophysical properties. The optical sensing applications of these compounds can be potentially expanded via structural modification, broadening their absorption amplitude and spectral emission range from the ultraviolet to near‐infrared (NIR) region. In this review, several recent practical applications of the heptamethine cyanine dyes for ion and small molecule sensing, as well as bioimaging, are covered and discussed.

No abstract

No abstract