Role of heteroaromatic cycles in the inter- and intra-molecular dynamics of excited aryl ketones

Although the photophysics and photochemistry of aromatic carbonyl compounds have been extensively studied over several years, the interest in their photobehaviors is still alive and they continue to be investigated by exploiting advanced experimental and computational technologies. In this article complete series of pyridyl, di-pyridyl, thienyl, di-thienyl and thienyl-pyridyl ketones are reviewed, mainly from the spectroscopic and photochemical points of view. Properties and reactivity of their excited states have been investigated through stationary absorption and emission spectra, time resolved transient spectroscopy, dynamic luminescence techniques and computational methods. The results reported demonstrate that the photophysics and photochemistry of these molecules can be modulated by changing the rings linked to the carbonyl (pyridyl, thienyl, phenyl) and their linking position, as also the microenvironment where they are included. Of special importance are their properties of triplet photosensitizers and their ability in photogenerating free radicals. Enhancing or depressing such properties may be required in applications and this can be achieved by structure and environment changes.