Coumarins are a family of compounds that have been studied extensively for their practical applications, as textile dyes, optical brighteners, laser dyes, sensitisers in phototherapy, biological labels. Coumarin derivatives have been also used in making fluorogenic enzyme substrates. Disperse dyes containing an electron-donating group, such as N,N-diethylamino, and an heterocyclic residue in po...

Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7diethylamino an...

Coumarins are a class of compounds with benzopyrone ring system. In the present work 7-hydroxy-4-methyl coumarin was prepared by the reaction of resorcinol and ethylacetoacetate mixture in the presence of concentrated sulphuric acid. 7-hydroxy-4-methyl coumarin was acetylated with acetic anhydride in the presence of acetic acid. The product formed was treated with bromine in glacial acetic acid...

The photophysical characteristics of a group of coumarins with a 3:4-fused ring system (2-substituted-4,5-dioxo-l,2-dihydro-4H,5H-pyrano-[3:4-c] [l]-benzopyrans) in solutions at room temperature, in frozen ethanol matrix at 77 K, in solid phase and in PVC films are reported. The low fluorescence quantum yield of the compounds investigated in solution is explained as a result of internal convers...

One-pot and facile preparations of 6-(2-hydroxy-5-R-benzoyl)-4-methyl-2-R1- pyrazolo[3,4-b]pyridines 4a-o are described, using the reaction of 3-formyl chromones 1 with 5-amino-1-R1-pyrazoles 2. An enamine-intermediate 2-ethyloxy-6-R-3-(3-methyl-1- phenylpyrazol-5-ylaminomethylene)chroman-4-one 3 was isolated at lower temperatures. Acyloxy-derivatives 5 of compounds 4 were obtained by acylation...

Our laboratory has been credited for the discovery of a unique membrane bound enzyme termed Acetoxy Drug: Protein Transacetylase (TAase) catalyzing the transfer of acetyl group from polyphenolic peracetates (PA) to certain functional proteins resulting in the modulation of their catalytic activity. In this report, we have synthesized eight novel 4-methylcoumarins and demonstrated the comparison...

It has long been known that coumarins (α-pyrones) and xanthones (γ-pyrones) together form a large class of naturally occurring compounds exhibiting a wide range of biological activities. However, the interest of the scientific community for these secondary metabolites, as well as for their structural analogues, has never decreased since these “old compounds” are constantly generating promising—...

Mosquitoes are the major vectors of parasites and pathogens affecting humans and domestic animals. The widespread development of insecticide resistance and negative environmental effects of most synthetic compounds support an interest in finding and developing alternative products against mosquitoes. Natural coumarins and synthetic coumarin analogues are known for their several pharmacological ...