A series of novel non-symmetrical coumarin-fused BODIPY dyes were synthesised. Their absorption and emission properties are strongly influenced by substitution in the coumarin moiety. Diethylamino-substituted dyes showed near-IR emission with large Stokes shifts (up to 144 nm) and good fluorescence quantum yields.

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Novel push-pull fluorescent dyes, 7-(diethylamino)furo[3,2-c]coumarin and 7-(diethylamino)thieno[3,2-c]coumarin derivatives, were designed and synthesized using formyl derivatives of furo- and thieno[3,2-c]coumarins as key intermediates. Electron absorption and emission spectra of the dyes were recorded in different solvents. The longest-wave bands in the electron absorption spectra of the dyes are suggested to be of push-pull nature.

Abstract3-Formylcoumarins 2 are formed as single products in high yields upon reduction of 3-cyanocoumarins 1 with Raney nickel in formic acid. The starting materials 1 are easily accessible by Knoevenagel condensation of commercially available salicylaldehydes.

The azo coupling reaction of 2,3 dihydrofuro[3,2 с] coumarin 3 one with the arene diazonium salts was studied. The dependence of the product composition on the structure of the diazo component was shown. The solvatochromic properties of the compounds obtained were studied.