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Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (−COCN2−) attached to position 5′ or 6′ of the pendant phenyl rings. For that, the mixture of 5′- or 6′-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones Ar1COCN2Ar2. The high performance liquid chromatography (HPLC) separation gave four individual regioisomers of Ar1COCN2Ar2. Photolysis of the model compound─C6H5COCN2C6H5─in aqueous acetonitrile at pH 7.3 and under irradiation with 365 nm light provided diphenylacetic acid amide (Wolff rearrangement). However, under the same conditions, Ar1COCN2Ar2gave mainly α-diketones Ar1COCOAr2. The migration ability of the very bulky dye residues was low, and the Wolff rearrangement did not occur. We observed only moderate fluorescence increase, which may be explained by the insufficient quenching ability of diazoketone bridge (−COCN2−) and its transformation into another (weaker) quencher, 1,2-diarylethane-1,2-dione.

Nucleophilic addition of phosphinic acid, phosphites, sodium dialkyl phosphites, phosphoramidites, phosphinites, and phosphonites to highly polarized or cationic fluorophores, followed by oxidation, results in new “PONy” dyes with auxochromic phosphinate, phosphonate, or phosphonamidate groups. The reaction was applied to a wide variety of coumarins, (thio)pyronins, and N-alkylacridinium and 5,6-dihydrobenzo[c]xanthen-12-ium salts as well as a meso-chlorinated BODIPY to provide compact dyes with red-shifted absorption and emission bands and Stokes shifts up to 8200 cm–1.

The domino ‘Staudinger–aza-Wittig–1,5-phosphonium-rearrangement–fragmentation’ reaction of 1-azido-2-hydroxy-4,6-dioxohexanes allows a convenient synthesis of functionalized 1-acetamido-2-alkylidenecyclopentanes.

The domino ‘Staudinger–aza-Wittig–1,5-phosphonium-rearrangement–fragmentation’ reaction of 1-azido-2-hydroxy-4,6-dioxohexanes allows a convenient synthesis of functionalized 1-acetamido-2-alkylidenecyclopentanes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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