The effect of solvent polarity in the reaction of 1,2-dichlorohexafluorocyclopentene and pyridine

Phosphorylated 3‐Heteroarylcoumarins and Their Use in Fluorescence Microscopy and Nanoscopy

“…Selective protection of the hydroxy-group in maminophenol (1-H) was carried out as described in the literature [6] and led to compound 1-TBDMS. [7d,e] The saponificaton of ethyl ester followed by sulfonation of 4-methyl group in the 2,2,4-trimetyl-1,2-dihydroquinoline fragment provided coumarin 6-H, [7f] which readily reacted with perfluorocyclopentene and afforded red-emitting betain 7-H. [8] Overall yields of water-soluble coumarins 6-H and 7-H were approximately 12 and 6 %, respectively. At room temperature, this reaction proceeded smoothly and with good regioselectivity.…”

“…[7b,c] Next, a coumarin ring was formed by the sequential esterification and Knoevenagel reactions, and the desired compound 5-Et was obtained in 52 % yield. [7d,e] The saponificaton of ethyl ester followed by sulfonation of 4-methyl group in the 2,2,4-trimetyl-1,2-dihydroquinoline fragment provided coumarin 6-H, [7f] which readily reacted with perfluorocyclopentene and afforded red-emitting betain 7-H. [8] Overall yields of water-soluble coumarins 6-H and 7-H were approximately 12 and 6 %, respectively.…”

Highly Fluorescent Pyridinium Betaines for Light Harvesting

“…[5] Betaine dyes are an important class of chromophores characterized by their dipolar electronic ground state,w hich cannot be represented by aneutral mesomeric form. [6][7][8] One of the most intensely studied groups of molecules in this class are the pyridinium N-phenolates,with Reichardtsdye being the most well-known. [9] Intramolecular charge transfer upon excitation of the p-p*transition from the phenolate donor to the pyridinium acceptor results in the perichromism observed for these dyes,m aking them important polarity sensors.…”

Hoch fluoreszierende Pyridiniumbetaine für die Lichtsammlung

“…Betainfarbstoffe gehören zu einer wichtigen Chromophorklasse, welche durch ihren dipolaren elektronischen Grundzustand charakterisiert wird, der nicht durch neutrale mesomere Grenzformen dargestellt werden kann . Eine der am intensivsten untersuchten Betainformen sind die Pyridinium‐ N ‐phenolate, wobei der Reichardt‐Farbstoff als bekanntester Vertreter aufzuführen ist .…”

“…Die Verbindungen 1 a – 1 e wurden durch Addition von Octafluorcyclopenten zu einer angemessenen Menge der gewünschten Pyridyl‐Vorstufe in einem gekühlten THF‐Wasser‐Gemisch als Lösungsmittel vorbereitet. Für den Ablauf der Reaktion wird der in Abbildung gezeigte Mechanismus vorgeschlagen, demzufolge auf die anfängliche nucleophile Substitution zwei Hydrolyseschritte und die chromatographische Aufreinigung erfolgen . Durch die Kristallisation aus Ethylacetat werden Einkristalle erhalten, die für eine weitere Strukturanalyse aller fünf Strukturen verwendbar sind.…”