"Reduced" Coumarin Dyes with an O‐Phosphorylated 2, 2‐Dimethyl‐4‐(hydroxymethyl)‐1, 2, 3, 4‐tetrahydroquinoline Fragment: Synthesis, Spectra, and STED Microscopy. Issue 33 (7th July 2016)

• Record Type: Journal Article
• Authors: Nizamov, Shamil; Sednev, Maksim V.; Bossi, Mariano L.; Hebisch, Elke; Frauendorf, Holm; Lehnart, Stephan E.; Belov, Vladimir N.; Hell, Stefan W.
• Is Part Of: Chemistry. Volume 22:Issue 33(2016)
• Page Start: 11631
• Page End: 11642
• Publication Date: 2016-07-07
• Subjects: bioconjugation -- coumarins -- dyes/pigments -- fluorescence -- STED microscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201601252
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Large Stokes‐shift coumarin dyes with an O ‐phosphorylated 4‐(hydroxymethyl)‐2, 2‐dimethyl‐1, 2, 3, 4‐tetrahydroquinoline fragment emitting in the blue, green, and red regions of the visible spectrum were synthesized. For this purpose, N ‐substituted and O ‐protected 1, 2‐dihydro‐7‐hydroxy‐2, 2, 4‐trimethylquinoline was oxidized with SeO2 to the corresponding α, β‐unsaturated aldehyde and then reduced with NaBH4 in a "one‐pot" fashion to yield N ‐substituted and 7‐ O ‐protected 4‐(hydroxymethyl)‐7‐hydroxy‐2, 2‐dimethyl‐1, 2, 3, 4‐tetrahydroquinoline as a common precursor to all the coumarin dyes reported here. The photophysical properties of the new dyes ("reduced coumarins") and 1, 2‐dihydroquinoline analogues (formal precursors) with a trisubstituted C=C bond were compared. The "reduced coumarins" were found to be more photoresistant and brighter than their 1, 2‐dihydroquinoline counterparts. Free carboxylate analogues, as well as their antibody conjugates (obtained from N ‐hydroxysuccinimidyl esters) were also prepared. All studied conjugates with secondary antibodies afforded high specificity and were suitable for fluorescence microscopy. The red‐emitting coumarin dye bearing a betaine fragment at the C‐3‐position showed excellent performance in stimulation emission depletion (STED) microscopy. Abstract : Colorful ! Large Stokes‐shift coumarin dyes with an O ‐phosphorylated 4‐(hydroxymethyl)‐2, 2‐dimethyl‐1, 2, 3, 4‐tetrahydro‐quinoline fragment emitting in the blue, green, and red regions of the visible spectrum were synthesized and one of them (see figure) was used in two‐color super‐resolution fluorescence microscopy. Full color separation (from the rhodamine dye KK114) and optical resolution of 65–80 nm were achieved.