Synthesis of novel water‐soluble fluorescent coumarins bearing sulphonic and hydroxyl groups

Abstract

Two dihydroxynaphtaldehydes (2,5-dihydroxynaphtaldehyde and 2,7-dihydroxynaphtaldehyde) and 2,4dyhydroxybenzaldehyde were sulphonated. These intermediates were used in subsequent reactions with 2-cyanomethylbenzothiazole, 2-cyanomethylbenzoimidazole and 1-methyl-2-cyanomethylbenzoimidazole to synthesise sulphonated coumarin derivatives. The absorption and steady-state fluorescence characteristics of the prepared coumarins were studied in ethanol and in water.

New 3‐(Heteroaryl)‐2‐iminocoumarin‐based Borate Complexes: Synthesis, Photophysical Properties, and Rational Functionalization for Biosensing/Biolabeling Applications

“…Indeed, this hydrophilic group is known to be chemically inert under aw ide range of conditions (especially towards BF 3 ·Et 2 O), and the synthesis of such sulfonated iminocoumarins from 5-formyl-2,4-dihydroxybenzenesulfonic acid is welld ocumented in the literature. [12,17] Thus, the sulfonated iminocoumarin was treated with BF 3 ·Et 2 Ou nder the same conditions as described previously to give the corresponding sulfonated "7-hydroxy-Borico" dye 3.D ue to the high polarity of this BF 2 complex, the reactionm ixture was purified by flash columnc hromatography on an RP-C 18 cartridge,w ith aqueous triethylammonium bicarbonate buffer (TEAB,5 0mm,p H7.5) and CH 3 CN as eluents. The use of an on-acidic aqueousm obile phase was required to prevent premature boron decomplexation and subsequent hydrolysis of the iminem oiety.Afurther RP-C 18 purification with ultrapure water and CH 3 CN as eluents was also necessary to completely remove contaminant boron salts and to recover the soluble "7-hydroxy-Borico" dye 3 in pure form and as aT EA salt.…”

“…Aqueous buffers (PBS, aqueous 0.1 m acetate, and borate buffers used for thiolysis fluorescence assay and phenol pK a determination) and mobile phases for HPLC were prepared with water purified by means of aMilliQ system (purified to 18.2 MW cm). Triethylammonium acetate (TEAA, 2.0 m)a nd triethylammonium bicarbonate (TEAB, 1.0 m)b uffers were prepared from distilled TEA and glacial acetic acid or CO 2 gas, respectively.T he following starting materials were synthesized according to literature procedures:3 -(2-benzothiazolyl)-7-hydroxy-2-iminocoumarin, [14] 3-(2-benzimidazolyl)-7-hydroxy-2-iminocoumarin, [15] 3-(2-benzothiazolyl)-7-hydroxy-2-iminocoumarin-6-sulfonic acid, [12,17] tert-butyl 4-aminobenzylcarbamate, [36] and sodium thiophosphate (NaThioPi). [37] DOTA-NHS was synthesized and provided by the CheMatech company (Dijon, France).…”

Synthesis, characterization and spectroscopic properties of water soluble coumarins substituted with oligomeric alkoxy functions

“…1) are among the most frequently used methods for making them water soluble. 11 However, while such coumarin derivatives are soluble in basic aqueous solutions they are practically insoluble under neutral or acidic conditions. Esterication of carboxylic acid in 3 with oligomeric ethylene glycol or with dendrimers incorporating multiple oxygen atoms is another method to prepare water soluble coumarins, 12 but such esters get hydrolyzed under acidic or basic conditions.…”

Fluorescent Dyes with Large Stokes Shifts of 80−200 nm for Optical Microscopy and Nanoscopy

“…[25] Table 2 contains the spectral data for 7-hydroxycoumarins 1-9 and 4-cyano-7-hydroxycoumarins 10-14 with various substituents at C-3 (Figure 3). In aqueous borate buffer (pH 9), the spectra of Deligeorgiev et al [27] prepared the 3-(2-benzothiazolyl)-7-hydroxycoumarin 15 with a sulfonic acid residue (σ p = 0.09 [28] in the Hammett equation) at C-6 (Figure 4). In aqueous solution, this coumarin (λ abs,max = 398 nm) shows an absorption spectrum with a maxi- The absorption specta of 7-hydroxy-3-pyridylcoumarins 18-20 (Figure 5a) have an intense band with maxima located between 388 and 398 nm in aqueous NaHCO 3 (see Table 3).…”