Straightforward Access to Water‐Soluble Unsymmetrical Sulfoxanthene Dyes: Application to the Preparation of Far‐Red Fluorescent Dyes with Large Stokes’ Shifts

Abstract

An efficient synthesis of water-soluble unsymmetrical sulforhodamine/sulforhodol fluorophores containing a single julolidine fragment is presented. Owing to their valuable spectral properties in aqueous buffers, these dyes, especially those bearing a free aniline or phenol moiety, are valuable components of fluorogenic probes for a variety of biosensing applications. A further extension of this synthetic methodology to unusual phenols, namely 7-N,N-dialkylamino-4-hydroxy coumarins has enabled us to provide a new family water-soluble dyes of large Stokes' shift with far-red spectral features.

Azo‐Based Fluorogenic Probes for Biosensing and Bioimaging: Recent Advances and Upcoming Challenges

“… Structures and spectral absorption features of universal azo‐based dark quenchers recently reported in the literature (nd=not determined). Notably, for MPQ‐6, the absorption (Abs) maxima and QR were determined in the context of a 20‐mer quencher–oligonucleotide conjugate.…”

“…Thus, the development of effective azo-based NIR dark quenchers remains am ajor challenge in the field of chemistry of such azod yes. With regard to biolabeling of peptides/proteins with an azobased quencher,t he recent development of bench-stable diazonium reagents and mild conditions to perform tyrosine-selective( or its genetically encoded 2-naphthol analogue) modificationso fp eptides/proteins through site-specific azo cou- [46,48] (nd = not determined). Notably,for MPQ-6, the absorption(Abs) maxima and QR were determined in the context of a2 0-mer quencher-oligonucleotide conjugate.…”

Far‐Red Emitting Fluorescent Dyes for Optical Nanoscopy: Fluorinated Silicon–Rhodamines (SiRF Dyes) and Phosphorylated Oxazines

“…To further improve dye 1 a ‐H by increasing its polarity and solubility in aqueous solutions, we attached a special solubilizing moiety—the so‐called “universal hydrophylizer” (H 3 N + CH(CH 2 SO 3 − )CONH(CH 2 ) 2 CO 2 H) 5a. 18 Such postsynthetic modifications, also introduced by Romieu and co‐workers, were shown to drastically improve the solubility of dyes in water 4l,m,r. Most importantly for immunolabeling, the polarity of dye residues prevents precipitation in the labeled proteins, reduces their “stickiness”, unspecific binding, and the fluorescent background.…”

Groebke–Blackburn–Bienaymé multicomponent reaction: emerging chemistry for drug discovery

“…In view of this, several imidazo-annulated heterocycles bearing pyridines, pyrimidines, pyrazines, azines and diazines have emerged as versatile drug templates in broad areas of medicinal chemistry, ranging from antiviral, antibacterial, fungicidal, anti-ulcer and anti-inflammatory applications [37]. Fluorescent dyes have been widely used in the photovoltaic cells, optical sensors, light-emitting diodes (LEDs), fluorescent colourants and biological labels [86,87]. The latter are most often used to prepare various bioconjugates for immunochemistry and histochemistry via modification of antibodies, amino acids, peptides, oligonucleotides, nucleic acids, carbohydrates and other biological molecules [88][89][90].…”