Coumarin-Based Small-Molecule Fluorescent Chemosensors

Abstract

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012− 2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

BODIPY‐Based Fluorescent Probes for Biothiols

“…In general, appropriately designed reaction‐based probes for the detection of biothiols and discrimination among biothiol species take advantage of the strong reducibility and nucleophilicity of the sulfhydryl group. The main strategies used in the development of BODIPY‐based probes for H 2 S detection include reduction of azide or nitro groups, Michael addition, thiolysis of aryl nitro groups, cleavage of sulfonamide, sulfonate esters, or S−S bonds . For detection of Cys/Hcy/GSH and discrimination among these, useful reactions are: Michael addition, cyclization with aldehydes, conjugate addition–cyclization with acrylates, native chemical ligation, cleavage of sulfonamide/sulfonate esters, disulfide bond cleavage followed by cyclization, Se−N bond cleavage, and aromatic substitution–rearrangement …”

“…Ar epresentative chemodosimeter is composed of af luorophore moiety as the signaling unit linked with af unctional group, which acts as as pecific responses ite for the analytes.T he observable optical signal from an analyte-specific bioorthogonal reactioni sm ostly irreversible among reaction-based fluorescent probes. [10][11][12][13][14][15][16][17] To successfully develop ar eaction-based fluorescent probe, the choice of signaling unit is crucial to obtain favorable optical properties for the probe. Among the various scaffolds of fluorophores, 4,4-difluoro-4-borata-3a,4a-diaza-s-indacene (BODIPY)d yes ( Figure 1) have been recognized as promising candidates for the construction of fluorescent probeso wing to their outstanding characteristics, such as high molar absorption coefficient, favorable fluorescenceq uantum yield, excellent chemicala nd photo stability, low sensitivityt ot he polarity of solvents, as well as insensitivityt op H. [18] Severale xcellent reviewsh ighlighting BODIPY-based fluorescent probesf or metal ions, reactive oxygen species( ROS), reactive nitrogen species(RNS), and pH have been reported.…”

“…The main strategies used in the development of BODIPY-based probes for H 2 Sd etection include reduction of azide or nitrog roups, Michael addition, thiolysis of aryl nitro groups,c leavage of sulfonamide, sulfonate esters, or SÀSb onds. [11,14,29] For detection of Cys/Hcy/GSH and discrimination amongt hese, useful reactionsa re:M ichael addition, cyclization with aldehydes,c onjugate addition-cyclization with acrylates, native chemical ligation, cleavageo fs ulfonamide/sulfonate esters, disulfide bond cleavage followed by cyclization,S e ÀNb ond cleavage, and aromatic substitution-rearrangement. [11,12,22,25,27,28] BODIPY-based Probes for Biothiols Selectivep robes for H 2 S As the smallest thiol, H 2 Sd ominantly exists as the anionic HS À in aqueous solutionatp hysiological pH and thus acts as an ex-cellent nucleophile.…”

Solid-State Emissive Metallo-Supramolecular Assemblies of Quinoline-Based Acyl Hydrazone

“…Zinc is the second most abundant transition metal ion in the human body that plays important metabolic roles, including those in neurological signaling and enzymatic reactions, cell growth, protein and DNA synthesis, and immune function [5,6]. Several artificial receptors for Zn ion have been developed based on quinoline [7][8][9][10][11][12][13], coumarin [14][15][16][17][18][19][20], benzoxazole [21][22][23][24], BODIPY [25,26], BINOL [27][28][29], fluorescein [30][31][32], and rhodamine [33][34][35][36][37] fluorophores.…”

A novel nanomagnetic solid acid catalyst for the synthesis of new functionalized bis‐coumarin derivatives under microwave irradiations in green conditions

“…These compounds are widely used in insecticidal, antifungal, anticoagulant, antihelminthic, and hypnotic agents, and also in HIV protease inhibition and phytoalexin, an as reducing and stabilizing agents and ligands 4–9 . Thus far, many bis‐coumarin analogs have been discovered from natural sources, 10–13 including dicoumarol ( Melilotus alba ), gerberinol ( Gerbera lanuginose ), and ismailin ( Diospyros ismaili ) (Figure 1).…”