A fluorescent probe for hypochlorite based on the modulation of the unique rotation of the N–N single bond in acetohydrazide

Long, Lingliang; Wu, Yujuan; Wang, Lin; Gong, Aihua; Hu, Feilong; Zhang, Chi

doi:10.1039/c5cc03972j

Cited by 95 publications

(34 citation statements)

References 51 publications

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“…Concerning potential sensing applications this is attractive, since “blacklight” can be used for the efficient excitation of the fluorophore producing a bright, blue fluorescence. A coumarin‐tagged azolium salt as the precursor to the respective NHC–metal complexes is easily available from the amide‐forming reaction of 7‐NEt 2 ‐coumarin‐3‐carboxylic acid chloride 1 and the aminoethyl‐substituted azolium salt 2 in 78 % yield (Scheme ), followed by an ion‐exchange reaction converting the BF 4 – into the chloride salt 3· HCl.…”

Section: Resultsmentioning

confidence: 99%

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

Halter

Plenio

2018

Eur J Inorg Chem

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7-NEt 2 -and julolidene-coumarin-substituted azolium salts were synthesized and used to prepare the respective coumarin-substituted NHC-metal complexes: [AuCl(NHC)], [PdCl(allyl)(NHC)], [MCl(CO) 2 (NHC)] (M = Rh, Ir), [MCl(cod)(NHC)] (M = Rh, Ir), [PdCl 2 (Cl-py)(NHC)], [PdC(allyl)] 2 , and [RuCl 2 -(ind)(NHC)(SIMes)] -sorted according to the respective fluorescence quantum yields of between = 0.70 [Au] and = 0.005 [Ru]. The fluorescence intensity of the complexes depends on the electron density at the metal and can be increased by elec- [a] Nonetheless, Bodipy fluorophores also possess a few less favorable properties: [24] a) often small Stokes shifts are observed, as little as 10 nm are not unusual; b) treatment with strong bases causes problems with acidic protons, nucleophiles can react with the BF 2 unit; and c) typically excitation requires > 500 nm light, excitation maxima approaching 400 nm are rare. [25] It therefore appears rewarding, to look for alternatives, to complement the weaknesses of Bodipy. Coumarin is an established lipophilic fluorophore whose fluorescence properties can be designed and which has found use in numerous applications and it can be easily modified to allow UV-light excitation of the fluorescence. [26] We therefore set out to synthesize, coumarintagged organometallic complexes and to study the fluorescence properties during ligand-substitution reactions. Results and Discussion Synthesis of Coumarin-Tagged Azolium Salts and NHC-Metal ComplexesIt was decided to use 7-NEt 2 coumarins since these fluorophores are characterized by blue to ultraviolet excitation Scheme 1. Synthesis of a coumarin-substituted azolium salt (Mes = 2,4,6trimethylphenyl). Reagents and conditions: a) coumarin acid chloride 1, azolium salt 2, Et 3 N, CH 2 Cl 2 , room temp., 24 h; yield 78 %; b) 3·HBF 4 and Amberlite IRA910 Cl resin, 1:1 MeOH/CH 2 Cl 2 , room temp., overnight, yield 99 %.Scheme 2. Synthesis of coumarin-tagged NHC-metal complexes. Reagents and conditions: a) [AuCl(Me 2 S)], 3·HCl, K 2 CO 3 , 60°C, acetone; b) 3·HCl, [PdCl(allyl)] 2 and K 2 CO 3 acetone, 60°C, 4 h; c) PdCl 2 , 3·HCl, 3-Cl-pyridine solvent, K 2 CO 3 , 80°C, 24 h; d) 3·HCl, Ag 2 O, 40°C, CH 2 Cl 2 then [(SIMes)RuCl 2 (ind)(py)], (ind = 2phenylindene-1-ylidene), 60°C, toluene; e) [RhCl(cod)] 2 , acetone, 60°C, 3·HCl, K 2 CO 3 or [IrCl(cod)] 2 , CH 2 Cl 2 , 40°C, 3·HCl, Ag 2 O; f) CO, 30 min, room temp., CH 2 Cl 2 .

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Section: Resultsmentioning

confidence: 99%

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

Halter

Plenio

2018

Eur J Inorg Chem

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“…The Zhang group in 2015 reported that the rotation of the C-N single bond in the acetohydrazide moiety lead to the quenching of the fluorescence of af luorophore as shown below (Scheme 109). [118] Based on this straightforwardc oncept, they designeda nd synthesized the probe for selectived etec-tion of hypochlorite. The probe exhibiteda lmost non-fluorescent due to the rotation of the N-N-single bond in the acetohydrazide moiety;h owever, upon reaction with HOCl, the C-N single bond in the probe was cleaved and led to the recovery of the fluorescence.…”

Section: Scheme93mentioning

confidence: 99%

“…The Zhang group in 2015 reported that the rotation of the C–N single bond in the acetohydrazide moiety lead to the quenching of the fluorescence of a fluorophore as shown below (Scheme ) . Based on this straightforward concept, they designed and synthesized the probe for selective detection of hypochlorite.…”

Section: Introductionmentioning

confidence: 99%

Imaging of Hypochlorous Acid by Fluorescence and Applications in Biological Systems

Yudhistira

Mulay

Kim

et al. 2019

Chemistry An Asian Journal

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In recent decades, HOCl research has attracted a lot of scientists from around the world. This chemical species is well known as an important player in the biological systems of eukaryotic organisms including humans. In the human body, HOCl is produced by the myeloperoxidase enzyme from superoxide in very low concentrations (20 to 400 μm); this species is secreted by neutrophils and monocytes to help fight pathogens. However, in the condition called “oxidative stress”, HOCl has the capability to attack many important biomolecules such as amino acids, proteins, nucleotides, nucleic acids, carbohydrates, and lipids; these reactions could ultimately contribute to a number of diseases such as neurodegenerative diseases (AD, PD, and ALS), cardiovascular diseases, and diabetes. In this review, we discuss recent efforts by scientists to synthesize various fluorophores which are attached to receptors to detect HOCl such as: chalcogen‐based oxidation, oxidation of 4‐methoxyphenol, oxime/imine, lactone ring opening, and hydrazine. These synthetic molecules, involving rational synthetic pathways, allow us to chemoselectively target HOCl and to study the level of HOCl selectivity through emission responses. Virtually all the reports here deal with well‐defined and small synthetic molecular systems. A large number of published compounds have been reported over the past years; this growing field has given scientists new insights regarding the design of the chemosensors. Reversibility, for example is considered important from the stand point of chemosensor reuse within the biological system; facile regenerability using secondary analytes to obtain the initial probe is a very promising avenue. Another aspect which is also important is the energy of the emission wavelength of the sensor; near‐infrared (NIR) emission is favorable to prevent autofluorescence and harmful irradiation of tissue; thus, extended applicability of such sensors can be made to the mouse model or animal model to help image internal organs. In this review, we describe several well‐known types of receptors that are covalently attached to the fluorophore to detect HOCl. We also discuss the common fluorophores which are used by chemist to detect HOCl, Apart from the chemical aspects, we also discuss the capabilities of the compounds to detect HOCl in living cells as measured through confocal imaging. The growing insight from HOCl probing suggests that there is still much room for improvement regarding the available molecular designs, knowledge of interplay between analytes, biological applicability, biological targeting, and chemical switching, which can also serve to further sensor and theurapeutic agent development alike.

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“…Fluorometric analysis with OCl À -selective molecular sensors is one promising method for this purpose since this facilitates simple quantication or imaging of OCl À with a common uorescence spectrometer or microscope apparatus. 9 A number of uorescent OCl À sensors have been reported; [10][11][12][13][14][15][16][17] however, many of them require tedious multi-step procedures for the synthesis of sensors or a solution containing a large amount of organic solvents for sensing due to the low solubility of the sensors in water. Among the previously reported OCl À sensors, a "dihydroperimidine"-based sensor designed by Goswami et al 18 has the simplest structure, which can be prepared by a facile condensation.…”

Section: Introductionmentioning

confidence: 99%

A coumarin–dihydroperimidine dye as a fluorescent chemosensor for hypochlorite in 99% water

2019

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A fluorescent probe for hypochlorite based on the modulation of the unique rotation of the N–N single bond in acetohydrazide

Cited by 95 publications

References 51 publications

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

Imaging of Hypochlorous Acid by Fluorescence and Applications in Biological Systems

A coumarin–dihydroperimidine dye as a fluorescent chemosensor for hypochlorite in 99% water

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