The Chemiexcitation of the Chemiluminescence of Lophine Peroxide Anions via a Partially Cyclic Transition State

Lu, Gonghao; Wada, Jun; Kimoto, Takashi; Iga, Hiroshi; Nishigawa, Hideki; Kimura, Masao; Hu, Zhizhi

doi:10.1002/ejoc.201300976

Cited by 7 publications

(19 citation statements)

References 15 publications

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“…In the case of 1 p , a significant difference in heat evolution was not observed between reactions in the coated quartz cell vs. the transparent quartz cell, as shown in Figure b. The Φ CL of 1 p was measured by comparing CL intensity with a standard lophine peroxide CL reaction . The results are summarized in Table .…”

Section: Figurementioning

confidence: 95%

Transformation of Stored Energy into Light in the Chemiluminescence of 1,2‐Dioxetanes

Oda

Araki

et al. 2018

ChemPhotoChem

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The CL was measured using a photodiode array (PDA, HAMAMATSU PHOTONICS), which recorded integrated light yield in terms of the number of photons. The CL emissions of the silylated peroxides 1 m, 1 p, 2 and 3 (1 10 À2 M) in DMSO (1 mL) were counted by PDA after initiation with 0.2 ml of a DMSO solution of TBAF (0.1 M) at 25 8C. The CL efficiencies of 1 m, 2, and 3 were estimated by comparison with dioxetane 3 as a standard (F CL = 0.21). [13] The CL efficiency of 1 p was estimated by comparison with lophine peroxide as a standard (F CL = 6.2 10 À6 ). [9] The error (SD) is the deviation from the average of three measurements.

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Section: Figurementioning

confidence: 95%

Transformation of Stored Energy into Light in the Chemiluminescence of 1,2‐Dioxetanes

Oda

Araki

et al. 2018

ChemPhotoChem

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“…Such transformation is historically important in the CL field for being used by Wiedemann in 1888 to define the term itself (“Das bei chemischen Prozessen auftretende Leuchten würde Chemilumineszenz genannt”, i.e., the light emission observed during chemical processes must be called chemiluminescence) . Despite being the first-reported CL system, the mechanism of the lophine decomposition reaction, responsible for the generation of light, is not fully understood . Detailed mechanistic studies of other CL transformations subsequently reported revealed that the light observed as a product of these reactions is generated from the exothermic decomposition of cyclic peroxide intermediates. − …”

Section: Introductionmentioning

confidence: 99%

“…To perform CL studies, a wide variety of lophine derivatives, substituted in the 2-phenyl group (Scheme a, L1 - 6 ) and in 4-phenyl and 5-phenyl (Scheme a, L7 - 13 ), were conveniently obtained by condensation of their corresponding benzaldehyde with benzil and NH 4 OAc in acidic conditions. , The CL mechanism for L1 and some of its derivatives (e.g., L2 , L7 , and L8 , Scheme a) involves the reaction of lophine anion with oxygen, probably through a single-electron transfer (SET) process, generating a neutral lophine radical and a superoxide ion O 2 ●– (Scheme b). − These radicals combine to produce a peroxyanion ( H – ) that, after cyclization, results in a 1,2-dioxetane intermediate (Scheme c, D – ). The decomposition of cyclic peroxide D – in the so-called chemiexcitation step generates a deprotonated benzoylamidine derivative in the excited state (Scheme c, B – * ). ,,,− Finally, the last step consists in the fluorescence decay of B – * to the ground state, generating light and B – as final reaction products (Scheme c). ,− ,− This CL mechanism (Scheme b,c) shares some common aspects with bioluminescent systems comprising 1,2-dioxetanones as high-energy intermediates (HEIs) .…”

Section: Introductionmentioning

confidence: 99%

“…Kimura et al, studying the CL of H7 - 11 (Scheme a) with KOH in MeOH/CH 2 Cl 2 1:5, commented that H – cyclization to produce D – (Scheme c) could be the rate-determining step of the CL reaction . Lu et al studied the isomeric silylperoxides ( R )- S12 and ( R )- S13 (Scheme a), whose CL was triggered by addition of fluoride tetrabutylammonium (TBAF) in CHCl 3 or acetone . The lower CL quantum yield (Φ CL ) in acetone for ( R )- S12 when compared to ( R )- S13 was attributed to the involvement of a partially cyclic transition state (TS) at the chemiexcitation step .…”

Section: Introductionmentioning

confidence: 99%

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Evidence for the Formation of 1,2-Dioxetane as a High-Energy Intermediate and Possible Chemiexcitation Pathways in the Chemiluminescence of Lophine Peroxides

et al. 2021

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A kinetic study of the chemiluminescent (CL) reaction mechanism of lophine-derived hydroperoxides and silylperoxides induced by a base and fluoride, respectively, provided evidence for the formation of a 1,2-dioxetane as a high-energy intermediate (HEI) of this CL transformation. This was postulated using a linear Hammett relationship, consistent with the formation of negative charge on the transition state of HEI generation (ρ > 1). The decomposition of this HEI leads to chemiexcitation with overall low singlet excited state formation quantum yield (ΦS from 1.1 to 14.5 × 10–5 E mol–1); nonetheless, ΦS = 1.20 × 10–3 E mol–1 was observed with both peroxides substituted with bromine. The use of electron-donating substituents increases chemiexcitation efficiency, while it also reduces the rate for both formation and decomposition of the HEI. Different possible pathways for HEI decomposition and chemiexcitation are discussed in light of literature data from the perspective of the substituent effect. This system could be explored in the future for analytical and labeling purposes or for biological oxidation through chemiexcitation.

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“…The triphenylimidazole structural framework has been intensely studied throughout the years, by many different research groups, due to its fluorescence (FL) and chemiluminescence (CL) properties. The typical direct CL of 2,4,5‐triphenylimidazole (also known as lophine) with oxygen in an alkaline media, first described by Radziszewski in 1877, was studied mainly to elucidate its reaction mechanism . However, lophine and its derivatives were also applied in other CL systems, being used as activators of the peroxyoxalate reaction or enhancers of the luminol transformation .…”

Section: Introductionmentioning

confidence: 99%

The decomposition of triphenylimidazole‐para‐acetate follows specific base catalysis and can be conveniently followed by fluorescence

et al. 2019

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The kinetics of the decomposition reaction of 4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl acetate (1) in basic alcoholic media was investigated, using a simple fluorescence (FL) spectrophotometric procedure. The process was conveniently studied using FL, since the triphenylimidazole-derived ester 1 and its reaction products (the corresponding phenol 2 and phenolate 2 − ) are all highly fluorescent (Φ FL > 37%). By carefully selecting excitation and emission wavelengths, observed rate constants k 1 in the order of 10 −3 to 10 −2 s −1 were obtained from either reactant consumption (λ ex = 300 nm, λ em = 400 nm) or product formation (λ ex = 350 nm, λ em = 475 nm); these were shown to be kinetically equivalent. Intensity-decay time profiles also gave a residual FL intensity parameter, shown to be associated to the distribution of produced species 2 and 2 − , according to the basicity of the medium. Studying the reaction in both methanol (MeOH) and isopropanol (iPrOH), upon addition of HO − , provided evidence that the solvent's conjugate base is the active nucleophilic species.When different bases were used (tBuO − , HO − , DBU and TEA), bimolecular rate constants k bim ranging from 4.5 to 6.5 L mol −1 s −1 were obtained, which proved to be non-dependent on the base pK aH , suggesting specific base catalysis for the decomposition of 1 in alcoholic media. KEYWORDS imidazole, kineticslight emissionlophine, rate constant 1 | INTRODUCTIONThe triphenylimidazole structural framework has been intensely studied throughout the years, by many different research groups, due to its fluorescence (FL) [1][2][3][4][5][6][7][8][9] and chemiluminescence (CL) [10][11][12][13][14][15][16][17][18][19][20][21][22] properties. The typical direct CL of 2,4,5-triphenylimidazole (also known as lophine) with oxygen in an alkaline media, first described by Radziszewski in 1877, [23] was studied mainly to elucidate its reaction mechanism. [11][12][13][18][19][20][21][22]24] However, lophine and its derivatives were also applied in other CL systems, being used as activators of the peroxyoxalate reaction [10] or enhancers of the luminol transformation. [25][26][27] In part, the vast array of application of these molecules, from FL to CL measurements, depends on the high FL quantum yields (Φ FL > 0.1) presented by them. [1][2][3][4][5][6][7][8][9][10]17,[24][25][26][27] In 1993, Kuroda et al. reported that triphenylimidazole-para-acetate (1, IUPAC name 4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl acetate), as well as another three ester analogs based on pertinent fatty acids, could be applied on the evaluation of lipase activity through FL measurements. [8] Although ester 1 itself was not the most suitable for interaction with the lipase, it was primarily used to define the methodology for activity determination. Briefly, the method consisted on hydrolyzing the ester with the enzyme, followed by separation and FL

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The Chemiexcitation of the Chemiluminescence of Lophine Peroxide Anions via a Partially Cyclic Transition State

Cited by 7 publications

References 15 publications

Transformation of Stored Energy into Light in the Chemiluminescence of 1,2‐Dioxetanes

Transformation of Stored Energy into Light in the Chemiluminescence of 1,2‐Dioxetanes

Evidence for the Formation of 1,2-Dioxetane as a High-Energy Intermediate and Possible Chemiexcitation Pathways in the Chemiluminescence of Lophine Peroxides

The decomposition of triphenylimidazole‐para‐acetate follows specific base catalysis and can be conveniently followed by fluorescence

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