Excited state intramolecular proton transfer in 3-hydroxy flavone and 5-hydroxy flavone: A DFT based comparative study

Ash, Sankarlal; De, Sankar Prasad; Pyne, Santanu; Misra, Ajay

doi:10.1007/s00894-009-0578-y

Cited by 32 publications

(20 citation statements)

References 56 publications

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“…6) have different antioxidant capabilities. For instance, the 3-OH (on the C ring) and 5-OH (on the A ring) isomers electrochemically favor high antioxidant activity, possibly because these hydroxyl groups are near the carbonyl group (C=O on C-4) allowing the formation of intramolecular hydrogen bonds (e.g., and ) [38] to result in easier oxidation. In contrast, the 7-OH (on the A ring) and 4′-OH (on the B ring) isomers, where the hydroxyl groups are far from the carbonyl group, do not show antioxidant activities.…”

Section: Natural Polyphenolics As Essmentioning

confidence: 99%

Polyphenolic compounds as electron shuttles for sustainable energy utilization

Hsueh

Chen

2019

Biotechnol Biofuels

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For renewable and sustainable bioenergy utilization with cost-effectiveness, electron-shuttles (ESs) (or redox mediators (RMs)) act as electrochemical “catalysts” to enhance rates of redox reactions, catalytically accelerating electron transport efficiency for abiotic and biotic electrochemical reactions. ESs are popularly used in cellular respiratory systems, metabolisms in organisms, and widely applied to support global lives. Apparently, they are applicable to increase power-generating capabilities for energy utilization and/or fuel storage (i.e., dye-sensitized solar cell, batteries, and microbial fuel cells (MFCs)). This first-attempt review specifically deciphers the chemical structure association with characteristics of ESs, and discloses redox-mediating potentials of polyphenolics-abundant ESs via MFC modules. Moreover, to effectively convert electron-shuttling capabilities from non-sustainable antioxidant activities, environmental conditions to induce electrochemical mediation apparently play critical roles of great significance for bioenergy stimulation. For example, pH levels would significantly affect electrochemical potentials to be exhibited (e.g., alkaline pHs are electrochemically favorable for expression of such electron-shuttling characteristics). Regarding chemical structure effect, chemicals with ortho- and para-dihydroxyl substituents-bearing aromatics own convertible characteristics of non-renewable antioxidants and electrochemically catalytic ESs; however, ES capabilities of meta-dihydroxyl substituents can be evidently repressed due to lack of resonance effect in the structure for intermediate radical(s) during redox reaction. Moreover, this review provides conclusive remarks to elucidate the promising feasibility to identify whether such characteristics are non-renewable antioxidants or reversible ESs from natural polyphenols via cyclic voltammetry and MFC evaluation. Evidently, considering sustainable development, such electrochemically convertible polyphenolic species in plant extracts can be reversibly expressed for bioenergy-stimulating capabilities in MFCs under electrochemically favorable conditions.

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Section: Natural Polyphenolics As Essmentioning

confidence: 99%

Polyphenolic compounds as electron shuttles for sustainable energy utilization

Hsueh

Chen

2019

Biotechnol Biofuels

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“…Since the discovery of the phenomenon in methylsalicylate by Weller in 1956, 15 and the realistic interpretation by Otterstedt 16 and Kasha, 17 many investigations have been reported. A non exhaustive list of studies includes works focussed on salicylic acid, 18 – 22 methyl salicylate, 23 – 28 salicylideneaniline, 29 – 32 hydroxy-acetophenones, 26 , 28 , 33 hydroxy-indanone, 20 – 22 , 26 hydroxy flavones, 17 , 34 – 41 (pyridyl)-pyrroles, -pyrazoles and -indoles, 42 – 49 fluorescent protein chromogens, 50 , 51 hydroxy-benzofluorenone, 52 phenyl-phenol, 53 hydroxyphenyl-oxazole (HO), 28 hydroxyphenyl-benzoxazoles (HBO), 54 – 69 hydroxybenzofuran-benzoxazoles (HBBO), 70 hydroxyphenyl-benzothiazole (HBT) 54 , 61 , 62 , 71 – 80 and hydroxyphenyl-benzimidazoles (HBI). 56 , 60 – 62 , 77 , 81 – 88 The typical HBO and HBI structures, two of the most popular ESIPT cores, are displayed in Fig.…”

Section: Introductionmentioning

confidence: 99%

Tuning ESIPT fluorophores into dual emitters

et al. 2016

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“…[27][28][29][30] Furthermore a variety of theoretical investigations have been performed. [31][32][33][34][35][36][37][38][39] The direct structural proof for the ESPT of isolated 3-HF in the gas phase was given by our group by applying structure sensitive combined IR/UV methods (IR/R2PI for the S 0 state and UV/IR/UV for the S 1 state) under isolated molecular beam conditions. 30 In comparison to the calculated vibrational frequencies of different (TD)-DFT optimised structures the presence of the tautomeric form in the electronically excited state could be demonstrated not only for 3-HF but also for 2-(2-naphthyl)-3-hydroxychromone (2-NHC), a derivative, differing in the naphthyl substituent on the chromone moiety.…”

Section: Introductionmentioning

confidence: 99%

A combined IR/IR and IR/UV spectroscopy study on the proton transfer coordinate of isolated 3-hydroxychromone in the electronic ground and excited state

Stamm

Weiler

Brächer

et al. 2014

Phys. Chem. Chem. Phys.

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In this paper the excited state proton transfer (ESPT) of isolated 3-hydroxychromone (3-HC), the prototype of the flavonols, is investigated for the first time by combined IR/UV spectroscopy in molecular beam experiments. The IR/UV investigations are performed both for the electronically excited and electronic ground state indicating a spectral overlap of transitions of the 3-HC monomer and clusters with water in the electronic ground state, whereas in the excited state only the IR frequencies of the proton-transferred monomer structure are observed. Due to the loss of isomer and species selectivity with respect to the UV excitations IR/IR techniques are applied in order to figure out the assignment of the vibrational transitions in the S0 state. In this context the quadruple resonance IR/UV/IR/UV technique (originally developed to distinguish different isomers in the electronically excited state) could be applied to identify the OH stretching vibration of the monomer in the electronic ground state. In agreement with calculations the OH stretching frequency differs significantly from the corresponding values of substituted hydroxychromones.

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Excited state intramolecular proton transfer in 3-hydroxy flavone and 5-hydroxy flavone: A DFT based comparative study

Cited by 32 publications

References 56 publications

Polyphenolic compounds as electron shuttles for sustainable energy utilization

Polyphenolic compounds as electron shuttles for sustainable energy utilization

Tuning ESIPT fluorophores into dual emitters

A combined IR/IR and IR/UV spectroscopy study on the proton transfer coordinate of isolated 3-hydroxychromone in the electronic ground and excited state

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