Fluorescence and Phosphorescence from Higher Excited States of Organic Molecules

Transfer of both chirality and energy information plays an important role in biological systems. Here we show a chiral donor π-gelator and assembled it with an achiral π-acceptor to see how chirality and energy can be transferred in a composite donor–acceptor system. It is found that the individual chiral gelator can self-assemble into nanohelix. In the presence of the achiral acceptor, the self-assembly can also proceed and lead to the formation of the composite nanohelix. In the composite nanohelix, an energy transfer is realized. Interestingly, in the composite nanohelix, the achiral acceptor can both capture the supramolecular chirality and collect the circularly polarized energy from the chiral donor, showing both supramolecular chirality and energy transfer amplified circularly polarized luminescence (ETACPL).

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“…9b. The Jablonski energy diagram indicated that our system obeys Kasha's rule during the energy transfer process43.…”

Section: Resultsmentioning

confidence: 80%

Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

et al. 2017

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“…The photoluminescence emission wavelength depends on the excitation wavelength with the frequency difference between the excitation and the emission being almost kept constant to be two times of ν st NH or ν st OH . So one important nonradiative process of the excited B* and B′* is via stretching vibration of N-H or O-H50, and preferably via the intramolecular N-H of carbamato anion in comparison with the O-H of water1314.…”

Section: Discussionmentioning

confidence: 99%

“…Photoluminescence is a process of emission of photons occurred when fluorophores of certain compounds return from an excited state to a lower energy state, and most of the fluorophores usually have extended conjugated structures filled with delocalized electrons which absorb and emit photons, such as p-hydroxybenzylidene-imidazolidone units in fluorescent proteins, fluorescein, rhodamine, and vitamin B 2 1314. However, many types of amino-containing polymers, e.g., poly(amido amines)1516171819202122232425, poly(amino esters)2627, polyethylenimine (PEI)2829, polyurea dendrimer30, without extended conjugated structures have been reported to be photoluminescent since amino-containing dendrimers were reported to be able to emit photoluminescence1931.…”

mentioning

confidence: 99%

Photoluminescence from Amino-Containing Polymer in the Presence of CO2: Carbamato Anion Formed as a Fluorophore

Pan

Wang

Lay

et al. 2013

Sci Rep

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Organic photoluminescent materials are important to many applications especially for diagnosis and detection, and most of organic photoluminescent materials contain fluorophores with extended conjugated structures. Recently some of amino-containing polymers without fluorophores with extended conjugated structure are observed to be photoluminescent, and one possible cause of the photoluminescence is oxidation of the amines. Here we show that photoluminescence can be produced by exposing a typical amino-containing polymer, polyethylenimine, to carbon dioxide. We demonstrate that carbamato anion formed via the reaction between the amine and carbon dioxide is a fluorophore; and the loosely-bound protonated water molecule can increase UV absorption but reduce the photoluminescence emission. Also carbamato anion shows solvent- and excitation wavelength-dependent emission of photoluminescence. The photoluminescence profile of carbamoto anion was discussed. These results will facilitate the understanding of photoluminescence observed from amino-containing materials and the design of new fluorophores.

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“…This indirectly affects the electronic transition probability and photoluminescence properties. 58, 61 For the photoluminescence origin of amorphous CNDs, the light emission characteristics has been generally ascribed to surface-related defect sites, and radiative recombination of excited surface states. 60 In this study, based on the energy gap calculation and the observation of the fluorescence-based spectro-electrochemistry analysis, we propose that the photoluminescence arises from a combination of the C=C core regions, the surface functional groups (C=O, C-O, and COOH), and the surface electronic state transitions.…”

Section: Resultsmentioning

confidence: 99%

A fluorescence-electrochemical study of carbon nanodots (CNDs) in bio- and photoelectronic applications and energy gap investigation

Zeng

Zhang

Arvapalli

et al. 2017

Phys. Chem. Chem. Phys.

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Carbon nanodots (CNDs) have attracted great attention due to their superior solubility, biocompatibility, tunable photoluminescence, and opto-electronic properties. This work describes a new fluorescence-based spectroelectrochemistry approach to simultaneously study the photoluminescence and wavelength dependent photocurrent of microwave synthesized CNDs. The fluorescence of CNDs has a selective quench upon a reversible redox couple, ferricyanide/ferrocyanide,− reaction during the cyclic voltammetry. The CNDs modified gold slide electrode demonstrates wavelength dependent photocurrent generation during the fluorescence-electrochemical study, suggesting potential application in photoelectronics. UV-Vis absorption and electrochemistry are used to quantify the energy gap of the CNDs, and then to calibrate a Hückel model for the CNDs electronic energy levels. The Hückel (or tight binding) model treatment of an individual CND as a molecule combines the conjugated π states (C=C) with the functional groups (C=O, C-O, and COOH) associated with the surface electronic states. This experimental and theoretical investigation of the CNDs provides a new perspective on the optoelectronic properties of CNDs and should aid in their development for practical use in biomedicine, chemical sensing, and photoelectric devices.

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Fluorescence and Phosphorescence from Higher Excited States of Organic Molecules

Cited by 374 publications

References 382 publications

Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

Photoluminescence from Amino-Containing Polymer in the Presence of CO2: Carbamato Anion Formed as a Fluorophore

A fluorescence-electrochemical study of carbon nanodots (CNDs) in bio- and photoelectronic applications and energy gap investigation

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