Excited-State Dynamics of Melamine and Its Lysine Derivative Investigated by Femtosecond Transient Absorption Spectroscopy

Zhang, Yuyuan; Beckstead, Ashley A.; Hu, Yuesong; Piao, Xijun; Bong, Dennis; Kohler, Bern

doi:10.3390/molecules21121645

Cited by 18 publications

(21 citation statements)

References 37 publications

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“…The photoluminescence decay lifetime of g‐CN measured herein is close to the reported photoluminescence lifetime of g‐CN prepared at a calcination temperature of 550 °C . In addition, the fluorescence lifetime of melamine is quite short and close to the IRF timescale, which indicates that there is almost no fluorescence emission from melamine; this agrees with the reported result for a study of its excited dynamics . Kohler et al.…”

Section: Resultsmentioning

confidence: 96%

“…[26] In addition, the fluorescencel ifetime of melaminei sq uite short and close to the IRF timescale, whichi ndicatest hat there is almost no fluorescencee mission from melamine; this agrees with the reported result for as tudy of its excited dynamics. [27] Kohler et al explored the excited-state dynamics of melamine in aqueous solution and observed that the excited melamine molecules could decay to the electronic ground state within tens of picoseconds after excitation at l = 240 nm. [27] UV/Vis Absorption Spectra, Fluorescence Spectra, and Fluo-rescenceDecay of an AqueousSolution of Melem…”

Section: Fluorescence Decay Measurements On Melemmentioning

confidence: 99%

“…[27] Kohler et al explored the excited-state dynamics of melamine in aqueous solution and observed that the excited melamine molecules could decay to the electronic ground state within tens of picoseconds after excitation at l = 240 nm. [27] UV/Vis Absorption Spectra, Fluorescence Spectra, and Fluo-rescenceDecay of an AqueousSolution of Melem…”

Section: Fluorescence Decay Measurements On Melemmentioning

confidence: 99%

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Photophysics and Photocatalysis of Melem: A Spectroscopic Reinvestigation

Wen

Lü

et al. 2018

Chemistry An Asian Journal

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Graphitic carbon nitride (g-CN) is one potential metal-free photocatalyst. The photocatalytic mechanism of g-CN is related to the heptazine ring building unit. Melem is the simplest heptazine-based compound and g-CN is its polymeric product. Thus, studies on the photophysical properties of melem will help to understand the photocatalytic mechanism of heptazine-based materials. Herein, the spectroscopic features of melem were systematically explored through measuring its absorption spectrum, fluorescence spectrum, and fluorescence decay. Both fluorescence spectroscopy and fluorescence decay measurements show that the condensation of melamine to melem causes stronger photoluminescence, whereas the condensation of melem to g-CN causes weaker photoluminescence. In addition, all observations reveal that a mixture of monomer melem and its higher condensates is more easily obtained during the preparation of melem, and that the higher condensates of melem affect the photophysical properties of melem dominantly. The photocatalytic hydrogen evolution of melem has also been measured and the monomer melem has negligible photoinduced water-splitting activity.

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Section: Resultsmentioning

confidence: 96%

Section: Fluorescence Decay Measurements On Melemmentioning

confidence: 99%

Section: Fluorescence Decay Measurements On Melemmentioning

confidence: 99%

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Photophysics and Photocatalysis of Melem: A Spectroscopic Reinvestigation

Wen

Lü

et al. 2018

Chemistry An Asian Journal

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“…The excited-state lifetime of the lysine derivative is slightly longer (18 ps), but the dominant deactivation pathway is otherwise the same as for melamine. In both cases, the vast majority of excited molecules return to the electronic ground state on the aforementioned time scales, but a minor population is trapped in a long-lived triplet state 91 .…”

Section: Derivativesmentioning

confidence: 99%

How nature covers its bases

Boldissar

Vries

2018

Phys. Chem. Chem. Phys.

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The response of DNA and RNA bases to ultraviolet (UV) radiation has been receiving increasing attention for a number of important reasons: (i) the selection of the building blocks of life on an early earth may have been mediated by UV photochemistry, (ii) radiative damage of DNA depends critically on its photochemical properties, and (iii) the processes involved are quite general and play a role in more biomolecules as well as in other compounds. A growing number of groups worldwide have been studying the photochemistry of nucleobases and their derivatives. Here we focus on gas phase studies, which (i) reveal intrinsic properties distinct from effects from the molecular environment, (ii) allow for the most detailed comparison with the highest levels of computational theory, and (iii) provide isomeric selectivity. From the work so far a picture is emerging of rapid decay pathways following UV excitation. The main understanding, which is now well established, is that canonical nucleobases, when absorbing UV radiation, tend to eliminate the resulting electronic excitation by internal conversion (IC) to the electronic ground state in picoseconds or less. The availability of this rapid "safe" de-excitation pathway turns out to depend exquisitely on molecular structure. The canonical DNA and RNA bases are generally short-lived in the excited state, and thus UV protected. Many closely related compounds are longer lived, and thus more prone to other, potentially harmful, photochemical processes. It is this structure dependence that suggests a mechanism for the chemical selection of the building blocks of life on an early earth. However, the picture is far from complete and many new questions now arise.

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“…Gustavsson, Markovitsi, and co-workers [ 25 ] report on the time-resolved fluorescence decay and fluorescence anisotropy measurements of seven mono-, di-, and tri-methylated xanthine derivatives in water and in methanol. Kohler and co-workers [ 26 ] study the excited-state dynamics of melamine (a proto-nucleobase) and its lysine derivatives by using time-resolved infrared spectroscopy. Mališ and Došlić [ 27 ] present a comparative computational investigation concerning the excited-state dynamics of three neutral model peptides containing the phenylalanine residue, with a focus on the role that chemical substitution and solvation play on their nonradiative relaxation pathways.…”

mentioning

confidence: 99%