Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Reva, Igor; Lapiński, Leszek; Jesus, A. J. Lopes; Nowak, Maciej J.

doi:10.1063/1.5003326

Cited by 11 publications

(23 citation statements)

References 69 publications

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“…Indole and 3-formylindole differ by the formyl group bonded to C3 in the pentagonal ring (see Figure c). The latter compound has both 1 H - trans and 1 H - cis isomers, which are detectable, and may influence the shape and peak positions of the measured photoabsorption spectrum.…”

Section: Resultsmentioning

confidence: 99%

“…The calculations of C, N, and O K-edge NEXAFS spectra were carried out with the Amsterdam Density Functional (ADF) program. , The TP-DFT ,− was employed with the generalized gradient approximation (GGA) PW86x Perdew and hybrid B3LYP − xc potentials, while TDDFT calculations in the linear-response regime used both B3LYP and the range-separated hybrid CAM-B3LYP exchange-correlation (xc) potentials . In the case of 3-formylindole, all calculations were performed for its more stable 1 H - trans isomer …”

Section: Methodsmentioning

confidence: 99%

“…64 In the case of 3formylindole, all calculations were performed for its more stable 1H-trans isomer. 11 For the TP-DFT calculations with PW86x and B3LYP, an even-tempered quadruple-ζ with three polarization and three diffuse functions (ET-QZ3P-3DIFFUSE in the ADF database) Slater-type orbitals (STO) basis set has been employed for the core-excited C, N, and O atoms, to properly describe transitions to diffuse Rydberg states. A triple ζ polarized (TZP in the ADF database) basis set of STOs was adopted for the core orbitals of nonexcited C, N, and O atoms, in particular, a frozen core (FC) TZP.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Because of their importance, indoles have been extensively studied using various spectroscopic techniques. Recently, the photoinduced structural transformations of selected indoles isolated in cryogenic noble-gas matrices were studied by Reva and co-workers. − It was found that the tendency of indole and other indole derivatives to undergo hydrogen-atom transfer from N1 to the C3 atom of the indole ring (see Figure ) seems to be strongly related to the formation of C3-centered radicals, which facilitate the reattachment of the labile hydrogen atom at this position. Early photoelectron spectra (PES) of nitrogen-containing heterocycles were measured with a He I source (21.2 eV) and assigned on the basis of molecular orbital (MO) calculations. − A comprehensive electronic-structure analysis of boron-containing (BN) indoles and indole was carried out by Chrostowska et al using a combined UV-PES and computational chemistry approach .…”

Section: Introductionmentioning

confidence: 99%

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Carbon and Nitrogen K-Edge NEXAFS Spectra of Indole, 2,3-Dihydro-7-azaindole, and 3-Formylindole

et al. 2021

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The near-edge X-ray absorption fine structure (NEXAFS) spectra of indole, 2,3-dihydro-7-azaindole, and 3-formylindole in the gas phase have been measured at the carbon and nitrogen K-edges. The spectral features have been interpreted based on density functional theory (DFT) calculations within the transition potential (TP) scheme, which is accurate enough for a general description of the measured C 1s NEXAFS spectra as well as for the assignment of the most relevant features. For the nitrogen K-edge, the agreement between experimental data and theoretical spectra calculated with TP-DFT was not quite satisfactory. This discrepancy was mainly attributed to the many-body effects associated with the excitation of the core electron, which are better described using the time-dependent density functional theory (TDDFT) with the range-separated hybrid functional CAM-B3LYP. An assignment of the measured N 1s NEXAFS spectral features has been proposed together with a complete description of the observed resonances. Intense transitions from core levels to unoccupied antibonding π* states as well as several transitions with mixed-valence/Rydberg or pure Rydberg character have been observed in the C and N K-edge spectra of all investigated indoles.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carbon and Nitrogen K-Edge NEXAFS Spectra of Indole, 2,3-Dihydro-7-azaindole, and 3-Formylindole

et al. 2021

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“…Recently, the photoinduced structural transformations of indole, 7-azaindole, and 3-formylindole isolated in cryogenic noble-gas matrices were studied by Nowak and co-workers. , It was found that the tendency of indole and other indole derivatives to undergo hydrogen-atom transfer from N1 to C3 seems to be strongly related with the formation of C3-centered radicals, which facilitate the reattachment of the labile hydrogen atom at this position. The authors have observed that the pattern of photochemical transformations found for 7-AI isolated in solid n -H 2 and irradiated with UV (λ > 270 nm) light, is significantly different from that observed for the compound trapped in solid Ar.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Photoemission Study of Indole and Its Derivatives in the Gas Phase

et al. 2020

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The valence and core-level photoelectron spectra of gaseous indole, 2,3-dihydro-7-azaindole, and 3-formylindole have been investigated using VUV and soft X-ray radiation supported by both an ab initio electron propagator and density functional theory calculations. Three methods were used to calculate the outer valence band photoemission spectra: outer valence Green function, partial third order, and renormalized partial third order. While all gave an acceptable description of the valence spectra, the last method yielded very accurate agreement, especially for indole and 3-formylindole. The carbon, nitrogen, and oxygen 1s core-level spectra of these heterocycles were measured and assigned. The double ionization appearance potential for indole has been determined to be 21.8 ± 0.2 eV by C 1s and N 1s Auger photoelectron spectroscopy. Theoretical analysis identifies the doubly ionized states as a band consisting of two overlapping singlet states and one triplet state with dominant configurations corresponding to holes in the two uppermost molecular orbitals. One of the singlet states and the triplet state can be described as consisting largely of a single configuration, but other doubly ionized states are heavily mixed by configuration interactions. This work provides full assignment of the relative binding energies of the core level features and an analysis of the electronic structure of substituted indoles in comparison with the parent indole.

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Matrix Isolation in Heterocyclic Chemistry

Roque¹,

Nunes²,

Fausto³

2022

Heterocycles

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Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Cited by 11 publications

References 69 publications

Carbon and Nitrogen K-Edge NEXAFS Spectra of Indole, 2,3-Dihydro-7-azaindole, and 3-Formylindole

Carbon and Nitrogen K-Edge NEXAFS Spectra of Indole, 2,3-Dihydro-7-azaindole, and 3-Formylindole

Experimental and Theoretical Photoemission Study of Indole and Its Derivatives in the Gas Phase

Matrix Isolation in Heterocyclic Chemistry

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