Vibrationally resolved 1Lb (1A′)↔S0 (1A′) electronic spectra of benzimidazole and indene: Influence of Duschinsky and Herzberg–Teller effects on weak dipole-allowed transitions

Pan, Yang; Pang, Min; Li, Ming; Shen, Wei; He, Rongxing

doi:10.1016/j.saa.2015.06.101

Cited by 2 publications

(2 citation statements)

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“…As seen in other PAH systems, the substitution of the H with a CN group introduces very small perturbations in the S 0 vibrational spectra. 83 It is therefore reasonable to approach the S 0 and T 1 vibrational analysis in CNI by inferring to the widely studied low-lying electronic states in bare indene 35,40,41,82 and indenyl radical. 24,28,84 The tabulated calculated harmonic vibrational frequencies of the radical anion S 0 and T 1 states in all the CNI isomers can be found in the Supporting Information (Tables S19−S25).…”

Section: Resultsmentioning

confidence: 99%

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Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet–Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions

Abeysooriya,

White,

Workman

et al. 2024

J. Phys. Chem. A

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Isomer-specific negative ion photoelectron spectra (NIPES) of cyanoindene (C 9 H 7 CN) and cyanofluorene (C 14 H 9 N), acquired through the computation of Franck−Condon (FC) factors that utilize harmonic vibrational frequencies and normal mode vectors derived from density functional theory (DFT) at the B3LYP/aug-cc-pVQZ and 6-311++G(2d,2p) basis sets, are reported. The adiabatic electron affinity (EA) values of the ground singlet (S 0 ) and the lowest lying triplet (T 1 ) states are used to predict site-specific S 0 −T 1 energies (ΔE ST ). The vibrational spectra of the S 0 and T 1 states are typified by ring distortion and ring C−C stretching vibrational progressions. Among all the S 0 isomers in C 9 H 7 CN, the 2-cyanoindene (2-C 9 H 7 CN) is found to be the most stable at an EA of 0.716 eV, with the least stable isomer being the 1-C 9 H 7 CN at an EA of 0.208 eV. In C 14 H 9 N, the most stable S 0 isomer, 2-cyanofluorene (2-C 14 H 9 N), has an EA of 0.781 eV. The least stable S 0 isomer in C 14 H 9 N is the 9-C 14 H 9 N, with an EA of 0.364 eV. The FC calculations are designed to mimic simulations that would be performed to aid in the analysis of experimental spectra obtained in NIPE spectroscopic techniques. The vibrational spectra, adiabatic EAs, and ΔE ST values reported in this study are intended to act as a guide for future gas-phase ion spectroscopic experiments and astronomical searches, especially with regard to the hitherto largely unexplored C 14 H 9 N isomers.

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Section: Resultsmentioning

confidence: 99%

“…Although bare indene and fluorene, together with their ions and radicals, have been studied extensively, ,− there is a scarcity of information regarding the spectroscopy and ion chemistry of cyanoindene (CNI) and cyanofluorene (CNF). This scarcity of information is even greater with the CNF.…”

Section: Introductionmentioning

confidence: 99%

Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet–Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions

Abeysooriya,

White,

Workman

et al. 2024

J. Phys. Chem. A

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Picosecond excited-state lifetimes of protonated indazole and benzimidazole: The role of the N–N bond

Marlton

McKinnon

Greißel

et al. 2021

The Journal of Chemical Physics

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Certain chemical groups give rise to characteristic excited-state deactivation mechanisms. Here, we target the role of a protonated N–N chemical group in the excited-state deactivation of protonated indazole by comparison to its isomer that lacks this group, protonated benzimidazole. Gas-phase protonated indazole and protonated benzimidazole ions are investigated at room temperature using picosecond laser pump–probe photodissociation experiments in a linear ion-trap. Excited state lifetimes are measured across a range of pump energies (4.0–5.4 eV). The 1ππ* lifetimes of protonated indazole range from 390 ± 70 ps using 4.0 eV pump energy to ≤18 ps using 4.6 eV pump energy. The 1ππ* lifetimes of protonated benzimidazole are systematically longer, ranging from 3700 ± 1100 ps at 4.6 eV pump energy to 400 ± 200 ps at 5.4 eV. Based on these experimental results and accompanying quantum chemical calculations and potential energy surfaces, the shorter lifetimes of protonated indazole are attributed to πσ* state mediated elongation of the protonated N–N bond.

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Vibrationally resolved 1Lb (1A′)↔S0 (1A′) electronic spectra of benzimidazole and indene: Influence of Duschinsky and Herzberg–Teller effects on weak dipole-allowed transitions

Cited by 2 publications

References 39 publications

Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet–Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions

Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet–Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions

Picosecond excited-state lifetimes of protonated indazole and benzimidazole: The role of the N–N bond

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