Laser Spectroscopic Characterization of Supersonic Jet-Cooled 2,6-Diazaindole (26DAI).

The article presents a comprehensive laser spectroscopic characterization of a nitrogen-rich indole derivative, namely, 2,6-diazaindole (26DAI), in the gas phase. A supersonic jet-cooled molecular beam of 26DAI was characterized using two-color resonant two-photon ionization (2C-R2PI) and laser-induced fluorescence spectroscopy (LIF) to investigate the electronic excitation. The S ← S origin transition was obtained at 33915 cm, which was red-shifted from that of one (indole) and two (7-azaindole) nitrogen-containing indole derivatives by 1317 and 713 cm, respectively.

Spectroscopic characterization of the complexes of 2-(2'-pyridyl)-benzimidazole and (HO), (CHOH), and (NH) isolated in the gas phase.

The hydrogen-bonded docking preferences of small solvent molecules on 2-(2'-pyridyl)-benzimidazole (PBI) were studied experimentally aided by computational findings. The PBI-S complexes (S = HO, CHOH, and NH) were produced in a supersonically jet-cooled molecular beam and probed using resonant two-photon ionization and laser-induced fluorescence spectroscopy, with multiple isomers confirmed by UV-UV hole-burning spectroscopy. Two distinct isomers of PBI-HO and PBI-(HO) complexes were identified, while PBI-CHOH and PBI-NH each formed a single 1 : 1 and 1 : 2 complex.

Spectroscopic Characterization of Hydrogen-Bonded 2,7-Diazaindole Water Complex Isolated in the Gas Phase.

We present a systematic experimental analysis of the 1:1 complex of 2,7-diazaindole (27DAI) with water in the gas phase. The complex was characterized by using two-color-resonant two-photon ionization (R2PI), laser-induced fluorescence (LIF), single vibronic level fluorescence (SVLF), and photoionization efficiency (PIE) spectroscopic methods. The 0 band of the S←S electronic transition of the 27DAI-HO complex was observed at 33,074 cm, largely red-shifted by 836 cm compared to that of the bare 27DAI.

Laser spectroscopic characterization of supersonic jet cooled 2,7-diazaindole.

We report the first gas phase comprehensive study of the electronic spectroscopy of 2,7-diazaindole molecule in the ground and excited states. Single vibronic level fluorescence spectroscopy (SVLF) was performed to determine the ground state vibrations of the molecule, which depicted a large Franck-Condon activity beyond 2600 cm. For the excited state characterization, laser-induced fluorescence (LIF) and two-color resonant two-photon ionization spectroscopy (2C-R2PI) were performed.

Competing Excited-State Hydrogen and Proton-Transfer Processes in 6-Azaindole-S and 2,6-Diazaindole-S Clusters (S=H O, NH ).

Excited state hydrogen (ESHT) and proton (ESPT) transfer reaction pathways in the three and four solvent clusters of 6-azaindole (6AI-S ) and 2,6-diazaindole (26DAI-S )(S=H O, NH ) were computationally investigated to understand the fate of photo-excited biomolecules. The ESHT energy barriers in (H O) complexes (39.6-41.

Excited-state deactivation solvent-to-chromophore proton transfer in an isolated 1 : 1 molecular complex: experimental validation by measuring the energy barrier and kinetic isotope effect.

We have experimentally demonstrated conclusive evidence of solvent-to-chromophore excited-state proton transfer (ESPT) as a deactivation mechanism in a binary complex isolated in the gas phase. This was achieved by determining the energy barrier of the ESPT processes, qualitatively analysing the quantum tunnelling rates and evaluating the kinetic isotope effect. The 1 : 1 complexes of 2,2'-pyridylbenzimidazole (PBI) with HO, DO and NH, produced in supersonic jet-cooled molecular beam, were characterised spectroscopically.