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.

A combined spectroscopic and computational investigation on the solvent-to-chromophore excited-state proton transfer in the 2,2'-pyridylbenzimidazole-methanol complex.

This article demonstrates experimental proof of excited state 'solvent-to-chromophore' proton transfer (ESPT) in the isolated gas phase PBI (2,2'-pyridylbenzimidazole)-CHOH complex, aided by computational calculations. The binary complexes of PBI with CHOH/CHOD were produced in a supersonic jet-cooled molecular beam and the energy barrier of the photo-excited process was determined using resonant two-colour two-photon ionization spectroscopy (R2PI). The ESPT process in the PBI-CHOH complex was confirmed by the disappearance of the Franck-Condon active vibrational transitions above 000 + 390 cm.

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.

Accurate measurement of sequential Ar desorption energies from the dispersion-dominated Ar complexes of aromatic molecules.

We present experimental determination of the energies associated with the gradual desorption of Ar atoms from the aromatic molecular surface. Non-covalently bound 2,2'-pyridylbenzimidazole-Ar complexes were produced in the gas phase and characterized using resonant two-photon ionization (R2PI) spectroscopy. The single Ar desorption from the PBI-Ar, PBI-Ar and PBI-Ar complexes were measured as 581 ± 18, 656 ± 30 and 537 ± 31 cm, respectively.

A combined experimental and computational study on the deactivation of a photo-excited 2,2'-pyridylbenzimidazole-water complex excited-state proton transfer.

In this report, we present solvent assisted excited-state proton transfer coupled to the deactivation of a photo-excited 2,2'-pyridylbenzimidazole bound to a single water molecule. Experimentally, the mass-selected 1 : 1 complex was probed using two-colour resonant two-photon ionization (2C-R2PI) and UV-UV hole-burning (HB) spectroscopy in a supersonically jet-cooled molecular beam. Computationally, three structural isomers were identified as the normal, the tautomer and the proton transfer product of the PBI-HO complex in the excited S state using B3LYP-D4/def2-TZVPP and ADC(2) (MP2)/cc-pVDZ levels of theory.

Solvent assisted excited-state deactivation pathways in isolated 2,7-diazaindole-S (S = Water and Ammonia) complexes.

The role of solvent molecules in the deactivation of photo-excited 2,7-diazaindole (DAI) - (HO) and DAI - (NH) complexes were computationally investigated. An excited-state proton transfer (ESPT) path from the solvent to the DAI molecule was followed using the TD-DFT-D4 (B3LYP) level of theory. The computed potential energy profile of ESPT process has shown intersection between ππ* and nπ* states facilitated via relative stabilization of the nπ* state with decreasing N(7)-H bond length.

A combined spectroscopic and computational investigation on dispersion-controlled docking of Ar atoms on 2-(2'-pyridyl)benzimidazole.

The dispersion-controlled docking of inert Ar atoms on the face of polycyclic 2-(2'-pyridyl)-benzimidazole (PBI) was studied experimentally aided by computational findings. The PBI-Ar (n = 1-3) complexes were produced in a supersonically jet-cooled molecular beam and probed using resonant two-photon ionization coupled with a time-of-flight mass spectrometric detection scheme and laser-induced fluorescence spectroscopy. The ground state vibrational frequencies were obtained from single vibronic level fluorescence spectroscopy.

T and V-shaped donor-acceptor-donor molecules involving pyridoquinoxaline: large Stokes shift, environment-sensitive tunable emission and temperature-induced fluorochromism.

The intramolecular charge transfer-driven emission properties of T and V-shaped donor-acceptor-donor molecules involving a new acceptor core of pyridoquinoxaline were demonstrated. The T-shaped molecule exhibits a large Stokes shift, red emission in the solid state and remarkable viscosity and temperature-dependent tunable fluorescence including a thermally-induced single-component near white-light emission.