Can isomer structures of hydrogen-bonded solute x solvent clusters be assigned by correlating gas-phase experimental S0 <--> S1 transitions with vertical or adiabatic excitation energies calculated by time-dependent density functional theory (TD-DFT)? We study this question for 7-hydroxyquinoline (7HQ), for which an experimental database of 19 complexes and clusters is available. The main advantage of the adiabatic TD-B3LYP S0 <--> S1 excitations is the small absolute error compared to experiment, while for the calculated vertical excitations, the average offset is +1810 cm(-1). However, the empirically adjusted vertical excitations correlate more closely with the experimental transition energies, with a standard deviation of sigma = 72 cm(-1). For the analogous correlation with calculated adiabatic TD-DFT excitations, the standard deviation is sigma = 157 cm(-1). The vertical and adiabatic TD-DFT correlation methods are applied for the identification of isomers of the 7-hydroxyquinoline.(MeOH) n , n = 1-3 clusters [Matsumoto, Y.; Ebata, T.; Mikami, N. J. Phys. Chem. B 2002, 106, 5591]. These confirm that the vertical TD-DFT/experimental correlation yields more effective isomer assignments.
[Show abstract][Hide abstract] ABSTRACT: Laser resonant two-photon ionization UV spectra provide clear evidence that the effect of increasing the length of the hydrogen-bonded chain consisting of molecules such as NH(3), H(2)O, or CH(3)OH on the pi --> pi* excitations of cis-7-hydroxyquinoline (cis-7HQ) is strongly cooperative [ Thut ; et al. J. Phys. Chem. A 2008 , 112 , 5566. ] A theoretical analysis of the experimental data is provided to identify the origin of this cooperativity for four chains. The computational method to determine the changes of the electronic structure of a molecule due to interactions with its environment uses the nonempirical expression for the embedding potential [ Wesolowski ; Warshel J. Phys. Chem. 1993 , 97 , 8050. ] It is concluded that the electronic coupling between the molecules at the ends of the chain, which are hydrogen-bonded to cis-7HQ, plays a crucial role in this cooperativity.
The Journal of Physical Chemistry A 08/2009; 113(36):9766-71. DOI:10.1021/jp906483z · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The structure and spectroscopic properties of 5-methyl-2-(8-quinolinyl)benzoxazole and its complexes with Zn(II) ion were studied using a DFT and TD DFT methods with def2-TZVP basis set. It was shown that the type of functional used (B3-LYP or pbe0) implemented in TURBOMOLE package does not have essential influence on the geometry (small differences in bond length, valence and dihedral angles) of studied compounds in both ground and excited states. However, significant differences were obtained for the position of vertical absorption and emission transition but not for the oscillator strength of transition. Application of pbe0 functional seems to reproduce better the experimental spectrum.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 12/2009; 75(2):773-81. DOI:10.1016/j.saa.2009.11.053 · 2.35 Impact Factor
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