Fluorescence-dip infrared spectroscopy of the tropolone-H2O complex

Abstract

Articles you may be interested inInfrared spectroscopy of OH stretching vibrations of hydrogenbonded tropolone(H2O) n (n=1-3) and tropolone (CH3OH) n (n=1 and 2) clusters Ab initio study of the structure of radical cations derived from Hbonded complexes: a comparison between [H2CO.H2O]+. and [H2CO.HF]+. AIP Conf. Proc. 330, 235 (1995); 10.1063/1.47691Vibronic and electronic states of doubly charged H2S studied by Auger and charge transfer spectroscopy and by a b i n i t i o calculations Fluorescence dip infrared spectroscopy ͑FDIRS͒ is used to probe the effect of a solvent water molecule on intramolecular H-atom tunneling in tropolone. As with the bare molecule discussed in paper I, the FDIR spectrum of the tropolone-H 2 O complex is recorded in the O-H and C-H stretch regions. Three OH stretch fundamentals are observed in the spectrum, and can be assigned nominally to a free OH stretch of the water molecule ͑3724 cm Ϫ1 ͒, a hydrogen bonded OH stretch of water ͑3506 cm Ϫ1 ͒, and the OH stretch of tropolone ͑ϳ3150 cm Ϫ1 ͒. The breadth and complexity of the bands is highly mode specific. The free OH stretch transition is sharp ͑1.8 cm Ϫ1 FWHM͒ and has weak combination bands built on it at ϩ73 and ϩ1600 cm Ϫ1 . The former is assigned to a combination band with the in-plane bending mode of the tropolone-H 2 O hydrogen bond, while the latter is the free OH/intramolecular water bend combination band. The water hydrogen-bonded OH fundamental is also a sharp transition which, after correction for the decreased infrared power at its frequency, is clearly the strongest transition in the spectrum. It is flanked by three close-lying satellite bands 13, 23, and 34 cm Ϫ1 above it, and also supports a weak combination band at ϩ69 cm Ϫ1 due to the in-plane intermolecular bending mode. The tropolone OH absorption is in the same frequency region as in the bare molecule, but broadened to over 100 cm Ϫ1 in TrOH-H 2 O. Distinct substructure in the band is present, with spacings reminiscent of those in the water H-bonded OH stretch region. Ab initio calculations on tropolone-H 2 O are carried out at both the MP2 and Becke3LYP levels of theory. Two isomers with similar binding energies and vibrational frequencies are identified. In one isomer ͑isomer I͒, the water molecule serves as a hydrogen-bonded bridge between the tropolone OH and keto groups. In the other ͑isomer II͒, the water molecule is exterior to the tropolone and hydrogen bonded to the keto oxygen. The experimental evidence does not conclusively distinguish between these two possibilities, though the exterior structure seems somewhat more in keeping with the data as a whole.

Fluorescence-Dip Infrared Spectroscopy of Jet-Cooled 5-Hydroxytropolone

“…In both cases, this substructure has an average spacing of about 10-15 cm -1 , comparable to that observed in the intramolecularly H-bonded O-H stretch band in the tropolone-H 2 O complex. 29 This, together with the similar overall widths of the bands, implies that the syn and anti conformer 2-OH stretch V ) 1 states are mixed with a specific set of dark states common to all these systems.…”

“…20 Here, we apply density functional theory (DFT) methods to 5-HOTrOH, both for comparison with the MP2 calculations on 5-HOTrOH and to provide a seamless comparison with the analogous DFT results on tropolone (TrOH) and its 1:1 complex with water. 29 The DFT methods employ the Becke3LYP nonlocal exchange-correlation functional 30,31 which has been found to provide results of comparable accuracy to MP2 calculations for TrOH, 17 TrOH‚H 2 O, 29 (H 2 O) n , and benzene-(H 2 O) n clusters. 32 In the Becke3LYP procedure, the energy terms contain contributions from local and nonlocal exchange and correlation functionals 31 as well as from exact exchange.…”

Hydrogen Bonding in Aromatic Alcohol-Water Clusters: A Brief Review

“…By observing that the IR spectra for the tropolone-(H 2 O) 1 cluster exhibited two distinct band for the two OH stretching modes of the water moiety, the two groups proposed TP11 and TP12 (Figure 15) as the probable structures for the tropolone-(H 2 O) 1 cluster. Preference of the two groups differed (for example, Mikami and co-workers 38 preferred the structure TP11 on the basis of several spectroscopic arguments and by comparing the IR spectra for the tropolone-(CH 3 OH) 1 cluster, while Zwier and co-workers 39 expressed slight preference for TP12), however, and further detailed analysis would be needed for unambiguous elucidation of the structure. For the tropolone-(H 2 O) 2 cluster, Mikami and co-workers proposed TP21 and TP22 as the two most probable structures, but definite assignment was not made.…”

Coupling of internal rotation of methyl group with proton transfer in the S1 state of 5-methyltropolone

“…The electronic spectra of TRN͑OH͒-͑H 2 O͒ 1 have been measured by three groups including our group. [14][15][16] The most stable structure of the TRN͑OH͒-H 2 O 1:1 complex is predicted to be ''exterior'' or ''ring'' form. The exterior structure is illustrated in Fig.…”