Structure and vibrations of catechol and catechol⋅H2O(D2O) in the <i>S</i> and <i>S</i>1 state

Journal of Chemical Physics - Tập 104 Số 23 - Trang 9362-9375 - 1996
Markus Gerhards1, W. Perl1, Stephan Schumm1, U. Henrichs1, Ch. Jacoby1, Karl Kleinermanns1
1Heinrich-Heine Universität Düsseldorf, Institut für Physikalische Chemie and Elektrochemie I, Universitätsstrasse 26.43.02, D-40225 Düsseldorf, German

Tóm tắt

The inter- and intramolecular vibrations in the S0 and S1 state of catechol, d2-catechol, catechol(H2O)1, and d2-catechol (D2O)1 have been investigated experimentally by resonant two photon ionization (R2PI), spectral hole burning (SHB), and dispersed fluorescence spectroscopy (DF). The experimental frequencies are compared to the vibrational frequencies obtained from ab initio normal mode calculations using the 6-31G(d,p) basis set. In order to get a complete interpretation of the S0 state spectra of d2-catechol the strong coupling of the two OD torsional motions has been taken into account. A two-dimensional calculation of the torsional eigenvalues based on an ab initio potential [6-31G(d,p) basis] obtained from single point calculations is presented. Due to these calculations all vibrations in the S0 state can be assigned. Furthermore a new assignment of the vibrations in the S1 state of d2-catechol is given. In the case of catechol (H2O)1 [d2-catechol(D2O)1] different structural isomers are discussed. Using HF ab initio calculations (including MP2, BSSE, and ZPE corrections) a trans-linear hydrogen bonding arrangement turns out to be more stable by an amount of 840 cm−1 compared to a cyclic structure which is also a minimum of the PES. Normal mode calculations have been carried out for both structures and anharmonic corrections are calculated for the τ and β2 mode of the trans-linear arrangement. The prediction of the ab initio calculations is supported by the vibrational transitions observed in the spectra of the S0 and S1 state, which can be assigned on the basis of the vibrations calculated for the trans-linear structure. The most important feature of the R2PI spectrum of catechol(H2O)1 [d2-catechol(D2O)1] is the occurrence of intermolecular vibrations of very low frequencies (14, 37 cm−1). These vibrations and the low frequency torsional modes in the spectra of the S1 state of the catechol monomer strongly support the assumption that catechol is nonplanar in the S1 state with respect to the OH groups. Due to this nonplanarity a double minimum potential for the intermolecular ρ1 mode of catechol(H2O)1 is postulated. Using this assumption the low frequency vibrations of the R2PI spectra as well as the vibrations observed in the spectra of the S0 state can be assigned.

Từ khóa


Tài liệu tham khảo

1966, Acta Crystallogr., 21, 170, 10.1107/S0365110X66002482

1971, Acta Crystallogr. Sect. B, 27, 1684

1987, J. Mol. Struct., 159, 243, 10.1016/0022-2860(87)80042-X

1990, J. Mol. Struct., 240, 263, 10.1016/0022-2860(90)80515-L

1960, Spectrochim. Acta, 16, 528, 10.1016/0371-1951(60)80009-4

1961, Spectrochim. Acta, 17, 1049, 10.1016/0371-1951(61)80039-8

1982, J. Mol. Struct., 95, 151

1993, J. Mol. Struct., 293, 59, 10.1016/0022-2860(93)80014-M

1991, Spectrochim. Acta Part A, 47, 133, 10.1016/0584-8539(91)80185-L

1975, J. Phys. Chem., 79, 199, 10.1021/j100570a003

1993, Spectrochim. Acta Part A, 49, 1759, 10.1016/0584-8539(93)80243-4

1974, Spectrochim. Acta Part A, 30, 2141, 10.1016/0584-8539(74)80064-4

1990, Theochem., 204, 337, 10.1016/0166-1280(90)85085-2

1978, J. Mol. Struct., 48, 271, 10.1016/0022-2860(78)80030-1

1983, J. Mol. Struct., 92, 173

1993, Vib. Spectr., 4, 321, 10.1016/0924-2031(93)80006-2

1950, J. Chem. Phys., 18, 1135, 10.1063/1.1747901

1985, Chem. Phys. Lett., 121, 453, 10.1016/0009-2614(85)87212-2

1994, J. Chem. Phys., 101, 8418, 10.1063/1.468104

1995, Chem. Phys. Lett., 240, 506, 10.1016/0009-2614(95)00567-N

1995, J. Chem. Phys., 103, 584, 10.1063/1.470093

1959, J. Chem. Phys., 31, 1562, 10.1063/1.1730653

1962, J. Chem. Phys., 37, 1800, 10.1063/1.1733371

1990, J. Am. Chem. Soc., 112, 7854, 10.1021/ja00178a002

1991, J. Chem. Phys., 95, 7862, 10.1063/1.461315

See AIP document no. PAPS JCPSA-104-9362-15 for 15 pages of additional Figures including (a) the eigenfunctions of the two-dimensional calculations on the OH torsional vibrations of catechol, (b) the (a,a,dd) and the (d,d,aa) structure of catechol(H2O)1, and (c) the intermolecular vibrations of the cyclic structure of catechol(H2O)1.

1970, Mol. Phys., 19, 553, 10.1080/00268977000101561

1993, J. Chem. Phys., 98, 3763, 10.1063/1.464055

1991, J. Chem. Phys., 94, 1717, 10.1063/1.459944

1994, Z. Phys. D, 29, 223, 10.1007/BF01437141

1993, J. Chem. Phys., 99, 1469, 10.1063/1.465316

Thông tin
Thông tin xuất bản

Journal of Chemical Physics

Tập 104 Số 23

9362-9375

Thông tin tác giả