An exploration of electronic structure and nuclear dynamics in tropolone: II. The A (1)B2 (pi* pi) excited state.

The first excited singlet state of tropolone (A (1)B(2)) and the attendant pi(*)<--pi electronic transition have been examined computationally by applying several quantum chemical treatments built upon the aug-cc-pVDZ basis set, including time-dependent density functional theory (TDDFT/B3LYP), configuration interaction singles with perturbative corrections [CIS and CIS(D)], and equation-of-motion coupled-cluster schemes [EOM-CCSD and CR-EOMCCSD(T)]. As in the case of the X (1)A(1) ground state [L. A. Burns, D. Murdock, and P. H. Vaccaro, J. Chem. Phys. 124, 204307 (2006)], geometry optimization procedures and harmonic force-field calculations predict the electronically excited potential surface to support a global minimum-energy configuration of rigorously planar (C(s)) symmetry. Minimal Hartree-Fock (HF/CIS) and density-functional (DFT/TDDFT) approaches yield inconsistent results for the X (1)A(1) and A (1)B(2) manifolds; however, coupled-cluster (CCSD/EOM-CCSD) methods give fully relaxed proton-transfer barrier heights of DeltaE(pt) (X)=3296.1 cm(-1) and DeltaE(pt) (A)=1270.6 cm(-1) that are in accordance with the experimentally observed increase in vibrationless tunneling splitting upon electronic excitation. Detailed analyses show that this reduction in DeltaE(pt) stems from a variety of complementary factors, most notably an overall contraction of the proton-transfer reaction site (whereby the equilibrium O...O donor-acceptor distance decreases from 2.53 to 2.46 A) and a concomitant shortening of the intramolecular hydrogen bond. Further refinement of A (1)B(2) energies through single-point perturbative triples corrections [CR-EOMCCSD(T)] leads to 1316.1 cm(-1) as the best current estimate for DeltaE(pt) (A). Direct comparison of the lowest-lying out-of-plane torsional mode [nu(39)(a(2))] for X (1)A(1) and A (1)B(2) tropolone reveals that its disparate nature (cf. nu(39) (X)=101.2 cm(-1) and nu(39) (A)=42.0 cm(-1)) mediates vibrational-averaging effects which can account for inertial defects extracted by rotationally resolved spectroscopic measurements.

[1]  Steve Scheiner,et al.  Hydrogen Bonding: A Theoretical Perspective , 1997 .

[2]  L. Arnaut,et al.  Excited-state proton transfer reactions I. Fundamentals and intermolecular reactions , 1993 .

[3]  R. L. Redington,et al.  State-specific spectral doublets in the FTIR spectrum of gaseous tropolone , 2002 .

[4]  R. L. Redington,et al.  Tunneling splittings for "O...O stretching" and other vibrations of tropolone isotopomers observed in the infrared spectrum below 800 cm(-1). , 2008, Journal of Physical Chemistry A.

[5]  R. L. Redington,et al.  Implications of comparative spectral doublets observed for neon-isolated and gaseous tropolone(OH) and tropolone(OD). , 2005, The Journal of chemical physics.

[6]  T. Tsuji,et al.  Vibrational mode-specific tunneling splittings in the à states of deuterated tropolones , 1991 .

[7]  R. L. Redington,et al.  Ã 1B2–X̃ 1A1 26v0 transitions of 18O‐enriched tropolone , 1990 .

[8]  Manabu Oumi,et al.  A doubles correction to electronic excited states from configuration interaction in the space of single substitutions , 1994 .

[9]  John D. Watts,et al.  Coupled-cluster calculations of the excitation energies of benzene and the azabenzenes , 1997 .

[10]  J. Hollas,et al.  The near ultra-violet spectrum of tropolone vapour and its relevance to the molecular structure. I. Rotational band contour analysis , 1972 .

[11]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[12]  L. Burns,et al.  Mode-specific tunneling dynamics in the ground electronic state of tropolone. , 2007, The Journal of chemical physics.

[13]  M. Takahashi,et al.  The role of electronic and geometric factors in ‘‘proton tunneling:’’ A comparative study of tropolone and 9‐hydroxyphenalenone by threshold photoelectron spectroscopy , 1993 .

[14]  Amnon Kohen,et al.  Enzyme Catalysis: Beyond Classical Paradigms† , 1998 .

[15]  G. Hummer,et al.  Water conduction through the hydrophobic channel of a carbon nanotube , 2001, Nature.

[16]  G. Feher,et al.  Proton transfer in reaction centers from photosynthetic bacteria. , 1992, Annual review of biochemistry.

[17]  H. Kohguchi,et al.  Determination of the proton tunneling splitting of tropolone in the ground state by microwave spectroscopy , 1999 .

[18]  W. Siebrand,et al.  Mode‐specific hydrogen tunneling in tropolone: An instanton approach , 1996 .

[19]  S. Scheiner,et al.  Theoretical study of hydrogen bonding and proton transfer in the ground and lowest excited singlet states of tropolone , 1994 .

[20]  H. Sekiya,et al.  Excited-state double-proton transfer in a model DNA base pair : Resolution for stepwise and concerted mechanism controversy in the 7-azaindole dimer revealed by frequency- and time-resolved spectroscopy , 2008 .

[21]  Andrew C. Simmonett,et al.  Popular theoretical methods predict benzene and arenes to be nonplanar. , 2006, Journal of the American Chemical Society.

[22]  T. Crawford,et al.  An Introduction to Coupled Cluster Theory for Computational Chemists , 2007 .

[23]  D R Yarkony,et al.  Modern electronic structure theory , 1995 .

[24]  S. Novick,et al.  High-resolution studies of tropolone in the S0 and S1 electronic states: isotope driven dynamics in the zero-point energy levels. , 2006, The Journal of chemical physics.

[25]  R. P. Steer,et al.  Photophysics of tropolone , 1999 .

[26]  J. Pople,et al.  Self‐consistent molecular orbital methods. XX. A basis set for correlated wave functions , 1980 .

[27]  P. Vaccaro,et al.  An exploration of electronic structure and nuclear dynamics in tropolone. I. The X 1A1 ground state. , 2006, The Journal of chemical physics.

[28]  T. Oka.  On negative inertial defect , 1995 .

[29]  R. L. Redington,et al.  Quantum tunneling in the midrange vibrational fundamentals of tropolone. , 2006, Journal of Physical Chemistry A.

[30]  Walter Gordy,et al.  Microwave Molecular Spectra , 1970 .

[31]  R. L. Redington,et al.  Laser fluorescence excitation spectrum of jet‐cooled tropolone: The à 1B2–X̃ 1A1 system , 1988 .

[32]  J. Hollas,et al.  The near ultra-violet absorption spectrum of tropolone vapour , 1973 .

[33]  R. Ahlrichs,et al.  Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory , 1996 .

[34]  Per-Olov Löwdin,et al.  Proton Tunneling in DNA and its Biological Implications , 1963 .

[35]  L. Arnaut,et al.  Excited-state proton transfer reactions II. Intramolecular reactions , 1993 .

[36]  Karol Kowalski,et al.  Extension of renormalized coupled-cluster methods including triple excitations to excited electronic states of open-shell molecules. , 2005, The Journal of chemical physics.

[37]  Mark S. Gordon,et al.  General atomic and molecular electronic structure system , 1993, J. Comput. Chem..

[38]  Karol Kowalski,et al.  Efficient computer implementation of the renormalized coupled-cluster methods: The R-CCSD[T], R-CCSD(T), CR-CCSD[T], and CR-CCSD(T) approaches , 2002 .

[39]  O. Kühn,et al.  The all-Cartesian reaction plane Hamiltonian: formulation and application to the H-atom transfer in tropolone. , 2005, The Journal of chemical physics.

[40]  E. Riedle,et al.  Microscopic Mechanism of Ultrafast Excited-State Intramolecular Proton Transfer: A 30-fs Study of 2-(2‘-Hydroxyphenyl)benzothiazole† , 2003 .

[41]  Stephen R. Langhoff,et al.  Quantum mechanical electronic structure calculations with chemical accuracy , 1995 .

[42]  Michael J. Frisch,et al.  Toward a systematic molecular orbital theory for excited states , 1992 .

[43]  K. Jordan,et al.  Fluorescence‐dip infrared spectroscopy of tropolone and tropolone‐OD , 1996 .

[44]  J. M. Lluch,et al.  Bidimensional tunneling splitting in the à 1B2 and X̃ 1A1 states of tropolone , 1995 .

[45]  Timothy Clark,et al.  Efficient diffuse function‐augmented basis sets for anion calculations. III. The 3‐21+G basis set for first‐row elements, Li–F , 1983 .

[46]  Shoji Takada,et al.  Effects of vibrational excitation on multidimensional tunneling: General study and proton tunneling in tropolone , 1995 .

[47]  John F. Stanton,et al.  Many‐body methods for excited state potential energy surfaces. I. General theory of energy gradients for the equation‐of‐motion coupled‐cluster method , 1993 .

[48]  Filipp Furche,et al.  Adiabatic time-dependent density functional methods for excited state properties , 2002 .

[49]  R. Vivie-Riedle,et al.  Ultrafast Excited-State Proton Transfer of 2-(2‘-Hydroxyphenyl)benzothiazole: Theoretical Analysis of the Skeletal Deformations and the Active Vibrational Modes† , 2003 .

[50]  P. Vaccaro,et al.  Rotation–tunneling analysis of the origin band in the tropolone π*←π absorption system , 2004 .

[51]  R. L. Redington.  Heavy atoms and tunneling in the X̃ state of tropolone , 1990 .

[52]  R. L. Redington,et al.  IR spectra of tropolone(OH) and tropolone(OD) , 2000 .

[53]  M. Head‐Gordon,et al.  Analytical gradient of the CIS(D) perturbative correction to single‐excitation configuration interaction excited states , 1995 .

[54]  P. Bunker,et al.  Molecular symmetry and spectroscopy , 1979 .

[55]  J. M. Lluch,et al.  On the planarity of the tropolone molecule in the A˜1B2 excited state: A time dependent DFT geometry optimisation , 2005 .

[56]  G. Scuseria,et al.  An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules , 1998 .

[57]  J. Gauss,et al.  Analytic energy gradients for the equation‐of‐motion coupled‐cluster method: Implementation and application to the HCN/HNC system , 1994 .

[58]  T. H. Dunning.  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , 1989 .

[59]  Henk Fidder,et al.  Ultrafast chemistry: using time-resolved vibrational spectroscopy for interrogation of structural dynamics. , 2005, Annual review of physical chemistry.

[60]  T. Dunning,et al.  Electron affinities of the first‐row atoms revisited. Systematic basis sets and wave functions , 1992 .

[61]  E. Gross,et al.  Density-Functional Theory for Time-Dependent Systems , 1984 .

[62]  Gradients for the partitioned equation-of-motion coupled-cluster method , 1999 .

[63]  J. Watson.  Approximations for the inertial defects of planar molecules , 1993 .

[64]  John F. Stanton,et al.  The equation of motion coupled‐cluster method. A systematic biorthogonal approach to molecular excitation energies, transition probabilities, and excited state properties , 1993 .

[65]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[66]  M. Gutman,et al.  The dynamic aspects of proton transfer processes , 1990 .

[67]  A. Zewail,et al.  Double proton transfer dynamics of model DNA base pairs in the condensed phase , 2007, Proceedings of the National Academy of Sciences.

[68]  H. Sekiya,et al.  Electronic spectra of jet-cooled tropolone. Effect of the vibrational excitation on the proton tunneling dynamics , 1990 .

[69]  T. Sewell,et al.  Semiclassical Calculations of Tunneling Splitting in Tropolone , 1998 .

[70]  E. Hirota.  Nonlinear Spectroscopy for Molecular Structure Determination , 1998 .

[71]  T. Oka,et al.  Calculation of inertia defect: Part I. General formulation , 1961 .

[72]  J. Klinman,et al.  Hydrogen-Transfer Reactions , 2006 .

[73]  M. Wójcik,et al.  Vibrational interactions in hydrogen-bonds studied by theoretical methods and vibrational spectroscopy , 2007 .

[74]  Hiroki Nakamura,et al.  Theoretical study of multidimensional proton tunneling in the excited state of tropolone , 2000 .

[75]  Mark S. Taylor,et al.  Asymmetric catalysis by chiral hydrogen-bond donors. , 2006, Angewandte Chemie.

[76]  Wolfram Koch,et al.  A Chemist's Guide to Density Functional Theory , 2000 .

[77]  M. Rubner,et al.  Molecular-Level Processing of Conjugated Polymers. 4. Layer-by-Layer Manipulation of Polyaniline via Hydrogen-Bonding Interactions , 1997 .

[78]  John F. Stanton,et al.  The ACES II program system , 1992 .

[79]  R. L. Redington.  H atom and heavy atom tunneling processes in tropolone , 2000 .

[80]  Conrad C. Huang,et al.  UCSF Chimera—A visualization system for exploratory research and analysis , 2004, J. Comput. Chem..

[81]  On the integration accuracy in molecular density functional theory calculations using Gaussian basis sets , 2000, physics/0006069.

[82]  John F. Stanton,et al.  A comparison of single reference methods for characterizing stationary points of excited state potential energy surfaces , 1995 .

[83]  Karol Kowalski,et al.  New coupled-cluster methods with singles, doubles, and noniterative triples for high accuracy calculations of excited electronic states. , 2004, The Journal of chemical physics.

[84]  D. Herschbach,et al.  INFLUENCE OF VIBRATIONS ON MOLECULAR STRUCTURE DETERMINATIONS III. INERTIAL DEFECTS , 1964 .