Proton transfer dynamics via high resolution spectroscopy in the gas phase and instanton calculations.

Tunneling splittings have been observed in the eigenstate-resolved electronic spectrum of the 2-hydroxypyridine/2-pyridone dimer in the gas phase. Deuterium substitution experiments show that these splittings are caused by a concerted double proton transfer reaction along the O-H...O and N...H-N hydrogen bonds that hold the dimer together, substitution of the weaker and longer N...H-N bond having the larger effect. Tunneling splittings calculated by the instanton method for the zero-point level of the ground state are in good agreement with experiment for all observed isotopomers, showing that the dynamics occurs in this state, rather than in the electronically excited state.

[1]  Emilio Martínez-Núñez,et al.  New interpretation of ground- and excited-state tunneling splitting in 2-pyridone . 2-hydroxypyridine , 2004 .

[2]  C. Tautermann,et al.  The ground state tunneling splitting of the 2-pyridone · 2-hydroxypyridine dimer , 2003 .

[3]  Andreas Müller,et al.  Hydrogen bonding and tunneling in the 2-pyridone·2-hydroxypyridine dimer. Effect of electronic excitation , 2002 .

[4]  A. Fernández-Ramos,et al.  Proton tunnelling in polyatomic molecules: A direct-dynamics instanton approach , 1999 .

[5]  A. Kohen,et al.  Isotope Effects In Chemistry and Biology , 2005 .

[6]  D. Pratt.  High resolution spectroscopy in the gas phase: even large molecules have well-defined shapes. , 1998, Annual review of physical chemistry.

[7]  Markus Meuwly,et al.  Energetics, dynamics and infrared spectra of the DNA base-pair analogue 2-pyridone·2-hydroxypyridine , 2003 .

[8]  A. Myers,et al.  Laser techniques in chemistry , 1995 .

[9]  T. Elsaesser,et al.  Ultrafast hydrogen bonding dynamics and proton transfer processes in the condensed phase , 2002 .

[10]  Antonio Fernández-Ramos,et al.  DOIT: a program to calculate thermal rate constants and mode‐specific tunneling splittings directly from quantum‐chemical calculations , 2001, J. Comput. Chem..

[11]  A. Zewail,et al.  Femtosecond Dynamics of Double Proton Transfer in a Model DNA Base Pair: 7-Azaindole Dimers in the Condensed Phase , 1999 .

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