title: Interaction in the indole···imidazole heterodimer: structure, Franck-Condon analysis and energy decomposition.
abstract: The complex of indole and imidazole has been studied using a combination of theoretical chemistry techniques, with the relevant calculations compared to existing experimental resonant two-photon ionisation data. Results of fitted multidimensional Franck-Condon simulations based on ground and excited state geometry optimizations and harmonic vibrational frequencies confirm that the V-shaped herringbone structure is that observed by experiment. The ground state interaction energy of these important biomolecular building blocks has been evaluated at a benchmark quality level using explicitly correlated coupled cluster theory, and the V-shaped structure is shown to be approximately 2 kcal mol(-1) more strongly bound than other possible conformers. The non-covalent interaction energy is decomposed into physical components using symmetry-adapted perturbation theory and it can be seen that although electrostatics dominate the interaction, dispersion plays a vital role in determining the optimal geometry.
authors.affiliation: School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: J Grant
authors.initials: JG
authors.lastname: Hill
authors.forename: Aloke
authors.initials: A
authors.lastname: Das
mesh_terms: D019281:Dimerization; D007093:Imidazoles / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D007093:Imidazoles; D007211:Indoles; C029899:imidazole; C030374:indole