title: Mimicking trimeric interactions in the aromatic side chains of the proteins: a gas phase study of indole...(pyrrole)2 heterotrimer.
abstract: Aromatic trimeric interactions are extremely significant in the stabilization of the specific structures of the proteins as well as protein-protein, and protein-ligand interactions. Here we have reported a direct evidence of the observation of a cyclic asymmetric structure of indole...(pyrrole)(2) trimer bound by three N-H...π hydrogen bonding interactions in a supersonic jet. The experiment has been performed by using resonant two-photon ionization (R2PI), IR-UV, and UV-UV double resonance spectroscopic techniques. Density functional theory (DFT) calculations nicely corroborate the experimental results showing one weakly allowed IR-active band due to symmetric stretch of the N-H bonds and two strongly allowed IR-active bands due to two types of asymmetric stretches of the N-H bonds in the trimer. The present spectroscopic investigation demonstrates that the strength of the three N-H...π bound intermolecular interactions in the cyclic asymmetric trimer is quite different unlike the corresponding interactions of similar strength in a cyclic symmetric trimer.
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research (IISER), 900 NCL Innovation Park, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India.
authors.forename: Sumit
authors.initials: S
authors.lastname: Kumar
authors.forename: Aloke
authors.initials: A
authors.lastname: Das
mesh_terms: D019295:Computational Biology; D019281:Dimerization; D005740:Gases / Q000737:chemistry; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D008956:Models, Chemical; D017785:Photons; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D011758:Pyrroles / Q000737:chemistry / Q000378:metabolism*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: D005740:Gases; D007211:Indoles; D011506:Proteins; D011758:Pyrroles