title: Anion-pi and pi-pi cooperative interactions regulating the self-assembly of nitrate-triazine-triazine complexes.
abstract: We theoretically investigate the cooperative enhancement of the interactions between anions and electron-deficient aromatics by pi-pi stacking, focusing on the recent crystallographic observation of anion-pi-pi interactions in a synthesized coordination compound based on 1,3,5-triazine moieties. Using a combination of state-of-the-art dispersion-corrected density functional and quantum Monte Carlo calculations, we rationalize the unusual structural features observed in this nitrate-triazine-triazine complex. We show that the triazine rings are staggered and bent and slip with respect to each other with the nitrate bound off-center in a T-like configuration. Our results indicate that this pi-pi stacking is not simply enforced by the coordination of the triazines within the particular crystal structure but is regulated by cooperative anion-pi and pi-pi interactions. In the nitrate-triazine-triazine complex, this cooperative effect amounts to 6% of the total binding energy. Ways to further increase this energetic enhancement in the design of anion-host architectures are discussed.
authors.affiliation: Instituut-Lorentz, Leiden University, P.O. Box 9506, 2300 RA Leiden, The Netherlands.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Zaccheddu
authors.forename: Claudia
authors.initials: C
authors.lastname: Filippi
authors.forename: Francesco
authors.initials: F
authors.lastname: Buda
mesh_terms: D000838:Anions / Q000737:chemistry; D003198:Computer Simulation; D008956:Models, Chemical; D009010:Monte Carlo Method; D009566:Nitrates / Q000737:chemistry*; D011789:Quantum Theory; D014227:Triazines / Q000737:chemistry*
chemical_list: D000838:Anions; D009566:Nitrates; D014227:Triazines