Intermolecular Perturbation in the Self Assembly of Melamine

ANDRE NICOLAI PETELSKI; DARÍO JORGE ROBERTO DUARTE; SILVANA CARINA PAMIES; NÉLIDA MARÍA PERUCHENA; GLADIS LAURA SOSA

Torino

Congreso; 41° Congreso de Químicos Teóricos de Expresión Latina; 2015

Universidad de Torino , dipartimento di Chimica

One of the most active areas of research in the field of supramolecular chemistry is the study of self-assembly process, which constitutes a powerful method to create spontaneously complex structures. Recent interest in nanoscale devices has stimulated research of intra and intermolecular forces that control and lead to the creation of ordered two-dimensional nanostructures, from the self-assembly of small molecular building blocks. In this field, melamine, 1,3,5-Triazine-2,4,6-triamine, (M) and its derivatives have gained a special attention in the last twenty years. Following the elucidation of the crystal structure of M1, several researches have been carried out. Dewar et. al2 performed the first electronic structure study of M tautomeric forms, and recently Li et al3 studied various M clusters by DFT calculations. Despite these efforts, there are gaps regarding the interactions involved in the self-assembly process in this extraordinary compound.In this study we analyzed various complexes formed by M and three compounds: Cyanuric Acid (CA), a derivative of CA: 1-chloro-1,3,5-triazinane-2,4,6-trione (CACl) and finally water (W). That is: M/CA, M/CA2, M/CA3, M/CACl y M/W. All geometries where fully optimized at the B3LYP/6-311++G** level of theory using Gaussian 03. The interactionsand their effects over M structure were analyzed by the Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) Analysis. The aromaticity of M was examined through various aromaticity indices and the curvature of electron density perpendicular to ring plane at the ring critical point, all of them calculated with MultiWFN.Quantitative insights into the electronic structure of M and molecular interactions involved in the complexes were gained. NBO analysis highlights that after complexation, -NH2 groups in M change their hybridization and the effect of interactions is different in all complexes, accounting the intermolecular perturbation. In addition, all aromatic indices suggest that M ring loses its aromaticity in the following increasing order: M/CACl < M/W < M/CA < M/CA2. Finally, QTAIM study reveals that the strongest interaction is N?H-N in M/CA complexes; N?Cl is below it and N?H-O in M/W complex is the weakest.