Intramolecular hydrogen bonding and conformational preferences on fluorinated amino-alcohols

• Grant number: 18/02634-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2018
• End date: October 31, 2020
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Claudio Francisco Tormena
• Grantee: Cassia Chiari
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 15/08541-6 - Nuclear magnetic resonance spectroscopy: beyond molecular structure assignment, AP.TEM
• Associated scholarship(s): 19/18193-6 - Intramolecular hydrogen bonding involving fluorine atom, BE.EP.IC

Abstract

The aim of this proposal is to evaluate the influence and strength of possible intramolecular hydrogen bonding (IntraHB) involving N-H---O, O-H---N, O-H---F and N-H---F molecular moieties as a driving force on the conformational preferences of some fluorinated amino-alcohols. To achieve our purpose we intent to merge experimental information from Nuclear Magnetic Resonance Spectroscopy with those obtained from quantum mechanical calculations. As first step, the compounds under investigation will be synthesized and their structures unequivocally determined from their 1H, 13C and 19F NMR spectra. The information related to spatial proximities between atoms, which is crucial to determine the conformacional preferences, will be investigated from homo- and hetero-nuclear NOE experiments and through scalar coupling constant involving OH and NH groups with fluorine atom (hydrogen bonding coupling pathway). Quantum chemistry calculation will be performed applying DFT and ab initio approaches with Dunning types basis set (aug-cc-pVDZ and aug-cc-pVTZ) at the Gaussian09 package of programme, to determine structure for the most stable conformers in isolated phase and including solvent effect. The electronic structure will be analysed through Natural Bonding Orbital (NBO) analysis and through topological NCI and QTAIM approaches to evaluate the occurrence of IntraHB and its strength.