title: (1) H NMR analysis of O-methyl-inositol isomers: a joint experimental and theoretical study.
abstract: Density functional theory (DFT) calculations of (1) H NMR chemical shifts for l-quebrachitol isomers were performed using the B3LYP functional employing the 6-31G(d,p) and 6-311 + G(2d,p) basis sets. The effect of the solvent on the B3LYP-calculated NMR spectrum was accounted for using the polarizable continuum model. Comparison is made with experimental (1) H NMR spectroscopic data, which shed light on the average uncertainty present in DFT calculations of chemical shifts and showed that the best match between experimental and theoretical B3LYP (1) H NMR profiles is a good strategy to assign the molecular structure present in the sample handled in the experimental measurements. Among four plausible O-methyl-inositol isomers, the l-quebrachitol 2a structure was unambiguously assigned based only on the comparative analysis of experimental and theoretical (1) H NMR chemical shift data. The B3LYP infrared (IR) spectrum was also calculated for the four isomers and compared with the experimental data, with analysis of the theoretical IR profiles corroborating assignment of the 2a structure. Therefore, it is confirmed in this study that a combined experimental/DFT spectroscopic investigation is a powerful tool in structural/conformational analysis studies.
authors.affiliation: Departamento de Química, ICE, Universidade Federal de Juiz de Fora, Campus Martelos, 36036-330, Juiz de Fora, MG, Brazil. wbdealmeida@gmail.com
authors.forename: Mauro V
authors.initials: MV
authors.lastname: De Almeida
authors.forename: Mara Rubia C
authors.initials: MR
authors.lastname: Couri
authors.forename: João Vitor
authors.initials: JV
authors.lastname: De Assis
authors.forename: Cleber P A
authors.initials: CP
authors.lastname: Anconi
authors.forename: Hélio F
authors.initials: HF
authors.lastname: Dos Santos
authors.forename: Wagner B
authors.initials: WB
authors.lastname: De Almeida
mesh_terms: D002236:Carbohydrate Conformation; D007294:Inositol / Q000031:analogs & derivatives* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D011522:Protons; D011789:Quantum Theory; D012015:Reference Standards; D013237:Stereoisomerism
chemical_list: D011522:Protons; D007294:Inositol