title: Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz.
abstract: Samples of efavirenz (EFZ) were evaluated to investigate the influence of the micronization process on EFZ stability. A combination of X-ray diffraction, thermal analysis, FTIR, observations of isotropic chemical shifts of (1)H in distinct solvents, their temperature dependence and spin-lattice relaxation time constants (T1), solution (1D and 2D) (13)C nuclear magnetic resonance (NMR), and solid-state (13)C NMR (CPMAS NMR) provides valuable structural information and structural elucidation of micronized EFZ and heptane-recrystallized polymorphs (EFZ/HEPT). This study revealed that the micronization process did not affect the EFZ crystalline structure. It was observed that the structure of EFZ/HEPT is in the same form as that obtained from ethyl acetate/hexane, as shown in the literature. A comparison of the solid-state NMR spectra revealed discrepancies regarding the assignments of some carbons published in the literature that have been resolved.
authors.affiliation: Fundação Oswaldo Cruz, FIOCRUZ/Farmanguinhos, Rua Sizenando Nabuco, 100, 21041-250 RJ, Brazil; Universidade Federal do Rio de Janeiro, Instituto de Química, Av. Athos da Silveira Ramos 149, bl.A, s.605, Ilha do Fundão, 21941-909 RJ, Brazil.
authors.forename: Eduardo Gomes Rodrigues de
authors.initials: EGR
authors.lastname: Sousa
authors.affiliation: Fundação Oswaldo Cruz, FIOCRUZ/Farmanguinhos, Rua Sizenando Nabuco, 100, 21041-250 RJ, Brazil.
authors.forename: Erika Martins de
authors.initials: EM
authors.lastname: Carvalho
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Química, Av. Athos da Silveira Ramos 149, bl.A, s.605, Ilha do Fundão, 21941-909 RJ, Brazil; Universidade Federal do Rio de Janeiro, Instituto de Pesquisas de Produtos Naturais, RJ, Brazil. Electronic address: rsangil@iq.ufrj.br.
authors.forename: Rosane Aguiar da Silva
authors.initials: RADS
authors.lastname: San Gil
authors.affiliation: Fundação Oswaldo Cruz, FIOCRUZ/Farmanguinhos, Rua Sizenando Nabuco, 100, 21041-250 RJ, Brazil.
authors.forename: Tereza Cristina Dos
authors.initials: TCD
authors.lastname: Santos
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Química, Av. Athos da Silveira Ramos 149, bl.A, s.605, Ilha do Fundão, 21941-909 RJ, Brazil.
authors.forename: Leandro Bandeira
authors.initials: LB
authors.lastname: Borré
authors.affiliation: Fundação Oswaldo Cruz, FIOCRUZ/Farmanguinhos, Rua Sizenando Nabuco, 100, 21041-250 RJ, Brazil.
authors.forename: Osvaldo Andrade
authors.initials: OA
authors.lastname: Santos-Filho
authors.affiliation: Universidade de São Paulo, Instituto de Física de São Carlos, CP 369, 13560-970 São Carlos, SP, Brazil.
authors.forename: Javier
authors.initials: J
authors.lastname: Ellena
mesh_terms: D000480:Alkynes; D048588:Benzoxazines / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D003521:Cyclopropanes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D012996:Solutions
chemical_list: D000480:Alkynes; D048588:Benzoxazines; D003521:Cyclopropanes; D012996:Solutions; C098320:efavirenz
keywords: (1)H NMR; (13)C CPMAS NMR; efavirenz; polymorphism