Zobrazeno 1 - 10
of 200
pro vyhledávání: '"Rubén H. Contreras"'
Publikováno v:
Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual)
Universidade de São Paulo (USP)
instacron:USP
Universidade de São Paulo (USP)
instacron:USP
At present times it is usual practice to mark biological compounds replacing an H for an F atom to study, by means of (19)F NMR spectroscopy, aspects such as binding sites and molecular folding features. This interesting methodology could nicely be i
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6440d219b59eb1aa98b6f9112d96b76b
https://doi.org/10.1021/jp501929t
https://doi.org/10.1021/jp501929t
Autor:
Jorge Casanueva, Jesús San Fabián, Ernesto Díez, Angel L. Esteban, Maria P. Galache, Rubén H. Contreras
Publikováno v:
Molecular Physics. 112:2138-2154
Equations for the intramolecular surfaces of the 3JHH coupling constants in ethane, ethylene, and acetylene are formulated, and the corresponding coefficients are estimated from calculations at the DFT/B3LYP level. The chosen variables are changes in
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::71ee1aacf8e011480ad49a2229b91b4f
https://doi.org/10.1080/00268976.2014.891768
https://doi.org/10.1080/00268976.2014.891768
Autor:
Reynier Suardíaz, Rubén H. Contreras, Miguel Fernández-Oliva, J. San Fabián, J. M. García de la Vega, Carlos Pérez, Rachel Crespo-Otero
Publikováno v:
Magnetic Resonance in Chemistry. 51:775-787
Optimized shifting and/or scaling factors for calculating one-bond carbon-hydrogen spin-spin coupling constants have been determined for 35 combinations of representative functionals (PBE, B3LYP, B3P86, B97-2 and M06-L) and basis sets (TZVP, HIII-su3
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::cc9e092b164cb04ecae9cb06c96bd9d7
https://doi.org/10.1002/mrc.4014
https://doi.org/10.1002/mrc.4014
Publikováno v:
Magnetic Resonance in Chemistry. 51:334-338
SOPPA(CCSD) calculations show that the FC term is the most important contribution to the through-space transmission of JFN coupling constants for the fluoroximes studied in this work. Because of the well-known behavior of FC term, a new rationalizati
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::5a0b910e979814f522002feb177c5e34
https://doi.org/10.1002/mrc.3950
https://doi.org/10.1002/mrc.3950
Publikováno v:
International Journal of Quantum Chemistry. 112:3158-3163
NMR J FH coupling constants transmitted through space are known to show several unusual peculiarities. The main three are (a) in many cases their experimental values are reported to be positive and in others, negative; (b) theoretical values show tha
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ee61d795553d21f7263c0c76fdfeb594
https://doi.org/10.1002/qua.24100
https://doi.org/10.1002/qua.24100
Autor:
Rubén H. Contreras, Roberto Rittner, Matheus P. Freitas, Cláudio F. Tormena, Rodrigo A. Cormanich, Cleber P. A. Anconi, Marilua A. Moreira, Teodorico C. Ramalho
Publikováno v:
Magnetic Resonance in Chemistry. 49:763-767
The present study shows that a hydrogen bond between the OH group and the fluorine atom is not involved in the 1hJFH spin–spin coupling transmission either for 4-bromo-2-fluorophenol or 2-fluorophenol. In fact, according to a quantum theory of atom
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::068a9ab7072427934522d728bc75fe50
https://doi.org/10.1002/mrc.2838
https://doi.org/10.1002/mrc.2838
Autor:
Janaína D. Vilcachagua, Roberto Rittner, Lucas C. Ducati, Rubén H. Contreras, Cláudio F. Tormena
Publikováno v:
The Journal of Physical Chemistry A. 115:1272-1279
Interesting insight into the electronic molecular structure changes associated with substituent effects on the Fermi contact (FC) and paramagnetic spin-orbit (PSO) terms of 1JCF NMR coupling constants (SSCCs) in o-X-, m-X-, and p-X-fluorobenzenes (X
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8fea155af4eb79bfe9ca126c9dde09a7
https://doi.org/10.1021/jp110290b
https://doi.org/10.1021/jp110290b
Publikováno v:
Magnetic Resonance in Chemistry. 48:S151-S158
Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distributi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::7a9cde1e1e4b635f967eef1471ab4465
https://doi.org/10.1002/mrc.2669
https://doi.org/10.1002/mrc.2669
Autor:
J. San Fabián, Rubén H. Contreras, Reynier Suardíaz, Rachel Crespo-Otero, Carlos Pérez, J. M. García de la Vega
Publikováno v:
International Journal of Quantum Chemistry. 110:532-539
The potential of NMR spin–spin coupling constants as probes to studyfine details of electronic molecular structures is briefly discussed in this work throughtwo different examples. A qualitative analysis of the polarization propagator expressionf
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::66d9f23399453e406499670ac50c8aef
https://doi.org/10.1002/qua.22136
https://doi.org/10.1002/qua.22136
Autor:
Francisco Prado Eugenio dos Santos, Rubén H. Contreras, Cláudio F. Tormena, Susimaire Pedersoli, Roberto Rittner
Publikováno v:
Journal of Molecular Structure. 891:508-513
A rationalization of the stereochemical behavior of 1 J CH and 2 J CH coupling constants, involving nuclei in the vicinity of a carbonyl group were carried out in fluoroacetamide ( 1 ), chloroacetamide ( 2 ), bromoacetamide ( 3 ) and cyanoacetamide (
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2a3566d0088ee63f3a24b3205d834d02
https://doi.org/10.1016/j.molstruc.2008.04.040
https://doi.org/10.1016/j.molstruc.2008.04.040