Simulação de desdobramentos complexos de espectros de RMN de ¹H

Abstract

Recebido em 10/2/05; aceito em 20/5/05; publicado na web em 01/12/05 SIMULATION OF COMPLEX SPLITTINGS OF 1 H NMR SPECTRA. Complex 1 H NMR spectra multiplets that cannot be easily understood by simple inspection are rather frequent in the daily work of the organic chemistry analyst. The multiple and excellent new techniques available from modern instruments usually provide satisfactory solutions, but there are still many cases where a simulation is necessary, at least to obtain a final confirmation. It is extremely convincing to see that a graph, obtained by calculations with chemical-shift and coupling-constant values only, can be virtually identical to the experimental spectrum. This paper describes a computer program to make such calculations. The program is free and can be downloaded from http://artemis.ffclrp.usp.br/ NMR.htm (click on SimEsp_NMR_Compil.zip). All routines are also available and may be used without any restrictions. The paper includes a fairly detailed discussion about how the calculations are made.

Detailed 1H and 13C NMR structural assignment and relative stereochemistry determination for three closely related sesquiterpene lactones

“…Minor doubts about multiplicities and J values were eliminated using spectral simulations by FOMSC3 and SimEsp NMR programs. [16,17] The similarity observed by the comparison between the experimental and calculated signals, strongly suggests that the coupling constant values and the multiplicities shown on Tables 1-6 are correct.…”

A New Alkamide with an Endoperoxide Structure from Acmella ciliata (Asteraceae) and Its in Vitro Antiplasmodial Activity

“…The corrected multiplicities in the 1 H-NMR spectra were established with the aid of FOMSC3 software [13]. …”

Complete assignment of NMR data of 22 phenyl‐1H‐pyrazoles' derivatives

“…1 H and 13 C chemical shifts, together with J-coupling constants ( 1 H/ 1 H and 1 H/ 19 F), for all 1-phenyl-1H-pyrazoles' derivates were assigned and are summarized in Tables 1 and 2. A careful analysis was undertaken of the expansions of multiple signals from the 1 H NMR spectra, measuring as many coupling constants as possible and clarifying the multiplicities. Doubts concerning multiplicities and J-coupling constants values were eliminated using spectral simulations with the software firstorder multiplet simulator/checker (FOMSC3) [14] which calculates and plots NMR first-order multiplets starting from information about coupling constants values. The similarity observed from the comparison between the experimental and simulated spectra, as shown in Fig.…”