Comparison of the 13C Relaxation Times and Proton Scalar Couplings of BPTI with Values Predicted by Molecular Dynamics

1994 ◽  
Vol 104 (3) ◽  
pp. 240-249 ◽  
Author(s):  
S. Balasubramanian ◽  
R. Nirmala ◽  
D.L. Beveridge ◽  
P.H. Bolton
1981 ◽  
Vol 78 (1) ◽  
pp. 227-236 ◽  
Author(s):  
S. Ochiai ◽  
K. Iimura ◽  
M. Takeda ◽  
M. Ohuchi ◽  
K. Matsushita

1987 ◽  
Vol 52 (2) ◽  
pp. 541-546 ◽  
Author(s):  
Vladimír Mlynárik

Carbon-13 relaxation times in the rotating frame were used to study the exchange between unequally populated rotamers of 2-furaldehyde. Calculated free activation energy and activation enthalpy are in good agreement with the results of 1H line shape analysis. Accuracy and reliability of this method in comparison with the line shape analysis is discussed.


1982 ◽  
Vol 201 (3) ◽  
pp. 605-613 ◽  
Author(s):  
D Kaplan ◽  
G Navon

The conformation of bilirubin and its dimethyl ester in dimethyl sulphoxide (DMSO) was investigated by n.m.r. spectroscopy. The chemical shifts of the pyrrole NH and Lactam protons of bilirubin and its dimethyl ester in DMSO indicate a strong interaction with the solvent. Inter-proton distances were calculated from nuclear Overhauser effects (NOE), selective and non-selective relaxation times (T1) and rotational correlation times taken from 13C relaxation times. The interproton distances indicate that the conformation of the skeleton of bilirubin and its dimethyl ester in DMSO is similar to that of bilirubin and mesobilirubin in the crystalline state and in chloroform solutions, except for a possible slight twist of the pyrrolenone rings about the methine bonds, which may be a consequence of solvation of the NH groups by DMSO. Unlike in chloroform solutions, no direct hydrogen-bonding occurs between the carboxylic acid and the lactam groups of bilirubin in DMSO, as shown by the absence of an NOE between these groups. The fast exchange of the pyrrole NH protons with 2H shows that no hydrogen-bonding occurs between these protons and the propionic residues, in line with their solvation by DMSO. From the above results, and from the slowness of the internal motion of the propionic residues of bilirubin and its dimethyl ester, it is concluded that these residues are tied to the skeleton via bound solvent molecules.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1355 ◽  
Author(s):  
Michelina Soccio ◽  
Daniel E. Martínez-Tong ◽  
Giulia Guidotti ◽  
Beatriz Robles-Hernández ◽  
Andrea Munari ◽  
...  

Poly(2,5-alkylene furanoate)s are bio-based, smart, and innovative polymers that are considered the most promising materials to replace oil-based plastics. These polymers can be synthesized using ecofriendly approaches, starting from renewable sources, and result into final products with properties comparable and even better than those presented by their terephthalic counterparts. In this work, we present the molecular dynamics of four 100% bio-based poly(alkylene 2,5-furanoate)s, using broadband dielectric spectroscopy measurements that covered a wide temperature and frequency range. We unveiled complex local relaxations, characterized by the simultaneous presence of two components, which were dependent on thermal treatment. The segmental relaxation showed relaxation times and strengths depending on the glycolic subunit length, which were furthermore confirmed by high-frequency experiments in the molten region of the polymers. Our results allowed determining structure–property relations that are able to provide further understanding about the excellent barrier properties of poly(alkylene 2,5-furanoate)s. In addition, we provide results of high industrial interest during polymer processing for possible industrial applications of poly(alkylene furanoate)s.


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