The Amide Rotational Barrier in Isonicotinamide:Dynamic NMR and Ab Initio Studies

Garett M.Leskowitz; Nima Ghaderi; Ryan A.Olsen

首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The Amide Rotational Barrier in Isonicotinamide:Dynamic NMR and Ab Initio Studies

【24h】

The Amide Rotational Barrier in Isonicotinamide:Dynamic NMR and Ab Initio Studies

机译：异烟酰胺中酰胺的旋转势垒：动态核磁共振和从头算研究

获取原文

获取原文并翻译 | 示例

掌桥外文数据库（机构版） >>

开具论文收录证明 >>

文献代查 >>

页面导航

摘要
著录项
相似文献
相关主题

摘要

We report use of dynamic nuclear magnetic resonance (NMR) to measure the amide rotational barrier in isonicotinamide.A significant challenge to obtaining good transition rates from dynamic NMR data is suppression of errors due to inherent line widths associated with transverse relaxation.We address this challenge with a fitting procedure that incorporates transverse relaxation over the temperature range of interest simply and reliably.The fitting model is nonlinear in only one of the fit parameters,namely,the activation enthalpy.This reduces parameter estimation to solution of a single transcendental equation,which avoids both a fine search over a multidimensional parameter space and extrapolation of a "limiting line width" solely from slow-exchange data.The activation enthalpy DELTAH~(not=) measured for isonicotinamide,+14.1 +- 0.2 kcal/mol,falls between those of its regioisomers picolinamide and nicotinamide,which were reported in an earlier study.In that study,ab initio calculations of the rotational barriers helped to discern the relative importance of steric,electronic,and hydrogen-bonding effects in this biochemically significant combination of pyridine-ring and carboxamide moieties.A direct comparison between isonicotinamide and nicotinamide,where steric and hydrogen-bonding effects differ only slightly,permits a closer study of electronic considerations.

机译：我们报道了使用动态核磁共振（NMR）来测量异烟酰胺中的酰胺旋转障碍。从动态NMR数据获得良好过渡速率的一个重大挑战是抑制与横向弛豫相关的固有线宽所引起的误差。通过拟合过程可以简单，可靠地在目标温度范围内纳入横向弛豫。拟合模型仅在一个拟合参数（即激活焓）中是非线性的，这将参数估计简化为单个先验方程的解，避免在多维参数空间上进行精细搜索，也避免了仅从慢交换数据外推“极限线宽”。对于异烟酰胺测得的活化焓DELTAH〜（not =），+ 14.1±-0.2 kcal / mol，介于在较早的研究中已经报道了其区域异构体吡啶啉酰胺和烟酰胺的化合物。在该研究中，从头算旋转障碍的作用有助于辨别在这种具有重要化学意义的吡啶环和羧酰胺基团组合中，空间，电子和氢键作用的相对重要性。异烟酰胺和烟酰胺之间的直接比较，其中空间键和氢键作用只是不同稍微允许对电子注意事项进行更深入的研究。

著录项

来源
《The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory》 |2005年第6期|共7页
作者
Garett M.Leskowitz; Nima Ghaderi; Ryan A.Olsen;
展开▼
作者单位

展开▼
收录信息
原文格式 PDF
正文语种 eng
中图分类
关键词

相似文献

外文文献
中文文献
专利

1. The Amide Rotational Barrier in Isonicotinamide:Dynamic NMR and Ab Initio Studies [J] . Garett M.Leskowitz, Nima Ghaderi, Ryan A.Olsen The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory . 2005,第6期

机译：异烟酰胺中酰胺的旋转势垒：动态核磁共振和从头算研究
2. Ab initio study on the six lowest energy conformers of iso-octane: conformational stability, barriers to internal rotation, natural bond orbital and first-order hyperpolarizability analyses, UV and NMR predictions, spectral temperature sensitivity, and scaled vibrational assignment [J] . Eddine Hachim Mouhi, Sadik Karima, Byadi Said, Journal of molecular modeling . 2019,第8期

机译：AB Initio关于异辛烷的六个最低能量符合子的研究：构象稳定性，内部旋转的屏障，天然键轨道和一阶的超极化性分析，UV和NMR预测，光谱温度灵敏度和缩放振动分配
3. Ab initio SCF study of the barrier to internal rotation in simple amides. Part 3. Thioamides [J] . Vassilev NG., Dimitrov VS. Journal of Molecular Structure . 2003,第1a3期

机译：从头开始的SCF研究简单酰胺中内部旋转的障碍。第3部分。硫代酰胺
4. Solvent effects on electronic properties, geometries and itnernal rotation barriers of bithiophenes. An ab initio self-consistent reaction field theoretical study [C] . V.Hernandez, J.T.Lopez Navarrete Symposium M on new prospects on electronic properties of organic materials;Symposium K on fullerenes: From new molecules to new materials . 1996

机译：溶剂对联噻吩的电子性质，几何形状和行程旋转壁垒的影响。从头开始自洽反应场理论研究
5. Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations, and vibrational assignments of some halopropenes and substituted dimethyl ether molecules. [D] . Tang, Qun. 1993

机译：拉曼光谱和红外光谱，构象稳定性，内部旋转的障碍，从头算和某些卤代丙烯和取代的二甲醚分子的振动分配。
6. Crystallographic and Dynamic Aspects of Solid‐State NMR Calibration Compounds: Towards ab Initio NMR Crystallography [O] . Xiaozhou Li, Lukas Tapmeyer, Dr. Michael Bolte, -1

机译：固态NMR校准化合物的晶体学和动力学方面：从头开始进行NMR晶体学
7. Rotational barriers in ammonium hexachlorometallates as studied by NMR, tunneling spectroscopy and ab initio calculations [O] . Birczynski, A., Lalowicz, Z.T., Lodziana, Zbigniew 2004

机译：通过NmR，隧道谱和从头计算研究六氯金属铵中的旋转障碍
8. Ab Initio Study of the Internal Rotation Barrier of Formamide and the Formamide-H2O Complex. (Reannouncement with New Availability Information) [R] . Wang, X. C., Facelli, J. C., Simons, J. 1993

机译：甲酰胺和甲酰胺 - H2O复合物内旋转阻隔的从头算研究。（重新公布新的可用性信息）

The Amide Rotational Barrier in Isonicotinamide:Dynamic NMR and Ab Initio Studies

摘要

著录项

相似文献

相关主题

期刊订阅