Computational Chemical Software to Aid in the Structural Determination of Organic Molecules by Means of Nuclear Magnetic Resonance

计算化学软件有助于通过核磁共振确定有机分子的结构

基本信息

批准号：
03554020
负责人：
OSAWA Eiji
金额：
$ 10.75万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

(1) Program CONFLEX for Conformational Sparch of Flexible Molecules The program was completed within the year 1992 and has been deposited in the Japan Chemistry Program Exchange for public use. The algorithm of CONFLEX is unique in that the Program not only effects systematic rotations to the rotatable bonds, but also simulates elementary processes occurring in the thermal conformational interconversions. A remarkable aspect of this algorighm is its ability of confining the search to within the low-energy region and still capable of finding new domains in the conformational space by crossing over energy barriers. One can arbitrarily control the extent of search depending on the nature of computer resource and the purpose of search. Careful tests revealed that CONFLEX is superior in its performace than any other existing programs. Thereupon the program has been applied to a number of pending problems including the origin of regiospecific O-methylation reaction of Erythromycins, the caus … More e of failure in taxane synthesis and other problems involving macrocyclic conformation and macrocyclization reactions.(2) Program for Universal Molecular Mechanics Calculations Within the year 1992, we have been able to complete that part of molecular mechanics force field program which takes care of the careful evaluation of solvent effects on intramolecular steric interactions. The original idea of this part rests on Clark Still, Columbia University, but we have modified the original formulations to a considerable extent. Technically speaking, we use the first and second analytical derivatives of molecular volume, not the molecular surface as other investigators does, as the key variables. This part is general and can be implemented in other force field programs.(3) Program 3JHH2 for Calculation of Vicinal Coupling Constants The present version of program 3JHH2 has been critically analyzed, together with other known algorithmus for computing coupling constants, for its performance over a variety of organic molecules. As it turned out, all of the presently known methods have unexpectedly low precision in reproducing and predicting coupling constants. Unexpectedly, the greatest source of error is the experimental precision. It is concluded that a new approach is necessary in the use of Karplus equation. Based on the conclusion we will start a new project beginning from the year 1993. Less

(1)用于柔性分子构象Sparch的程序CONFLEX 该程序于1992年完成，并已存放在日本化学程序交换中心供公众使用。CONFLEX的算法的独特之处在于该程序不仅对结构进行系统旋转。该算法的一个显着方面是它能够将搜索限制在低能量区域内并且仍然能够进行。能够通过跨越能量障碍在构象空间中寻找新的域，可以根据计算机资源的性质和搜索目的任意控制搜索范围。仔细的测试表明，CONFLEX 的性能优于任何其他现有的。随后，该程序已应用于许多悬而未决的问题，包括红霉素区域特异性O-甲基化反应的起源、紫杉烷合成失败的原因以及涉及大环构象和大环化的其他问题。 (2) 通用分子力学计算程序 1992 年，我们已经完成了分子力学力场程序的一部分，该程序负责仔细评估溶剂对分子内空间相互作用的影响。这部分由哥伦比亚大学的Clark Still负责，但我们对原来的公式进行了相当大的修改，从技术上讲，我们使用分子体积的一阶和二阶解析导数，而不是像其他研究人员那样使用分子表面作为关键。这部分是通用的，可以在其他力场程序中实现。 (3)用于计算邻耦合常数的程序3JHH2 已经对程序3JHH2的当前版本以及用于计算耦合常数的其他已知算法进行了严格的分析。事实证明，所有目前已知的方法在再现和预测耦合常数方面的精度都出乎意料地低，最大的误差来源是实验精度。结论是在使用Karplus方程时需要一种新的方法。基于这个结论我们将从1993年开始一个新的项目。