EXCITED STATES OF BIOMOLECULES

许多具有重要生物意义的分子都有一个关键官能团--羰基 组件。因此，肽的主链是一条酰胺链；类固醇激素 含有丙烯醛亚基，维生素K和辅酶Q含有对苯二酚 子结构。Szent-Gyorgyi甚至假设乙二醛对 多肽中的酰胺类物质是一种重要的肿瘤调节机制。 尽管这些化合物很重要，但它们的电子结构是 人们对此知之甚少。关于低能量的可能性存在着严重的争论 双自由基结构。光谱学在没有理论的情况下一直无法解开 光谱测试结果令人满意。 有了现代计算机，从头算量子化学能够计算 简单系统的激发能在正负0.3 eV内。这些 计算使用压缩笛卡尔-高斯基集，广义SCF 每个状态的程序，以及广泛的CI和/或微扰理论。 我们的直接目标是确定激发的V态的性质 二甲基乙酰胺。同时，我们将继续调查 低能双自由基电荷转移络合物在氨或金属间形成的可能性 甲酰胺和乙二醛或甲基乙二醛。我们还将调查这一事件的性质 吡嗪的3(n，pi)，特别强调准确评估 零场和超精细磁参数。

Many biologically important molecules have a carbonyl group as a key functional component. Thus the peptide backbone is a chain of amides; steroid hormones contain the acrolein subgroup, and vitamin K and coenzyme Q contain para-quinone substructures. Szent-Gyorgyi has even postulated that the action of glyoxal on the amides in peptides is an important cancer regulation mechanims. In spite of their importance the electronic structures of these compounds are poorly understood. There is serious debate over the possibility of low energy biradical structures. Spectroscopy, without theory, has been unable to unravel the spectra satisfactorily. With modern computers, ad initio quantum chemistry is able to compute the excitation energies of simple systems to within plus minus 0.3 eV. These computations use contracted Cartesian Gaussian basis sets, generalized SCF procedures for each state, and extensive CI and/or perturbation theory. Our immediate objective is to determine the nature of the excited V state of dimethyl acetamide. Concurrently we will continue to investigate the possibility of a low energy biradical charge transfer complex between ammonia or formanide and glyoxal or methyl glyoxal. We will also investigate the nature of the 3(n, pi) of pyrazine with particular emphasis on an accurate evaluation of the zero-field and hyperfine magnetic parameters.