The Molecular Basis of Optical Activity: Optical Rotatory Dispersion and Circular Dichroism

The Molecular Basis of Optical Activity: Optical Rotatory Dispersion and Circular Dichroism
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DOI:
10.1042/bst0080767
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发表时间:
1980-12
影响因子:
3.9
通讯作者:
P. Bayley
P. Bayley
中科院分区:
生物学3区
文献类型:
--
作者:
P. Bayley

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我们在科学经验的早期就被介绍到的旋光性现象,似乎只能用一种数学语言来令人满意地解释,而这种数学语言即使在多年以后也很少有人掌握。什么是“令人满意的解释”(通常是某种物理模型及其性质的适当数学描述)取决于读者的询问水平。对于光学活动,天空是极限,那些害怕飞行的人应该小心。最容易达到的一点是,旋光性来自左旋和右旋圆偏振光的不同吸收和折射。进一步的启发需要理解发色团性质的电子基础,而一个很好的洞察力可以通过经典的振荡器,箭头,手指摇摆和常识来获得。但除此之外,真正的门徒必须大胆尝试量子力学,量子力学是处理分子光谱性质的通用弗兰卡语。在何种程度上,一个物理可视化的模型,然后可以确定承担一个相反的关系,以严格的治疗:因此,光学性质成为物理观测的电子状态(本征态)之间的过渡,而不是个别的“光学”电子的行为。这种对旋光性的处理方法的成功是有限的:理论家们通常的回答是:“等我的波函数更好的时候我再回来。”与此同时,留给我们的是一个复杂的,往往令人生畏的文献,包含英雄的进展,构成了我们目前的理解的分子基础的光学活性。Charney博士的书试图将这些方法整合到一本书中,并展示如何将手性性质和分子结构相关的这一具有挑战性的问题用于许多发色团系统。他没有什么特别的目的,这既是他的优点,也是他的缺点。他承认从毕奥和公司开始的许多星星表演者的贡献,并且坚持不懈的读者将能够在上下文中放置许多处理特定模型和机制的原始论文。然而,这本书读起来有些不平衡,因为这一点,似乎相当不确定它是为谁打算。基本的材料出现在奇数点;而开始更精细的点也出现在间隔;但一般的治疗需要相当熟悉的材料和方法。具体章节致力于辐射与物质,电子和振动态,光学活性模型,群论,发色系统(与理论工作的广泛书目),聚合物,定向系统和振动,磁性和发光手性活动的相互作用。一个一致的符号是贯穿始终,本身是一个有价值的除了这方面的文献。这是一本个人书籍,为寻求更广泛地了解手视现象的知情读者提供了相当大的帮助。它在各级都有很好的参考,并得到了很好的介绍。至于生物化学主题,它可以被视为背景文本,因为熟悉的发色团肽,芳香族化合物,嘌呤和嘧啶得到有限的,但光荣的提及。虽然它显示了巨大的进步,即使在半定量水平上理解结构和临床性质之间的关系,我们仍然有很长的路要走,能够指定立体化学的所有有趣的化学和生物化学系统。这本书表明,对于基本的物理性质,理解是坚定的。
It seems to be one of Mother Nature’s imponderables that the phenomenon of optical activity, to which we are all introduced early in our scientific experience, should be satisfactorily explained only in terms of a mathematical language which relatively few have mastered even years later. What constitutes a ‘satisfactory explanation’(usually some physical model and the appropriate mathematical description of its properties) depends upon the level of enquiry of the reader. For optical activity, the sky’s the limit and those with fear of flying should beware. The point which most reach with relative ease is that optical activity derives from the differential absorption and refraction of left-and right-handed circularly polarized light. Further enlightenment requires understanding the electronic basis of chromophoric properties, and a good insight can be obtained with classical oscillators, arrows, finger-wagging and common sense. But beyond this, the true disciple must take the plunge with quantum mechanics, which is the lingua franca for treatment of molecular spectroscopic properties. The extent to which a physically visualizable model can then be identified bears an inverse relationship to the rigour of the treatment: thus optical properties become the physical observables of transitions between electronic states (eigenstates) rather than the behaviour of individual ‘optical’electrons. The success of such treatments of optical activity is limited: the theoreticians’ usual repost is:‘I’ll come back when my wavefunctions are better’. Meanwhile we are left with a complex and often forbidding literature, containing heroic advances which constitute our present understanding of the molecular basis of optical activity. Dr. Charney’s book seeks to integrate a number of these approaches within a single volume, and to show how this challenging problem of relating chiroptical properties and molecular structure has been treated for a number of chromophoric systems. He has no particular axe to grind and this is both a strength and weakness. He acknowledges the contributions of many star performers from Biot and Co. onwards, and the persistent reader will be able to place in context many original papers dealing with specific models and mechanisms. However, the book reads somewhat unevenly because of this and appears rather uncertain for whom it is intended. Elementary material appears at odd points; rather finer points for the initiated likewise appear at intervals; but the general treatment requires considerable prior familiarity with the material and the methods. Specific chapters are devoted to the interaction of radiation with matter, electronic and vibronic states, models of optical activity, group theory, chromophoric systems (with extensive bibliography of theoretical work), polymers, oriented systems and vibrational, magnetic and luminescent chiral activity. A consistent notation is used throughout, itself a valuable addition to this literature. This is a personal book and offers considerable help to the informed reader seeking a wider understanding of chiroptical phenomena. It is well referenced at all levels and well presented. As regards biochemical topics it can be regarded as a background text since the familiar chromophores of peptide, aromatics, purines and pyrimidines get limited but honourable mention. While it shows the enormous progress even at a semi-quantitative level in understanding the relationship between structure and clinical properties, we are still a long way from being able to assign stereochemistry at will for the full range of interesting chemical and biochemical systems. This books shows that, for the fundamental physical properties, the understanding is firmly …