Fluorescence investigations of supramolecular systems

超分子结构由两个或两个以上的分子组成，只有相对较弱的分子间引力才能将它们聚集在一起。一个简单的例子是主客体包合物，在这个包合物中，一个“客体”分子被包含在一个更大的笼状“宿主”分子的空腔中，就像桶里的球一样。尽管缺乏真正的化学键将组分结合在一起，但这种结构可能会出人意料地坚固，并有许多应用。例如，如果宿主可溶于水，这可能会使原本不能溶解的客人变得可溶。例如，这可以改善药物输送。这样的系统也可以用作分子传感器，当目标分子存在时，它会发出某种信号。研究这类体系的最好方法之一是使用荧光光谱学。荧光是某些分子在电子被激发(获得多余能量)时发出的光，例如在吸收光(路标)或电(荧光灯)后发出的光。分子组分的荧光在形成超分子结构时会发生显著的变化，为研究其形成、性质和结构提供了一种高度灵敏和准确的方法。这一建议涉及使用荧光来研究和表征超分子体系的各种方法。我们小组已经在非荧光宿主中使用荧光客体进行了广泛的工作。我们使用的宿主包括类似分子桶的分子和分子南瓜。在这项提议中，一个新的感兴趣的领域是荧光主体的研究。这一点很重要，因为它允许对任何感兴趣的客人进行研究，而不要求它是荧光的。我们建议使用这种荧光主体作为构建块，可以使用适当的双头客体连接在一起，以获得广泛的超分子结构，如分子补丁玩具。由于这些结构将是荧光的，它们可能会有广泛的有用的应用，包括作为荧光分子传感器，在特定物质存在时开启或关闭。

Supramolecular structures consist of two or more molecules held together only by relatively weak intermolecular forces of attraction. One simple example is a host-guest inclusion complex, in which a "guest" molecule becomes included within the cavity of a larger, cage-like "host" molecule, like a ball in a bucket. Such structures can be surprisingly robust, despite the lack of true chemical bonds holding the components together, and have numerous applications. For example, if the host is soluble in water, this can make otherwise insoluble guests soluble. This can allow for improved drug delivery, for example. Such systems can also be useful as molecular sensors, which give some sort of a signal when a target molecule is present. One of the best ways to study such systems is using fluorescence spectroscopy. Fluorescence is the light that certain molecules emit when their electrons are excited (gain excess energy), for example after absorbing light (road signs), or by electricity (fluorescent lights). The fluorescence of the molecular components can undergo significant changes when they form supramolecular sturctures, providing a hihgly sensitive and accurate method for studying their formation, properties, and structures. This proposal involves various ways of using fluorescence to study and characterize supramolecular systems. Our group has done extensive work using fluorescent guests in non-fluorescent hosts. The hosts we have used include molecules which resemble molecular buckets and molecular pumpkins. In this proposal, one of the new areas of interest is the study of fluorescent hosts. This is important, as it allows for the study of any guest of interest, with no requirement for it to be fluroescent. We are proposing the use of such fluorescent hosts as building blocks, which can be joined together using appropriate double-headed guests to give extensive supramolecular structures, like molecular Tinkertoy. Since these structures will be flourescent, they could have a wide range of useful applications, including as fluorescent molecular sensors which turn on or off in the presence of particular substances.