Matrix isolation vibrational circular dichroism spectroscopic studies of chiral molecules and solvent effects.

几乎所有重要的生物分子都是手性的。事实上，生命的化学成分几乎完全建立在左旋氨基酸和右旋糖类的基础上，这种模式被称为“生命的同质”。药物通常是手性的，因为在许多情况下，只有使用正确左手的药物才能在受体部位进行适当的“握手”。我们的研究重点是利用实验光谱和从头算方法来理解手性和手性识别现象。目前，我们正在进行两个截然不同但相互关联的研究计划。一种是手性分子团簇的气相高分辨光谱，另一种是用振动圆二色谱(VCD)研究凝聚相。VCD光谱是近年来出现的一种确定手性分子绝对结构和构象结构的可行工具。然而，由于构象分布和溶质-溶剂相互作用的影响，对构象柔性手性分子的VCD研究受到了严重的限制，因为它们的VCD光谱往往很宽，特征很少。我们建议在VCD光谱仪中实现基质隔离组件，以显著提高VCD光谱研究多构象手性分子的灵敏度。我们还建议使用基质隔离技术来制备用于VCD光谱研究的溶质-溶剂小团簇，以逐步探索溶质-溶剂分子间的相互作用。特别是，我们将研究手性，即VCD信号强度，如何通过与手性分子的分子间相互作用转移到非手性溶剂，如水。他们说，这一结果将引起一大批从事合成有机化学、生物分析化学和环境化学的化学家的浓厚兴趣。拖延获得这一重要文书将是我们追求创新想法的严重挫折，并将阻碍我们领导这一令人振奋的新领域并作出重大贡献的努力。

Nearly all important biological molecules are chiral. In fact, the chemistry of life is built almost exclusively on left-handed amino acids and right-handed sugars, a pattern known as the 'homochirality of life'. Pharmaceuticals are often chiral since in many cases only drugs with the correct handedness are capable of executing a proper 'hand shake' at the receptor site. Our research focuses on understanding the phenomena of chirality and chiral recognition using experimental spectroscopic and ab initio methods.     Presently, we are pursuing two distinct yet inter-linked research programs. One centers on the gas phase high resolution spectroscopy of chiral molecular clusters and the other one focuses on condensed phase studies using vibrational circular dichrosim (VCD) spectroscopy. VCD spectroscopy has emerged in recent years as a viable tool for the determination of absolute and conformational structures of chiral molecules. VCD studies of conformationally flexible chiral molecules, however, experience severe limitations since their VCD spectra tend to be broad and with few features because of conformational distributions and solute-solvent interactions. We propose to implement a matrix isolation assembly into the VCD spectrometer to significantly enhance the sensitivity of VCD spectroscopy for the investigations of multiconformational chiral molecules. We further propose to use matrix isolation technique to prepare small solute-solvent clusters for VCD spectroscopic studies in order to probe solute-solvent intermolecular interactions in a step wise manner. In particular, we will study how chirality, i.e.VCD signal strength, is transferred to an achiral solvent, such as water, through intermolecular interactions with a chiral molecule.      The results will be of significant interest to a large group of chemists who practice synthetic organic chemistry, bioanalytical chemistry, and environmental chemistry. A delay in obtaining this important instrument would be a severe setback for us to pursue our innovative idea and will hamper our efforts to lead and to contribute significantly to this exciting new field.