Schmidt J, Hoffmann A, Spiess H W, Sebastiani D
Max-Planck-Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
J Phys Chem B. 2006 Nov 23;110(46):23204-10. doi: 10.1021/jp0640732.
We present an analysis of bulk (1)H NMR chemical shifts for a series of biochemically relevant molecular crystals in analogy to the well-known solvent NMR chemical shifts. The term bulk shifts denotes the change in NMR frequency of a gas-phase molecule when it undergoes crystallization. We compute NMR parameters from first-principles electronic structure calculations under full periodic boundary conditions and for isolated molecules and compare them to the corresponding experimental fast magic-angle spinning solid-state NMR spectra. The agreement between computed and experimental lines is generally very good. The main phenomena responsible for bulk shifts are packing effects (hydrogen bonding and pi-stacking) in the condensed phase. By using these NMR bulk shifts in well-ordered crystalline model systems composed of biologically relevant molecules, we can understand the individual spectroscopic signatures of packing effects. These local structural driving forces, hydrogen bonding, pi-stacking, and related phenomena, stand as a model for the forces that govern the assembly of much more complex supramolecular aggregates. We show to which accuracy condensed-phase ab initio calculations can predict structure and structure-property relationships for noncovalent interactions in complex supramolecular systems.
我们对一系列与生物化学相关的分子晶体进行了体相¹H NMR化学位移分析，类似于众所周知的溶剂NMR化学位移。术语“体相位移”表示气相分子结晶时NMR频率的变化。我们在全周期边界条件下从第一性原理电子结构计算中计算NMR参数，并针对孤立分子进行计算，然后将它们与相应的实验快速魔角旋转固态NMR光谱进行比较。计算值与实验谱线之间的一致性通常非常好。导致体相位移的主要现象是凝聚相中的堆积效应（氢键和π堆积）。通过在由生物相关分子组成的有序晶体模型系统中使用这些NMR体相位移，我们可以理解堆积效应的各个光谱特征。这些局部结构驱动力，即氢键、π堆积及相关现象，可作为控制更为复杂的超分子聚集体组装的力的模型。我们展示了凝聚相从头算计算能够以何种精度预测复杂超分子系统中非共价相互作用的结构和结构 - 性质关系。
