PhXF3形成tetrel bond的作用机制及其在晶体工程中的应用

Very recently, tetrel bond has become one of hot topics in intermolecular interactions because it has potential applications in the fields of chemical reactions, crystal materials, and molecular recognition. However, compared with the study of hydrogen bond, so far the study of tetrel bond is a little, particularly in solution. On base of the extensive existence of both aromatic rings and XF3(X = C and Si) groups in materials, medicines, and biological systems, PhXF3 with a sigma-hole will be selected as a Lewis acid to form a tetrel bond in this project. Some binary and ternary systems composed of PhXF3 will be studied with spectroscopic and theoretical methods. Four important scientific questions will be mainly solved in this project: (1) proper theoretical methods used for studying tetrel bonds, (2) spectroscopic evidences for the existence of tetrel bonding in solution, (3) structures, properties, and nature of tetrel bonds, particularly competition and cooperativity, and (4) novel crystal materials synthesized by tetrel bonds. The aims of this project are to (1) unveil the mechanism of the formation of tetrel bond involving PhXF3, (2) expand the applications of two-dimensional infrared spectroscopy and excess infrared spectroscopy in studying tetrel bonds, and (3) apply tetrel bonds to crystal engineering. More importantly, this study would bring new vigor and vitality as well as provide new ideas for the applications of intermolecular interactions in the field of crystal engineering. Hence, this project is of great importance in science and application.

Tetrel bond作用在化学反应、晶体材料和分子识别等领域有着潜在应用前景，最近成为分子间相互作用研究的一个热点。鉴于芳香环和XF3（X = C和Si）基团在材料、药物和生物体系中大量存在，故本课题研究PhXF3作为Lewis酸形成的tetrel bond。本项目重点解决四个科学问题：研究tetrel bond作用的合适理论计算方法；tetrel bond在溶液中存在的光谱证据；tetrel bond作用的结构、性质、本质和规律，特别是竞争和协同性；利用tetrel bond合成新型晶体材料。通过本项目研究，不仅揭示PhXF3形成tetrel bond的作用机制，拓展二维红外相关光谱和超额红外光谱在tetrel bond中的应用，而且将tetrel bond作用应用到晶体工程中，为分子间相互作用在晶体工程领域中的应用注入新活力并提供新思路。因此，本项目研究具有重要的科学意义和应用价值。

Tetrel bond是一种新型分子间相互作用，其在化学反应、晶体材料和分子识别等领域有着潜在应用前景。我们对比了不同理论计算方法，确定MP2/aug-cc-pVTZ方法较为适合研究tetrel bond。我们提出几种新型tetrel bond，比如假卤离子tetrel bond、卡宾tetrel bond和π-π tetrel bond。我们研究了不同电子给体如乙炔及其衍生物、H3ZO (Z=N, P, As)、氰基乙醛、甲脒、H2CX (X = O, S, Se)、1,4-二氮杂二环[2.2.2]辛烷、6-OTX3-富烯、无机苯等形成的tetrel-bonded复合物，并表征了其结构、性质、作用能和本质。我们研究了杂化、取代和溶剂化对tetrel bond的影响，发现按照NCH(sp) < NHCH2(sp2) < NH3(sp3)杂化顺序增强tetrel bond，电子给体中的给电子基团增强tetrel bond，溶剂的极性增加也会增强tetrel bond。质子化也对H+–PyTX3和H+–furanTF3 (T = C, Si, Ge; X = F, Cl)和NH3间的作用产生显著影响，其不仅影响作用类型和强度，而且对作用顺序和本质也产生影响。我们研究了几个典型体系中tetrel bond与其他类型作用的竞争关系，比如二甲基亚砜与TF3X (T = C和Si; X = 卤原子)体系间的tetrel bond和卤键，HArF与TH3X (T = C和Si; X = F, Cl, Br, I)体系间的氢键、卤键和tetrel bond。最后我们研究了假卤离子tetrel bond在SN2反应中可能起的作用，发现其在反应初始阶段以及反应结束阶段分别起着前驱体和后驱体的作用。当F2TO的T原子与丙二醛的羟基氧或羰基氧形成T•••O tetrel bond时，其可以增强和减弱丙二醛中的分子内氢键，进而促进或阻止分子内质子转移，这种效应对F2SiO特别明显。与此不同地是，F2TO的T原子只能与甘氨酸的羰基氧生成T•••O tetrel bond且增强分子内氢键，当其作用能超过280 kJ/mol时也可引起质子转移。