【作者】 张璐；

【导师】 潘方方；

【作者基本信息】 华中师范大学 ， 无机化学， 2019， 硕士

【摘要】 近年来,氢键(HB)、卤键(XB)、范德华作用、疏水作用等非共价作用力作为设计构筑超分子系统最重要的作用力而备受关注。其中,氢键和卤键由于具有强度适中、高度方向性和强度可调节性等特点成为晶体工程、材料化学等领域常用的非共价作用力。本论文重点研究了溶液及固相中分子或离子间氢键和卤键的情况,以及在特定体系中从溶液到晶体这一过程氢键与卤键所起的作用,这不仅有助于我们更深入地认识分子自组装形成晶体的过程,而且还可以更好地指导设计合成特殊性质的超分子材料。第一章首先简要介绍了卤键、氢键等非共价作用力的特点、作用力本质,及其在生物科学、材料化学、晶体工程等领域的应用,最后阐述了它们在物质结晶过程中所起的作用。第二章分别以1,4-二碘四氟苯(DITFB)和对苯二酚为卤键和氢键的供体,以1,2-双(4-吡啶)乙烯(BPE)为受体,系统分析了结晶条件(包括固体研磨法、溶剂辅助的固体研磨法、快速溶剂挥发法、溶剂缓慢挥发法等)对最终形成超分子加合物的影响。并针对DITFB和BPE二者的溶液混合后立即产生卤键共晶沉淀的现象,通过对比实验、溶液及固相反应、相变实验,借助晶体结构、X-射线粉末衍射、扫描电镜、透射电镜、粒径分析及量化计算等手段解释了卤键共晶沉淀产生的原因,并尝试揭示从溶液到晶体这一过程中卤键、氢键、π…π堆积等非共价键所起的作用。第三章以苯酚、4-碘苯酚分别作为氢键和卤键供体,以四烷基卤化铵、四苯基卤化膦中的卤阴离子(Cl-,Br-,I-)作为氢键或卤键受体(即电子供体)。通过核磁滴定和晶体结构分析探究了卤素阴离子在溶液和固相中参与形成氢键、卤键的情况。通常,卤离子形成氢键和卤键的能力取决于其电负性和给电子能力等,然而,在溶液中,溶剂效应能极大地影响卤阴离子与氢键、卤键供体的键合。在晶体学上,Z’>1,即不对称单元中有多个缺乏对称性关联的相同分子的现象通常被称为溶液结构的“化石”,它对理解化合物结晶前在溶液中的自组装很有帮助。第四章研究了3,5-双(三氟甲基)苯酰胺(BTFMBA)及3,5-双(三氟甲基)苯酰胺·四丁基硝酸铵(BTFMBA·TBAN)共晶化合物中出现的这种特殊晶体学现象。BTFMBA晶体结构的不对称单元中包含8个BTFMBA分子(Z’=8),每四个BTFMBA分子形成一个由C-H…O、N-H…O氢键连接的螺旋链。BTFMBA和TBAN以6:1共晶,最小不对称单元中包含24个独立粒子(Z"=24),每个硝酸根被六个BTFMBA分子通过氢键包围形成一个盘状结构。结构分析发现分子间强氢键作用是产生Z’>1现象的根本原因,并且这些氢键作用在相应化合物晶体的成核、晶体生长过程中得以保持,使最终得到的结构出现低对称性的现象。第五章对本论文的研究成果及创新点进行了总结分析,并对设计合成高效识别分离阴离子的传感器以及构筑结构和功能多样化的超分子材料进行了展望。更多还原

【Abstract】 Non-covalent interactions such as hydrogen bonds(HBs),halogen bonds(XBs),van der Waals interactions and hydrophobic interactions have attracted much attention since they were found important in the design and construction of supramolecular systems.Among them,HBs and XBs are commonly used in crystal engineering,material chemistry and other fields due to their moderate strength,high directionality and adjustability.This thesis focuses on the molecular assembly via HBs and XBs between molecules or ions in solution and solid phase,as well as the role of such non-covalent bonds in the process of crystallization.This will not only help us to understand the process from self-assembly of molecules in solution to crystal formation,but also better guide the design and synthesis of supramolecular materials with specific properties.In the first chapter,the characteristics of non-covalent interactions such as halogen bonds and hydrogen bonds,the nature of these interactions,their applications in biology,material chemistry,crystal engineering,as well as their effects on the crystallization process of materials are briefly introduced.In the second chapter,1,4-diiodotetrafluorobenzene(DITFB)and hydroquinone(HQ)were used as XB donor and HB donor,respectively,and 1,2-bis(4-pyridine)ethylene(BPE)as bond acceptor.We systematically investigated the influence of the crystallization conditions to the final supramolecular products.Surprisingly,it was found that precipitation occurred immediately after mixing the solutions of DITFB and BPE.Through comparative experiments,solid-state reaction and phase transformation experiments,the causes of precipitation were explained by means of X-ray single crystal diffraction,X-ray powder diffraction,scanning electron microscopy,transmission electron microscopy,particle size analysis and DFT calculations.The effects of non-covalent bonds including HBs,XBs and π…π stacking in the process of crystallization were investigated.In the third chapter,phenol and 4-iodophenol were used as hydrogen bond and halogen bond donors respectively,and halides(Cl-,Br-,I-)in tetraalkyl ammonium halide and tetraphenyl phosphine halide as HB or XB acceptors(electron donors).The formation of HBs and XBs by halogen anions in solution and solid phases was investigated by 1H NMR and crystal structure analysis.Generally,the ability of halides to form HBs and XBs depends on their electronegativity and electron donation ability.However,in solution,solvent effect can greatly affect the bonding of halides.Z’>1 in crystallography,viz,more than one molecules of the same type in the asymmetric unit is regarded as the "fossil" of solution.It is extremely important for the understanding of molecular assembly in solution and crystallization.In the fourth chapter,such special crystallographic phenomena were found in the structures of 3,5-bis(trifluoromethyl)benzamide(BTFMBA)and its cocrystal with tetrabutylammonium nitrate(BTFMBA·TBAN).In BTFMBA,the asymmetric unit consists of eight BTFMBA molecules(Z’=8).Every four BTFMBA molecules form a helical chain linked by C-H…O,N-H…O HBs.BTFMBA and TBAN cocrystalize with the ratio of 6:1,and the smallest asymmetric unit contains 24 independent particles(Z"=24).Each NO3-is surrounded by six BTFMBA molecules through HBs to form a disc-like structure.Structural analysis shows that the intermolecular hydrogen bonding played a fundamental role in the appearance of Z’>1 phenomenon,and these hydrogen bonding can be maintained during the nucleation and crystal growth of the corresponding compounds,resulting in the low symmetry of the final structures.The last chapter involves the summary and novelty of this project,and the prospects of non-covalent bonding in designing highly effective sensors for anion recognition and separation,as well as constructing supramolecular materials with diverse structures and functions.更多还原