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1.
为了了解怎样利用核磁共振技术研究氢键的键合方式,本文以联酰胺衍生物为例,分别运用变温核磁共振氢谱和变浓度核磁共振氢谱分析了羰基(CO)与氨基(H—N)之间形成氢键的形式。结果表明,本文举例中联酰胺基团中的CO与H—N以分子间氢键形式存在。  相似文献   

2.
在各种分子间相互作用中,氢键占有很特殊的地位,被称作为超分子化学中的万能相互作用。讨论了氢键在超分子、自组装、分子识别、晶体工程、材料化学和催化过程等现代化学领域中的作用。  相似文献   

3.
分别以四苯甲烷和四苯基卟啉为中心,端位引入四氟碘代苯,合成了两类四齿卤键供体分子,并合成了3,3’,5,5’-四甲基-4,4’-联吡啶(TMBP)作为卤键受体分子.以四苯甲烷为中心的卤键供体分子和TMBP基于分子间I…N卤键和H…N氢键在固相中自组装,得到一类超分子网络结构.晶体结构显示,一个四面体卤键供体分子通过两组I…N卤键和两组H…N氢键结合四个TMBP分子,与之对应,一个TMBP分子通过一组I…N卤键和一组H…N氢键结合两个四面体分子,形成单层网络结构,网格为宽度2.37nm的正方形结构,层与层之间通过其它氢键和卤键进一步堆积.卟啉类四齿卤键供体分子的晶体数据显示,通过较为复杂的分子间C—I…π及H…F等弱相互作用,供体分子自身进行平面组装,层与层之间通过π-π堆积等作用进一步堆积.  相似文献   

4.
张翼  杨颙 《化学教育》2007,28(2):7-9
氢键在化学、物理和生物等研究领域发挥着非常重要的作用。特别是反常蓝移氢键和双氢键的发现,更加引起了科学家们的广泛关注。着重介绍了反常蓝移氢键和双氢键的发展过程和最新进展。此外,介绍了一种简单而精确的氢键判定标准。  相似文献   

5.
氢键的形成能够使参与形成氢键的原化学键力常数降低,吸收频率移向低波数方向,同时吸收强度增加。为了介绍怎样利用红外光谱技术研究氢键的键合方式,本文以联酰胺衍生物为例,主要运用变温红外光谱技术分析NH伸缩振动波数、强度以及形成氢键的键长随温度的变化来研究羰基(C O)与氨基(H—N)之间的氢键形式。结果表明,本文举例中联酰胺基团中的C O与H—N以分子间氢键形式存在。  相似文献   

6.
基于氢键的自组装超分子体系   总被引:1,自引:0,他引:1  
白炳莲  李敏 《化学通报》2003,66(12):821-827
氢键自组装超分子是超分子体系中相对较新颖和引入注意的领域,它在化学和生物体系中占据非常重要的位置。本文主要介绍目前文献报道的一系列由不同氢键缔合方式形成的自组装超分子。  相似文献   

7.
基于氢键的自组装超分子体系   总被引:4,自引:0,他引:4  
白炳莲  李敏 《化学通报》2004,67(2):124-131
氢键自组装超分子是超分子体系中相对较新颖和引人注意的领域,它在化学和生物体系中占据非常重要的位置。本文主要介绍目前文献报道的一系列由不同氢键缔合方式形成的自组装超分子。  相似文献   

8.
非共价键结合的超分子聚合物由于其特殊的结构及性能引起了广泛的关注.本文在介绍超分子化学、氢键及超分子聚合物的基础上,主要综述了以氢键为结合力的多重氢键作用、羧基(D)与吡啶基(A)作用以及氢键与其它非共价键协同作用形成的超分子聚合物体系,并对超分子聚合物的研究现状及前景进行了评述.  相似文献   

9.
基于氢键作用结合的超分子聚合物   总被引:4,自引:1,他引:4  
王毓江  唐黎明 《化学进展》2006,18(2):308-316
非共价键结合的超分子聚合物由于其特殊的结构及性能引起了广泛的关注。本文在介绍超分子化学、氢键及超分子聚合物的基础上,主要综述了以氢键为结合力的多重氢键作用、羧基(D)与吡啶基(A)作用以及氢键与其它非共价键协同作用形成的超分子聚合物体系,并对超分子聚合物的研究现状及前景进行了评述。  相似文献   

10.
基于氢键作用结合的超分子聚合物   总被引:1,自引:0,他引:1  
非共价键结合的超分子聚合物由于其特殊的结构及性能引起了广泛的关注。本文在介绍超分子化学、氢键及超分子聚合物的基础上,主要综述了以氢键为结合力的多重氢键作用、羧基(D)与吡啶基(A)作用以及氢键与其它非共价键协同作用形成的超分子聚合物体系,并对超分子聚合物的研究现状及前景进行了评述。  相似文献   

11.
12.
Halogen bonds are a subset of noncovalent interactions with rapidly expanding applications in materials and medicinal chemistry. While halogen bonding is well known in organic compounds, it is new in the field of boron cluster chemistry. We have synthesized and crystallized carboranes containing Br atoms in two different positions, namely, bound to C‐ and B‐vertices. The Br atoms bound to the C‐vertices have been found to form halogen bonds in the crystal structures. In contrast, Br atoms bound to B‐vertices formed hydrogen bonds. Quantum chemical calculations have revealed that halogen bonding in carboranes can be much stronger than in organic architectures. These findings open new possibilities for applications of carboranes, both in materials and medicinal chemistry.  相似文献   

13.
The C--H…H dihydrogen-bonded complexes of methane, ethylene, acetylene, and their derivatives with magnesium hydride were systematically investigated at MP2/aug-cc-PVTZ level. The results confirm that the strength of dihydrogen bonding increases in the following order of proton donors: C(sp3)-H〈C(sp2)-H〈C(sp)-H and chlorine substituents enhance the C-H…H interaction. In the majority of the complexes with a cyclic structure, the Mg-H proton-accepting bond is more sensitive to the surroundings than C-H proton-donating bond. The nature of the electrostatic interaction in these C-H…H dihydrogen bonds was also unveiled by means of the atoms in mo- lecules(AIM) analysis. The natural bond orbital(NBO) analysis suggests that the charge transfer in the cyclic com- plexes is characteristic of dual-channel. The direction of the net charge transfer in the cyclic complexes is contrary to that previously found in dihydrogen bonded systems.  相似文献   

14.
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16.
IR and vibrational circular dichroism (VCD) spectra of a chiral amine–borane in solution are investigated. By comparison of experimental and calculated spectra, unique VCD spectral signatures, which can be attributed to the formation of dihydrogen‐bonded dimers in solution, are identified for the first time. These VCD features are highly sensitive to the specific dihydrogen‐bonding topologies utilized by the chiral amine–borane subunits and thus provide direct structural information of these dihydrogen‐bonded species in solution. Differences in the dihydrogen binding arrangements in solution and in solid state are also revealed.  相似文献   

17.
Ductility is a common phenomenon in many metals but is difficult to achieve in molecular crystals. Organic crystals bend plastically on one or two face-specific directions but fracture when stressed in any other arbitrary directions. An exceptional metal-like ductility and malleability in the isomorphous crystals of two globular molecules, BH3NMe3 and BF3NMe3, is reported, with characteristic tensile stretching, compression, twisting, and thinning. The mechanically deformed samples, which transition to lower symmetry phases, retain good long-range order amenable to structure determination by single-crystal X-ray diffraction. Molecules in these high-symmetry crystals interact through electrostatic forces (B−N+) to form columnar structures with multiple slip planes and weak dispersive forces between columns. On the other hand, the limited number of facile slip planes and strong dihydrogen bonding in BH3NHMe2 negates ductility. Our study has implications for the design of soft ferroelectrics, solid electrolytes, barocalorics, and soft robotics.  相似文献   

18.
19.
Ductility is a common phenomenon in many metals but is difficult to achieve in molecular crystals. Organic crystals bend plastically on one or two face‐specific directions but fracture when stressed in any other arbitrary directions. An exceptional metal‐like ductility and malleability in the isomorphous crystals of two globular molecules, BH3NMe3 and BF3NMe3, is reported, with characteristic tensile stretching, compression, twisting, and thinning. The mechanically deformed samples, which transition to lower symmetry phases, retain good long‐range order amenable to structure determination by single‐crystal X‐ray diffraction. Molecules in these high‐symmetry crystals interact through electrostatic forces (B??N+) to form columnar structures with multiple slip planes and weak dispersive forces between columns. On the other hand, the limited number of facile slip planes and strong dihydrogen bonding in BH3NHMe2 negates ductility. Our study has implications for the design of soft ferroelectrics, solid electrolytes, barocalorics, and soft robotics.  相似文献   

20.
A series of iridium and rhodium pincer complexes have been synthesized and characterized: [(POCOP)Ir(H)(H(2))] [BAr(f)(4)] (1-H(3)), (POCOP)Rh(H(2)) (2-H(2)), [(PONOP)Ir(C(2)H(4))] [BAr(f)(4)] (3-C(2)H(4)), [(PONOP)Ir(H)(2))] [BAr(f)(4)] (3-H(2)), [(PONOP)Rh(C(2)H(4))] [BAr(f)(4)] (4-C(2)H(4)) and [(PONOP)Rh(H(2))] [BAr(f)(4)] (4-H(2)) (POCOP = κ(3)-C(6)H(3)-2,6-[OP(tBu)(2)](2); PONOP = 2,6-(tBu(2)PO)(2)C(5)H(3)N; BAr(f)(4) = tetrakis(3,5-trifluoromethylphenyl)borate). The nature of the dihydrogen-metal interaction was probed using NMR spectroscopic studies. Complexes 1-H(3), 2-H(2), and 4-H(2) retain the H-H bond and are classified as η(2)-dihydrogen adducts. In contrast, complex 3-H(2) is best described as a classical dihydride system. The presence of bound dihydrogen was determined using both T(1) and (1)J(HD) coupling values: T(1) = 14 ms, (1)J(HD) = 33 Hz for the dihydrogen ligand in 1-H(3), T(1)(min) = 23 ms, (1)J(HD) = 32 Hz for 2-H(2), T(1)(min) = 873 ms for 3-H(2), T(1)(min) = 33 ms, (1)J(HD) = 30.1 Hz for 4-H(2).  相似文献   

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