Boron–Nitrogen Double Tweezers Comprising Arylboronic Esters and Diamines: Self‐Assembly in Solution and Adaptability as Hosts for Aromatic Guests in the Solid State,ChemPlusChem

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Boron–Nitrogen Double Tweezers Comprising Arylboronic Esters and Diamines: Self‐Assembly in Solution and Adaptability as Hosts for Aromatic Guests in the Solid State
ChemPlusChem ( IF 3.0 ) Pub Date : 2020-01-07 , DOI: 10.1002/cplu.201900717
Angel D. Herrera‐España ₁ , Herbert Höpfl ₁ , Hugo Morales‐Rojas ₁

Affiliation

The thermodynamic stability of 1 : 1 and 2 : 1 boron–nitrogen (B←N) adducts formed between aromatic boronic esters with mono‐ and diamines was studied in solution by NMR and UV‐vis spectroscopy with association energies (ΔG°) ranging from −11 to −28 kJ mol⁻¹. The effect of different substituents in the boronic ester, the nature of the diamine linker, and the effect of the solvent was explored. Stable 2 : 1 B←N adducts with diamines such as 1,3‐diaminopropane were produced in solutions of hydrogen‐bonding acceptor solvents (acetonitrile and ethyl acetate), which can be isolated in the solid state as crystalline solvates, whereas the use of noncoordinating solvents such as 1,2‐dichloroethane afforded mainly 1 : 1 B←N adducts. In suitable combinations, aromatic bis‐pyridyl diamines produced stable 2 : 1 B←N adducts that were isolated either as solvent‐free solids, solvates, or cocrystals. In these crystalline forms, double‐tweezer hosts were observed with an exceptional syn/anti conformational guest‐adaptability driven by simultaneous donor‐acceptor and C−H⋅⋅⋅π interactions in the tweezer cavities, resembling preorganized covalent tweezer hosts. Interestingly, cocrystals with electron‐rich guests such as tetrathiafulvalene and pyrene showed non‐centrosymmetric crystal lattices with infinite π‐stacked donor–acceptor columns.

中文翻译：

包含芳族硼酸酯和二胺的硼-氮双镊子：在溶液中的自组装和作为固态芳香族的宿主的适应性

通过NMR和UV-vis光谱研究了缔合能（ΔG °）范围内的芳香族硼酸酯与单胺和二胺之间形成的1∶1和2∶1硼氮（B←N）加合物的热力学稳定性。从-11至-28 kJ mol ^-1。探索了硼酸酯中不同取代基的作用，二胺连接基的性质以及溶剂的作用。在氢键受体溶剂（乙腈和乙酸乙酯）的溶液中生成与二胺（如1,3-二氨基丙烷）形成的稳定的2：1 B←N加合物，可以将其固态分离为结晶溶剂合物，而使用非配位溶剂（例如1,2-二氯乙烷）主要提供1：1的B←N加合物。在合适的组合中，芳族双吡啶二胺可产生稳定的2：1 B←N加合物，可分离为无溶剂固体，溶剂化物或共晶体。在这些结晶形式，用一个特殊的观察双镊子主机顺/反镊子腔中同时供体-受体和CH-H⋅⋅⋅π相互作用驱动的构象客体适应性，类似于预先组织的共价镊子宿主。有趣的是，带有富电子的客体（如四硫富瓦烯和pyr）的共晶体表现出非中心对称的晶格，并带有无限的π堆积的施主-受主柱。

更新日期：2020-01-07

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