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首页> 外文期刊>Chemistry: A European journal >Novel Flexible Frameworks of Porous Cobalt(II) Coordination Polymers That Show Selective Guest Adsorption Based on the Switching of Hydrogen-Bond Pairs of Amide Groups
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Novel Flexible Frameworks of Porous Cobalt(II) Coordination Polymers That Show Selective Guest Adsorption Based on the Switching of Hydrogen-Bond Pairs of Amide Groups

机译：基于酰胺基氢键对的转换显示选择性客体吸附的多孔钴（II）配位聚合物的新型柔性骨架

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Four porous crystalline coordination polymers with two-dimensional framework of a double-edged axe-shaped motif, {[Co(NCS)_2(3-pia)_2]·2EtOH·11H_2O}_n (1a), {[Co(NCS)_2(3-pia)_2]·4Me_2CO}_n (3a), {[Co(NCS_2(3-pia))3]·4T HF}_n (3b) AND {[Co(NCS)_2(3-pna)_2]_n} (5), have been synthesized by the reaction of cobalt(II) thiocyanate with N-(3-pyridyl)isonicotin-amide (3-pia) of N-(3-pyridyl)nicotin-amide (3-pna). X-ray crystallographic characterization reveals that adjacent layers are stacked such that channels are created, except in 5. The channels form a hydrogen-bonded interior for guest molecules; in practice, 1a contains ethanol and water molecules as guestsin the channels with hydrogen bonds, whereas 3b (3a) contains tetrahydrofuran (acetone) molecules. In 1a, the "double-edged axe-shaped" motifs in adjacent sheets are not located over the top of each other, while the motifs in 3b stack so perfectly as to overlap each otherin an edge-to-edge fashion. This subtle change in the three-dimensional framework is associated with the template effect of the guests. Compound 5 has no guest molecules and, therefore, the amide groups in one sheet are used for hydrogen-bonding links with used for hydrogen-bonding links with adjacent sheets. Removal of the guest molecules from 1a and 3b (3a) causes a structural converesion accompanied by a color change. Pink 1a cannot retain its original framework and changes into a blue amorphous compound. On the other hand,the framework of pink 3b (3a) is transformed to a new crystalline framework of violet 4. Interestingly, 4 reverts to the original pink crystals of 3b (3a) when it is exposed to THF (or acetone) vapor. Spectroscopic measurements (visible, EPR, and IR) provide a clue to the crystal-to-crystal transformation; on removal of the guests, the amide groups are used to form the beta sheet-type hydrogen bonding between the sheets, and thus the framework withstands significant stress on removal of guest molecules. This mechanism is attributed to the arrangement of the adjacent sheetsso suited in regularity tht the beta sheet-type structure forms efficiently. The apohost 4 does not adsorb cyclopentate, showing a guest selectivity that, in addition to size, hydrogen-bonding capability is required for the guest molecule. The obtained compound is categorized as a member of a new generation of compounds tending towards functional porous coordination polymers.
机译：四种具有双轴斧形图案二维框架的多孔晶体配位聚合物，{[Co（NCS）_2（3-pia）_2]·2EtOH·11H_2O} _n（1a），{[Co（NCS） _2（3-pia）_2]·4Me_2CO} _n（3a），{[Co（NCS_2（3-pia））3]·4T HF} _n（3b）和{[Co（NCS）_2（3-pna） _2] _n}（5）是通过硫氰酸钴（II）与N-（3-吡啶基）烟酰胺（3--N）的N-（3-吡啶基）异烟酰胺（3-pia）反应合成的pna）。 X射线晶体学表征表明，相邻的层堆叠在一起，从而创建了通道（除了5中除外）。通道形成了用于客体分子的氢键键合内部。在实践中，1a包含乙醇和水分子作为具有氢键的通道中的客人，而3b（3a）包含四氢呋喃（丙酮）分子。在图1a中，相邻薄片中的“双刃斧形”图案没有位于彼此的顶部，而3b中的图案则完美地堆叠在一起，从而以边到边的方式彼此重叠。三维框架中的这种细微变化与来宾的模板效果相关。化合物5没有客体分子，因此，一张纸中的酰胺基用于氢键连接，而与相邻纸页的氢键连接。从1a和3b（3a）中除去客体分子会导致结构转换，并伴有颜色变化。粉红色1a无法保留其原始框架，而变成蓝色的无定形化合物。另一方面，粉红色3b（3a）的框架转换为紫罗兰色4的新晶体框架。有趣的是，当4b暴露于THF（或丙酮）蒸气时，4还原为3b（3a）的原始粉红色晶体。光谱测量（可见光，EPR和IR）为晶体到晶体的转化提供了线索。在除去客体时，酰胺基用于在薄片之间形成β薄片型氢键，因此骨架在除去客体分子时承受很大的应力。该机制归因于相邻薄片的布置，从而使β薄片类型的结构有效地规则地适合。脱辅基主体4不吸附环戊酸酯，显示出客体选择性，该客体选择性除了大小外，客体分子还需要氢键合能力。获得的化合物被归类为趋向于功能性多孔配位聚合物的新一代化合物的成员。

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