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首页> 外文期刊>Crystal growth & design >Weakly bonded molecular networks built from tetranitro- and tetracyanospirobifluorenes
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Weakly bonded molecular networks built from tetranitro- and tetracyanospirobifluorenes

机译：由四硝基和四氰基螺双芴构建的弱键合分子网络

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Three tetranitro and three tetracyano derivatives of 9,9'-spirobifluorene were synthesized and crystallized, and their structures were determined by X-ray crystallography. 2,2',7,7'-Tetranitro-9,9'-spirobi[9H-fluorene] (4) self-associates via C-H••• O interactions to give an open supramolecular network, with 31% of the total volume of the crystal available for including guests. Tetracyano analogue 5 also crystallizes to give a porous network, but no significant C-H••• N interactions are present; instead, molecular association is directed primarily by π-stacking. An extended tetranitro analogue, 2,2', 7,7'-tetrakis(4-nitrophenyl)-9,9'-spirobi [9H-fluorene] (6), crystallizes as a nearly close-packed structure held together by a combination of C-H••• O interactions and π-stacking. Tetracyano analogue 7 crystallizes to form an open structure maintained by π-stacking, without significant C-H••• N contacts. Extended meta-substituted analogues, 2,2',7,7'-tetrakis(3-nitrophenyl)-9,9'-spirobi[9H-fluorene] (8) and 2,2',7,7'-tetrakis(3-cyanophenyl)-9,9'-spirobi[9H-fluorene] (9), were also synthesized and crystallized. The two structures are closely similar and show close-packed architectures involving mainly π-stacking. Together, these observations suggest that cyano groups are not effective acceptors for the formation of C-H••• N interactions strong enough to direct molecular association in competition with aryl-aryl interactions, at least in the spirobifluorene system. In contrast, nitro groups can be used to help direct association via C-H••• O interactions, either in competition with or in cooperation with other weak interactions.
机译：合成并结晶了9,9'-螺二芴的三个四硝基和三个四氰基衍生物，并通过X射线晶体学确定了它们的结构。 2,2'，7,7'-四硝基-9,9'-螺双[9H-芴]（4）通过C-H＆BULL;＆BULL;＆BULL;自缔合O相互作用形成一个开放的超分子网络，其中31％的晶体可供客人使用。 Tetracyano类似物5也会结晶形成多孔网络，但没有明显的C-H＆BULL;＆BULL;＆BULL;。存在N个交互;取而代之的是，分子缔合主要由π堆积指导。扩展的四硝基类似物2,2'，7,7'-四（4-硝基苯基）-9,9'-spirobi [9H-芴]（6）结晶为几乎紧密堆积的结构，通过结合在一起的C-H＆BULL;＆BULL;＆BULL; O相互作用和π堆积。 Tetracyano类似物7结晶形成一个通过π堆叠保持的开放结构，而没有明显的C-H＆BULL;＆BULL;＆BULL; N个联系人。扩展的间位取代类似物2,2'，7,7'-四（3-硝基苯基）-9,9'-spirobi [9H-芴]（8）和2,2'，7,7'-四（还合成并结晶了3-氰基苯基）-9，9'-螺双[9H-芴]（9）。这两个结构非常相似，显示出主要涉及π堆栈的紧凑结构。总之，这些观察结果表明氰基不是形成C-H＆BULL;＆BULL;＆BULL;的有效受体。 N相互作用足够强，至少在螺二芴系统中，足以指导分子缔合与芳基-芳基相互作用。相反，硝基可用于帮助通过C-H＆BULL;＆BULL;＆BULL;进行直接缔合。 O交互，与其他弱交互竞争或合作。

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