Variable Conformation of Benzophenone in a Series of Resorcinarene-Based Supramolecular Frameworks

Ten supramolecular complexes incorporating benzophenone (BZP) as a guest have been synthesized
by hydrothermal and conventional methods and characterized by X-ray diffraction. They are CMCR·3bipy·2H2O·BZP (CMCR = C-methylcalix[4]resorcinarene; bipy = 4,4‘-bipyridine) 1, CMCR·bipy·BZP·H2O 2, CMCR·2bpe·BZP
(bpe = trans-1,4-bis(pyridyl)ethylene) 3, CMCR·2bpmh·BZP (bpmh = bis-(1-pyridin-4-yl-methylidene)-hydrazine)
4, CMCR·2bpeh·BZP·ethanol (bpeh = bis-(1-pyridin-4-yl-ethylidene)-hydrazine) 5, CMCR·2bipy·BZP 6, CECR·2bipy·BZP·0.5bipy (CECR = C-ethylcalix[4]resorcinarene) 7, CECR·2bpe·0.5BZP·0.5ethanol 8, CMCR·2bix·2BZP (bix =
1,4-bis(imidazol-1yl-methyl)benzene) 9, and CECR·2bix·2BZP 10. The resorcinarene molecule adopts a chair
conformation in 1, giving rise to a 3D stepped network. Compounds 2 and 3 have a brick-wall structure with boat-shaped CMCR but different spacer connectivity. A 3D 3-fold interpenetrating network exists in compound 4, whereas
a wavelike framework is found in 5. Crystals of 6, 7, and 8 contain carcerand-like capsules. The use of a more rigid
spacer generates 9 and 10, which exhibit a double buckled framework with large channels. The 10 phases contain
12 independent benzophenone molecules (9 and 10 each having two independent benzophenone molecules), eight of
which are fully ordered within the supramolecular framework. Benzophenone occurs as a monomer in 1, 5, 8 and
as a dimer in 2, 3, 4, 6, and 7, while polymeric aggregates are found in 9 and 10. The dihedral angles between the
two phenyl rings of benzophenone vary from 42.0 to 67.9°, and correlate with the central C−C−C bond angles,
which decrease with increasing dihedral angle. Quantum-mechanical calculations indicate the energy of the distortion
imposed by the framework to range up to 32 kJ/mol, which is significant relative to the ∼85 kJ/mol lattice energy
of the known neat benzophenone phases.

本数据集报道了10种以二苯甲酮（benzophenone, BZP）为客体的超分子配合物，通过水热法与常规合成法制备，并经X射线衍射表征。具体配合物如下：1为CMCR·3bipy·2H₂O·BZP（其中CMCR为C-甲基杯[4]间苯二酚芳烃，bipy为4,4'-联吡啶）、2为CMCR·bipy·BZP·H₂O、3为CMCR·2bpe·BZP（bpe为反式-1,4-二(吡啶基)乙烯）、4为CMCR·2bpmh·BZP（bpmh为双(1-吡啶-4-基亚甲基)肼）、5为CMCR·2bpeh·BZP·乙醇（bpeh为双(1-吡啶-4-基亚乙基)肼）、6为CMCR·2bipy·BZP、7为CECR·2bipy·BZP·0.5bipy（CECR为C-乙基杯[4]间苯二酚芳烃）、8为CECR·2bpe·0.5BZP·0.5乙醇、9为CMCR·2bix·2BZP（bix为1,4-二(咪唑-1-基甲基)苯）、10为CECR·2bix·2BZP。

配合物1中的间苯二酚芳烃分子采取椅式构象，形成三维阶梯状网络。配合物2与3均以船型CMCR构建砖墙结构，但二者连接基的连接模式存在差异。配合物4呈现三维三重互穿网络结构，而配合物5则为波浪状骨架。配合物6、7与8的晶体中存在类穴状胶囊结构。采用刚性连接基合成的配合物9与10展现出带有大孔道的双褶皱骨架。

10种配合物中共包含12个独立的二苯甲酮分子（配合物9与10各含2个独立二苯甲酮分子），其中8个在超分子骨架中完全有序。二苯甲酮在配合物1、5、8中以单体形式存在，在2、3、4、6、7中以二聚体形式存在，而在9与10中则以聚合物聚集体形式存在。二苯甲酮两个苯环之间的二面角范围为42.0°至67.9°，且与中心C-C-C键角相关联，键角随二面角增大而减小。量子力学计算结果表明，骨架引入的畸变能最高可达32 kJ/mol，相较于已知纯二苯甲酮相约85 kJ/mol的晶格能，该畸变能具有显著影响。