Kobayashi Kenji, Ishii Kei, Sakamoto Shigeru, Shirasaka Toshiaki, Yamaguchi Kentaro
Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
J Am Chem Soc. 2003 Sep 3;125(35):10615-24. doi: 10.1021/ja035337q.
The guest- or solvent-induced assembly of a tetracarboxyl-cavitand 1 and a tetra(3-pyridyl)-cavitand 2 into a heterodimeric capsule 1.2 in a rim-to-rim fashion via four intermolecular CO(2)H.N hydrogen bonds has been investigated both in solution and in the solid state. In the (1)H NMR study, a 1:1 mixture of1a and 2a (R = (CH(2))(6)CH(3)) in CDCl(3) gave a mixture of various complicated aggregates, whereas this mixture in CDCl(2)CDCl(2) or p-xylene-d(10) exclusively produced the heterodimeric capsule 1a.2a. It was found that an appropriate 1,4-disubstituted-benzene is a suitable guest for inducing the exclusive formation of 1a.2a in CDCl(3). The ability of a guest to induce the formation of guest-encapsulating heterodimeric capsule, guest@(1a.2a), increased in the order p-ethyltoluene < 1-ethyl-4-methoxybenzene < or = 1-ethyl-4-iodobenzene < or = 1,4-dibromobenzene < 1-iodo-4-methoxybenzene < or= 1,4-dimethoxybenzene < or = 1,4-diiodobenzene. The (1)H NMR study revealed that a CH-halogen interaction between the inner protons of the methylene-bridge rims (-O-H(out)CH(in)-O-) of the 1a and 2a units and the halogen atoms of 1,4-dihalobenzenes and a CH-pi interaction between the methoxy protons of 1,4-dimethoxybenzene and the aromatic cavities of the 1a and 2a units play important roles in the formation of 1,4-dihalobenzene@(1a.2a) and 1,4-dimethoxybenzene@(1a.2a), respectively. A preliminary single-crystal X-ray diffraction analysis of guest@(1b.2b) (R = (CH(2))(2)Ph; guest = 1-iodo-4-methoxybenzene or p-xylene) confirmed that the guest encapsulated in 1b.2b is oriented with the long axis of the guest along the long axis of 1b.2b and that the iodo and the methoxy groups of the encapsulated 1-iodo-4-methoxybenzene are specifically oriented with respect to the cavities of the 2b and 1b units, respectively.
已对四羧基穴状配体1和四（3-吡啶基）穴状配体2通过四个分子间CO₂H…N氢键以边对边方式组装成异二聚体胶囊1·2的过程进行了溶液和固态研究。在¹H NMR研究中，1a和2a（R = (CH₂)₆CH₃）在CDCl₃中的1:1混合物产生了各种复杂聚集体的混合物，而该混合物在CDCl₂CDCl₂或对二甲苯-d₁₀中仅生成异二聚体胶囊1a·2a。发现合适的1,4-二取代苯是在CDCl₃中诱导专一形成1a·2a的合适客体。客体诱导形成客体包封的异二聚体胶囊guest@(1a·2a)的能力按以下顺序增加：对乙基甲苯＜1-乙基-4-甲氧基苯＜或 = 1-乙基-4-碘苯＜或 = 1,4-二溴苯＜1-碘-4-甲氧基苯＜或 = 1,4-二甲氧基苯＜或 = 1,4-二碘苯。¹H NMR研究表明，1a和2a单元的亚甲基桥边缘（-O-H(out)CH(in)-O-）的内部质子与1,4-二卤代苯的卤原子之间的CH-卤素相互作用以及1,4-二甲氧基苯的甲氧基质子与1a和2a单元的芳香腔之间的CH-π相互作用分别在1,4-二卤代苯@(1a·2a)和1,4-二甲氧基苯@(1a·2a)的形成中起重要作用。对guest@(1b·2b)（R = (CH₂)₂Ph；客体 = 1-碘-4-甲氧基苯或对二甲苯）的初步单晶X射线衍射分析证实，封装在1b·2b中的客体的长轴沿1b·2b的长轴取向，并且封装的1-碘-4-甲氧基苯的碘和甲氧基分别相对于2b和1b单元的腔具有特定的取向。
