Molecular Recognition and Catalytic Functions of Novel Macrocyclic Compounds

我们制备了一种以l -天冬氨酸残基为连接单元的章鱼环烷，其连接单元介于一个大环和四个双链烃段之间。这种阳离子寄主强烈结合阴离子和非离子疏水客体，并行使源于疏水和静电相互作用的诱导配合客体结合行为。我们还制备了具有三个邻苯二酚基团和六个烃链的六爪环烷，前者作为金属结合位点。研究了六爪环烷铁配合物在水中的包合行为。当环烷的儿茶酚段与Fe^<3+>配位时，疏水客体的结合常数比没有金属配位的六柱环烷的结合常数大。由于疏水、静电和配位效应，金属结合六爪环烷对有机客体表现出明显的包合能力。维生素B_<12>依赖酶催化多种异构化反应，并伴有碳骨架重排。为了模拟维生素B_<12>依赖酶的催化功能，我们研究了疏水性维生素B_<12>衍生物。我们成功构建了以章鱼环烷为脱酶模型和疏水性维生素B_<12>为辅酶模型的人工维生素B_<12>依赖全酶。章鱼环烷作为一种有效的脱酶模型，通过将吡哆醛-5′-磷酸和疏水烷基铵底物同时加入宿主空体中，形成人工维生素b_6依赖性全酶，从而获得希夫碱，显示出底物的选择性。我们制备了另一种结构特征的环烷；一种笼型立方体分子，具有六个面，每个面由2,11,20,29 -四氮[3.3.3.3]副环环环组成。该寄主具有8个叔胺基，在酸性介质中作为多阳离子寄主。宿主表现出大小敏感和区域选择性的分子识别。第二笼型环烷由两个大环骨架1,6,20,25 -tetraaza[6.1.6.1]组成。[2, 11, 20, 29-四aza][3.3.3.3]副环环烷段。这种阳离子宿主将阴离子和非离子疏水荧光客体纳入其内腔，并对水介质中选定的氨基酸进行了明显的手性识别。少

We prepared an octopus cyclophanes having L-aspartate residues as connector units interposed between a macrocyclic ring and four double-chain hydrocarbon segments. This cationic host strongly binds anionic and nonionic hydrophobic guests and exercises the induced-fit guest-binding behavior originating from both hydrophobic and electrostatic interactions. We also prepared a hexapus cyclophane having three catechol moieties and six hydrocarbon chains, the former acting as the metal binding sites. The inclusion behavior of a Fe-complex of the hexapus cyclophane was examined in water. When the catechol segments of the cyclophane are coordinated to Fe^<3+>, the binding constant for hydrophobic guests becomes larger than that of the hexapus cyclophane without metal coordination. The present metal-bound hexapus cyclopahne exhibits marked inclusion capability toward organic guests, as arising from hydrophobic, electrostatic, and coordination effects. Vitamin B_<12>-dependent enzymes catalyze v … More arious isomerization reactions accompanied with carbon-skeleton rearrangements. In order to simulate catalytic functions of vitamin B_<12>-dependent enzymes, we have been dealing with hydrophobic vitamin B_<12> derivatives. We succeeded in constructing an artificial vitamin B_<12>-dependent holoenzyme composed of an octopus cyclophane as an apoenzyme model and hydrophobic vitamin B_<12> as a coenzyme model. The octopus cyclophane acts as an effective apoenzyme model for constitution of an artificial vitamin B_6-dependent holoenzyme by simultaneous incorporation of pyridoxal-5'-phosphate and a hydrophobic alkylammonium substrate into the host cavity to give the Schiff-base species, showing the substrate selectivity.We prepared cyclophanes of another structural feature ; a cage-type cubical molecule with six faces each consisting of a 2, 11, 20, 29-tetraaza[3.3.3.3] paracyclophane ring. This host possesses eight tertiary aminomoieties and acts as a polycationic host in acidic media. The host shows size-sensitive and regioselective molecular discrimination. The second cage-type cyclophane is composed of two macrocyclicskeletons, 1, 6, 20, 25-tetraaza[6.1.6.1.] paracyclophane 2, 11, 20, 29-tetraaza[3.3.3.3] paracyclophane segments. This cationic host incorporates anionic and nonionic hydrophobic fluorescent guests into its in ternal cavityand exercises marked chiral discrimination toward selected amino acids in aqueous media. Less