Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
Chemistry. 2010 Jan 18;16(3):907-18. doi: 10.1002/chem.200901484.
Novel macrocyclic receptors that bind electron-donor aromatic substrates through pi-stacking donor-acceptor interactions are obtained by cycloimidisation of an amine-functionalised aryl ether sulfone with pyromellitic and 1,4,5,8-naphthalenetetracarboxylic dianhydrides. These macrocycles can form complexes with a wide variety of pi-donor substrates, including tetrathiafulvalene, naphthalene, anthracene, pyrene, perylene and functional derivatives of these polycyclic hydrocarbons. The resulting supramolecular assemblies range from simple 1:1 complexes to [2]- and [3]pseudorotaxanes and even (as a result of crystallographic disorder) an apparent polyrotaxane. Direct five-component self-assembly of a metal-centred [3]pseudorotaxane is also observed on complexation of a macrocyclic ether imide with 8-hydroxyquinoline in the presence of palladium(II) ions. Binding studies in solution were carried out by using (1)H NMR and UV/Vis spectroscopy, and the stoichiometries of binding were confirmed by Job plots based on the charge-transfer absorption bands. The highest association constants were found for strong pi-donor guests with large surface areas, notably perylene and 1-hydroxypyrene, for which K(a) values of 1.4x10(3) and 2.3x10(3) M(-1), respectively, were found. Single-crystal X-ray analyses of the receptors and their derived complexes reveal large induced-fit distortions of the macrocyclic frameworks as a result of complexation. These structures provide compelling evidence for the existence of strong attractive forces between the electronically complementary aromatic pi systems of host and guest.
新型大环受体通过芳基醚砜的环亚胺化与均苯四甲酸二酐和 1,4,5,8-萘四羧酸二酐反应得到，可与各种π供体底物（包括四硫富瓦烯、萘、蒽、芘、苝和这些多环烃的功能衍生物）形成配合物。所得超分子组装物的范围从简单的 1:1 配合物到[2]-和[3]假轮烷，甚至（由于晶体结构无序）形成明显的聚轮烷。在钯（II）离子存在下，大环醚酰亚胺与 8-羟基喹啉络合时，也观察到金属中心[3]假轮烷的五元组分自组装。通过使用（1）H NMR 和 UV/Vis 光谱进行溶液中的结合研究，并基于电荷转移吸收带的 Job 图确认结合的化学计量。发现对于具有大表面积的强π供体客体，结合常数最高，特别是苝和 1-羟基芘，其 K(a)值分别为 1.4x10(3)和 2.3x10(3) M(-1)。受体及其衍生配合物的单晶 X 射线分析表明，大环骨架由于络合而发生了大的诱导契合变形。这些结构为主体和客体之间存在互补的电子芳香π体系之间存在强吸引力提供了有力的证据。
