Institute of Advanced Materials, Centro de Innovación en Química Avanzada, Universitat Jaume I, Avenida Vicente Sos Baynat s/n, Castellón E-12071, Spain.
Inorg Chem. 2023 Feb 6;62(5):1820-1826. doi: 10.1021/acs.inorgchem.2c00677. Epub 2022 Apr 1.
Two different metallotweezers, each with two pyrene-imidazolylidene-gold(I) arms, were used as hosts for a series of planar aromatic guests. The metallotweezer with a dibenzoacridinebis(alkynyl) spacer () orients the two pyrene-imidazolylidene-gold(I) arms in a parallel disposition, with an interpanel distance of about 7 Å. The second metallotweezer () contains a carbazolylbis(alkynyl) spacer that directs the two pyrene panels in a diverging orientation. Determination of the association constants via H NMR titrations demonstrates that the binding strength shown by is significantly larger than that found by , with binding affinities as large as 10 M (in CDCl), for the encapsulation of ,'-dimethylnaphthalenetetracarboxydiimide with . The differences in the binding affinities are due to binding models associated with formation of the related host-guest complexes. While operates via a "lock and key" model, in which the host does not suffer distortions upon formation of the inclusion complex, operates via a guest-induced fit model. The large association constants shown by with two planar guests were used for promotion of the template-directed synthesis of , which in the absence of an external template is produced in an equimolecular mixture with its self-aggregated congener, clippane []. This observation strongly suggests that the mechanically interlocked clippane is formed through a self-template-directed mechanism, while bonds are broken/formed during the synthetic protocol.
两种不同的金属钳，每个都有两个苝-咪唑基-金（I）臂，被用作一系列平面芳香客体的主体。带有二苯并吖啶双（炔基）间隔基（）的金属钳将两个苝-咪唑基-金（I）臂定向为平行排列，间隔距离约为 7 Å。第二个金属钳（）含有咔唑基双（炔基）间隔基，将两个苝基面板定向为发散方向。通过 1 H NMR 滴定法测定结合常数表明，与 相比， 表现出的结合强度明显更大，与 结合亲和力高达 10 M（在 CDCl 中），用于包封 - 二甲基萘四羧酸二酰亚胺与 。结合亲和力的差异归因于与形成相关主体-客体配合物相关的结合模型。虽然 采用“锁和钥匙”模型，其中主体在形成包含配合物时不受扭曲，但 采用客体诱导适应模型。 与两个平面客体表现出的大结合常数被用于促进模板导向合成，在没有外部模板的情况下，它以等摩尔混合物的形式与自身聚集的同类物 clippane []产生。这一观察结果强烈表明，机械互锁的 clippane 通过自模板导向机制形成，而在合成方案中会发生键的断裂/形成。
