Nanohoops, an exciting class of fluorophores with supramolecular binding abilities, have the potential to become innovative tools within biological imaging and sensing. Given the biological importance of cell membranes, incorporation of macrocyclic materials with the dual capability of fluorescence emission and supramolecular complexation would be particularly interesting. A series of different-sized nanohoops—ethylene glycol-decorated [n]cyclo-para-pyrenylenes (CPYs) (n = 4–8)—were synthesised via an alternate synthetic route which implements a stannylation-based precursor, producing purer material than the previous borylation approach, enabling the growth of single-crystals of the Pt-macrocycle. Reductive elimination of these single-crystals achieved significantly higher selectivity and yields towards smaller ring-sized nanohoops (n = 4–6). The supramolecular binding capabilities of these CPYs were then explored through host–guest studies with a series of polycyclic (aromatic)hydrocarbons, revealing the importance of molecular size, shape, and CH–π contacts for efficient binding. CPYs were incorporated within the hydrophobic layer of lipid bilayer membranes, as confirmed by microscopic imaging and emission spectroscopy, which also demonstrated the size-preferential incorporation of the five-fold nanohoop. Molecular dynamics simulations revealed the position and orientation within the membrane, as well as the unique non-covalent threading interaction between nanohoop and phospholipid.

中文翻译：

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膜中的纳米环：磷脂双层膜内的有限超分子空间


纳米环是一类令人兴奋的具有超分子结合能力的荧光团，有潜力成为生物成像和传感领域的创新工具。考虑到细胞膜的生物学重要性，具有荧光发射和超分子络合双重能力的大环材料的结合将特别令人感兴趣。通过采用基于甲锡烷基化的前体的替代合成路线合成了一系列不同尺寸的纳米环——乙二醇修饰的[ n ]环对-芘基（CPY）（ n = 4-8），从而产生比之前的硼化方法，能够生长 Pt 大环单晶。这些单晶的还原消除实现了显着更高的选择性和较小环尺寸纳米环的产率（ n = 4-6）。然后通过一系列多环（芳香）烃的主客体研究探索了这些 CPY 的超分子结合能力，揭示了分子大小、形状和 CH-π 接触对于有效结合的重要性。通过显微成像和发射光谱证实，CPY 被掺入脂质双层膜的疏水层内，这也证明了五倍纳米环的尺寸优先掺入。分子动力学模拟揭示了膜内的位置和方向，以及纳米环和磷脂之间独特的非共价螺纹相互作用。