Mechanical force can trigger the predictable and precise release of small molecules from macromolecular carriers. In this article, based on mechanochemical simulations, we show that norborn-2-en-7-one (NEO), I, and its derivatives can selectively release CO, N₂, and SO₂ and produce two distinctly different products, A ((3E,5Z,7E)-dimethyl-5,6-diphenyldeca-3,5,7-triene-1,10-diyl bis(2-bromo-2-methylpropanoate)) and B (4′,5′-dimethyl-4′,5′-dihydro-[1,1′:2′,1’’-terphenyl]-3′,6′-diyl)bis(ethane-2,1-diyl) bis(2-bromo-2-methylpropanoate). Site-specific design in the pulling points (PP) ensures that by changing the regioselectivity, either A or B can be exclusively generated. Controlling the rigidity of the NEO scaffold by replacing a 6-membered ring with an 8-membered ring and concomitantly tuning the pulling groups makes it mechanolabile toward the selective formation of B. The diradical intermediate formed during I → A is predicted to be persistent for ∼150 fs. The structural design holds the key to the trade-off between mechanochemical rigidity and lability.

中文翻译：

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设计小分子机械化学货物释放的位点特异性

机械力可以触发小分子从大分子载体上可预测且精确的释放。在本文中，基于机械化学模拟，我们表明norborn-2-en-7-one (NEO)、I及其衍生物可以选择性地释放CO、N ₂和SO ₂并产生两种截然不同的产物，A ( (3 E ,5 Z ,7 E )-二甲基-5,6-二苯基十-3,5,7-三烯-1,10-二基双(2-溴-2-甲基丙酸酯))和B(4',5'-二甲基-4',5'-二氢-[1,1':2',1''-三联苯]-3',6'-二基)双(乙烷-2,1-二基) )双(2-溴-2-甲基丙酸酯)。拉点 (PP) 中的位点特定设计确保通过改变区域选择性，可以专门生成A或B。通过用 8 元环替换 6 元环并同时调整牵引基团来控制 NEO 支架的刚性，使其具有机械稳定性，可选择性形成B。I → A过程中形成的双自由基中间体预计将持续~150 fs。结构设计是机械化学刚性和不稳定性之间权衡的关键。