Burke David W, Yamashita Masataka, Wang Zaoming, Kuzumoto Mako, Urayama Kenji, Saito Kei, Furukawa Shuhei
Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University Yoshida, Sakyo-ku Kyoto 606-8501 Japan
Department of Material Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku Kyoto 615-8510 Japan.
Chem Sci. 2025 Apr 3;16(19):8509-8522. doi: 10.1039/d5sc00535c. eCollection 2025 May 14.
Polymer-based soft materials constructed from defined molecular pores, such as metal-organic polyhedra (MOPs), promise to merge the outstanding and diverse mechanical properties of conventional nonporous polymers with atomically-precise molecular recognition capabilities. Thus far, soft MOP networks have been constructed primarily using rigid, labile coordination bonds or dynamic covalent bonds, providing static networks without intrinsic mechanisms to optimize their response to mechanical stimuli. Here, we report the construction of flexible, doubly crosslinked MOP gels mutually compatible coordination and covalent polymerization techniques. Our method employs dirhodium paddlewheel-based MOPs bearing both open metal sites, which enable their coordination-driven assembly, and photodimerizable coumarin side chains for covalent polymerization (Coumarin-RhMOPs). Incubation of Coumarin-RhMOPs with ditopic linkers enabled their coordination-driven polymerization into porous colloidal gels. Site-selective irradiation of coordination-linked Coumarin-RhMOP gels afforded doubly crosslinked gels with improved strain tolerance and higher stiffness. Selective dissociation of coordination-crosslinkers provided highly deformable covalent Coumarin-RhMOP gels. The postsynthetic addition of ditopic ligands to covalent gels enabled the reversible modulation of their mechanical properties. These findings highlight the possibility of incorporating multiple responsive crosslinks in porous MOP networks to rationally tune their responses to mechanical stress, paving the way to their practical implementation as next-generation chemical separators, catalysts, and drug delivery vehicles.
由定义明确的分子孔隙构建的聚合物基软材料，如金属有机多面体（MOPs），有望将传统无孔聚合物出色且多样的机械性能与原子精确的分子识别能力相结合。到目前为止，软质MOP网络主要是使用刚性、不稳定的配位键或动态共价键构建的，提供的是静态网络，没有内在机制来优化其对机械刺激的响应。在这里，我们报告了使用相互兼容的配位和共价聚合技术构建柔性、双交联MOP凝胶的方法。我们的方法采用基于双铑桨轮的MOPs，其兼具开放金属位点，可实现配位驱动组装，以及用于共价聚合的可光二聚化香豆素侧链（香豆素-RhMOPs）。将香豆素-RhMOPs与双官能连接体孵育，可使其通过配位驱动聚合成多孔胶体凝胶。对配位连接的香豆素-RhMOP凝胶进行位点选择性辐照，可得到具有更高应变耐受性和更高刚度的双交联凝胶。配位交联剂的选择性解离可提供高度可变形的共价香豆素-RhMOP凝胶。在共价凝胶上进行后合成添加双官能配体，可实现其机械性能的可逆调节。这些发现突出了在多孔MOP网络中纳入多个响应性交联以合理调节其对机械应力响应的可能性，为其作为下一代化学分离器、催化剂和药物递送载体的实际应用铺平了道路。
