Chen Jiawei, Zhang Qi, Chen Tao, Zheng Zeyu, Song Yuhang, Liu Huichong, Chen Ziqiao, Wang Jing, Wang Haoshang, Sun Huijun, Wang Xinchang, Chen Zhong, Wang Cheng, Tian Zhongqun
State Key Laboratory of Physical Chemistry of Solid Surfaces, School of Electronic Science and Engineering, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China.
Natl Sci Rev. 2024 Nov 13;12(1):nwae406. doi: 10.1093/nsr/nwae406. eCollection 2025 Jan.
Heterogeneous catalysts for parahydrogen-induced polarization (HET-PHIP) would be useful for producing highly sensitive contrasting agents for magnetic resonance imaging (MRI) in the liquid phase, as they can be removed by simple filtration. Although homogeneous hydrogenation catalysts are highly efficient for PHIP, their sensitivity decreases when anchored on porous supports due to slow substrate diffusion to the active sites and rapid depolarization within the channels. To address this challenge, we explored 2D metal-organic layers (MOLs) as supports for active Rh complexes with diverse phosphine ligands and tunable hydrogenation activities, taking advantage of the accessible active sites and chemical adaptability of the MOLs. By adjusting the electronic properties of phosphines, TPP-MOL-Rh-dppb (TPP = tris(4-carboxylphenyl)phosphine), featuring a -connected di(phosphine) ligand, generated hyperpolarized styrene achieving an over-2400-fold signal enhancement and a polarization level of 20% for H in methanol- solution. The TPP-MOL-Rh-dppb effectively inherited the high efficiency and pairwise addition of its homogenous catalyst while maintaining the heterogeneity of MOLs. This work demonstrates the potential of 2D phosphine-functionalized MOLs as heterogeneous solid support for HET-PHIP.
用于仲氢诱导极化的多相催化剂（HET-PHIP）可用于制备用于液相磁共振成像（MRI）的高灵敏度造影剂，因为它们可以通过简单过滤去除。尽管均相氢化催化剂对PHIP具有很高的效率，但由于底物向活性位点的扩散缓慢以及通道内的快速去极化，当它们固定在多孔载体上时，其灵敏度会降低。为了应对这一挑战，我们利用二维金属有机层（MOL）可及的活性位点和化学适应性，探索将其作为具有不同膦配体和可调氢化活性的活性Rh配合物的载体。通过调节膦的电子性质，具有σ-连接的二（膦）配体的TPP-MOL-Rh-dppb（TPP = 三（4-羧基苯基）膦）在甲醇-d溶液中生成了超极化苯乙烯，实现了超过2400倍的信号增强和H的20%极化水平。TPP-MOL-Rh-dppb有效地继承了其均相催化剂的高效率和成对加成特性，同时保持了MOL的多相性。这项工作证明了二维膦功能化MOL作为HET-PHIP的多相固体载体的潜力。
