Improving the potential of paraCEST through magnetic-coupling induced line sharpening

Xin Guo; Lei Zhang; Jiesheng Hu; Balázs Szilágyi; Meng Yu; Shizhen Chen; Gyula Tircsó; Xin Zhou; Jun Tao

doi:10.1039/d3sc04770a

Improving the potential of paraCEST through magnetic-coupling induced line sharpening

Chem Sci. 2023 Nov 21;14(48):14157-14165. doi: 10.1039/d3sc04770a. eCollection 2023 Dec 13.

Authors

Xin Guo¹, Lei Zhang^{2

3}, Jiesheng Hu¹, Balázs Szilágyi^{4

5}, Meng Yu¹, Shizhen Chen^{2

3}, Gyula Tircsó⁴, Xin Zhou^{2

3}, Jun Tao¹

Affiliations

¹ Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology Beijing 102488 China mengyu@bit.edu.cn taojun@bit.edu.cn.
² State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan National Laboratory for Optoelectronics Wuhan 430071 China chenshizhen@wipm.ac.cn.
³ University of Chinese Academy of Sciences Beijing 100049 China.
⁴ Department of Physical Chemistry, Faculty of Science and Technology, University of Debrecen Egyetem tér 1 H-4032 Debrecen Hungary.
⁵ Doctoral School of Chemistry, University of Debrecen Egyetem tér 1 H-4032 Debrecen Hungary.

Abstract

Magnetic coupling between paramagnetic centers is a crucial phenomenon in the design of efficient MRI contrast agents. In this study, we investigate the paraCEST properties and magnetic coupling effects of a novel homodinuclear Ni(ii) complex, 1, containing a Robson type macrocyclic ligand. A thorough analysis of the complex's electronic and magnetic properties revealed that the magnetic coupling effect reduces the transverse relaxation rate and enhances the sharpness of the proton resonances, leading to enhanced CEST efficiency. This novel mechanism, which we coined "magnetic-coupling induced line sharpening" (MILS), can be crucial for optimizing the performance of paramagnetic metal complexes in paraCEST imaging. Moreover, magnetic coupling plays a critical role in the relaxation properties of homodinuclear complexes. Our study not only paves the way for the creation of advanced paraCEST agents with enhanced CEST capabilities and sensitivity but also provides valuable guidance for the design of other MRI contrast agents utilizing dinuclear metal complexes.