biostudies-literatureShen YJapan Society for the Promotion of Science LondonMEXT Quantum Leap Flagship Programe03057https://www.ebi.ac.uk/biostudies/studies/S-EPMC12759173biostudies-literatureUnknown32(1)Co(II)-based coordination polymer is reported as a new benchmark single-chain magnet (SCM), exhibiting an energy barrier (U_eff) of 560 K and a blocking temperature (T_B) of 21.5 K‒both the highest values observed for SCM systems. The magnetic behavior originates from the synergistic balance between strong axial anisotropy (D_Co = -83 cm^-1) and moderate ferromagnetic exchange (J_Co-Co = +17.7 K), promoting long-range spin correlation over thousands of magnetic ions. Detailed analysis of the correlation length and domain-wall energy reveals a wide SCM regime and a 1D-to-3D magnetic crossover at low temperature. Unlike previously reported radical-bridged SCMs, this work demonstrates a clean, intrinsic design strategy for realizing extreme single-chain magnetism, offering new principles for developing robust molecular spin materials.Chemistry (Weinheim an der Bergstrasse, Germany)Cobalt(II) Single-Chain Magnet With Strong Anisotropy and Ferromagnetic IntraChain Coupling.PMC12759173JP25H00866Ohkoshi SIStefanczyk OCui MOhtsu HShen YYamashita MfalseCobalt(II) Single-Chain Magnet With Strong Anisotropy and Ferromagnetic IntraChain Coupling.Co(II)-based coordination polymer is reported as a new benchmark single-chain magnet (SCM), exhibiting an energy barrier (U_eff) of 560 K and a blocking temperature (T_B) of 21.5 K‒both the highest values observed for SCM systems. The magnetic behavior originates from the synergistic balance between strong axial anisotropy (D_Co = -83 cm^-1) and moderate ferromagnetic exchange (J_Co-Co = +17.7 K), promoting long-range spin correlation over thousands of magnetic ions. Detailed analysis of the correlation length and domain-wall energy reveals a wide SCM regime and a 1D-to-3D magnetic crossover at low temperature. Unlike previously reported radical-bridged SCMs, this work demonstrates a clean, intrinsic design strategy for realizing extreme single-chain magnetism, offering new principles for developing robust molecular spin materials.2026-01-01T00:00:00Z2026 Jan2026-06-06T09:28:20.451Z2026-05-28T03:12:04.731ZS-EPMC127591734131653010.1002/chem.202503057