Diamagnetic\nCarrier-Doping-Induced Continuous Electronic\nand Magnetic Crossover in One-Dimensional Coordination Polymers

The\npotential to introduce tunable electrical conductivity and\nmolecular magnetism through carrier doping in metal–organic\ncoordination polymers is particularly promising for nanoelectronics\napplications. Precise control of the doping level is essential for\ndetermining the electronic and magnetic properties. In this study,\nwe present a series of one-dimensional coordination polymers, {(HNEt<sub>3</sub>)<sub>0.5</sub>[Cu<sub><i>x</i></sub>Co<sub>(1–<i>x</i>)</sub>(L)]}<i><sub>n</sub></i> (HNEt<sub>3</sub> = triethylammonium, L = 1,2,4,5-tetrakis(methanesulfonamido)benzene),\ndoped with diamagnetic Cu<sup>1+</sup> carriers. Through comprehensive\ncharacterization of the structural, optical, and magnetic properties,\nwe observed continuous electronic and magnetic crossover as the doping\nlevel was gradually increased. When <i>x</i> < 0.5, the\ndoped compounds exhibit ferromagnetic insulating behavior with very\nhigh energy barriers (<i>U</i><sub>eff</sub> up to 560 K)\nand excellent slow relaxation of magnetization. At <i>x</i> = 0.5, {(HNEt<sub>3</sub>)<sub>0.5</sub>[Cu<sub>0.5</sub>Co<sub>0.5</sub>(L)]}<i><sub>n</sub></i> functions as a paramagnetic\nsemiconductor at high temperatures and a single-molecule magnet at\nlow temperatures. When <i>x</i> > 0.5, the doped compounds\nact as diluted antiferromagnetic semiconductors with narrow band gaps\n(<i>E</i><sub>a</sub> = 0.2 eV). The emergence of such rich\nelectronic and magnetic crossovers is ascribed to the cooperation\nof the strong electron-donating ability of the ligand and the pronounced\ncrystal-field effects. Our findings indicate that one-dimensional\n(1D) coordination polymers are promising for the design of novel low-dimensional\nmagnetic semiconductors.