Absorption induced modulation of magnetism in two-dimensional metal-phthalocyanine porous sheets

Metal-phthalocyanine porous sheets have uniformly dispersed metal sites in Pc framework, making absorption happen naturally. Here, we explore the effects of absorption of chlorine atoms on magnetism in transition metal embedded phthalocyanine (poly-TMPc) sheets with TM = Cr, Mn, and Fe. We show that when one Cl is absorbed on the TM, the strong square planar crystal field becomes weak in a square pyramidal configuration and the TM is in the +3 oxidized state, resulting in the magnetic moment of 3, 4, and 5 μ_B for Cr, Mn, and Fe, respectively, with weak antiferromagnetic couplings. When another Cl is introduced to the TM on the other side, it extracts one electron from the Pc framework making the substrate p-doped. The magnetic coupling is antiferromagnetic for poly-CrPc-2Cl and the poly-FePc-2Cl, while it becomes ferromagnetic for poly-MnPc-2Cl, suggesting that absorption can effectively modulate the bonding environment and tune the magnetic properties of the systems, and the controlled absorption can be used to tailor materials.