engleski

3D Oxalate-Based Coordination Polymers: Relationship between Structure, Magnetism and Color, studied by High-Field ESR Spectroscopy

The detailed high field electron spin resonance (HF-ESR) study of three 3D oxalate-based coordination polymers with antiferromagnetic ordering below 13 K, supported by crystallographic, photoluminescence (PL), elemental (EDX) and X-band ESR analysis, is presented. Two of the investigated compounds are described by the same chemical formula [[Cu(bpy)3][Mn2(C2O4)3]H2O]n, both exhibit PL but have different colors: green-blue and red-pink (CuMn2-Green and CuMn2-Red, respectively) while third compound [[Co(bpy)3][Mn2(C2O4)3]H2O]n is yellow (CoMn2-Yellow) without PL. Despite different colors of CuMn2-Green and CuMn2-Red, X-ray diffraction, EDX, as well as X-band ESR, could not reveal any difference between these compounds. Therefore, detailed temperature dependent multifrequency HF-ESR experiments were performed. Owing to very high resolution of HF-ESR, two different Mn(II) centers in CuMn2-Green and CoMn2-Yellow compounds could be resolved, while in CuMn2-Red only one Mn(II) center is detected. A possible difference in the ligand coordination of Mn(II) ions in the oxalate-networks of CuMn2-Green and CuMn2-Red, that gives rise to slightly different g-factors, is discussed with respect to the different colors of these compounds.

ESR ; High field ; High frequency ; Coordination polymer ; Mn(II)

nije evidentirano