Multifunctional Properties of a 1D Helical Co(II) Coordination Polymer: Toward Single-Ion Magnetic Behavior and Efficient Dye Degradation

This contribution deals with the synthesis and utilization of a new pyrazole-based unsymmetrical ligand, 3-(3-carboxyphenyl)-1 H -pyrazole-5-carboxylic acid (H 2 CPCA), for generating multifunctional materials. The reaction with the Co(II) salt in the presence of a co-ligand 2,9-dimethyl phenanthroline (dmphen) results in the formation of the helical compound {[Co 2 (dmphen) 2 (CPCA) 2 ]DMF} n ( 1 ). However, two isostructural monomeric complexes are formed {[M(HCPCA) 2 (H 2 O) 2 ], M = Co(II), ( 2 ) and Mn(II) ( 3 )} when reactions were carried out in the absence of dmphen. Compound 1 shows some highly encouraging single-ion magnetic (SIM) properties. Detailed magnetic studies unveil slow relaxation of magnetization of compound 1 , driven by the higher magnetic anisotropy of the cobalt ion, with the energy barrier of ∼9.2 K and relaxation time of 9.1 × 10 -5 s, suggesting a SIM behavior. Moreover, UV-vis and fluorescence studies confirm the selective dye degradation of compound 1 with methylene blue both in the presence and absence of H 2 O 2 , with the remarkable degradation efficiency of ∼98 and ∼82%, respectively.