Studies on two coordination polymers [M(μ4-pz25dc)]n (M = Cd or Zn, pz25dc = pyrazine-2,5-dicarboxylato) with three-dimensional pillared-layer three-nodal framework: Synthesis, structural characterization, strong optical non-linearities and optical limiting properties

Two isomorphous new candidates [M(μ₄-pz25dc)]_n (M = Cd, 1; Zn, 2; pz25dc = pyrazine-2,5-dicarboxylato) for nonlinear optical (NLO) materials have been synthesized hydrothermally and characterized crystallographically as pillared-layer three-nodal frameworks with one four-connected metal nodes and two crystallographically different four-connected ligand nodes. Their optical non-linearities are measured by the z-Scan technique with an 8 ns pulsed laser at 532 nm. These two coordination polymers both exhibit strong NLO absorptive abilities [α₂ = (63 ± 6) × 10⁻¹² m W⁻¹1, (46 ± 6) × 10⁻¹¹ m W⁻¹2] and effective self-focusing performance [n₂ = (67 ± 5) × 10⁻¹⁸1, (13 ± 3) × 10⁻¹⁸ m² W⁻¹2] in 1.02 × 10⁻⁴1 and 1.05 × 10⁻⁴ mol dm⁻³2 DMF solution separately. The values of the limiting threshold are also measured from the optical limiting experimental data. The heavy atom effect plays important role in the enhancement of optical non-linearities and optical limiting properties.     

Metal–radical complexes [M(NITm-Py)2(N3)2(DMSO)2] [M = Cu(II), Ni(II), Co(II)]: Syntheses,crystal structures and magnetic properties

Three new metal–radical complexes of the formula [M(NITm-Py)₂(N₃)₂(DMSO)₂] [M = Cu(II) 1, Ni(II) 2, Co(II) 3; NITmPy = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] were synthesized and characterized structurally as well as magnetically. Three complexes are three-spin complexes in which two NITmPy radical ligands are coordinated to the metal ion through the nitrogen atoms of the pyridyl rings. The magnetic behaviors of the three complexes are investigated. Complexes 1 and 2 show ferromagnetic interactions while antiferromagnetic coupling is predominant for complex 3. The magnetic properties are analyzed in connection with their structures and the magnetic exchange mechanism is discussed.