Porous Coordination Polymers Based on {Mn6} Single-Molecule Magnets

In this paper, three isostructural porous coordination polymers, namely, [Mn-6(mu(3)-O)(2)(sao)(6)(DMF)(4)(L-1)(2,3)]center dot 4DMF center dot 2H(2)O center dot 2CH(3)OH (1), [Mn-6(mu(3)-O)(2)(sao)(6)(DMF)(4)(L-2)(2/3)]center dot 4DMF center dot 2H(2)O center dot 2CH(3)OH (2), and [Mn-6(mu(3)-O)(2)(sao)(6)(DMF)(4)(L-3)(2/3)]center dot 4DMF center dot 4H(2)O-2CH(3)OH (3) (DMF = dimethylformamide, H(2)sao = salicylaldoxime, H3L1 = benzene-1,3,Strisbenzoic acid, H3L2 = 4,4',4 ''-s-triazine-2,4,6-triyltribenzoic acid, and H3L3 = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-s-triazine), based on the oximato-bridged {Mn-6} single-molecule magnet (SMM) and tricarboxylic acid ligands, were designed and synthesized. X-ray structural analysis shows that they possess a two-dimensional layered structure, where the {Mn-6} moieties are linked by the corresponding (L-x)(3-) carboxylate ligands (x = 1, 2, 3) forming a huge honeycomb layer. These compounds not only show the SMM behavior as confirmed by alternative current susceptibility measurements but also show selectivity for CO2 over N-2 at 273 K. On the basis of the magnetic fitting to the magnetic susceptibilities and the field dependence of magnetization for complexes 1-3, the spin ground states are S = 4. Compared with isolated {Mn-6} SMMs with S = 4, the out-of-phase susceptibilities of 1-3 show obvious peaks only under the external direct-current field of 2 kOe. However, no peaks in chi(m)'' are observed in the partially desolvated sample of compound 1.