Structurally Diverse Divalent Metal Adamantanedicarboxylate Coordination Polymers with Hydrogen-bonding Capable Dipyridyl Pillaring Ligands

Five new divalent metal coordination polymers containing either 1,3-adamantanedicarboxylate (adc) or 1,3-adamantanediacetate (ada) and pillaring dipyridyl ligands were prepared and structurally characterized by single-crystal X-ray diffraction. Using the V-shaped linker 4,4-dipyridylamine (dpa), three new phases were isolated. {[Zn-2(ada)(2)(dpa)(2)]center dot 4.5H(2)O}(n) (1) shows a (4,4) grid topology with embedded octameric water clusters. {[Co(ada)(dpa)(H2O)]center dot H2O}(n) (2) also manifests a 2D dimensionality, but with an intriguing novel (4)(12)(4.12(5)) looped topology. {[Cd(adc)(H2O)(2)]center dot H2O}(n) (3) did not incorporate dpa ligands during self-assembly, but exhibits an uncommon 3-connected 8(3) etb network topology. [Co(ada)(ebin)](n) (4) [ebin = ethanediaminebis(nicotinamide)] possesses a (3,6) triangular net based on {Co-2(OCO)(2)} dimeric units. {[Cd(adc)(ebin)]center dot 2H(2)O}(n) (5) also shows dimeric units, although linked into a decorated (4,4) grid topology. Magnetic susceptibility studies of compound 4 revealed a decrease in T-m product upon cooling, ascribed to antiferromagnetic coupling concomitant with single-ion effects [g = 2.39(2) with D = 40(3) cm(-1) and J = -3.55(4) cm(-1)]. Compounds 1 and 5 undergo blue-violet fluorescence upon ultraviolet irradiation; the zinc derivative 1 shows potential as a sensor for the solution-phase detection of nitrobenzene and m-nitrophenol. Thermal decomposition behavior of the five new phases is also discussed.