Zn(II) and Co(II) coordination polymers based on semi-rigid bis-pyridyl-bis-amide and angular dicarboxylate ligands: synthesis, structures and properties

Hydro(solvo)thermal reactions of N,N'-di(3-methylpyridyl)oxalamide (L-1) and N,N'-di(4-methylpyridyl)-oxalamide (L-2) with angular dicarboxylic acids and Zn(II) and Co(II) metal salts afforded six coordination polymers (CPs), namely, [Zn(L-1)(0.5)(FIPBB)center dot H2O)(n) (H2FIPBB = 4,4'-hexafluoroisopropylidenebis(benzoic acid)) (1), [Zn(L-2)(OBA)center dot CH3OH](n) (H(2)OBA = 4,4'-oxybis(benzoic acid)) (2), [Co(L-2)(0.5)(FIPBB)center dot 0.25CH(3)OH)](n) (3), [Co(L-1)(OBA)center dot 2H(2)O](n) (4), [Co(L-1) (0.5) (FIPBB)](n) (5), and [Co-2(L-1)(2)(FIPBB)(2)(H2O)(5)center dot 4H(2)O(]n) (6), which have been structurally characterized by using single-crystal X-ray diffraction. CPs 1 to 6 form a two-dimensional (2D) net with the bey, a polycatenated 2D net with the sql, a three-dimensional (3D) framework with the 6T9, a 2D net with the 3,5L2, 2D net with the bey and a one-dimensional (1D) looped chain with the 2,2,2,4C10 topologies, respectively. The distinct topological switch between 5 and 6 in the presence and absence of coordinated/cocrystallized water molecules was triggered under various temperatures through coordination and breakage of Co-O bonds. CPs 1 and 2 exhibit sustained porosities indicated by CO2 adsorption and exhibit high selectivity toward detection of pesticides such as 2,6-dichloro-4-nitroaniline (2,6-DCNA) and 4-nitroaniline (4-NA) with low detection limits and good recyclability up to five cycles. Integrating 1-octadecene with a long alkyl chain into 1 5 to modify the surface wettability induces hydrophobicity, which was verified by the measurement of water contact angels.