Synthesis, fluorescence, and sorption properties of cobalt coordination polymers of the N, N′-bis(4-pyridylmethyl)naphthalene diimide ligand.

Three cobalt coordination polymers, namely {[Co(4-pmntd)(CFSO)(HO)]·(CFSO)·(CHOH)·0.5(HCCl)·HO} ( 1), {[Co(4-pmntd)(HO)]·(NO)·HO} ( 2), and {[Co(4-pmntd)(pta)(CHOH)]·2(CHCl)} ( 3) (4-pmntd = N, N′-bis(4-pyridylmethyl)-naphthalene diimide; pta = terephthalate), have been synthesized by reactions of 4-pmntd with Co(CFSO)·4HO, Co(NO)·6HO, and Co(pta), respectively. The complexes have been characterized by elemental analyses, powder X-ray diffraction, thermogravimetric analyses, IR spectroscopy, and single-crystal X-ray diffraction. In complex 1, the ligand adopts U-mode, resulting in a dumbbell-like 2D (4, 4)-sql net structure in a non-interpenetrating edge-to-edge arrangement. The Z-mode ligand arrangement leads to 1D zigzag chains for complex 2, and a 2D twofold interpenetrating bat-like (4, 4)-sql net for complex 3. A solution of complex 2 in DMF showed a change in color and remarkably enhanced fluorescence upon the addition of two equivalents of acetate, whereas other anions did not induce a color change. Hence, complex 2 can act as a highly promising acetate-detecting reagent. Their thermal and the gas adsorption properties of complexes 1 and 3 were investigated. Graphical Abstract: Three 1D and 2D cobalt coordination polymers have been synthesized; their structural diversity in these complexes is attributed to different coordination abilities, geometries of counter-anions, and the different conformations adopted by the ligand. A solution of complex 2 showed a change in color and remarkably enhanced fluorescence upon the addition of two equivalents of acetate, whereas other anions did not induce a color change. Hence complex 2 can act as a highly promising acetate-detecting reagent. Their thermal properties and the gas adsorption property of complexes 1, 3 were investigated.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]