Sonochemical synthesis and characterization of four nanostructural nickel coordination polymers and photocatalytic degradation of methylene blue

Four nanostructural nickel(II) coordination polymers {[Ni(ttpa)(1,4-ndc)(H 2 O) 2 ]·2H 2 O} n ( 1 ), {[Ni(ttpa)(1,3-bda)]·2H 2 O·DMF} n ( 2·2H 2 O·DMF ), {[Ni(ttpa)(1,4-bdc)]·H 2 O} n ( 3 ) and {[Ni(ttpa)(aip)(H 2 O)]·3H 2 O} n ( 4·3H 2 O ) were synthesized using hydrothermal and sonochemical methods (ttpa = tris(4-(1,2,4-triazol-1-yl)phenyl)amine, 1,4-ndc = 1,4-naphthalenedicarboxylate, 1,3-bda = 1,3-benzenediacetate, 1,4-bdc = 1,4-benzenedicarboxylate, aip = 5-aminoisophthalate), and characterized by elemental analysis, IR spectra, scanning electron microscopy, single-crystal and powder X-ray diffraction analysis, optical band gaps, VB XPS spectra and luminescence. The effects of sonication power, time and frequency on the size and morphology of nano-sized 1–4 have been studied. 1 exhibits an unusual 2D + 2D → 3D inclined polycatenated motif based on the (3,3)-coordinated 6 3 -hcb topology. 2 shows a (3,4)-coordinated 2D network of the bey topology. 3 presents a rare example of the 4-fold interpenetrating array of (3,5)-coordinated 3D network belonging to the 35T1 topology type. 4 displays an unusual 2D → 3D polythreaded network based on 2D sql networks. 1–4 exhibit luminescent emissions at 409, 399, 413 and 402 nm, respectively. 1–4 are semiconducting in nature, with E g of 2.12 eV ( 1 ), 2.34 eV ( 2 ), 2.32 eV ( 3 ), and 2.47 eV ( 4 ). 1–4 are good catalysts for the degradation of MB under visible light irradiation. The effects of the size and morphology of nano-sized 1–4 on the photocatalytic efficiencies were studied. The higher sonication frequency obtains uniform and smaller nano-sized coordination polymers which have higher catalytic efficiencies.