Syntheses, structures, and properties of five coordination polymers containing fluorescent whitener

Fluorescent whitener (4,4'-bis(2-sulfonatostiryl)biphenyl) was incorporated with M/4,4'-bipy (M=Cd, Co; 4,4'-bipy=4,4'-bipyridine) 2D frameworks, Mn/4,4'-bipyH fragment, and the [Zn2(Im)2(ImH)4]2+ (ImH=imidazole) chain under hydrothermal conditions to obtain seven new coordination polymers: [Cd(4,4'-bipy)(L)(H2O)2] (1), [Co(4,4'-bipy)2(L)].2H2O (2), [Co(4,4'-bipy)2(H2O)2](4,4'-bipy)(L).2H2O (3), [Mn(4,4'-bipyH)2(L)2(H2O)2].4H2O (4), and [Zn2(Im)2(ImH)4](L) (5). Their structures were determined by single-crystal X-ray diffraction. In 1, binuclear [Cd2] units are bridged by 4,4'-bipys into a 2D cationic framework, which is further penetrated by L anions. 2 has an organic-inorganic hybrid layer consisting of [Co(4,4'-bipy)2] squarelike motifs and L anions. 3 features a pcu-like 3D cationic framework with the inclusion of L anions. In 4, the [Mn(4,4'-bipyH)2(H2O)2]4+ cationic fragment is sandwiched by L anions into a sandwichlike hybrid layer. 5 exhibits a 3D honeycomb-like structure with each nanotube encapsulating two parallel L anionic chains. TGA and PXRD indicate solids 1, 4, and 5 are thermally stable up to 280, 200, and 250 degrees C under an air atmosphere, respectively. 1 has bright blue-green luminescence with a peak maximum band at about 470 nm. 4 exhibits tunable emission between dark-red and weak-green under the excitation of 500 and 280 nm, respectively. 5 displays a bright blue-green emission with a peak band at 454 nm and a shoulder peak at 473 nm. It is attractive that the luminescent properties of solids 1, 4, and 5 are almost retained after heat treatment at 200, 200, and 250 degrees C for 2 h under an air atmosphere, respectively.