Syntheses, structures and photoluminescence of Cd(II) coordination polymers based on in situ synthesized bifunctional ligands

• Four Coordination Polymers based on bifunctional ligands have been synthesized.
• Compound 1 is constructed by Cd-btm2- layers and large bridging metalloligands.
• It is notable that btm2- takes on six different coordination modes in 1 and 2.
• Compounds 1–4 show luminescence behaviours.

By employing Cd(II) salt, NaN3, and CN–(CH2)n–NC (n = 1, 2) and with the absence or presence of secondary ligands, four new cadmium coordination frameworks, named, {[Cd4(btm)4(H2O)2]·3H2O}n (1); [Cd2(btm)2(H2O)]n (2); [Cd2(bte)(PMA)0.5(H2O)]n (3); and [Cd(tzp)(2,2′-bipy)]n (4) (H2btm = bis(tetrazole) methane: H2bte = 1,2-bis(tetrazole-5-yl)ethane; H2tzp = 1H-tetrazolate-5-propionic acid; bipy = bipyridine; PMA = 1,2,4,5-benzenetetracarboxylic acid) were synthesized via in situ hydrothermal reaction. Single crystal X-ray diffraction reveals that compounds 1–3 are all three-dimensional (3D) frameworks. Compound 1 is constructed by Cd1– and Cd3–btm2 − layers and large bridging metalloligands. Compound 2 exhibits a 3D framework with two-dimensional (2D) Cd–btm2 − (adopting μ6:κN1, N1′: κN2: κN3: κN4: κN3′: κN4′coordination mode) layers pillared by μ3:κN1, N1′: κN2: κN4′ btm2 −. Compound 3 is built up by the Cd–bte2 − layers and the linker PMA, with left- and right-handed helical chains arranged alternately. It is notable that btm2 − takes on six different coordination modes in 1 and 2. Compound 4 represents a 2D layered framework, which can be simplified into a Shubnikov plane net (4.8^2) topological network with 3-connected T shape linker tzp2 − ligands. In addition, the research results show that compounds 1–4 exhibit different fluorescent behaviors and thermal stabilities.

Four new cadmium coordination frameworks {[Cd4(btm)4(H2O)2]·3H2O}n (1); [Cd2(btm)2(H2O)]n (2); [Cd2(bte)(PMA)0.5(H2O)]n (3); and [Cd(tzp)(2,2′-bipy)]n (4) (H2btm = bis(tetrazole) methane: H2bte = 1,2-bis(tetrazole-5-yl)ethane; H2tzp = 1H-tetrazolate-5-propionic acid; bipy = bipyridine; PMA = 1,2,4,5-benzenetetracarboxylic acid) were synthesized via in situ hydrothermal reaction.Figure optionsDownload as PowerPoint slide