Assembly of Metal-Calixarene Compounds with a Ditetrazole Linker: From Isolated Cluster, Coordination Chain to Coordination Cage

Abstract

Three metal-calixarene compounds with N, N -bis[1(2) H -tetrazol-5-yl]amine (H 3 bta), [Co 16 Cl 6 (TC4A) 4 (Hbta) 4 (CH 3 OH) 10 (OH) 2 (H 2 O) 6 ] ( CIAC-232 ), [Co 17 (TC4A) 4 (bta) 4 (HCOO) 6 (CH 3 OH) 4 (H 2 O) 4 ] ( CIAC-233 ), and [Co 20 Cl 2 (TC4A) 5 (bta) 2 (atz) 2 (HCOO) 2 (ox) 4 (CH 3 OH) 6 (H 2 O) 4 ] ( CIAC-234 ) (H 4 TC4A = p - tert -butylthiacalix[4]arene, H 2 ox = oxalic acid, Hatz = 5-aminotetrazole), were obtained under the solvothermal conditions in different solvents. CIAC-232 featuring an isolated {Co 16 } cluster was synthesized in the sole methanol solvent, while CIAC-233 contained some coordination chains from a mixed methanol–DMF solvent. In-situ generated formic acid from the decomposition of DMF acts as the linker to bridge the isolated {Co 17 } clusters into the coordination chains in CIAC-233 . The attempt to replace the formate linkers with the oxalate anions results in the formation of a helmet-like open {Co 20 } coordination cage CIAC-234 due to the different coordination geometries of the oxalate anions. Magnetic properties and gas adsorption of these compounds were studied.