Variations of Structures and Gas Sorption Properties of Three Coordination Polymers Induced by Fluorine Atom Positions in Azamacrocyclic Ligands

Abstract

Three coordination polymers of [(NiL(1))(3)(TCBA)(2)] (1), [(NiL(2))(3)(TCBA)(2)] (2), and [(NiL(3))(3)(TCBA)(2)] (3) have been constructed using azamacrocyclic Ni(II) complexes [NiL(1)](ClO(4))(2)/[NiL(2)](ClO(4))(2)/[NiL(3)](ClO(4))(2) and TCBA(3-) as building blocks (L(1) = 3,10-bis(2-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane; L(2) = 3,10-bis(3-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane; L(3) = 3,10-bis(4-fluorobenzyl)-1,3,5,8,10,12- hexaazacyclotetradecane; TCBA(3-) = tri(4-carboxy-benzyl)amine). The results of X-ray diffraction analyses reveal that 1 shows a 2D Borromean structure, while 2 and 3 form 2D layer structures, and the 2D layers are further connected by the interlayer F···F interactions in 2 and C-H···F interactions in 3 to generate two 3D porous structures with 1D fluorine atoms interspersed channels. Gas sorption measurements illustrate that the desolvated 2 and 3can adsorb N(2), H(2), and CO(2) molecules. The different structures and gas sorption properties of 1 and 2/3 are mainly induced by the different positions of F atoms in azamacrocycle ligands.