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

Three coordination polymers of [(NiL1)3(TCBA)2] (1), [(NiL2)3(TCBA)2] (2), and [(NiL3)3(TCBA)2] (3) have been constructed
using azamacrocyclic
Ni­(II) complexes [NiL1]­(ClO4)2/[NiL2]­(ClO4)2/[NiL3]­(ClO4)2 and TCBA3‑ as building blocks (L1 = 3,10-bis­(2-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane;
L2 = 3,10-bis­(3-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane;
L3 = 3,10-bis­(4-fluorobenzyl)-1,3,5,8,10,12- hexaazacyclotetradecane;
TCBA3‑ = 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 3 can adsorb N2, H2, and CO2 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.