Nickel(II) Coordination Polymers Supported by Bis-pyridyl-bis-amide and Angular Dicarboxylate Ligands: Role of Ligand Flexibility in Iodine Adsorption

Abstract

Reactions of N‚N’-bis(3-pyridylmethyl)oxalamide (L1), N‚N’-bis(4-pyridylmethyl)oxalamide (L2), or N,N’-bis(3-pyridylmethyl)adipoamide) (L3) with angular dicarboxylic acids and Ni(II) salts under hydro(solvo)thermal conditions afforded a series of coordination polymers: {[Ni(L1)(OBA)(H2O)]·H2O}n (H2OBA = 4,4-oxydibenzoic acid), 1, {[Ni(L1)(SDA)(H2O)2]·H2O·CH3OH}n (H2SDA = 4,4-sulfonyldibenzoic acid), 2, {[Ni(L2)(OBA)]·C2H5OH}n, 3, {[Ni(L2)(OBA)]·CH3OH}n, 4, {[Ni2(L2)(SDA)2(H2O)3]·5H2O}n, 5, {[Ni2(L2)(SDA)2(H2O)3]·H2O·2C2H5OH}n, 6, {[Ni(L3)(OBA)(H2O)2]·2H2O}n, 7, {[Ni(L3)(SDA)(H2O)2]·2H2O}n, 8, and {[Ni(L3)0.5(SDA)(H2O)2]·0.5C2H5OH}n, 9, which have been structurally characterized by using single-crystal X-ray crystallography. Complex 1 exhibits an interdigitated 2D layer with the 2,4L2 topology and 2 is a 2D layer with the sql topology, while 3 and 4 are 3D frameworks resulting from polycatenated 2D nets with the sql topology and 5 and 6 are 2-fold interpenetrated 3D frameworks with the dia topology. Complexes 7 and 8 are 1D looped chains and 9 is a 2D layer with the 3,4L13 topology. The various structural types in 1–9 indicate that the structural diversity is subject to the flexibility and donor atom position of the neutral spacer ligands and the identity of the angular dicarboxylate ligands, while the role of the solvent is uncertain. The iodine adsorption of 1–9 was also investigated, demonstrating that that the flexibility of the spacer L1–L3 ligands can be an important factor that governs the feasibility of the iodine adsorption. Moreover, complex 9 shows a better iodine adsorption and encapsulates 166.55 mg g−1 iodine in the vapor phase at 60 °C, which corresponded to 0.38 molecules of iodine per formula unit.

Cu(II) Coordination Polymers Containing Mixed Ligands with Different Flexibilities: Structural Diversity and Iodine Adsorption

“…By fixing the similar factors, we have shown that the best adsorption factor of 290.0 mg g −1 at 60 °C for 360 min was observed for 5 , demonstrating the important role of the flexibility of the neutral spacer ligands, L 1 , L 2 and L 3 , in determining the iodine adsorption capacities of 1 – 6 . For comparison, it is noted that the interpenetrated Th-SINAP-16 and Th-SINAP-21 appear to exhibit uptake amounts of 354 and 375 mg g −1 , respectively, after 0.5 h of iodine adsorption [ 21 ], whereas the Ni(II) CP {[Ni( L 3 )(OBA)(H 2 O) 2 ]·2H 2 O} n encapsulates 166.55 mg g −1 iodine at 60 °C [ 16 ].…”

“…The ability of the CPs to adapt iodine molecules to the voids of the network structures may govern the iodine adsorption capacity [16][17][18][19]. The solvent accessible volumes calculated by using the PLATON program [20] for 1-6 were 1.5, 17.3, 34.4, 2.9, 11.8 and 10.4%, respectively, of the unit cell volume, indicating that complex 3, which displays the three-fold interpenetrated 3D net with (4 12 •6 3 )-pcu topology, may accommodate more iodine than the other complexes.…”

Zn(ii) and Co(ii) coordination polymers based on semi-rigid bis-pyridyl-bis-amide and angular dicarboxylate ligands: synthesis, structures and properties

“…The ligands N ‚ N′ -bis(3-pyrid-yl-methyl)oxalamide ( L 1 ) and N ‚ N′ -bis(4-pyrid-yl-methyl)oxalamide ( L 2 ) were prepared according to a published procedure with some modification. 15…”

Cu(Ⅱ) Coordination Polymers Containing Mixed Ligands with Different Flexibility: Structural Diversity and Iodine Adsorption

“…The ability of the CPs to adapt iodine molecules to the voids of the network structures may govern the iodine adsorption capacity [18][19][20][21]. The solvent accessible volumes calculated by using the PLATON program [22] for 1 -6 were 1.5, 17.3, 34.4, 2.9, 11.8 and 10.4 %, respectively, of the unit cell volume, indicating that complex 3 that displays the 3-fold interpenetrated 3D net with the (4 12 6 3 )pcu topology may accommodate more iodine than the other complexes.…”