Solvothermal reactions of HgX2 with 2,2′-(1,2-phenylene)-bis­(N-pyridin-3-yl)­acetamide, L, in ethanol afforded [Hg­(L)­X2] n (X = Cl, 1; Br, 2; I, 3), which are isostructural one-dimensional (1D) zigzag chains, while layering reactions of a ethanoic solution of L with a methanoic solution and an acetonitrile solution of HgI2, respectively, gave 1D helical chains [Hg­(L)­I2·MeOH] n , 4, and [Hg­(L)­I2·MeCN] n , 5. In marked contrast to 1 and 2, the iodide-containing 3 is able to exhibit reversible structural transformation with 4 and 5 by adsorption and desorption of methanol and acetonitrile, suggesting the importance of N–H---X and Hg---X interactions in the evaluation of structural transformation. Moreover, complexes 4 and 5 exhibit reversible crystal to crystal transformation triggered by solvent exchange. Complexes 3–5 represent a unique example that the solvents show a significant effect on folding and unfolding of the HgI2 single-stranded helical coordination polymers.

Solvothermal reactions of Cd(ii) salts and naphthalene-1,4-dicarboxylic acid with bis(N-pyrid-3-ylmethyl)adipoamide and bis(N-pyrid-3-ylmethyl)suberoamide yield three Cd(ii) coordination polymers that undergo reversible crystal-to-crystal transformation and linker exchange.

The structural transformation in 1D helical and mesohelical Hg(ii) chains which demonstrate elastic stretching during the process is investigated.

Hydrothermal reactions of N,N′-di-3-pyridyladipoamide (L) with 1,2,4,5-benzenetetracarboxylic acid (1,2,4,5-H 2 btec) in water without and with NaOH afforded [Co(L)(1,2,4,5btec) 0.5 ] n , 1, and [Co(L)(1,2,4,5-btec) 0.5 (H 2 O) 2 ] n , 2, respectively, while immersion of 1 into water at room temperature gave {[Co(L) 0.5 (1,2,4,5-btec) 0.5 (H 2 O) 4 ]•2H 2 O} n , 3, which have been structurally characterized. Complexes 1−3 display a 2-fold interpenetrated 3D framework, a unique 2D layer, and a 1D chain, respectively. While complexes 1 and 2 adopt the same point symbol of (4.6 4 .8) 2 (4 2 .6 2 .8 2 ) for nets, they differ in the vertex symbols that are [4.

The synthesis, structures and properties of six coordination networks based on N, N'-di(4-pyridyl)suberoamide (L) and angular dicarboxylate ligands, {[Co(L)(MBA)] ⋅ 2H 2 O} n (H 2 MBA = diphenylmethane-4,4'-dicarboxylic acid), 1, {[Co(L) 0.5 (MBA)] ⋅ CH 3 OH} n , 2, [Co(L) 0.5 (MBA)] n , 3, {[Co 2 (L)(OBA) 2 ] ⋅ 7CH 3 OH} n [H 2 OBA = 4,4'-oxybis(benzoic acid)], 4, {[Co(L)(hfipbb)] ⋅ 2H 2 O} n [H 2 hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)], 5, and {[Co(L)(SDA)] ⋅ H 2 O} n (H 2 SDA = 4,4'-sulfonyldibenzoic acid), 6, are reported. Complex 1 is a 1D → 2D polycatenane derived from the helical channels, whereas both complexes 2 and 3 show 2D layers with the (4 2 .6 8 .8.10 4 )(4) 2 -2,6L1 topology, which are further entangled to form a 2-fold 2D → 2D interpenetration network and a 2D → 3D inclined polycatenation network, respectively, and complex 4 shows a 3-fold 3D → 3D interpenetration network with the (4 12 ⋅6 3 )-pcu topology. The unusual topological features of 5 and 6 consist of 2-and 3-fold interpenetrated layers with the (4 4 ⋅6 2 )-sql topology, which are further catenated to the two adjacent such sheets in parallel and uniform fashions to give 2D → 3D polycatenated networks. Complexes 1, 5 and 6 represent a unique example that the angular dicarboxylate ligands show significant effect on the degree of interpenetration of polycatenation coordination networks withinterpenetrating modes. The CO 2 capture is preferable to N 2 and H 2 in the gas sorption for the desolvated product of 4.