Five coordination polymers formed from combinations of copper(II) acetate and 4′-(4-alkyloxyphenyl)-3,2′:6′,3″-terpyridines with methoxy (1), n-butoxy (2), n-pentyloxy (3) and n-heptyloxy (4) substituents are reported. Reaction of 1 with Cu(OAc)₂∙H₂O leads to the 1D-polymer [Cu₂(μ-OAc)₄(1)]_n in which {Cu₂(μ-OAc)₄} paddle-wheel units are connected by ligands 1, or [{Cu₄(μ₃-OH)₂(μ-OAc)₂(μ₃-OAc)₂(AcO-κO)₂(1)₂}·2MeOH]_n in which centrosymmetric tetranuclear clusters link pairs of ligands 1 to give a double-stranded 1D-polymer. Layering solutions of Cu(OAc)₂∙H₂O (in MeOH) over 2, 3 or 4 (in CHCl₃) leads to the assembly of the 1D-polymers [2{Cu₂(μ-OAc)₄(2)}·1.25MeOH]_n, [Cu₂(μ-OAc)₄(3)]_n and [{Cu₂(μ-OAc)₄(4)}·0.2CHCl₃]_n. In all compounds, the 3,2′:6′,3″-tpy unit coordinates only through the outer pyridine rings, but the conformation of the 3,2′:6′,3″-tpy responds to changes in the length of the alkyloxy tails leading to changes in the conformation of the polymer backbone and in the packing of the chains in the crystal lattice in the chains featuring {Cu₂(μ-OAc)₄} paddle-wheel linkers.

The tetratopic ligands 1,4-bis(2-ethylbutoxy)-2,5-bis(3,2’:6’,3’’-terpyridin-4’-yl)benzene (1) and 1,4-bis(3-methylbutoxy)-2,5-bis(3,2’:6’,3’’-terpyridin-4’-yl)benzene (2) have been prepared and characterized by ¹H and ¹³C{¹H} NMR, IR, and absorption spectroscopies and mass spectrometry. Reactions of 1 and 2 with cobalt(II) thiocyanate under conditions of crystal growth at room temperature result in the formation of [{Co(1)(NCS)₂}·MeOH·3CHCl₃]_n and [{Co(2)(NCS)₂}·0.8MeOH·1.8CHCl₃]_n. Single-crystal X-ray diffraction reveals that each crystal lattice consists of a trinodal self-penetrating (6².8⁴)(6⁴.8²)(6⁵.8)₂ net. The nodes are defined by two independent cobalt centres and the centroids of two crystallographically independent ligands which are topologically equivalent.

The isomers 4′-(4-(trifluoromethyl)phenyl)-4,2′:6′,4″-terpyridine (1), 4′-(3-(trifluoromethyl)phenyl)-4,2′:6′,4″-terpyridine (2), 4′-(4-(trifluoromethyl)phenyl)-3,2′:6′,3″-terpyridine (3), and 4′-(3-(trifluoromethyl)phenyl)-3,2′:6′,3″-terpyridine (4) have been prepared and characterized. The single crystal structures of 1 and 2 were determined. The 1D-polymers [Cu₂(hfacac)₄(1)₂]_n·2nC₆H₄Cl₂ (Hhfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione), [Cu(hfacac)₂(2)]_n·2nC₆H₅Me, [Cu₂(hfacac)₄(3)₂]_n·nC₆H₄Cl₂, [Cu₂(hfacac)₄(3)₂]_n·nC₆H₅Cl, and [Cu(hfacac)₂(4)]_n·nC₆H₅Cl have been formed by reactions of 1, 2, 3 and 4 with [Cu(hfacac)₂]·H₂O under conditions of crystal growth by layering and four of these coordination polymers have been formed on a preparative scale. [Cu₂(hfacac)₄(1)₂]_n·2nC₆H₄Cl₂ and [Cu(hfacac)₂(2)]_n·2nC₆H₅Me are zig-zag chains and the different substitution position of the CF₃ group in 1 and 2 does not affect this motif. Packing of the polymer chains is governed mainly by C–F...F–C contacts, and there are no inter-polymer π-stacking interactions. The conformation of the 3,2′:6′,3″-tpy unit in [Cu₂(hfacac)₄(3)₂]_n·nC₆H₄Cl₂ and [Cu(hfacac)₂(4)]_n·nC₆H₅Cl differs, leading to different structural motifs in the 1D-polymer backbones. In [Cu(hfacac)₂(4)]_n·nC₆H₅Cl, the peripheral 3-CF₃C₆H₄ unit is accommodated in a pocket between two {Cu(hfacac)₂} units and engages in four C–H_phenyl...F–C_hfacac contacts which lock the phenylpyridine unit in a near planar conformation. In [Cu₂(hfacac)₄(3)₂]_n·nC₆H₄Cl₂ and [Cu(hfacac)₂(4)]_n·nC₆H₅Cl, π-stacking interactions between 4′-trifluoromethylphenyl-3,2′:6′,3″-tpy domains are key packing interactions, and this contrasts with the packing of polymers incorporating 1 and 2. We use powder X-ray diffraction to demonstrate that the assemblies of the coordination polymers are reproducible, and that a switch from a 4,2′:6′,4″- to 3,2′:6′,3″-tpy metal-binding unit is accompanied by a change from dominant C–F...F–C and C–F...H–C contacts to π-stacking of arene domains between ligands 3 or 4.

We have prepared and characterized 1,4-dibromo-2,5-bis(2-phenylethoxy)benzene (1) and 1,4-dibromo-2,5-bis(3-phenylpropoxy)benzene (2). Their single-crystal structures confirm that, at the molecular level, they are similar with the phenylalkoxy chains in extended conformations. However, there are significant differences in packing interactions. The packing in 1 is dominated by C–Br...π(arene) interactions, with each Br located over one C–C bond of the central arene ring of an adjacent molecule. In contrast, the packing of molecules of 2 involves a combination of C–H...Br hydrogen bonds, Br...Br interactions, and arene–arene π-stacking. The single-crystal structures of both orthorhombic and triclinic polymorphs of 1 have been determined and the packing interactions are shown to be essentially identical.

The tetratopic 1,4-bis(2-phenylethoxy)-2,5-bis(3,2′:6′,3′′-terpyridin-4′-yl)benzene (1) and 1,4-bis(3-phenylpropoxy)-2,5-bis(3,2′:6′,3′′-terpyridin-4′-yl)benzene (2) ligands have been prepared and fully characterised. Combination of ligand 1 or 2 and [M(hfacac)₂]·xH₂O (M = Cu, x = 1; M = Zn, x = 2) under conditions of crystal growth by layering led to the formation of [Cu₂(hfacac)₄(1)]_n·3.6n(1,2-Cl₂C₆H₄)·2nCHCl₃, [Zn₂(hfacac)₄(1)]_n·nMeC₆H₅·1.8nCHCl₃, [Cu₂(hfacac)₄(2)]_n·nMeC₆H₅·2nH₂O, [Cu₂(hfacac)₄(2)]_n·2.8nC₆H₅Cl and [Cu₂(hfacac)₄(2)]_n·2n(1,2-Cl₂C₆H₄)·0.4nCHCl₃·0.5nH₂O. For each compound, single-crystal X-ray analysis revealed the assembly of a planar (4,4)-net in which the tetratopic ligands 1 or 2 define the nodes. The metal centres link two different bis(3,2′:6′,3′′-tpy) ligands via the outer pyridine rings; whereas copper(II) has N-donors in a trans-arrangement, zinc(II) has them in cis. This difference between the copper(II) and zinc(II) coordination polymers modifies the architecture of the assembly without changing the underlying (4,4)-network.

The consistent assembly of a (6⁵.8) cds net is observed in reactions of cobalt(II) thiocyanate with 1,4-bis(n-alkyloxy)-2,5-bis(3,2′:6′,3″-terpyridin-4′-yl)benzene ligands in which the n-alkyloxy substituents are n-propyl (ligand 3), n-butyl (4), n-pentyl (5), n-hexyl (6), n-heptyl (7), and n-octyl (8). Crystals were grown by layering a methanol solution of Co(NCS)₂ over a 1,2-dichlorobenzene solution of each ligand. The choice of crystallization solvents is critical in directing the assembly of the cds net. Single-crystal structures of [Co(NCS)₂(3)]_n^.3.5nC₆H₄Cl₂, [Co(NCS)₂(4)]_n^.5.5nC₆H₄Cl₂, [Co(NCS)₂(5)]_n^.4nC₆H₄Cl₂, [Co(NCS)₂(6)]_n^.3.8nC₆H₄Cl₂, [Co(NCS)₂(7)]_n^.3.1nC₆H₄Cl₂, and [Co(NCS)₂(8)]_n^.1.6nC₆H₄Cl₂^.2nMeOH (C₆H₄Cl₂ = 1,2-dichlorobenzene) are presented and compared. The n-alkyloxy chains exhibit close to extended conformations and are accommodated in cavities in the lattice without perturbation of the coordination framework.