Versatility within (4,4) networks assembled from 1,4-bis(n-alkyloxy)-2,5-bis(3,2′:6′,3′'-terpyridin-4′-yl)benzene and [Cu(hfacac)2] (Hhfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione)

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The reactions of 1,4-bis(n-alkyloxy)-2,5-bis(3,2′:6′,3′'-terpyridin-4′-yl)benzene ligands with methoxy (1), ethoxy (2), n-propoxy (3), n-butyloxy (4), n-pentyloxy (5), n-hexyloxy (6), n-heptyloxy (7) and n-octyloxy (8) substituents with [Cu(hfacac)2].H2O (Hhfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) under conditions of crystal growth by layering have been investigated using different combinations of solvents. The products have been structurally characterized and in all cases, Cu(II) is octahedrally sited in a trans-{Cu(hfacac)2(N)2} environment in which N is a pyridine donor in one of the outer rings of a 3,2′:6′,3′'-tpy unit. The coordination assemblies fall into four categories. The most populated class consists of (4,4) nets in which each bis(3,2′:6′,3′'-tpy) ligand 1 and 4–8 acts as a 4-connecting node and the Cu(II) centres lie within the plane defined by the nodes; changes in conformation of the 3,2′:6′,3′'-tpy units do not affect the assembly of the (4,4) network. One of two assemblies isolated with ligand 2 is also a (4,4) net, but powder X-ray diffraction (PXRD) data indicate that this is not representative of the bulk material. [Cu2(hfacac)4(3)]n.5.5nC6H5Cl exhibits a unique structure consisting of a (4,4) net with the Cu(II) centres lying above and below the plane of the net. A third class of assembly was found for [Cu3(hfacac)6(5)2]n and comprises a (4,4) net in which half of the ligands are 4-connecting nodes and half coordinate through two pyridine rings and are therefore linkers; the efficient packing in this structure leaves no solvent-accessible voids. A 1D-coordination polymer in which all the bis(3,2′:6′,3′'-tpy) ligands are 2-connecting linkers was observed for [Cu2(hfacac)4(2)2]n.1.5nCHCl3.4nMeOH and PXRD data confirm that the structure is representative of the bulk material. Structural studies have been complemented by thermogravimetic analyses of selected compounds.