Anion-dependent host-guest properties of porous assemblies of coordination complexes (PACs), [Cu(A)₂(py)₄] (A = PF₆, BF₄, CF₃SO₃, and CH₃SO₃; py = pyridine), based on Werner-type copper(II) complexes in the solid state.

We report the syntheses and crystal structures of novel porous assemblies of coordination complexes (PACs) with/without guest molecules, α-[Cu(A)₂(py)₄] (α-PAC-2-A (A = PF₆, BF₄, CF₃SO₃, and CH₃SO₃); py = pyridine), γ-{[Cu(PF₆)₂(py)₄]·2guest} (γ-PAC-2-PF₆ ⊃ 2guest (guest = acetone and py)), γ-{[Cu(BF₄)₂(py)₄]·2acetone} (γ-PAC-2-BF₄ ⊃ 2acetone), and β-{[Cu(CH₃SO₃)₂(py)₄]·2.67H₂O} (β-PAC-2-CH₃SO₃ ⊃ 2.67H₂O). The single-crystal X-ray diffraction analyses of α-PAC-2-A show that α-PAC-2-A have dense packing structures, in which anions of the discrete coordination complexes form weak hydrogen-bonding and anion-π interactions. In contrast, γ-PAC-2-PF₆ ⊃ 2guest, γ-PAC-2-BF₄ ⊃ 2acetone, and β-PAC-2-CH₃SO₃ ⊃ 2.67H₂O form guest-including structures with coordination environments around the Cu(II) atoms similar to the α-forms. The vapour adsorption measurements for MeCN and acetone in α-PAC-2-A suggest that the adsorption associated with structural transformations is induced by weak Lewis-base PF₆⁻ and BF₄⁻ anions covered only with fluorine atoms, which weaken the host-host interactions.