Crystallisation of H3BTC, H3TPO or H2SDA with MII (M = Co, Mn or Zn) and 2,2′-bipyridyl: design and control of co-ordination architecture, and magnetic properties (H3BTC = benzene-1,3,5-tricarboxylic acid, H3TPO = tris(4-carboxylphenyl)phosphine oxide, H2SDA = cis-stilbene-4,4′-dicarboxylic acid)†

Abstract

The hydrothermal reaction of benzene-1,3,5-tricarboxylic acid (H₃BTC) with M^II (M = Mn, Co or Zn), tris(4-carboxyphenyl)phosphine oxide (H₃TPO) or cis-stilbene-4,4′-dicarboxylic acid (H₂SDA) with Co^II and 2,2′-bipyridyl (BIPY) gave 1-D co-ordination networks formulated as: [M(HBTC)(BIPY)(H₂O)] (M = Mn 1, Co 2, or Zn 3; [Co₃(BTC)₂(BIPY)₂(H₂O)₆]·4H₂O 4, [Co₃(TPO)₂(BIPY)₂(H₂O)₆]·xH₂O 5 and [Co(SDA)(BIPY)(H₂O)] 6. Structures 1 and 2 consist of double stranded chains of alternating HBTC dianions and dimeric units M^II–M^II linked by two µ-(1,1) bridging carboxylates. Magnetic properties of 1 and 2 indicate the presence of ferromagnetic exchange interactions within the dimers. Structures 4 and 5 consist of chains with a molecular ladder motif which are stacked creating large channels lined by hydrated cobalt(II) ions. The H₂O/D₂O solvent exchange in structure 5, studied by infrared spectroscopy and thermal gravimetric analysis–mass spectrometry, provides evidence for the porosity and zeolitic nature of the material.