A 2D metal–organic framework based on dizinc coordination units bridged through both flexible and rigid ligands

• A new 2D metal–organic framework with flexible siloxane bridges was obtained.
• Polymeric nature is manifested through glass transition evidenced by DSC.
• Due to the dimethylsiloxane units, the polymer shows low water vapor sorption.
• The compound shows different sorption capacity for H2 and N2 at low pressure.

A new coordination polymer has been obtained by reacting 1,3-bis(3-carboxypropyl)tetramethyldisiloxane and 4,4′-azopyridine with Zinc(II) perchlorate in excess. The structure of the crystalline compound separated in good yield was identified by spectral and X-ray diffraction analysis proving to be a 2D metal–organic framework. The thermal behavior was investigated by thermogravimetry and differential scanning calorimetry. The presence of the tetramethyldisiloxane moiety confers increased hydrophobic character to the metallo–organic structure as was emphasized by water vapour sorption measurements performed at different temperatures in dynamic regime. The suitability of the polymer for the gas sorption was tested for hydrogen and nitrogen as guest molecules at 77 K and 0–1 atm pressure range.

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