Diverse cobalt(ii) coordination polymers for water/ethanol separation and luminescence for water sensing applications

Abstract

Four cobalt coordination polymers, namely, {[Co(3-pmpmd)Cl₂]·2.6CH₃OH}_n (1), {[Co₂(3-pmpmd)₄(NCS)₄]·2CH₃OH·5CHCl₃}_n (2), {[Co(3-pmpmd)1.5(NO₃)₂]·0.8CH₃OH}_n (3) and {[Co(3-pmpmd)₂(NCS)₂]·CHCl₃}_n (4) (3-pmpmd = N,N′-bis(3-pyridylmethyl)pyromellitic diimide) have been synthesized and characterized. The different conformations of the diimide ligand are crucial for obtaining structural diversity. The adsorption isotherms of complex 3 for water and ethanol are quite different; 3 adsorbs water with a gate-opening phenomenon, but it does not adsorb ethanol and therefore, it has the potential capacity to capture water from ethanol.