Ab initio crystal structure determination, thermal behaviour, and magnetic characterization of a new nickel coordination polymer based on carboxyethylphosphonic acid and 4,4′-bipyridine

• A new Ni coordination polymer has been obtained by hydrothermal synthesis.
• The crystal structure has been ab initio determined from powder synchrotron data.
• The material, with 2D structure, is stable until 170 °C. A higher temperature, an anhydrous phase is detected.
• The sample has a paramagnetic behaviour with antiferromagnetic interactions and zero-field splitting at low temperature.

Crystalline powder aggregates of a new nickel coordination polymer with 2-carboxyethylphosphonic acid (H2PPAH) and 4,4′-bipyridine, Ni2(HPPA)2(4,4′-bipy)2(H2O), has been obtained by hydrothermal synthesis, and their crystal structure has been ab initio determined from synchrotron powder data. The compound shows a layer structure in bc plane, with Ni atoms in two different environments. The loss of the coordinated water by heating leads to the apparition of an anhydrous phase, which remains stable when cooling down to room temperature. Synthesized material presents a paramagnetic behaviour with weak antiferromagnetic interactions and zero-field splitting at low temperature (T < 50 K).

Ni2(HPPA)2(4,4′-bipy)2(H2O) has a layered architecture stablished by π–π stacking and hydrogen bonding interactions, showing paramagnetic behaviour with weak antiferromagnetic interactions and zero-field splitting at low temperature and an anhydrous phase stable in air at room temperature.Figure optionsDownload as PowerPoint slide