Nanoscale Coordination Polymer of Dimanganese(II) as Infinite, Flexible Nanosheets with Photo‐Switchable Morphology

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Abstract
An original co‐ligand association, consisting of 4,4'‐azopyridine and 1,3‐bis(carboxypropyl)tetramethyldisiloxane, is used for complexing MnII, to obtain a 2D dinuclear coordination array having infinite horizontal dimensions and nanometric thickness. Due to the shielding effect of the tetramethyldisiloxane units facing outwards on both sides, the sheets are free of any chemical or physical intermolecular interactions, as crystallographic analysis reveals. The compound shows two glass transitions, at –51 and 33 °C, and begins to decompose at 292 °C. The co‐existence in the structure of the highly hydrophobic tetramethyldisiloxane spacers and the polar metal complexed units confers amphiphilic character to the compound, making it capable of reducing the surface tension of the DMF, from 35.8 to 29.4 mN/m, at a critical micellar concentration around 1 wt.‐% complex. The presence of aggregates in solution is evidenced by dynamic light scattering. The light sensitive azopyridine units make the compound photo‐responsive. This behavior occurs both in solution as well as in the film, where the compound self‐assembles in micellar morphology when UV‐irradiated. Both conductivity and dielectric permittivity of the film increase as a result of trans–cis configuration. Magnetic measurement data indicate two antiferromagnetic coupled spins, S = 5/2, that are able to interact with small external magnetic field, i.e., during MFM scanning.
Funding Information
  • Executive Agency for Higher Education, Scientific Research, Development and Innovation Funding (PN‐III‐P4‐ID‐PCCF‐2016‐0050)

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