Nanoscale Coordination Polymer of Dimanganese(II) as Infinite, Flexible Nanosheets with Photo‐Switchable Morphology. Issue 21 (26th May 2020)

• Record Type: Journal Article
• Authors: Shova, Sergiu; Vlad, Angelica; Damoc, Madalin; Tiron, Vasile; Dascalu, Mihaela; Novitchi, Ghenadie; Ursu, Cristian; Cazacu, Maria
• Is Part Of: European journal of inorganic chemistry. Issue 21(2020)
• Page Start: 2043
• Page End: 2054
• Publication Date: 2020-05-26
• Subjects: Metal‐organic frameworks -- Multitasking materials -- Nanocoordination -- Dinuclear coordination polymers -- Photochemistry -- Magnetic properties; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202000098
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : An original co‐ligand association, consisting of 4, 4'‐azopyridine and 1, 3‐bis(carboxypropyl)tetramethyldisiloxane, is used for complexing Mn II, 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. Abstract : A coordination polymer was obtained as a 2D array having infinite horizontal dimensions and nanometric thickness, free of any chemical or physical intermolecular interactions. Thanks to the dimanganese clusters, azo linkages, and the highly hydrophobic and flexible tetramethyldisiloxane motifs, this material is capable of acting as a surface‐active agent or molecular switching material responsive to external stimuli (optical and magnetic).