SBA-15 mesoporous silica free-standing thin films containing copper ions bounded via propyl phosphonate units - preparation and characterization

• Functionalized free-standing SBA-15 thin films were synthesized for a first time.
• Thin films synthesis procedure was described in details.
• Structural properties of the films were thoroughly investigated and presented.
• Magnetic properties of the novel material was investigated and presented.

The SBA-15 silica thin films containing copper ions anchored inside channels via propyl phosphonate groups are investigated. Such materials were prepared in the form of thin films, with hexagonally arranged pores, laying rectilinear to the substrate surface. However, in the case of our thin films, their free standing form allowed for additional research possibilities, that are not obtainable for typical thin films on a substrate. The structural properties of the samples were investigated by X-ray reflectometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The molecular structure was examined by Raman spectroscopy supported by numerical simulations. Magnetic measurements (SQUID magnetometry and EPR spectroscopy) showed weak antiferromagnetic interactions between active units inside silica channels. Consequently, the pores arrangement was determined and the process of copper ions anchoring by propyl phosphonate groups was verified in unambiguous way. Moreover, the type of interactions between magnetic atoms was determined.

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