Silanol-functionalized tetranuclear copper complex and its nanoscale-heterogenization by immobilization on glass surface from solution

[Display omitted] •A tetranuclear copper complex bearing silanol reactive groups is obtained.•The structure of the complex was completely elucidated by X-ray single crystal diffraction.•Chemical bonding of the copper complex to the glass surface is proved by XPS analysis.•Glass covered with copper complex shows high phase contrast in MFM images. 3-Formylsalicylic acid (3-FSA) was treated in a weak acid medium with 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane to form a salen-type ligand, followed by the addition of copper(II) chloride to build the corresponding coordination compound in a one-pot procedure. Along with the CH=N bond formation, Si-O-Si bond was also broken down to form the Si-OH ones tailing the remained monoamine. As single crystal X-ray diffraction revealed, when the copper salt is added, a tetranuclear complex, [Cu4(L1)2(L2)2Cl2(H2O)2], is formed consisting in two asymmetric dinuclear units, [Cu2L1L2Cl(H2O)], in which a molecule of 3-FSA (H2L1) and one of derived azomethine (H2L2), both doubly deprotonated and tridentate, participate in the coordination of oxo-bridged {Cu4} core. The coordination sphere is completed by chlorine atoms and water molecules. In the tetranuclear structure, the azomethine groups and implicitly the silanol arms are located in trans-position. The thermal behavior of the complex was studied by TGA and DSC. Besides the intrinsic properties induced by the presence of the metal ion (magnetic, biological, etc.), the free reactive silanol group may allow post-functionalization of the complex or, as found herein, its chemical binding to a suitable substrate. The attachment of the complex to the glass surface was proven by XPS but also highlighted by MFM due to its intrinsic magnetism.