Nature of Polyoxometalate Intramolecular Coordination to Quaternary Ammonium Salts from Paramagnetic Relaxation Enhancement

Polyoxometalates (POMs) exhibit catalytic activity toward a variety of harmful chemicals such as chemical warfare agents, qualifying them as promising candidates as additives to create self-decontaminating surfaces and materials. However, POMs exhibit poor solubility and dispersion behavior in organic matrices, including polymeric coatings. In an effort to improve compatibility with polymer coatings and impart surface segregating behavior, we describe the encapsulation of a Ni(II)-containing POM, α2-K8P2W17O61(Ni2+·OH2)·17H2O (Ni-POM), with a series of amphiphilic alkyl ethoxy dimethyl quaternary ammonium salts (QASs) and elucidate their structural coordination. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were utilized to confirm that QASs are coordinated to the Ni-POM and that the average number of QAS coordinated to each Ni-POM increases with increasing alkyl moiety length. The 1H NMR spectra of the Q...