Power of Infrared and Raman Spectroscopies to Characterize Metal-Organic Frameworks and Investigate Their Interaction with Guest Molecules.

The variety of functionalities and porous structures inherent to metal-organic frameworks (MOFs) together with the facile tunability of their properties makes these materials suitable for a wide range of existing and emerging applications. Many of these applications are based on processes involving interaction of MOFs with guest molecules. To optimize a certain process or successfully design a new one, a thorough knowledge is required about the physicochemical characteristics of materials and the mechanisms of their interaction with guest molecules.

Effect of methanol on the Lewis acidity of rutile TiO2 nanoparticles probed through vibrational spectroscopy of coadsorbed CO.

Infrared spectroscopy of adsorbed CO has been used to characterize the effect of adsorbed methanol on the Lewis acidity of 4 nm rutile TiO(2) nanoparticles. Measurements of CO absorbance and vibrational frequency have revealed that CO adsorbs primarily at one class of Lewis acid sites on clean TiO(2) particles, where evidence for lateral interactions between neighboring molecules suggests dense coverage occurs near saturation. The response of the CO infrared intensities and frequencies to methanol exposure has shown that methanol uptake occurs primarily at the Lewis acid sites and through hydrogen bonding to surface OH groups.

Uptake of a chemical warfare agent simulant (DMMP) on TiO2: reactive adsorption and active site poisoning.

Using Fourier transform infrared spectroscopy (FTIR) we studied the overall reaction pathways and ultimate fate of dimethyl methylphosphonate (DMMP), a chemical warfare agent simulant, on a commercial nanoparticulate (approximately 20 nm) titania material. Our data show that the initial uptake occurs through both molecular and reactive adsorption. Molecular adsorption is driven by hydrogen-bond formation to isolated hydroxyl groups.