Effect of Benzoic Acid as a Modulator in the Structure of UiO-66: An Experimental and Computational Study

The identification and quantification of defects are undoubtedly thorough challenges in the characterization of “defect-engineered” metal–organic frameworks (MOFs). UiO-66, known for its exceptional stability and defect tolerance, has been a popular target for defect-engineering studies. Herein, we show that synthesizing UiO-66 in the presence of an excess of benzoic acid is a reliable method for obtaining UiO-66 samples with a very high concentration of missing-cluster defects, allowing one to modulate specific properties (i.e., surface area and hydrophobicity). This was elucidated by a multitechnique marriage of experimental and computational methods: a combination of PXRD, dissolution/ 1 H NMR spectroscopy, and N 2 sorption measurements was used to quantify the defect loading, while vibrational spectroscopies (FTIR and Raman) allowed us to unequivocally identify the defect structure by comparison with DFT-simulated spectra and visual analysis of the computed vibrational modes.