The Interaction of Guest Molecules with Co‐MOF‐74: A Vis/NIR and Raman Approach

• Published in: Angewandte Chemie International Edition 2018-06, Vol.57 (25), p.7434-7439
• Main Authors: Strauss, Ina, Mundstock, Alexander, Hinrichs, Dominik, Himstedt, Rasmus, Knebel, Alexander, Reinhardt, Carsten, Dorfs, Dirk, Caro, Jürgen
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon dioxide; Crystals; gas sensing; Gas sensors; Gases; metal–organic frameworks; Micrometers; MOF–guest interaction; Molecular chains; Polarized light; Propane; Raman spectra; Raman spectroscopy; Spectrum analysis; UV/Vis spectroscopy
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201801966

Co‐MOF‐74 rod like crystals with a length of several hundred micrometers are synthesized by a solvothermal procedure and their interaction with different gases is evaluated for selective gas sensing. We show strongly anisotropic absorption behavior of the Co‐MOF‐74 crystals when illuminated with polarized light. The interactions of guests (CO2, propane, propene, Ar, MeOH, H2O) with Co‐MOF‐74, is studied by various spectroscopic techniques. Vis/NIR shows peak shifts of Co‐MOF‐74 depending on the interaction with the guest. In the visible and the NIR the maximum absorbance is shifted selectively corresponding to the intensity of the CoII–guest interaction. Even propene and propane could be distinguished at room temperature by their different interactions with Co‐MOF‐74. Raman spectroscopy was used to detect a modified vibrational behavior of Co‐MOF‐74 upon gas adsorption. We show that the adsorption of H2O leads to a characteristic shift of the peak maxima in the Raman spectra. It's a gas: Co‐MOF‐74 crystals were prepared via a solvothermal synthesis route. The crystals show selective responses in UV/Vis spectra as well as in Raman spectra, while interacting with different gases. Co‐MOF‐74 also shows a strong anisotropic absorption when illuminated with polarized light.