Local Structure of Framework Cu(II) in HKUST-1 Metallorganic Framework:  Spectroscopic Characterization upon Activation and Interaction with Adsorbates

Abstract

XRD, UV-Vis, EXAFS, XANES, and Raman techniques have been used to study the removal of water molecules coordinated to the Cu(II) framework atoms of the novel HKUST-1 metal-organic framework. The dehydration process preserves the crystalline nature of the material, just causing a reduction of the cell volume due to the shrinking of the [Cu 2 C 4 O 8 ] cage. The removal of adsorbed H 2 O molecule makes the framework Cu(II) sites available for interaction with other probe molecules. In situ IR spectroscopy has evidenced the formation at liquid nitrogen temperature of labile Cu(II)‚‚‚CO adducts characterized by a ν(C-O) ) 2178 cm -1 and at 15 K of Cu(II)‚‚‚H 2 adducts characterized by a ν(H-H) ) 4100 cm -1 . To the best of our knowledge, we have observed for the first time a clear signal of Cu(II) carbonyl and dihydrogen complexes formed inside a crystalline microporous hosting matrix. The sinking of the oxygens of the carboxyl units, undergone by the Cu(II) framework ions in the dehydration process, is responsible for the rather low coordinative unsaturation of Cu(II). The important shielding effect of the four oxygen framework atoms is testified by the low polarization factor of the Cu(II) site probed by both CO and H 2 molecules.

Stability and Hydrolyzation of Metal Organic Frameworks with Paddle-Wheel SBUs upon Hydration

“…The vibrational features of metal oxide clusters can be assigned by comparing to Cu(bdc)(dmf), copper acetate monohydrate Cu(OAc) 2 47 For the other three M(bdc)(ted) 0.5 [M=Zn, Ni, Co] compound and Zn(bdc)(dmf), the doublet mode can be also readily identified around 190-160 cm -1 in Fig.7 and Fig. S5.…”

Thin Film Structures of Metal-Organic Framework [Cu3(BTC)2(H2O)3]n on TiO2(110)

“…8985 eV is due to the 1s¼4p dipolar shakedown transition. 17 We found these peaks in the ultra thin film, indicating that HKUST-1 cage structure was formed on the TiO 2 (110) surface even at the 1 cycle LPE process.…”

“…8977 eV ascribed to the quadrupolar transition 1s¼3d and the white line, respectively. 17 They also assigned that the peak at ca. 8985 eV is due to the 1s¼4p dipolar shakedown transition.…”

Graphene-Like Layers from Unconventional Carbon Sources: New Perspectives on Hybrid Materials and π-system Synergisms

“…Following this ideas, we incorporated our conductive GL layers in a copper-based MOF, containing Cu 2+ dimers as the metallic units linked to oxygen atoms from benzene tricarboxylate (BTC) [85][86], and referred in literature as HKUST-1 or MOF-199. HKUST-1 combines high surface area, water stability [87], simple preparation procedure (anhydrous conditions are not required) at low costs conditions (since precursors are easily available and not expensive).…”