The interaction of a series of molecular probes (O
3, H
2S, CO, NH
3, (CH
3)
2CO, C
5H
5N and CH
3CN) with the hydrated SiO
2 surface has been investigated by QM/MM calculations and diffuse ...reflectance infrared Fourier transform spectroscopy. Theoretical estimates of O–H stretchings are shown to be improved by a new treatment of the molecular mechanics part of the model. Such a result is encouraging for the application of the adopted approach to other systems.
The electronic and molecular properties of interstitial O
3 in SiO
2 have been theoretically studied by coupling the molecular cluster model to the density functional theory. We find that, on passing ...from the free species to the interstitial one, electronic and molecular structures of O
3 are only slightly perturbed. Moreover, in agreement with the experimental assignment of Skuja et al., it is confirmed that the ubiquitous absorption band at 4.8 eV characterizing 7.9 eV photon-irradiated SiO
2 samples includes a contribution due to excitations between O
3 based occupied and unoccupied MOs.
The molecular and electronic structure of M(η3-C3H5)2 (M = Ni, Pd, Pt) has been investigated by means of quasi-relativistic gradient-corrected density functional calculations. Geometries have been ...fully optimized by considering both trans and cis arrangements of the bis(η3-allyl) moiety. Binding energy differences between isomers are always smaller than 0.2 kcal/mol; in particular, cis-Ni(η3-C3H5)2 is computed to be more stable than trans-Ni(η3-C3H5)2, while a reversed order is obtained for Pd and Pt analogues. Computed geometrical parameters of trans-Ni(η3-C3H5)2 compare very well with available structural data. Moreover, a new assignment of variable energy photoelectron spectroscopy measurements Li, X.; Bancroft, G. M.; Puddephatt, R. J.; Liu, Z. F.; Hu, Y. F.; Tan, K. H. J. Am. Chem. Soc. 1994, 116, 9543−9554 is proposed by assuming that the trans:cis ratio in the gas phase is close to one.
Gut beschirmte MOFs: Eine neue Serie von hydrophoben isoretikulären porösen Zirconiumoxid‐Dicarboxylat‐MOFs wurde entwickelt (siehe Bild, Zr blaue Polyeder, O rot, C schwarz). Die Materialien ...zeichnen sich durch ein eindimensionales Porensystem, eine seltene Kombination von Lewis‐Acidität und hydrophobem Charakter sowie eine höhere hydrothermische und mechanische Stabilität als ihre polymorphen UiO‐MOF‐Gegenstücke aus.
