Empty cage structures

Step 1 The apohost is converted from its stable, nonporous phase a to the jSq, empty cage structure ... 

The electrochemical properties of TNT-EMFs, M3N C2n n > 39) differ from those of the empty cage fullerenes (see Fig. 6) due to the interaction of the metal cluster with the carbon cage and because the structure of these carbon cages are generally different. As a consequence, the reductive processes are electrochemically irreversible but chemically reversible. The oxidative processes occur at lower potentials because the HOMO orbital is mainly localized on the trimetallic nitride clusters and the HOMO-LUMO gaps in solution are smaller [25,58]. The endohedral metallo-fullerenes M C2n show similar behavior but even smaller HOMO-LUMO gaps [59]. 

Vibrational structures of several metallofullerenes have been studied by IR and Raman spectroscopy (Dunsch et al., 1998a Hulman et al., 1997 Kikuchi et al., 1993 Lebedkin et al., 1998a,b Pichler et al., 1996). Some of the vibrational absorption lines of Sc2C2 Cg2 (HI) are strongly enhanced if compared with the spectrum of the empty cage (Hulman et al., 1997 Krause et al., 1999 Pichler et al., 1996). With decreasing temperature, a dramatic narrowing of the lines was observed. The linewidth shows an... 

Based on the occupancies and thermal factors of the guest molecules in these structures, it was speculated that some of the cages might be completely empty. This speculation led to the conclusion that Dianin s compound might retain its cage structure upon complete removal of the... 

FuUerenes are three-dimensional carton structures where the bonds between the carbon atoms are bent to form an empty cage of sixty (Cm) or more carton atoms. 

Recent ah initio calculations showed that when small guest molecules (either nonpolar Ne or polar HF) are accommodated in the P-hydroquinone cage structure, the unit cell parameters of the empty host lattice remain largely unaffected. Moreover, the magnitudes of the... 

If Y-cyclodextrin is crystallized as "empty" molecule from water, it arranges in a fishbone type cage structure similar as observed for a- and (5-cyclodextrins (17). If, however, a small guest like n-propa-nol is added, a channel type structure is formed in which the Y-cyclo-dextrin molecules with eightfold symmetry are stacked along a fourfold symmetry axis and therefore exactly linear channels are produced (18), Fig. 3. 

Although the ionic model explains some spectroscopic and structural properties of EMFs, there are numerous studies which indicate that this model is oversimplified. While the analysis of MO energy levels in the EMFs and the corresponding empty cages can be indeed interpreted as an electron transfer to the cage from the metal, experimental (Alvarez et al. 2002 Kessler et al. 

Figure 7. Sodalite framework composition modification of cage structure for hydrated empty cages.

The establishment of the equilibrium state is also confirmed by a scrambling experiment using the dimer 3 with one of the Cgo cages labeled by He encapsulation. As shown in Scheme 4, the HSVM treatment of unlabeled (empty) Cgo with labeled 3 for 30 min in the presence of KCN as a catalyst resulted in scrambling of labeled Cgo in both monomer and in dimer 3 in a ratio of 3 7, as examined by He NMR spectroscopy [23]. The structure of... 

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