Sites guest

More recently, Harada et al. applied the complexation process to side-chain systems via Method 6 (Figure 10), in which the guest sites were introduced as pendant groups and thereafter the CD was threaded onto them [104, 105]. Different types of hydrocarbon chain as pendant groups were studied for their compatibility with different CDs. As the cyclic was not blocked, the products can be viewed as side-chain poly(pseudo rotaxane)s of Type 9. Probably because of the rapid exchange process between threaded and unthreaded forms, the isolation of the solid-state polyrotaxane was not reported. 

Figure 3 Illustration of the guest site and surrounding host environment in the four-stranded B-sheet region of Bl. Arrows indicate hydrogen bonds. The guest site is circled and highlighted in black. The nearest neighbor residues are also circled but highlighted in gray.

Figure 5 Comparison of CD spectra of BIT, BIG and BIP at the guest site. Measurements were made at 10 C.

The pseudolocal phonon approach to dephasing, in the field of micro-wave and electronic spectroscopy rests on the assumption that insertion of a guest in a host crystal leads to formation of phonons which are substantially localized at the guest sites. There seems to be an urgent need for a model system where the pseudolocal phonons themselves are accessible for a direct relaxation study. Specifically the lifetime of this phonon and its temperature dependence are crucial quantities in a test of the dephasing... 

Within the limits of the measurements, the results show unequivocally that the cobalt(II)/02 complex is serving as host for the organic guest molecule. The calculated distances between the center of electron spin density and the protons are shorter than in the cases where the electron is confined to a metal ion. This is expected since the O2 moiety resides between the metal ion site and the guest site. The limitations described advise against quantitative interpretation of the difference [53]. 

Kim et al. [230] developed very interesting pseudrotaxane type methodology that demonstrated the ability to supramolecularly modify the periphery of poly(propyleneimine) (PPI) dendrimers bearing diaminobutane substituents. These periphery substituents then served as guest sites that quantitatively self-assembled cucurbituril host molecules around the diaminobutane groups as illustrated in Figure 32. 

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