Towards more extended systems

The next step was to attempt the synthesis of a three-component Ru(II)- 

Crg(III)-Cr(j(III) complex. For synthetic reasons, the actual target has been the symmetric pentanuclear complex [89] 

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An interesting case, and a step forward from the isolated molecule toward more extended systems, is when an icosahedron of 12 spheres about a central sphere is surrounded by a second icosahedral shell exactly twice the size of the first [9-31]. This shell will contain 42 spheres and will lie over the first so that spheres will be in contact along the fivefold axes. Further layers can be added in the same fashion. The third layer is shown in Figure 9-30 as an example of icosahedral packing of equal spheres. The layers of spheres succeed each other in cubic close-packing sequence on each triangular face. Each sphere which is... 

The theoretical and (model) experimental work referred to above has largely been concerned with linear homopolymers adsorbed on regular surfaces. However, there is a vast literature of experimental studies on more complex systems. Unfortunately, in many cases the systems are either ill-defined and/or only adsorption isotherms have been established for drawing general conclusions or comparison with theory such studies are of little use. On the theoretical side, clearly the work needs to be extended towards these more complex systems. In particular, developments are required in the following areas (starts have already been made in some cases) ... 

When extending the quantum formalism from photons to more complicated systems one meets with the practical problem that an observable can no longer be represented by a finite matrix. Consider the position of a particle on a line segment. It can be specified as being within a certain interval, or box, on the line. To get a more precise location the size (number) of the boxes must decrease (increase), towards the infinitesimal (infinite). The general state G of the system is then represented by a normalized column vector with an infinite number of components... 

Generally, the dienyliron complexes discussed here are stable towards air and moisture (indeed, some of them can be recrystallized from hot water), and most can be stored for extended periods of time at room temperature. In spite of their stability, they are extremely reactive towards nucleophiles. The result of nucleophile addition to complex (3) is shown in equation (5), giving substituted cyclohexadieneiron complexes (10) resulting from exo attack. On the other hand, complexes (5) and (8) are more problematic mixtures of regioisomers (11) and (12 equation 6) result from (5), while the initial products from (8) are prone to isomerization to the more stable systems (14 Scheme 1). 

In order to extend their studies to more complex systems, the Stoddart group directed their efforts towards the synthesis of the bis-[2]-catenane 16. The approach... 

When the potential is scanned toward more positive values (Figure 9.8), it is possible to see the oxidation of atomic iodine to soluble iodine peaking at 0.95 V. Moreover, when the potential scan is extended toward more positive values, it is possible to see a large and broad anodic peak (not shown) corresponding to the formation of soluble iodate species. In the case of having lower amounts of specifically adsorbed anions, the reversible couple due to copper electroadsorption/desorption is slightly distorted. In fact, a new system has to be proposed as a consequence of the interaction between the anion and the metallic species. 

The rate of increase in the V values after the onset of crystallization decreased with increases in the amount of S-170. To extend our observations to a more demonstrative system, a DSC study was carried out as shown in Figure 6. of the pure sample was calculated as 3.4°C as shown in the top of Figure 6a the addition of 1 wt% of P-170 increased Tc to 13°C. As can be also seen, the exothermic peaks are shifted toward the high temperature side by increasing the amount of... 

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