Multi assembly approach

A scaled-up version of this central template-concentric sphere surface assembly approach has been demonstrated for the growth of multi-layer core-shell nano- and microparticles, based upon the repeated layer-by-layer deposition of linear polymers and silica nanoparticles onto a colloidal particle template (Figure 6.8) [60]. In this case, the regioselective chemistry occurs via electrostatic interactions, as opposed to the covalent bond formation of most of the examples in this chapter. The central colloidal seed particle dictates the final particle... 

Figure 9 Self assembly approach to de novo heme protein design, (a) bis-His ligated single heme parallel to the helices in the four a-helical bundle (b) bis-His ligated multi-hemes parallel to the helices in the four a-helical bundle. (Reprinted with permission from Ref 27. 2004 the American Chemical Society) (c) bis-His ligated multi-hemes perpendicular to each other in the four a-helical bundle. (Reprinted with permission from Ref 60. 2001 the Protein Society)...

The rate of energy and electron transfer in any of these systems is an ensemble average of all sites within the layered assembly, and thus there is no single rate for any of the processes in the assemblies. Nonetheless, in addition to the increased quantum yield, assemblies constructed with the HTiNbOs spacer exhibit a long-lived charge-separated state component not observed in the a-ZrP spaced assemblies, of x = 900 ps. While there is still much to be learned from the study of multi-chromophore arrays, this synthetic approach appears to hold much promise for the creation of organic-inorganic hybrid solid state devices. 

Analyses of Pitch. Modern analytical facilities of high-pressure liquid chromatography, gel permeation chromatography, an(j 1 nuclear magnetic resonance and mass spectrometry, associated with 1R and UV spectroscopy enable a total molecular constituent analysis of pitch composition to be obtained. The use of such information could then possibly be the route to prediction of pitch quality on carbonization. It would appear that such an approach would not be successful (ignoring the cost factor for such detailed analysis). The pitch cannot be considered as an assembly of molecules which pyrolyse independently of each other. The pitch carbonizes as a multi-phase system and experience today would indicate the impossibility of predicting all interactions, physical and chemical. 

One of the advantages of supramolecular chemistry over the covalent molecular approach resides in the possibility of inducing and/or transferring properties from singular molecules to self-organized multi-molecular assemblies. Chirality is one of these properties it stems from the electronic level (the helical nature of the electron rearrangement during a transition in chiral chromophores) and spreads up to the three-dimensional spatial disposition of atoms, or molecular components in molecular or supramolecular entities, respectively. 

As we have suggested recently [68] the technique involving separation of the CM motion and representation of the wave function in terms of explicitly correlated gaussians is not only limited to non- adiabatic systems with coulombic interactions, but can also also extended to study assembles of particles interacting with different types of two- and multi-body potentials. In particular, with this approach one can calculate the vibration-rotation structure of molecules and clusters. In all these cases the wave function will be expanded as symmetry projected linear combinations of the explicitly correlated fa of eqn.(29) multiplied by an angular term, Y M. 

Langmuir monolayers play some part in the preparation of multi-layer systems, now mostly referred to as self-assembled monolayers or multilayers (SAM s). However, this role is modest because it is difficult to make Langmuir-Blodgett layers sufficiently perfect and stable to function in new materials, such as electronic and bio-mimetic devices. One approach of stabilizing LB films is by working with molecules having double bonds that, after deposition, are polymerized. Such layers are stable enough to serve as a substrate for protein adsorption ). 

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