Supramolecular SPMs

Kawase, Oda, and coworkers have synthesized a unique series of belt-shaped paraphenylacetylene macrocydes 68-71 (Scheme 6.18A) and studied their host-guest supramolecular chemistry. The precursor polyenes 72-75 were synthesized using a modified McMurry reaction, and a subsequent bromination/dehydrobro-mination sequence with t-BuOK gave the desired SPMs 68-71. A 4 1 mixture of 72/74 gave the corresponding mixture of SPMs 68 and 70, which could be separated by GPC, while pure samples of 73 and 75 could be obtained to provide 69 and 71 directly [73,74]. Using the same bromination/dehydrobromination procedure, SPMs 76-78 were synthesized with 1,4- or 2,6-naphthylene units, respectively, at opposing positions (Scheme 6.18B). 

In the author s opinion, the better approach to experimentally study the morphology of the silica surface is with the help of physical adsorption (see Chapter 6). Then, with the obtained, adsorption data, some well-defined parameters can be calculated, such as surface area, pore volume, and pore size distribution. This line of attack (see Chapter 4) should be complemented with a study of the morphology of these materials by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning probe microscopy (SPM), or atomic force microscopy (AFM), and the characterization of their molecular and supramolecular structure by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, thermal methods, and possibly with other methodologies. 

The multifold application of porphyrins in supramolecular chemistry suggests to a closer look at the SPM studies of this molecule, before more complex interconnected supermolecules are discussed. 

Self assemblage of extended biomolecular structures on solid surfaces was verified by the SPM measurements. Supramolecular structures were detected on solid surfaces of practically all samples. Aiming to characterize transferability of the structures from the solution onto solid surface, we performed experiments with sufficiently stable lisozyme fibrils. In these experiments hen egg lysozyme fibrils were immobilized on several types of solid substrates listed in section 2 by deposition of the structures from buffer solution. Typical results of these tests are... 

It was proved experimentally that immobilization period can be effectively used for variation of the density of the supramolecular structures on the surfaces. Influence of the immobilization time on die arrangement of the combined structures is illustrated in Fig. 2 by typical SPM images obtained for hen egg lysozyme fibrils deposited on mica surfaces. After deposition of the lysozyme fibrils under similar conditions, the fibrils were rare on the surfaces if immobilization was shorter... 

In general, structures of supramolecular objects of hybrid proteins on the surfaces were individual for each set of fused molecules and different from lysozyme fibrils. Ball-like objects were the most typical objects detected on the surfaces in the experiments with the hybrid proteins. The structure is illustrated in Fig. 3a by typical SPM image. The size of the balls in these structures seemed dependent on the type of hybrid protein but quantitative description of the dependence requires additional studies. 

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