Organized assemblies molecules

Figure 1.2 September 2007 cover of a leading international chemistry journal dedicated to sol-gel materials shows mesostructured silicas derived from the cooperative assembly of soluble sol-gel precursors and organic surfactant molecules. (Reproduced from acs.org, with permission.)...

Diverse chiral nanometric ribbons and tubules formed by self-assembly of organic amphiphilic molecules can be transcribed to inorganic... 

The fluorescence polarization technique is a very powerful tool for studying the fluidity and orientational order of organized assemblies (see Chapter 8) aqueous micelles, reverse micelles and microemulsions, lipid bilayers, synthetic non-ionic vesicles, liquid crystals. This technique is also very useful for probing the segmental mobility of polymers and antibody molecules. Information on the orientation of chains in solid polymers can also be obtained. 

Figure 1. Various organized assemblies formed from a simple surfactant molecule in mixtures of...

M.J., and Valenda, S. (2004) Supramo-lecular self-assembled molecules as organic directing agent for synthesis of zeolites. Nature, 431, 287-290. 

Although more work is needed to clearly correlate the type of solubilization site occupied by different porphyrins with their reactivity in such sites towards atropisomerization, it is clear that different sites exist and that these sites show quite different reactivity in both thermal and photochemical processes. Preliminary studies have shown that related behavior probably occurs in other organized assemblies formed by dispersion of surfactant molecules in... 

Self-assembly is the spontaneous organization of molecules into stable, well-defined structures with the driving forces being noncovalent associations. The final structure is normally near or at the thermodynamic equilibrium arrangement allowing it to form spontaneously. Such formations can be done under conditions where defects are either minimized or eliminated. In nature, self-assembly is common as in the folding of proteins, formation of the DNA double helix, etc. 

Here, we are most interested in the interaction of these organized assemblies with another molecule, that is, molecular recognition. We will broadly classify these interactions into nonspecific and specific ones. In addition to the chemical interaction between the molecules, there has been a significant amount of work on achieving amphiphilic block copolymer assemblies that respond to physical stimuli, for example, temperature. We will not discuss this in any detail, except when relevant to the focused topic of chemical recognition. 

Organizational characteristics of surface-active molecules have been studied by several researchers due to their applications in many areas such as personal care, polymerization, catalysis, drug delivery, separation and purification, enhanced oil recovery and lubrication. The structure of supramolecular organized assemblies formed in different solvents, when a critical concentration is exceeded, determines their properties such as solubilization [1-3], catalysis [1,4-6], adsorption [7-11] and flocculation [12,13]. As such, many techniques have been used to determine their structural properties. In this paper, the results obtained using fluorescence probing for properties of assemblies in solution and at solid-liquid interfaces are discussed in detail after a brief review of relevant assemblies formed by them. 

Figure 15. (a) A schematic representation of organic amphiphilic molecules at air-water interface, (b) Schematic representation of the various deposition modes for monolayer films and the resulting L-B assemblies. (Reproduced with permission from H. Kuhn, D. Mobius, and H. Bucher, Physical Methods of Chemistry, Vol. I, Part IIIB, A. Weissberger and B. W. Rossiter, Eds., Wiley, New York, 1972, p. 577.)... 

This investigation shows that an organized assembly ranging from isolated molecules to expanded structures stabilized inside a sodalite host matrix (Figure 1) can be readily fabricated out of a material that is normally a I-VII semiconductor. The (8-2n)Na,2nAg,2X-SOD sodalites might find applications as electronically tunable nonlinear optical materials (see later). 

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