Template-controlled assembly

Pseudorotaxanes are precursors of both rotaxanes and catenanes they consist of a guest molecule threaded through a macrocyclic host. Stoppering both ends of the threaded molecule gives a rotaxane, cycliza-tion of the thread gives a catenane. Pseudorotaxane formation may occur by spontaneous self-assembly, or may be template-controlled. Anion size can be of paramount importance for such templates - Cl- is effective, Br, I- less good, and PFe ineffective when the recognition motif demands a small template (454). 

Ouyang, M., Remy, J.S. and Szoka, F.C. (2000) Controlled template-assisted assembly of plasmid DNA into nanometric particles with high DNA concentration. Bioconjug. Chem., 11, 104-112. 

Papaefstathiou, G. S. Kipp, A. J. MacGillivray, L. R. Exploiting Modularity in Template-Controlled Synthesis a New Linear Template to Direct Reactivity Within Discrete Hydrogen-Bonded Molecular Assemblies in the Solid State. Chem. Commun. 2001, 2432-2433. 

Fredricks, John R., Metal Template Control of Self-Assembly in Supramolecular Chemistry, 3, 1. 

A substrate functionalized with proper molecules can be used to anchor particles on its surface via surface exchange reaction, leading to controlled assembly of the particles. This self-assembly technique is known as molecule-mediated self-assembly and is commonly used for constructing various composite nanostructures [49-55]. Due to their excellent adhesion capability to various substrates, multifunctional polymers are routinely applied as templates to mediate the assembly of the particles. The assembly is carried out as follows a substrate is immersed into a polymer solution, and then rinsed, leading to a functionalized substrate. Subsequently, this substrate is dipped into the nanoparticle dispersion and then rinsed, leaving one layer of nanoparticles on the substrate surface. By repeating this simple two-step process in a cyclic fashion, a layer-by-layer assembled poly-mer/nanoparticle multilayer can be obtained. 

Fagan, Paul J., Molecular Engineering of Crystals by Electrostatic templating, 2, 107. Fredricks, John R., Metal Template Control of Self-Assembly in Supramolecular Chemistry, 3, 1. 

The paramagnetic nature of Cu ion was utilised to characterise these polymeric receptors by studying the interaction between the Cu centres and imidazole groups using ESR spectroscopy [17]. Results from the ESR experiments indicate that Cu -imidazole coordination bonds formed during the assembly of the monomer and template are conserved upon polymerisation. Furthermore, analysis of the ESR data obtained for different polymers suggested a defined arrangement of metal ion sites in the templated materials, which is absent in the non-templated control polymers. 

Fig. 39 Template-controlled solid-state reactivity, X-ray crystal structures of (a) four-component assembly 2(4-bn-res) 2(l,4-bpeb) (b) targeted cyclophane (c) four-component assembly 2(5-OMe-res) 2(l,6-bpht) and (d) targeted [5]-ladderane.

Fig. 2 Different paths to obtain hybrid materials from molecular sources. Path A Sol-gel routes (Al conventional route for hybrid nanocomposites, A2 molecularly homogenous hybrids). Path B Assembly of nanobuilding blocks (ANBB), of prefunctionalized or postfunctionalized clusters or nanoparticles. Route C or D involve the use of templates capable of self-assembly, giving rise to organized phases. Path E involves integrative synthesis combining precedent paths from A to D and other processes, such as the use of lithography, casting, organogels or latex beads as templates, controlled phase separations, or external fields. (From Ref. l) (View this art in color at www.dekker.com.)...

O.D. (2006) Controlled assembly of SERS substrates templated by colloidal crystal films. Journal of Materials Chemistry, 16, 1207-1211. 

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