Dynamic covalent capture

DYNAMIC COVALENT CAPTURE MERGING COVALENT AND NONCOVALENT SYNTHESIS... 

DCC is typically associated with the amplification of the fittest. In fact, nearly all studies discussed in the previous section rely on the self-selection of high-affinity binders from a dynamic library pool. Nonetheless, many processes in chemistry are guided by weak differences in energy. Examples are the interaction of a catalyst with the transition state of a chemical reaction, protein folding, as well as the self-assembly of nanoarchitectures. In all these cases, a few kilojoules of energy can make the difference between success and failure. This section deals with the application of DCC in the realm of weak interactions, using a methodology referred to as dynamic covalent capture The essential... 

Figure 22 Concept of dynamic covalent capture. A molecular recognition event is followed by the formation of a reversible covalent bond between the molecules.

Prins, Scrimin et al. have illustrated the potential of dynamic covalent capture for catalyst development (Figure 28a). Inspired by enzymes that operate according to a covalent catalysis mechanism. They focused... 

Figure 28 (a) Schematic illustration of the application of dynamic covalent capture for catalyst discovery, (b) target reaction,... 

The melting of the Si (100) surface has previously been investigated with classical molecular dynamics simulation. However, it is now known that these potentials fail to capture much of the this process. Upon melting. Si goes from a 4-fold coordinated semiconductor to a metallic liquid. The density of the liquid is about ten percent higher than in the solid. The average coordination number is between 6 and 7, which is rather low for a metal. This low coordination number is indicative of persistant remnants of covalent bonding. Moreover, recent ab initio simulations of the liquid show that spin effects play an important role. ... 

Cardullo. F. Crego Calama, M. Snellink-Ruel, B.H.M. Weidmann, J.-L. Bielejewska, A. Fokkens. R. Nibber-ing. N.M.M. Timmerman. P. Reinhoudt, D.N. Covalent capture of dynamic hydrogen-bonded assemblies. Chem. Commun. 21000. 367-368. 

Although Si is not necessarily a ceramic, it fulfills one requirement of the ceramic definition, namely it is covalently bonded. More illuminating illustrations of Lomer-Cottrell locks may be seen in Pt and Fe-Mn-Al-C steel. To observe Lomer-Cottrell locks in Pt, see Fig. 3.79 [54]. Using a newly-developed nanoscale deformation device, atomic scale and time-resolved dislocation dynamics were captured in situ by TEM during the deformation of a Pt ultrathin film with truly nanometer grains (diameter d< 10 nm). In larger grains (d 10 nm), full... 

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