Donor molecular recognition process

A different H-bonding network was obtained with 1,1,3,3-tetraphenyldisilox-ane-l,3-diol (24) [20]. In the molecular recognition process with hexamethylenetetramine (25), the diol acts as a double donor and the diamine as a double... 

Several researchers recognized and sought to exploit this approach. Fujita and coworkers, for example, developed so-called multiple-molecular recognition processes, in which the self-assembly of coordination bonds is accompanied in situ by the formation of weaker interactions such as K donor-acceptor and hydrophobic/hydro-philic interactions. Illustrated in Fig. 1 is an example of such an assembly, in which a molecular switch is created by the interlocking or diassociation, upon command, of two cyclic molecules. ... 

Molecular recognition processes may also involve charge transfer or, more generally, donor-acceptor interactions. In covalently based PLCs, they have been used, for instance, to enhance mesomorphic stability and even induce mesophases, when copolymers containing separate electron donor and electron acceptor pendant chains are prepared [63 -68] or when blends of the respective homopolymers are prepared [68-70]. 

HB is undoubtedly the most frequently utilized noncovalent interaction in molecular-recognition processes. However, halogen bonding (XB) is a noncovalent interaction that is in some ways analogous to HB, and it may therefore be used as a practical tool for cocrystal synthesis. In HB, a hydrogen atom is shared between an atom, group, or molecule that donates and another that accepts it. In XB, it is a halogen atom X that is shared between a donor atom D and an acceptor A. Thus, the two types of interaction can be described as in Scheme 13. 

Some of the materials highlighted in this review offer novel redox-active cavities, which are candidates for studies on chemistry within cavities, especially processes which involve molecular recognition by donor-acceptor ii-Jt interactions, or by electron transfer mechanisms, e.g. coordination of a lone pair to a metal center, or formation of radical cation/radical anion pairs by charge transfer. The attachment of redox-active dendrimers to electrode surfaces (by chemical bonding, physical deposition, or screen printing) to form modified electrodes should provide interesting novel electron relay systems. 

The breakthrough came when it was realized that the concepts of molecular recognition and supramolecular chemistry could be put to use to make catenane synthesis a rational and efficient processes. Two independent strategies—the use of metal complexation chemistry and TT donor-acceptor forces in organic systems—were exploited to make novel structures. 

Moreover, molecules are self-assembled and the formation of a stable LC complex occurs through selective hydrogen bonding. Schematic illustration of the process between the H-bond donor polymer and the H-bond acceptor molecule is shown in Fig. 5. This is a new type of molecular recognition in molecular aggregates. 

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