Expanding Monomer Diversity

Expanding Monomer Diversity 18.4.1 In situ Monomer Strategy... 

In a different reaction scheme, one can take advantage of the fimctional porphyrin macrocycle to create metalloporphyrin compounds and nanoarchitectures in 2D. Upon exposure of regular TPyP arrays self-assembled on Ag(lll) to iron monomers supplied by an atomic beam, selective com-plexation occurs whereby the template structure is strictly preserved [156]. This expands the diversity of metalloporphyrin layers conventionally realized by evaporation of integral species, because in-situ metalation provides a route towards novel metalloporphyrin nano architectures and patterned surfaces [156-158]. In a related reaction pathway, evidence could be obtained for in-situ complexation and metal center-induced switching of phenanthroline-based catenane units deposited the Ag(lll) surface [182]. 

The following case studies highlight the power of such a strategy in expanding the diversity of monomer collections utilised for parallel synthesis. 

The polyketides are a family of natural products containing many important pharmaceutical agents that are synthesized through the multienzyme complex, polyketide synthase, which can display substantial molecular diversity with respect to chain length, monomer incorporated, reduction of keto groups, and stereochemistry at chiral centers (189). This variability, together with the existence of several discrete forms of polyketide synthase, allows the generation of diverse structures like erythromycin, avermectin, and rapamycin. This biochemical diversity has been considerably expanded by the introduction of new sub strate species that were used by the enzymes to produce new or unnatural polyketides (190). 

To expand the variety of monomers available for polymerization and to increase the range of copolymer and nanoparticle architectures, attention has turned toward the development of methods whereby multiple polymerization techniques can be utilized to generate unique and functionally diverse materials. The grafting-from (Figure 6.29) approaches to ROMP-based micellar... 

Expanding Diversity of Other Limited-availability Monomer Sets... 

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