Polymeric assemblies acyclic

As to the thermodynamically controlled formation of acyclic polymeric assemblies in solution, there are only a few examples in the literature. The main problems are due to a) competition with cyclization processes b) low association constants c) low solubility of the oligomers. In fact the first reported polymeric assembly in solution made of zinc 5-(4-pyridyl)-10,15,20-triphenylporphyrin (ZnPyTPP) units [47], actually consists, as successively demonstrated, of a cyclic tetramer (Sect. 3.3). The linear polymer, however, was unambiguously detected in the solid state by X-ray analysis of a ZnPyTPP single crystal [47]. This is one of the first examples in the literature of met-alloporphyrins, illustrating the fact that the stability of an assembly may be strongly dependent on the aggregation state. 

Fig. 15 Cartoons illustrating the topological reduction of a bicyclic assembly to a closed acyclic assembly (a), and of a multicyclic polymeric assembly to an acyclic polymer (b)...

This chapter reviews main-chain- and side-chain-functionalized supramolecular polymers that were synthesized by ROMP and acyclic diene metathesis (ADMET) polymerization. Emphasis is placed on polymers assembled using directional supramolecular interactions, such as H-bonding, M-L coordination, and inclusion complexation, or a combination thereof. 

---