ABSTRACT
Supramolecular polymers represent a highly interesting approach towards new "smart materials". A recent strategy includes the combination of different "orthogonal" non-covalent binding sites within one polymer system. Different functionalities can be introduced in a highly defined way by controlled self-assembly processes. This feature article presents highlights in the supramolecular polymer chemistry of multiple hydrogen-bonding, metal complexation (especially of bi- and terpyridines) and host-guest interactions as well as recent advances in combining these interactions in novel polymers.
ABSTRACT
Using a hydroxy-functionalized terpyridine as initiator, a poly(epsilon-caprolactone) containing one terpyridine endgroup was prepared by tin octanoate-catalyzed controlled ring-opening polymerization. The omega-hydroxy group of this polymer was subsequently reacted with an isocyanato-ureidopyrimidinone, resulting for the first time in polymers bearing a metal-coordinating ligand on the one and a hydrogen-bonding unit on the other chain end. Hydrogen-bonded supramolecular dimers were shown to be present in chloroform solution. The subsequent addition of iron(II) ions resulted in the formation of high molecular weight supramolecular polymers with novel properties resulting from the combination of both types of noncovalent interactions in the main chain, as could be shown using capillary viscosimetry and rheometry.
ABSTRACT
Biotin, a well-known binding unit for the proteins avidin and streptavidin, was combined with the chelating ligand terpyridine via polymeric and nonpolymeric spacers. An omega-amino-functionalized terpyridyl-poly(ethylene glycol) was prepared and utilized for complex formation with iron(II), nickel(II), and ruthenium(II) ions. The biocompatibility of the complex formation was investigated in aqueous media. Moreover, biotin was functionalized with a methoxy-poly(ethylene glycol) as a model system. The compounds were characterized by UV/vis and NMR spectroscopy as well as MALDI-TOF mass spectrometry. The systems represent a new combination of strong noncovalent binding units from both biology and synthetic supramolecular chemistry.
Subject(s)
Biotin/chemical synthesis , Polymers/chemical synthesis , Pyridines/chemical synthesis , Biotin/analysis , Bridged-Ring Compounds/analysis , Bridged-Ring Compounds/chemical synthesis , Organometallic Compounds/analysis , Organometallic Compounds/chemical synthesis , Polymers/analysis , Pyridines/analysisABSTRACT
This critical review describes recent developments in the field of supramolecular chemistry of terpyridine-metal complexes. The synthesis and characteristics of single as well as multiple homo- and heterometallic complexes is discussed. Furthermore, complexes containing fullerenes, biological building blocks, extended aggregates of different architectures as well as rings are presented. A special emphasis is placed upon the properties (e.g. redox properties, luminescence etc.) of functional systems. Potential applications in optical nano-devices, molecular storage units, molecular switches and solar cells are discussed.
