Access to supramolecular polymers: large scale synthesis of 4'-chloro-2,2':6',2''-terpyridine and an application to poly(propylene oxide) telechelics

A new improved large scale synthesis of 4-chloro-2,2 : 6,2-terpyridine is described in detail. Williamson type ether reactions were utilized for a high yield reaction of 4-chloro-2,2 : 6,2-terpyridine with ,-bishydroxy-functionalized poly(propylene oxide). The completeness of the functionalization was proven by NMR, GPC and MALDI-TOF-MS investigations. The application of ruthenium(III)/(II) chemistry allowed then the construction of ABA type non-covalent architectures

Towards functionalized nanoparticles

Abstract onl

Towards functionalized nanoparticles

Abstract onl

Dimerization of Monofunctionalized Poly(ethylene oxide) via Metal-ligand Interactions and Hydrogen Bonds

Supramolecular chemistry utilizes noncovalent bonds for assembling large ordered structures. Among the interactions used, metal–ligand interactions and hydrogen bonds play important roles. We have studied the degree of association attainable with these two interactions by quantifying dimer formation between suitable bond-forming blocks which were covalently linked to a poly(ethylene oxide) chain (or a dye-labelled derivative). Dimer formation was monitored by sedimentation equilibrium analysis in the analytical ultracentrifuge. The partial specific volume, v, of the compounds was also determined by equilibrium sedimentation, using the ldquobuoyant density methodrdquo and the tetrahydrofuran/propylene carbonate solvent pair. Up to complete dimerization of the molecules was observed when complex formation was based on Fe(II)–terpyridine interactions. In contrast, under our experimental conditions, quadruple hydrogen-bonded arrays led to only 20–50% dimerization, with surprisingly low yields in apolar solvents and significant yields even in solvents also capable of participating in hydrogen-bond formation. With the compound studied, dimer formation was found to be largely irreversible

Studies on the partial specific volume of a poly(ethylene glycol) derivative in different solvent systems

The specific volume of charged supramolecular compounds dissolved in organic solvents varies considerably with the solvent system applied; in addition, it is influenced by the presence of salt. In this study we determined the specific volume of an uncharged molecule from the same molar mass range in order to find out whether it shows the same dependencies. To allow application of solvents of widely differing polarity, including water, a poly(ethylene glycol) derivative of molar mass 3,650 g/mol was used as a model system. The primary method applied for determining the specific volume was the buoyant density method, in which sedimentation equilibrium experiments using solvent mixtures of different density are performed and the specific volume is obtained as the reciprocal of that solvent density for which the compound is neutrally buoyant. A second method applied for determination of the specific volume was digital densimetry. We found that the strong influence of the solvent on the specific volume observed with charged compounds is also shown by the uncharged poly(ethylene glycol) derivative, the differences in the specific volume between different solvent systems amounting up to 15%; however, no significant dependence on the presence of salt was observed. We also found that, with the compound studied, a simple rule relating the specific volume and solvent polarity apparently does not exist