From dendrimers to fractal polymers and beyond

The advent of dendritic chemistry has facilitated materials research by allowing precise control of functional component placement in macromolecular architecture. The iterative synthetic protocols used for dendrimer construction were developed based on the desire to craft highly branched, high molecular weight, molecules with exact mass and tailored functionality. Arborols, inspired by trees and precursors of the utilitarian macromolecules known as dendrimers today, were the first examples to employ predesigned, 1 → 3 C-branched, building blocks; physical characteristics of the arborols, including their globular shapes, excellent solubilities, and demonstrated aggregation, combined to reveal the inherent supramolecular potential (e.g., the unimolecular micelle) of these unique species. The architecture that is a characteristic of dendritic materials also exhibits fractal qualities based on self-similar, repetitive, branched frameworks. Thus, the fractal design and supramolecular aspects of these constructs are suggestive of a larger field of fractal materials that incorporates repeating geometries and are derived by complementary building block recognition and assembly. Use of terpyridine-M2+-terpyridine (where, M = Ru, Zn, Fe, etc) connectivity in concert with mathematical algorithms, such as forms the basis for the Seirpinski gasket, has allowed the beginning exploration of fractal materials construction. The propensity of the fractal molecules to self-assemble into higher order architectures adds another dimension to this new arena of materials and composite construction

Nitric oxide releasing-dendrimers: an overview

Platforms able to storage, release or scavenge NO in a controlled and specific manner is interesting for biological applications. Among the possible matrices for these purposes, dendrimers are excellent candidates for that. These molecules have been used as drug delivery systems and exhibit interesting properties, like the possibility to perform chemical modifications on dendrimers surface, the capacity of storage high concentrations of compounds of interest in the same molecule and the ability to improve the solubility and the biocompatibility of the compounds bonded to it. This review emphasizes the recent progress in the development and in the biological applications of different NO-releasing dendrimers and the nitric oxide release pathways in these compounds

Synthesis of 2,2'-bipyridines : from versatile building blocks to sexy architectures and functional (nano)materials

The latest synthetic strategies to prepare 2,2-bipyridine and its mono-substituted, symmetrical and unsymmetrical 3,3-, 4,4-, 5,5-, and 6,6-disubstituted derivatives are critically discussed and evaluated. Different coupling procedures to achieve new symmetrical and unsymmetrical functionalized 2,2-bipyridines, such as Stille-type, Negishi-type, and Suzuki-type cross-coupling reactions are discussed in detail. Moreover, condensation procedures that allow further variations are presented. The application of functional group transformations for access to additional groups is examined

Triads Containing Terpyridine-Ruthenium(II) Complexes and the Perylene Fluorescent Dye

A perylene unit was modified with two terpyridine moieties. Each terpyridine chelating moiety was subsequently complexed with ruthenium(III) trichloride to yield a dinuclear bis(monoterpyridine-ruthenium(III) chloride)perylene derivative. Alternatively, it is possible to obtain the corresponding perylene derivative bearing two bis-terpyridine-ruthenium(II) complexes via conversion of the of the terpyridine-substituted perylene with [Ru(tpy)Cl3]. The compounds were characterized in detail by MALDI-TOF mass spectrometry, NMR, UV-vis as well as fluorescence spectroscopy

Thermal Stability, Rheology and Morphology of Metallo-Supramolecular Polymers Based on bis-Terpyridine Ruthenium (II) Complexes

Supramolecular polymers, based on poly(ethylene glycol) and terpyridine-ruthenium(II) complexes, were investigated regarding their thermal stability by TGA. In addition, the temperature-dependent melt viscosity was studied using a rheometer and the results were compared to the corresponding classical poly(ethylene glycol). Finally, the morphology of an annealed film was investigated by AFM