Synthetic efforts at the Center for Molecular Design and Recognition (CMDR), located on the fifth floor of the Goodyear Polymer Center at the University of Akron and founded by Professor George R. Newkome, a pioneer and founding father of dendrimer chemistry, are focused on the investigation of new molecules, polymers, and nanoscopic constructs that possess unique architectures and utilitarian features. Over the years, this has led our group to become involved in the preparation of numerous supramolecular and heterocyclic structures such as crown ethers, rotaxanes, and polypyridines. Presently, we are concentrating on the construction of highly branched architectures, known as dendrimers and hyperbranched polymers, along with their attendant properties. Associated with the construction of these macromolecules is also the design and preparation of building blocks that facilitate a modular synthetic approach aimed at the ability to fine tune the desired properties of higher order structures such as functional group density, internal void volume, hydrophilicity/lipophilicity, mode of assembly, and molecular recognition capability, to mention but a few.
An example of the versatility of this approach is evident in the ability to prepare the molecular equivalent of a "Rubik's Cube" termed a "Rubik's Sphere" (pictured in the upper left hand corner of this page). The Rubik's Sphere can be envisioned by considering the grafting of building blocks, or spherelets (analogous to cubelets), with differing terminal functionality to the surface of a spherical polymer (a dendrimer) whereby the properties of bond and branch rotation produce a dynamic and heterogeneous surface. Ramifications include the potential for terminal groups or units to rotate to 'separated' or 'adjacent' conformations which in turn affords the foundation to begin to control relative functional group positional parameters in large molecules. Other current projects in our laboratories involve the preparation of ligands with multiple metal attachment sites configured to facilitate the self-assembly of higher order architectures that span the organic-inorganic interface.
Synthetic efforts are also focused on the self-assembly of multiple metal arrays, where the metal juxtaposition is strictly controlled. This has led to the development of protocols that facilitate the creation of nanoscale, polymetal materials capable of acting as nanoscale energy storage devices. To date, numerous Ru-, Fe-, Cd-, Zn-, and Os-based arrays have been prepared, along with some mixed-metal constructs. Construction of these unique assemblies is predicated on the development of suitable building blocks possessing architectural elements that facilitate self-assembly, such as found in our bisterpyridine ligands possessing 120 degree terpyridine-terpyridine positioning.
The self-assembly process is well-suited to the construction of materials possessing repeating molecular motifs, or shapes, at differing size scales. Thus, the construction of non-dendritic, "Fractal" molecular architectures is also a prime target in our laboratories. Fractal materials are an extension of dendritic architecture which has been shown to exhibit fractal characteristics.
Our Fractal nanomolecular architectures are a logical extension of the dendritic chemistry developed in our laboratories. Thus, our efforts in both arenas are focused on atomic geometry and the potential to design and craft specific, polyatomic geometries that in-turn allow the construction of more and more complex structures. We herein dedicate this site to linking past discoveries and insights with that of current, state-of-the-art research. The manuscripts listed below describe some of our initial work related to the now well-known regime of dendritic chemistry.
Read about Prof. Newkome's pioneering work on Arborols and Unimolecular Micelles in a 1986 review written by Prof. Frederick Menger.
Read more about Prof. Newkome's pioneering work on Arborols and Unimolecular Micelles in this 1988 C&E News article written by Ward Worthy
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