Starburst Dendrimers: Molecular‐Level Control of Size, Shape, Surface Chemistry, Topology, and Flexibility from Atoms to Macroscopic Matter

Abstract

In memoriam Piero PinoStarburst dendrimers are three-dimensional, highly ordered oligomeric and polymeric compounds formed by reiterative reaction sequences starting from smaller molecules-"initiator cores" such as ammonia or pentaerythritol. Protecting group strategies are crucial in these syntheses, which proceed via discrete "Aufbau" stages referred to as generations. Critical molecular design parameters (CMDPs) such as size, shape, and surface chemistry may be controlled by the reactions and synthetic building blocks used. Starburst dendrimers can mimic certain properties of micelles and liposomes and even those of biomolecules and the still more complicated, but highly organized, building blocks of biological systems. Numerous applications of these compounds are conceivable, particularly in mimicking the functions of large biomolecules as drug carriers and immunogens. This new branch of "supramolecular chemistry" should spark new developments in both organic and macromolecular chemistry.

Theoretical models of hyperbranched polymers

“…De Gennes and Hevert [32] developed a self-consistent ®eld model which predicts a dendrimer structure emanating radially outward with a density pro®le minimum at the center of the dendrimer where all the terminal groups are on the periphery of the macromolecule and the ideal dendritic growth will only occur until a certain generation is reached at which point steric congestion will prevent further growth. Molecular modeling performed by Goddard et al [4,34] predicts internal cavities, most of the terminal Fig. 7.…”

“…Tomalia et al [4] did some very important pioneering work as they sought new synthetic strategies for producing biomorphic receptor mimetics leading to new insights into the molecular-level control of size, shape, topology,¯exibility and surface chemistry. They also discussed and stimulated our interest in the way starburst dendrimers can mimic certain properties of micelles and liposomes and even those of biomolecules and the still more complicated, but highly organized, building blocks of biological systems as well as mimicking the functions of large biomolecules as drug carriers and immunogens.…”

Dendrimers Clicked Together Divergently

“…The ability to tune the properties of dendrimers [1][2][3][4][5] has allowed their development for use in diverse applications, including drug delivery, [6][7][8][9][10][11][12][13][14][15] biomimicry, 8,9,[16][17][18][19] catalysis, 15,[20][21][22][23][24][25][26] organic light emitting diodes, 15,21,[27][28][29] molecular wires, 30,31 sensors, [32][33][34][35] imaging agents, 7,9 and various other utilities. 15,[36][37][38][39][40][41][42] Coincident with these developments is the increasing nee...…”

The symmetry of functionalized poly(propylene imine) dendrimers probed with hyper-Rayleigh scattering

“…The interest in dendritic macromolecules originates from the unique properties of these hyperbranched structures that have a defined number of generations and functional end-groups [ 1,2]. The high degree of control over molecular weight and shape has led to the synthesis of unimolecular micelles [3], spherical and cone-shape mesostructures [4], as well as stratified dendrimers possessing generations of different structure [5].…”

“…A variety of techniques have been used to study the three-dimensional architecture of dendrimers. Intrinsic viscosity measurements in conjunction with molecular-modelling studies have been used to verify the presence of globular structures [1]. More recently, transmission electron microscopy and scanning tunnelling spectroscopy have been used to verify the presence of globular structures at higher generations [2,8,9].…”