Molecular self-assembly is described as a strategy for synthesizing large hydrogen-bonded supramolecular aggregates that are based on the planar lattice formed of equimolar portions of cyanuric acid ...and melamine. The aggregates described in this paper contain four to ten individual molecules, are stabilized by networks of 18 to 54 hydrogen bonds, and have molecular weights in the range 2.7 to 6.5 kDa. Each of these aggregates has been characterized using ¹H NMR. spectroscopy, gel permeation chromatography, and vapor pressure osmometry. Physical-organic chemistry is used to (i) improve our criteria for the design of self-assembling structures and (ii) develop techniques for characterizing non-covalently bound aggregates in organic solution.
This work examines the influence of ions in solution on electroosmosis inside a fused silica capillary using capillary electrophoresis; it thereby examines “shielding” at charged interfaces. Theories ...are reviewed that model ionic solutions as continuous dielectrics: the nonlinear form of the Poisson−Boltzmann equation gives rise to the simplified, more commonly used Debye−Hückel (DH) equation. Capillary electrophoresis (CE) is used to measure the rate of electroosmotic flow as a function of the concentration of different monovalent and divalent cations in aqueous solution. These data are used to test three specific predictions of DH theory: this theory does not describe these data adequately. The central reason behind the inadequacy of DH theory here is its inability to account for details at the level of individual ions other than by mean-field electrostatics: that is, chemical characteristics of ionsfor example, polarizability, hydrated size, energy of hydration, ability to coordinate other ions by chelationare not accounted for. A model (the “dissociation model”) is described that treats the interactions between cations in solution and negatively charged groups on a surface in terms of discrete association equilibria with characteristic dissociation constants, K d eff. CE is then used as a tool to measure values of K d eff for different cations. These dissociation constants follow patterns that are consistent with ones that are familiar from studies in solution.
This chapter reviews work from our laboratory over the last 10 years as it pertains to efforts focused on the exploration of triazine dendrimers as vehicles for drug delivery. The discussion is ...restricted to our efforts in paclitaxel-laden constructs, an area that we have had the most success and have made the greatest investment in time and energy. Areas of emphasis include the evolution of synthetic strategies, characterization, biodistribution, biocompatibility, safety and toxicity, efficacy, and therapeutic advantage. Throughout, limitations and challenges to these efforts are delineated. This chapter is not intended to exhaustively recapitulate the published work. Interested readers are referred to the original research publications and the supporting information provided with each. Instead, the intent is to provide insight into the evolution of the design and to realize this opportunity to share intuitions currently guiding these efforts which, accordingly, are less (or as yet un-) substantiated with experiment.
