Multicomponent Host−Guest Chemistry of Carboxylic Acid and Phosphonic Acid Based Guests with Dendritic Hosts:  An NMR Study

Abstract

A new way to analyze supramolecular dendritic architectures is reported by making use of (13)C NMR and (31)P NMR. Two ethylene glycol guest molecules have been synthesized containing a (13)C labeled carboxylic acid headgroup (2) and a phosphonic acid headgroup (3). The binding of these guests to urea-adamantyl modified poly(propylene imine) dendrimers has been investigated with (13)C NMR and (31)P NMR next to 1D and 2D (1)H NMR techniques. Different amounts of guest 2 have been added to fifth generation dendrimer 1e, and the observed chemical shift values in (13)C NMR were fitted to a model that assumes 1:1 binding between guest and binding site. An association constant of 400 +/- 95 M(-)(1) is obtained for guest 2 with 41 binding sites per dendrimer. When different amounts of phosphonic acid guest 3 are added to dendrimer 1e, two different signals are observed in (31)P NMR. Deconvolution gives the fractions of free and bound guest, resulting in an association constant of (4 +/- 3) x 10(4) M(-)(1) and 61 +/- 1 binding sites. A statistical analysis shows that guest 2 forms a "polydisperse supramolecular aggregate", while guest 3 is able to form a "monodisperse supramolecular aggregate" when the amount of guest is high enough. The NMR results are compared with dynamic light scattering experiments, and a remarkable agreement is found. Phosphonic acid guest 3 is able to exchange with guest 2, which is in agreement with the obtained association constants, and shows that these techniques can be used to analyze multicomponent dendritic aggregates.

Evaluation of poly(amidoamine) dendrimers as potential carriers of iminodiacetic derivatives using solubility studies and 2D-NOESY NMR spectroscopy

“…1 H NMR spectroscopy is a powerful, widely used tool that gives information on the presence and types of intermolecular and intramolecular interactions in a host-guest system such as interaction mechanisms, binding sites, and binding affinities [12, 51]. …”

Interactions and Encapsulation of Vitamins C, B3, and B6 with Dendrimers in Water

“…The DAB dendrimers used are those of generations 2, 3, and 5 (G2, G3, and G5), terminated by 8,16, and 64 amino groups respectively, and the PAMAM dendrimers used are those of generations 1 and 4 (G1 and G4) terminated by 8 and 64 amino groups, respectively. The use of these two well-known amino-terminated dendrimer families will allow for the com- H en utilisant les dØplacements chimiques des protons des dendrimres et des vitamines et analysØes par comparaison avec la titration de la propylamine.…”

“…[7] Meijers group has also reported 31 P and 13 C NMR spectroscopic studies of host-guest chemistry of urea adamantyl ended dendrimers in CDCl 3 . [8] Seminal examples of stepwise host-guest interactions were reported by Yamamoto et al with their phenylazomethine dendrimers. [9] The path of fragile vitamins through biological membranes could be facilitated by biodegradable molecular containers [10] of dendritic or nanoparticle types.…”

Impact of a Water‐Soluble Gallic Acid‐Based Dendrimer on the Color‐Stabilizing Mechanisms of Anthocyanins

“…[39][40][41] Analysis of the 1 HNMR titration data with the proposed Equation (6) could be used to estimate the binding parameters of the complex such as the number of binding sites (n), the maximum chemical shift (Dd max )c hange, and the association constant (K)a tp H1. [42][43][44][45][46] To this end, the Dd obs was plotteda gainst the guest/host molar ratio and the data was fitted by using Equation (6). From the fitting, it was possible to achieve a Dd max = 0.0365 and to estimate the number of bind-ing sites (n)o ftheg uest to dendrimer of around2 95, which means that approximately two molecules of the flavylium cation of cy3glc could bind to each terminal sulfateg roup of the dendrimer,c onfirming the fact that the dendrimer has 162 terminal sulfate groups.…”