Paramagnetic NMR Investigation of Dendrimer-Based Host-Guest Interactions |
| |
| Authors: | Fei Wang Naimin Shao Yiyun Cheng |
| |
| Institution: | 1. Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai, People''s Republic of China.; 2. Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, Shanghai, People''s Republic of China.; Brandeis University, United States of America, |
| |
| Abstract: | In this study, the host-guest behavior of poly(amidoamine) (PAMAM) dendrimers bearing amine, hydroxyl, or carboxylate surface functionalities were investigated by paramagnetic NMR studies. 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO) derivatives were used as paramagnetic guest molecules. The results showed that TEMPO-COOH significantly broaden the 1H NMR peaks of amine- and hydroxyl-terminated PAMAM dendrimers. In comparison, no paramagnetic relaxation enhancement (PRE) was observed between TEMPO-NH2, TEMPO-OH and the three types of PAMAM dendrimers. The PRE phenomenon observed is correlated with the encapsulation of TEMPO-COOH within dendrimer pockets. Protonation of the tertiary amine groups within PAMAM dendrimers plays an important role during this process. Interestingly, the absence of TEMPO-COOH encapsulation within carboxylate-terminated PAMAM dendrimer is observed due to the repulsion of TEMPO-COO- anion and anionic dendrimer surface. The combination of paramagnetic probes and 1H NMR linewidth analysis can be used as a powerful tool in the analysis of dendrimer-based host-guest systems. |
| |
| Keywords: | |
|
|
