Water-soluble TRIS-terminated PAMAM dendrimers: microwave-assisted synthesis, characterization and Cu(ii) intradendrimer complexes

Abstract

This study is the first report describing the microwave-assisted synthesis (MAS) of poly(amido amine) (PAMAM) dendrimers with TRIS surface functional groups (PAMAM–TRIS). Six PAMAM–TRIS dendrimers were synthesized using both newly developed conventional and microwave methods. Five of them are novel. Three different cores, one polymeric Jeffamine® T-403 and two monomeric, ethylenediamine and diethylenetriamine, were used in the syntheses. All the reactions were monitored by attenuated total reflectance (ATR). It was observed that microwave reactions proceeded 3.5 to 4.0 times faster than conventional reactions. Therefore, a fast, easy and one-pot MAS of six different water-soluble PAMAM–TRIS dendrimers was accomplished with high (90–96%) yields in short (110–140 min) reaction times and under mild reaction conditions, using methanol as solvent. The other ester terminated half generation precursor PAMAM (PAMAM–OCH₃) dendrimers used for the synthesis of the PAMAM–TRIS dendrimers were obtained by utilizing conventional and microwave methods together. For the purification of all the PAMAM dendrimers, a liquid phase polymer-based retention (LPR) technique was used. The PAMAM–TRIS dendrimers were characterized by ¹H NMR, ¹³C NMR, ATR (IR), EA, potentiometric and spectroscopic titrations. Furthermore, Cu(II)–PAMAM–TRIS dendrimer complexes were prepared and characterized by UV-Vis spectroscopy. The synthesized PAMAM–TRIS dendrimers can be considered as new drug carrier systems and should find use in widespread application fields, especially in future pharmaceutical and catalytic studies but also in other fields.