Construction Of Supramolecular Dendrimer Driven By Host-Guest Hydrophobic Interactions

Dendrimers are monodispersed hyperbranched macromolecules with three-dimensions nanosized shapes. The multi-functionalization, solubility, viscosity and thermodynamic properties of dendrimers are very different from the regular linear polymer. The specificities of dendrimer structure makes it possible to construct function carrier and physical packing of small molecular using dendrimers. As an attractive and elegant class of architectures, they are capable of generating potential applications ranging from materials science to biology.However, even though the synthesis of dendritic molecules is iterative and involves simple repetitive synthetic steps, it is still often time-consuming and tedious to generate perfect nanoscale dendritic structures.Supramolecular chemistry is another key area of modern molecular science. Nanosized structure could be constructed employing noncovalent interactions from designed appropriate building blocks. Compared with covalent bonds, the noncovalent interaction indicate special properties including reversible, controllable and specific way etc. As a result, this conception was also applied to extend the generation of dendrimer molecular and generate new dendron structure. The self-assembled supramolecular dendrimers often displayed novel special characters and potential applications. Many molecular models have been established and investigated.Nowadays, the driving forces employed to construct supramolecular dendrimer that has been reported mainly included the hydrogen bonds and metal cooperate interactions. And some examples using ion interactions also have been reported. Compared to the supramolecular architectures formed through self-assembly of integrated dendritic unit synthesized beforehand,4 however, the design and synthesis of discrete dendrimers based on the complete self-assembly of nondendritic building blocks are still limited. The design and synthesis of complete self-assembled monodispersed dendrimers from simple building blocks based on noncovalent hydrophobic interactions presents a great challenge.Herein we report for the first time the approach for the supramolecular synthesis of dendrimers based on self-assembly driven by hydrophobically host-guest interaction, and the nanosized dendritic macromolecular functionalized through carrying catalytic center tellurium could act as an efficient artificial enzyme scaffold.First of all, we design and generate small molecular building blocks through organic synthesis method, including 6,6'-telluro-bis(6-deoxy-β-cyclo- dextrin) (6-TediCD) and a adamantine trimer molecular. The IR spectrum, H1 NMR and maldi-tof Mass spectrum were used to characterize the structures of these compoundsUnder the ultrasonic situation in the polar solvent, the regular growth of the dendritic complex can be obtained through controlling the reaction conditions. The aimed products was obtained after purifying the mixed solution on a column of Sephadex G-75 under the inspect of UV-vis spectrum. H1 NMR, Atom Force Microscope and Scanning electronic Microscope etc. were used to characterize the complex structure and shape. These dispersed sphere images in the experiments indicate that we have succeeded in preventing the formation of random crosslinking structure and achieving the regular growth of the dendritic complex.The compound 6-TediCD, one of the building blocks in our system, was previously designed as a peroxidase model for its special molecular structure. The supramolecular dendrimer based 6-TediCD also indicate high anti-oxidation activity. Based upon the disappearance of thiolate that can be easily followed spectrophotometrically at 410 nm, the initial rates of the reduction of hydrogenperoxide (ROOH) by CNBSH in the presence of dendrimer catalysts at pH 7.0 and 25°C are determined. As the dendrimer generation grows, the activity of dendrimer catalysts enhanced dramatically. The reasons of this phenomenon were attributed to dendrimer effects such as statistics and cooperative effect and the micro-environment generated by dendron structure.We have demonstrated a new strategy for synthesizing regular supramolecular dendritic macromolecules driven by hydrophobic host-guest interactions from nondendritic units for the first time. We anticipate that this strategy should become a promising and versatile one for the developing functional supramolecular dendrimers.