Using a successive method, PAMAM dendrimer‐encapsulated bimetallic PdPt nanoparticles have been successfully prepared with core‐shell structures (Pd@Pt DENs). Evidenced by UV‐vis spectra, high resolution transmission electron microscopy, and X‐ray energy dispersive spectroscopy (EDS), the obtained Pd@Pt DENs are monodispersed and located inside the cavity of dendrimers, and they show a different structure from monometallic Pt or Pd and alloy PdPt DENs. The core‐shell structure of Pd@Pt DENs is further confirmed by infrared measurements with carbon monoxide (IR‐CO) probe. In order to prepare Pd@Pt DENs, a required Pd/Pt ratio of 1:2 is determined for the Pt shell to cover the Pd core completely. Finally, a mechanism for the formation of Pd@Pt DENs is proposed. 相似文献
Poly(amidoamine) dendrimers are very interesting macromolecules with highly branched structures and globular-shaped branched polymeric architectures. They are widely used for drug and gene delivery applications. In order to provide important insight into the interactions of poly(amidoamine) dendrimers with some organic acceptors, the binding of small molecules to 4-hexylamino-1,8-naphthalimide-labelled PAMAM dendrimer (PD) have been studied by spectrophotomeric method. The acceptors used in this research include chloranilic acid (CLA), p-chloranil (CHL), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), 7,7?,8,8?-tetracyanoquinodimethane (TCNQ), picric acid (PA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and iodine monobromide (IBr). The spectrophotometric measurements proved that all the charge-transfer (CT) complexes are formed via a stoichiometry (PD: acceptor) of 1:2 (except for IBr acceptor). Accordingly the obtained complexes could be formulated as [(PD)(CLA)2], [(PD)(DCQ)2], [(PD)(DBQ)2], [(PD)(TCNQ)2], [(PD)(PA)2], [(PD)(CHL)2], [(PD)(DDQ)2] and [(PD)(IBr)4]. Benesi–Hildebrand and its modification methods were applied to estimate the spectroscopic and physical data. 相似文献
A novel procedure to fabricate a nonenzymatic hydrogen peroxide sensor was developed based on a silver-poly (amide amine) dendrimer nanocomposite synthesized by a microwave procedure. The formation of silver nanoparticles functionalized with the poly (amide amine) dendrimer was confirmed by ultraviolet visible spectroscopy, high resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The electroanalytical properties of a glassy carbon electrode modified with the silver-poly (amide amine) dendrimer nanocomposite were evaluated by the determination of hydrogen peroxide. The electrochemical sensor exhibited rapid response and high sensitivity to hydrogen peroxide with a linear dynamic range from 1.0 × 10–5 to 3.7 × 10–3 molar (r = 0.998) and a limit of detection of 5.06 micromolar. The sensitivity was 30.24 microampere · per millilmolar per square centimeter and the response time was three seconds at a working potential of ?0.35 volt. In addition, the sensor was unaffected by the presence of ascorbic acid, citric acid, and oxalic acid. These results indicate that the silver-poly (amide amine) dendrimer nanocomposite based sensor has application for the determination of hydrogen peroxide. 相似文献
Degradable dendrimer‐like PEOs were designed using an original ABC‐type branching agent featuring a cleavable ketal group, following an iterative divergent approach based on the anionic ring opening polymerization (AROP) of ethylene oxide and arborization of PEO chain ends. A seventh generation dendrimer‐like PEO carrying 192 peripheral hydroxyls and exhibiting a molar mass of 446 kg · mol−1 was obtained in this way. The chemical degradation of these dendritic scaffolds was next successfully accomplished under acidic conditions, forming linear PEO chains of low molar mass (≈2 kg · mol−1), as monitored by 1H NMR, SEC, and MALDI‐TOF mass spectrometry as well as by AFM.
