Cooperative Effects in Copper Polyamido­amine Dendrimer Complexes Catalyzing the Reduction of Molecular Oxygen

Abstract

Generation-dependent cooperation was observed in the reduction of molecular oxygen by a series of Cu 2+ complexes of pyridine-modified polyamidoamine (PAMAM) dendrimers. The cooperative behavior of the metal ions was examined by preparing (G2-G6)-dendri-PAMAM-(Py) n and testing the dendrimers for their ability to reduce oxygen catalytically in the presence of several Cu 2+ ion concentrations. Spectrophotometric measurements during the reactive metallic ion titrations revealed that the maximum numbers of reactive Cu 2+ ions available for O 2 reduction were 4.8, 7.6, 22.2, 57.3, and 81.7 in each of the second-to sixth-generation (G2-G6) dendrimer complexes, respectively. An analysis revealed

Accelerated hydrolysis of boronic acid in a modified poly(amidoamine) dendrimer: identification of a factor leading to the production of an impurity in boronic acid containing poly(amidoamine) dendrimers

“…In addition to the NMR spectra, we also acquired and analyzed UV-Vis spectra for the investigated compounds. A local UV-Vis absorption maximum of 3 was observed at a wavelength of 235 nm, identical to the location of the maximum for CPBA (1). In contrast, no absorption maximum was found at this wavelength for 4, but instead at a wavelength of 253 nm, identical to the location of the absorption maximum observed for HBA ( Figure 5).…”

“…Dendrimers constitute a special class of synthetic dendritic macromolecules with a precisely controlled architecture and a very large number of peripheral functional groups. Due to their characteristic properties, dendrimers have been used in various fields, including as catalysts 1 and metal ion extractors 2 . The current obstacles to the preparation of designed dendrimer products are the lack of efficient synthetic approaches and the tedious purification procedures.…”

“…The yellow oil was dissolved in MeOH (5 mL) and purified by column chromatography (sephadex LH20, 3.5 x 60 cm, eluted by MeOH). (0.02 g, 10 %) 1. H NMR (400 MHz, CD 3 OD, ppm) δ: 7.74 (d, J = 8, 2H), 6.84 (d, J = 8, 2H), 3.64~3.48 (m, 116H), 3.37 (m, 56H), 3.24 (m, 56H), 2.69 (m, 56H); 13 C NMR (100 MHz, CD 3 OD, ppm) δ: 173.1, 170.2, 162.1, 130.4, 126.3, 116.2, 53.7, 51.4, 49.9, 40.5, 40.4, 35.8, 30.7, 30.5; PDI: 1.22 ARS staining method analysis General Procedure An 83.2 µM solution of ARS in DMF as solution A.…”

Importance of Binding Affinity for the Activity of a Metallodendritic Chemical Nuclease

“…To explore the relationship between dendrimer binding affinity and nuclease activity, the number of Cu ions in each dendrimer must be the same to prevent any possible bias associated with a different number of Cu ions in each dendrimer. In previous work [29], each G2-dendrimer ( 2a ) molecule was found to bind to no more than six copper ions. Accordingly, six equivalents of copper ions were coordinated to each dendrimer generation ( 2a – 2e ) to form hexaCu complexes 5a – 5e , respectively, and these complexes were subjected to nuclease activity assays.…”

EPR Characterization of Copper(II) Complexes of PAMAM-Py Dendrimers for Biocatalysis in the Absence and Presence of Reducing Agents and a Spin Trap

“…In lower generations of metallodendrimers, each Cu­(II) ion individually catalyzed molecular oxygen reduction. In contrast, the active center in fifth and sixth generation dendrimers contained bicopper complexes . These metallodendrimers not only have promising applications for biomedical uses, like anticancer and antiamyloidogenesis drugs and biocatalysts, but also constitute an excellent model and a platform to study interactions of Cu­(II) in nanosized macromolecules.…”