a Formation of assembly of Fe3O4 nanoparticles (NPs) onto PEG-functionalized graphene oxide for efficient magnetic Imaging and drug delivery are reported. Nanoscale graphene oxide (GO) was first synthesized and functionalized by branched, biocompatible polyethylene glycol (PEG) to render high aqueous solubility and stability in physiological solutions. Next, the meso-2,3-dimercaptosuccinnic acid-modified Fe3O4 NPs were anchored onto GO sheets via formation of amide bond in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC). It is found that the Fe3O4-PEG-GO nanocomposites possess good physiological stability and low cytotoxicity. Furthermore, controlled loading of aromatic drugs, doxorubicin (DOX), a typical anticancer drug, onto the Fe3O4-PEG-GO nanocomposites via π-π stacking and hydrophobic interactions is investigated. It is demonstrated that Fe3O4-PEG-GO/DOX loaded with the anticancer drug shows remarkably high cytotoxicity. The Fe3O4-PEG-GO/DOX nanocomposites show significantly enhanced cellular MRI, being capable of detecting cells at the iron concentration of 10 µg mL -1 with cell density of 2 × 10 5 cells mL -1 . The current work provides a general approach toward rational design and synthesis of a versatile theranostic nanoplatform based on Fe3O4-PEG-GO NPs with good biocompatibility and capability of simultaneously performing imaging and therapy for clinical outcomes.

While the chemistry of gold clusters has been developed rapidly, the knowledge of trinuclear gold clusters with low-valent gold remains scarce. Herein, we report the synthesis, structural characterization, and density...

The bonding between gold and main-group metallic elements (M) featuring Auδ−−Mδ+ polarity, has been studied recently. The gold in the bonds is expected to have the oxidation number of −1, and hence, nucleophilic. However, the knowledge of the reactivity of the gold-metal bonds remains limited. Here, we report digold-substituted germanes of the form of R’2Ge(AuPR3)(AuGeR’2) (3a; R = Me, 3b; R = Et), featuring two Au-Ge(IV) and one Au-Ge(II) bonds. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene pπ nature. A pendular motion of AuPR3 group between Ge(IV) and Ge(II) of 3 occurs in the NMR time scale, suggesting that the Ge(II) center has an enhanced electrophilicity to be attacked by the nucleophilic gold (−I) atom. 3a reacts with nucleophilic Cl− and electrophilic MeOTf reagents at Ge(II) and Ge(IV) centers, respectively.

Digoldgermanes with a gold coordinated by a dialkylgermylene ligand, R’2Ge(AuPR3)(AuGeR’2) (3a; R = Me, 3b; R = Et), were synthesized as green solids through the reactions of stable dialkylgermylene 1 with R3PAuCl followed by the reduction with KC8 at ambient temperatures. The structural characteristics of 3a and 3b were elucidated using NMR spectroscopy, X-ray crystallography, and DFT calculations. An intense absorption maximum was observed at 590 nm in the UV-vis spectrum of 3a in hexane. A pendular motion of AuPR3 group between Ge(IV) and Ge(II) of 3a and 3b occurring in the NMR time scale was found by the dynamic 1H NMR analysis, suggesting that the Ge(II) ligand has an enhanced electrophilicity to be attacked by the nucleophilic gold atom which closes to ‒1 oxidation state. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene pπ nature. We show the bond formation and activation alternatively at Au or Ge atom, a methylation of digoldgermane 3a with MeOTf affords methylgermane 5. Moreover, the digoldgermane 3a reacts with Cl− ion of Ph4PCl and CH3C(O)Cl smoothly to form the corresponding chloride-addition product 7 and chlorogoldgermane 9, respectively. Cyclic trimerization reactions of aromatic isocyanates were high-efficiently catalyzed by 3a giving the corresponding 1,3,5-triaryl isocyanurates.