Iron species with terminal oxo ligands are implicated as key intermediates in several synthetic and biochemical catalytic cycles. However, there is a dearth of structural information regarding these types of complexes because their instability has precluded isolation under ambient conditions. The isolation and structural characterization of an iron(III) complex with a terminal oxo ligand, derived directly from dioxygen (O2), is reported. A stable structure resulted from placing the oxoiron unit within a synthetic cavity lined with hydrogen-bonding groups. The cavity creates a microenvironment around the iron center that aids in regulating O2 activation and stabilizing the oxoiron unit. These cavities share properties with the active sites of metalloproteins, where function is correlated strongly with site structure.

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NaFePO4 with an olivine structure is synthesized via chemical delithiation of LiFePO4 followed by electrochemical sodiation of FePO4. Butylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (BMP-TFSI) ionic liquid (IL) with various sodium solutes, namely NaBF4, NaClO4, NaPF6, and NaN(CN)2, is used as an electrolyte for rechargeable Na/NaFePO4 cells. The IL electrolytes show high thermal stability (>350 °C) and nonflammability, and are thus ideal for high-safety applications. The highest conductivity and the lowest viscosity of the electrolyte are obtained with NaBF4. At an elevated temperature (above 50 °C), the IL electrolyte is more suitable than a conventional organic electrolyte for the sodium cell. At 75 °C, the measured capacity of NaFePO4 in a NaBF4-incorporated IL electrolyte is as high as 152 mAh g(-1) (at 0.05 C), which is near the theoretical value (154 mAh g(-1)). Moreover, 60% of this capacity can be retained when the charge-discharge rate is increased to 1 C.

The graphene nanosheet electrode with excellent high-rate performance and satisfactory cyclability is an ideal anode for sodium-ion batteries.

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The charge transfer resistances of practical sodium-ion battery electrodes in an ionic liquid (IL) electrolyte are unexpectedly low. A Na0.44MnO2-hard carbon full cell with an IL electrolyte has higher capacities (117 mA h g(-1)@0.1 C based on Na0.44MnO2) and greater stability (3% capacity decay after 100 cycles) than its conventional-electrolyte-based counterpart at 25 °C.

A new magnetic resonance/optical nanoprobe with specific cellular targeting capabilities based on nontoxic CuInS2/ZnS quantum dots (QDs) with direct covalent attachment of a Gd(III)-complex for tumor-specific imaging is reported. We introduce amphiphilic poly(maleic anhydride-alt-1-octadecene) to interdigitate with hydrophobic, protective agents on the surface of CuInS2/ZnS QDs that allows phase transfer of hydrophobic QDs from the organic into aqueous phase. Carbodiimide chemistry is used to covalently couple the Gd(III) complex on the surface of CuInS2/ZnS QDs, and then folic acid is further utilized to functionalize this dual-modality nanoprobe for active tumor targeting based on the fact that the membrane-associated folate receptor is overexpressed in many tumor cells. The longitudinal relaxivity value is 3.72 mM(-1) s(-1) for the dual-modality nanoprobe and a clear, positive, and increasing contrast enhancement of magnetic resonance signals concurrently with increasing Gd(III) concentration is observed. The dual-modality nanoprobe exhibits negligible cytotoxicity with >80% cell viability at a concentration of up to 100 μg/mL in human cervical (HeLa), human liver carcinoma (HepG2), and human breast (MCF-7) cells after 24 h. The specificity of folic-acid-conjugated nanoprobe cellular uptake has been investigated by confocal scanning laser imaging, which revealed that HeLa cells, expressing the folate receptor, internalized a higher level of dual-modality nanoprobes than HepG2 and MCF-7 cells.

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