Abstract
We demonstrate a strategy inspired by natural siderophores for the dissolution of platinum nanoparticles that could enable their size-selective synthesis, toxicological assessment, and the recycling of this precious metal. From the fabrication of electronics to biomedical diagnosis and therapy, PtNPs find increasing use. Mitigating concerns over potential human toxicity and the need to recover precious metal from industrial debris motivates the study of bio-friendly reagents to replace traditional harsh etchants. Herein, we report a family of redox-active siderophore-viz. π-acceptor azo aromatic ligands (L) that spontaneously ionize and chelate Pt atoms selectively from nanoparticles of size ≤6 nm. The reaction produces a monometallic diradical complex, PtII(L˙−)2, isolated as a pure crystalline compound. Density functional theory provides fundamental insights on the size dependent PtNP chemical reactivity. The reported findings reveal a generalized platform for designing π-acceptor ligands to adjust the size threshold for dissolution of Pt or other noble metals NPs. Our approach may, for example, be used for the generation of Pt-based therapeutics or for reclamation of Pt nano debris formed in catalytic converters or electronic fabrication industries.
Highlights
We demonstrate a strategy inspired by natural siderophores for the dissolution of platinum nanoparticles that could enable their size-selective synthesis, toxicological assessment, and the recycling of this precious metal
We demonstrated siderophore-like reactivity of azo-aromatic ligands that spontaneously and size-selectively dissolve PtNPs forming monometallic Pt(II) complexes
These azo-aromatic ligands can be applied to decrease the polydispersity of a NP preparation, to prepare Pt-based therapeutics as PtNPs of suitable size (>6 nm) or the [PtII(LcÀ)2] complexes resulting from NP dissolution, and to detect PtNPs as a size-selective colorimetric assay
Summary
While PtNPs have found numerous applications, concerns over how to recover the precious metal from catalytic converters or fabricated electronics, as well as concerns about toxicity from increased human exposure have emerged.[17] The bene cial or detrimental physicochemical properties of PtNPs critically depend on their shape and size. PtNPs with diameters #6 nm were found to cause heptao- and genotoxicity, the nature and mechanism of the size-dependent effects remain unclear.[1,17,18,19] There is a pressing need to enable hEnergy Sciences Institute, Yale University, 810 West Campus Drive, West Haven, Connecticut 06516, USA iDepartment of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore jDepartment of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore † Electronic supplementary information (ESI) available.
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