Journal
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume 139, Issue 39, Pages 13701-13712Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jacs.7b01445
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Funding
- NSF project Ceramic Quasicrystals [NSF 1411014]
- NSF project Energy- and Cost-Efficient Manufacturing Employing Nanoparticles [NSF 1463474]
- Center for Photonic and Multiscale Nanomaterials (C-PHOM) - National Science Foundation (NSF) Materials Research Science and Engineering Center program [DMR 1120923]
- NSF [1403777]
- China Scholarship Council
- Tianjin University
- Swiss National Science Foundation Early Postdoc Mobility Fellowship [P2GEP2-165061]
- Swiss National Science Foundation (SNF) [P2GEP2_165061] Funding Source: Swiss National Science Foundation (SNF)
- Directorate For Engineering
- Div Of Civil, Mechanical, & Manufact Inn [1463474] Funding Source: National Science Foundation
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1411014] Funding Source: National Science Foundation
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The chirality of nanoparticles (NPs) and their assemblies has been investigated predominantly for noble metals and II VI semiconductors. However, ceramic NPs represent the majority of nanoscale materials in nature. The robustness and other innate properties of ceramics offer technological opportunities in catalysis, biomedical sciences, and optics. Here we report the preparation of chiral ceramic NPs, as represented by tungsten oxide hydrate, WO3-x center dot H2O, dispersed in ethanol. The chirality of the metal oxide core, with an average size of ca. 1.6 nm, is imparted by proline (Pro) and aspartic acid (Asp) ligands via bio-to-nano chirality transfer. The amino acids are attached to the NP surface through C-O-W linkages formed from dissociated carboxyl groups and through amino groups weakly coordinated to the NP surface. Surprisingly, the dominant circular dichroism bands for NPs coated by Pro and Asp are different despite the similarity in the geometry of the NPs; they are positioned at 400-700 nm and 500-1100 nm for Pro- and Asp-modified NPs, respectively. The differences in the spectral positions of the main chiroptical band for the two types of NPs are associated with the molecular binding of the two amino acids to the NP surface; Asp has one additional C-O-W linkage compared to Pro, resulting in stronger distortion of the inorganic crystal lattice and greater intensity of CD bands associated with the chirality of the inorganic core. The chirality of WO3-x center dot H2O atomic structure is confirmed by atomistic molecular dynamics simulations. The proximity of the amino acids to the mineral surface is associated with the catalytic abilities of WO3-x center dot H2O NPs. We found that NPs facilitate formation of peptide bonds, leading to Asp-Asp and Asp-Pro dipeptides. The chiroptical-activity, chemical reactivity, and biocompatibility of tungsten oxide create a unique combination of properties relevant to chiral optics, chemical technologies, and biomedicine.
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