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Metallic and bimetallic nanostructures have shown interesting chromatic and antibacterial properties, and they can be used in various applications. In this work, zinc (Zn) and iron (Fe) nanostructures were produced with different morphologies: (i) pure Zn; (ii) Zn-Fe nanoalloys; (iii) Zn-Fe nanolayers (Zn-Fe NLs); and (iv) Zn nanolayers combined with Fe nanoparticles (Zn NLs + Fe NPs). The aim was to produce components for food packaging materials with active and intelligent properties, including oxygen absorption capacity, chromatic properties, and antibacterial properties. Thus, the morphology, structure, and chemical composition of the samples were characterized and correlated with their oxidation, chromatic, and antibacterial properties. The results revealed a relevant reduction in the coating’s opacity after oxidation varying from 100 to 10% depending on the morphology of the system. All coatings exhibited significant antibacterial activity against S. aureus, revealing a direct correlation with Zn content. The incorporation of Fe for all atomic arrangements showed a negative impact on the antibacterial effect against E. coli, decreasing to less than half the zone of inhibition for Zn-Fe NLs and Zn NLs + Fe NPs and suppressing the antibacterial effect for Zn-Fe alloy when compared with the pure Zn system., This research was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the project NANOXYPACK-Nano-sized oxygen scavenger for new active food packaging (POCI-01-0145-FEDER-030789), co-financed by the European Regional Development Fund (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI)–COMPETE 2020. This research is also sponsored by FCT under the scope of strategic funding of UIDB/04469/2020 and UIDB/00285/2020 units., info:eu-repo/semantics/publishedVersion

A new mixed-valence ironIII-zincII diphosphate, Zn2+Fe3+2(P2O7)2, has been prepared by a dry way and characterized structurally by several techniques. Analysis of the powder diffraction pattern of the synthesized diphosphate showed that it is isostructural with the ironIII-ironII diphosphate, Fe2+Fe3+2(P2O7)2, crystallizing in an orthorhombic symmetry in the Pnma space group. Other physical properties were characterized using Mossbauer spectroscopy and Vibrating Sample Magnetometer measurements, which showed that this new phosphate with Fe3+ ions in VI coordination has a paramagnetic behavior at room temperature. Infrared and Raman spectroscopies were also used in this study to help characterizing structurally the new synthesized material.

A new valence-mixed iron(III)-zinc(II)-copper(II) pyrophosphate, Cu2+0.5 Zn2+0.5 Fe3+2 (P2O74−)2, has been synthesized by a dry-way method and structurally characterized by several techniques. The powder diffraction pattern of the new material shows that the pyrophosphate is isostructural with the iron(III)-iron(II) pyrophosphate Fe2+Fe3+2 (P2O74−)2, crystallizing in an orthorhombic arrangement in the Pnma space group. Cu2+Fe3+2 (P2O74−)2 was formed as a secondary phase, as determined both by X-ray diffraction and Mossbauer spectroscopy. Mossbauer spectroscopy and magnetometry measurements showed that Cu0.5Zn0.5Fe2(P2O7)2 is paramagnetic at room temperature and the iron ions are in octahedral coordination. Neel temperature is about 3 K. Infrared and Raman spectroscopies were also used in this study to characterize the new pyrophosphate.