Manipulating individual molecular spin states with electronic current has the potential to revolutionize quantum information devices. However, it is still unclear how a current can cause a spin ...transition in single-molecule devices. Here, we propose a spin-crossover (SCO) mechanism induced by electron–phonon coupling in an iron(II) phthalocyanine molecule situated on a graphene-decoupled Ir(111) substrate. We performed simulations of both elastic and inelastic electron tunneling spectroscopy (IETS), which reveal current-induced Fe–N vibrations and an underestimation of established electron-vibration signals. Going beyond standard perturbation theory, we examined molecules in various charge and spin states using the Franck–Condon framework. The increased probability of spin switching suggests that notable IETS signals indicate SCO triggered by the inelastic vibrational excitation associated with Fe–N stretching.
Chirality-induced spin selectivity (CISS), whereby helical molecules polarize the spin of electrical current, is an intriguing effect with potential applications in nanospintronics. In this nascent ...field, the study of the CISS effect using paramagnetic chiral molecules, which could introduce another degree of freedom in controlling the spin transport, remains so far unexplored. To address this challenge, herein we propose the use of self-assembled monolayers (SAMs) of helical lanthanide-binding peptides. To elucidate the effect of the paramagnetic nuclei, monolayers of the peptide coordinating paramagnetic or diamagnetic ions are prepared. By means of spin-dependent electrochemistry, the CISS effect is demonstrated by cyclic voltammetry and electrochemical impedance measurements for both samples. Additionally, an implementation of the standard liquid-metal drop electron transport setup has been carried out, and this process helped to demonstrate the peptides’ suitability for solid-state devices. Remarkably, the inclusion of a paramagnetic center in the peptide increases the spin polarization as was independently proved by different techniques. These findings permit the inclusion of magnetic biomolecules in the CISS field and pave the way to their implementation in a new generation of (bio)spintronic nanodevices.
The postharvest life of most fruit and vegetables is limited by fungus proliferation. The Aloe vera gel was added at different concentrations to test its antifungal potential against five fungi ...(Rhizoctonia solani, Curvularia hawaiiensis, Botryotinia fuckeliana, Penicillium italicum, Verticillium dahliae), which cause significant losses in basic agricultural products included in the world's diet: tuber potato, cereals, fruit and vegetables. The best results were for the fungus Verticillium dahlie, with a mycelial growth inhibition of 100% and 70% at 200 and 100 mL/L, respectively. Satisfying results were for fungi R. solani and B. fuckeliana, where the mycelial growth inhibition exceeded 50% in them all at 200 mL/L. Antifungal activity was maintained in B. fuckeliana by lowering the dose to 100 mL/L. The Aloe vera extract at 300 mL/L was applied as a coating in the postharvest treatment to blueberry fruit at 21 °C and 85% humidity. When the experiment ended, the percentage of rotted berries was significantly lower in the treated than in the control. The Aloe vera gel could be considered a promising postharvest treatment to maintain blueberry quality and turgor during storage.
•Aloe vera leaf extract inhibited postharvest fungi in a dose-dependent manner.•Verticillium dahliae had the best results with total inhibition of mycelial growth.•Antifungal activity was maintained in B. fuckeliana by lowering the dose.•The natural film created extended shelf life and maintained blueberry quality.
Three decades of research in molecular nanomagnets have raised their magnetic memories from liquid helium to liquid nitrogen temperature thanks to a wise choice of the magnetic ion and coordination ...environment. Still, serendipity and chemical intuition played a main role. In order to establish a powerful framework for statistically driven chemical design, here we collected chemical and physical data for lanthanide-based nanomagnets, catalogued over 1400 published experiments, developed an interactive dashboard (SIMDAVIS) to visualise the dataset, and applied inferential statistical analysis. Our analysis shows that the Arrhenius energy barrier correlates unexpectedly well with the magnetic memory. Furthermore, as both Orbach and Raman processes can be affected by vibronic coupling, chemical design of the coordination scheme may be used to reduce the relaxation rates. Indeed, only bis-phthalocyaninato sandwiches and metallocenes, with rigid ligands, consistently present magnetic memory up to high temperature. Analysing magnetostructural correlations, we offer promising strategies for improvement, in particular for the preparation of pentagonal bipyramids, where even softer complexes are protected against molecular vibrations.
Developing new functionalities of two-dimensional materials (2Dms) can be achieved by their chemical modification with a broad spectrum of molecules. This functionalization is commonly studied by ...using spectroscopies such as Raman, IR, or XPS, but the detection limit is a common problem. In addition, these methods lack detailed spatial resolution and cannot provide information about the homogeneity of the coating. Atomic force microscopy (AFM), on the other hand, allows the study of 2Dms on the nanoscale with excellent lateral resolution. AFM has been extensively used for topographic analysis; however, it is also a powerful tool for evaluating other properties far beyond topography such as mechanical ones. Therefore, herein, we show how AFM adhesion mapping of transition metal chalcogenide 2Dms (i.e., MnPS3 and MoS2) permits a close inspection of the surface chemical properties. Moreover, the analysis of adhesion as relative values allows a simple and robust strategy to distinguish between bare and functionalized layers and significantly improves the reproducibility between measurements. Remarkably, it is also confirmed by statistical analysis that adhesion values do not depend on the thickness of the layers, proving that they are related only to the most superficial part of the materials. In addition, we have implemented an unsupervised classification method using k-means clustering, an artificial intelligence-based algorithm, to automatically classify samples based on adhesion values. These results demonstrate the potential of simple adhesion AFM measurements to inspect the chemical nature of 2Dms and may have implications for the broad scientific community working in the field.
Molecular spin qubits are chemical nanoobjects with promising applications that are so far hampered by the rapid loss of quantum information, a process known as decoherence. A strategy to improve ...this situation involves employing so-called Clock Transitions (CTs), which arise at anticrossings between spin energy levels. At CTs, the spin states are protected from magnetic noise and present an enhanced quantum coherence. Unfortunately, these optimal points are intrinsically hard to control since their transition energy cannot be tuned by an external magnetic field; moreover, their resilience towards geometric distortions has not yet been analyzed. Here we employ a python-based computational tool for the systematic theoretical analysis and chemical optimization of CTs. We compare three relevant case studies with increasingly complex ground states. First, we start with vanadium(
iv
)-based spin qubits, where the avoided crossings are controlled by hyperfine interaction and find that these
S
= 1/2 systems are very promising, in particular in the case of vanadyl complexes in an L-band pulsed EPR setup. Second, we proceed with a study of the effect of symmetry distortions in a holmium polyoxotungstate of formula Ho(W
5
O
18
)
2
9
where CTs had already been experimentally demonstrated. Here we determine the relative importance of the different structural distortions that causes the anticrossings. Third, we study the most complicated case, a polyoxopalladate cube HoPd
12
(AsPh)
8
O
32
5−
which presents an unusually rich ground spin multiplet. This system allows us to find uniquely favorable CTs that could nevertheless be accessible with standard pulsed EPR equipment (X-band or Q-band) after a suitable chemical distortion to break the perfect cubic symmetry. Since anticrossings and CTs constitute a rich source of physical phenomena in very different kinds of quantum systems, the generalization of this study is expected to have impact not only in molecular spin science but also in other related fields such as molecular photophysics and photochemistry.
We employ a python computational tool to compare 3 relevant case studies with increasingly complex ground states: vanadyl complexes, Ho(
iii
) square antiprisms and Ho(
iii
) cubic structures.
Development of new memristive hardware is a technological requirement towards widespread neuromorphic computing. Molecular spintronics seems to be a fertile field for the design and preparation of ...this hardware. Within molecular spintronics, recent results on metallopeptides demonstrating the interaction between paramagnetic ions and the chirality induced spin selectivity effect hold particular promise for developing fast (ns-μs) operation times. R. Torres-Cavanillas et al., J. Am. Chem. Soc., 2020, DOI: 10.1021/jacs.0c07531. Among the challenges in the field, a major highlight is the difficulty in modelling the spin dynamics in these complex systems, but at the same time the use of inexpensive methods has already allowed progress in that direction. Finally, we discuss the unique potential of biomolecules for the design of multistate memristors with a controlled- and indeed, programmable-nanostructure, allowing going beyond anything that is conceivable by employing conventional coordination chemistry.
As genomic architectures become more complex, they begin to accumulate degenerate and redundant elements. However, analyses of the molecular mechanisms underlying these genetic architecture features ...remain scarce, especially in compact but sufficiently complex genomes. In the present study, we followed a proteomic approach together with a computational network analysis to reveal molecular signatures of protein function degeneracy from a plant virus (as virus-host protein-protein interactions). We employed affinity purification coupled to mass spectrometry to detect several host factors interacting with two proteins of Citrus tristeza virus (p20 and p25) that are known to function as RNA silencing suppressors, using an experimental system of transient expression in a model plant. The study was expanded by considering two different isolates of the virus, and some key interactions were confirmed by bimolecular fluorescence complementation assays. We found that p20 and p25 target a common set of plant proteins including chloroplastic proteins and translation factors. Moreover, we noted that even specific targets of each viral protein overlap in function. Notably, we identified argonaute proteins (key players in RNA silencing) as reliable targets of p20. Furthermore, we found that these viral proteins preferentially do not target hubs in the host protein interactome, but elements that can transfer information by bridging different parts of the interactome. Overall, our results demonstrate that two distinct proteins encoded in the same viral genome that overlap in function also overlap in their interactions with the cell proteome, thereby highlighting an overlooked connection from a degenerate viral system.
The anchoring of the molecule to an electrode is known to be a key factor in single-molecule spintronics experiments. Likewise, a relaxation down to the most stable geometry is a critical step in ...theoretical simulations of transport through single-molecule junctions. Herein we present a set of calculations designed to analyze and compare the effect of different anchoring points and the effect of perturbations in the molecular geometry and interelectrode distance. As model system we chose the V(α-C3S5)32− complex connecting two Au(1 1 1) electrodes in a slightly compressed geometry. In our calculations, the attachment happens through an S-Au bond, a common anchoring strategy in molecular spintronics experiments. Our results confirm that small alterations in the molecular geometry have important effects in the conductance. We were able to compare these effects with the ones arising from changing the anchoring position with a constant molecular geometry. Unexpectedly, we demonstrate that the anchoring position has only a lesser relevance in the spintronic behavior of the device, as long as all other parameters are kept frozen. As a consequence, we predict that for experimentalists aiming for reproducibility, the molecular design of rigid linkers is more relevant than the design of univocal anchoring positions.
The postharvest life of most fruit, vegetables and cereals is limited by fungal proliferation. The chemical composition of Mentha piperita, M. spicata and M. suaveolens essential oils (EO), and the ...antifungal activity against four pathogenic and post-harvest fungi isolated from food, were herein investigated to evaluate their potential as natural food preservatives. The EO were obtained by hydrodistillation of aerial parts leaves, stems and inflorescences (except for peppermint oil, which was purchased in a specialized store) and submitted to GC-MS and GC-FID analysis. Regarding the EO composition, carvone (41.1%) and limonene (14.1%) were the major compounds in M. spicata, menthol (47.0%) and menthone (23.1%), as well as other menthol derivatives (neomenthol -3.6%- and menthofurane -3.7%-) in M. piperita, and piperitone oxide (40.2%) and piperitenone oxide (31.4%) in M. suaveolens. Botryotinia fuckeliana was the most sensitive fungus. The three studied EO inhibited growth by 92–100%. The highest dose of M. suaveolens EO, 400 µg/mL, produced 100% MGI in all the studied fungi, except Fusarium oxysporum with 94.21%. The M. suaveolens EO can be considered to develop a low-risk enviro-friendly botanical biofungicide.
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