In this work, we address the synthesis of stable spin-crossover nanoparticles capable of undergoing a hysteretic spin transition at room temperature. For this purpose, we use the reverse-micelle protocol to prepare naked [Fe(NHtrz)](NO) and core@shell [Fe(NHtrz)](NO)@SiO nanoparticles. Through meticulous adjustment of synthetic parameters, we achieved nanoparticle sizes ranging from approximately 40 nm to 60 nm. Our findings highlight that [Fe(NHtrz)](NO) presents a modest thermal hysteresis of 7 K, which decreases by downsizing. Conversely, silica-coated nanoparticles with sizes of 60 and 40 nm demonstrate a remarkable hysteretic response of approximately 30 K, switching their spin state around room temperature. Moreover, the presence of a SiO shell substantially enhances the nanoparticles' stability against oxidation. In this context, the larger 60 nm [Fe(NHtrz)](NO)@SiO hybrid remains stable in water for up to two hours, enabling the observation of an unreported water-induced spin transition after 30 min. Therefore, this work also introduces an intriguing avenue for inducing spin transitions through solvent exchange, underscoring the versatility and potential of these nanoparticles.
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http://dx.doi.org/10.1039/d4dt00911h | DOI Listing |
JACS Au
January 2025
Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
In this report, we describe the photoluminescence of a homoleptic uranium(IV) alkoxide complex. Excitation of [Li(THF)][U(O Bu)] leads to the first example of photoluminescence from a well-defined actinide complex originating from an f-f excitation, supported by second order multiconfigurational electronic structure calculations including spin-orbit coupling. These calculations show strong spin-orbit coupling between the excited triplet and singlet states for the 5f-orbital manifold, which leads to a long-lived excited state lifetime of 0.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China.
It is always important and fascinating to explore new organic emitters that exploit unconventional pathways to unveil their emission with unique properties, such as thermally activated delayed fluorescence (TADF). In this study, we report that the rarely explored sulfur lone pair (n) is a promising alternative, where the correlated π* → n emission can be used to attain strong TADF and thus practical OLEDs. The designed strategy incorporates several key concepts (Figure 1a), in which the persulfide aromatic spirocycle enhances spin-orbit coupling, thereby increasing the intersystem crossing rate.
View Article and Find Full Text PDFNat Commun
January 2025
Institut de Chimie de Strasbourg (UMR 7177, CNRS-Unistra), Université de Strasbourg, 4 rue Blaise Pascal, CS 90032, F-, Strasbourg, France.
Electric fields represent an ideal means for controlling spins at the nanoscale and, more specifically, for manipulating protected degrees of freedom in multispin systems. Here we perform low-temperature magnetic far-IR spectroscopy on a molecular spin triangle (Fe) and provide initial experimental evidence suggesting spin-electric transitions in polynuclear complexes. The co-presence of electric- and magnetic-dipole transitions, allows us to estimate the spin-electric coupling.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Chemistry, University of California, Berkeley, CA, USA.
The construction of thin film heterostructures has been a widely successful archetype for fabricating materials with emergent physical properties. This strategy is of particular importance for the design of multilayer magnetic architectures in which direct interfacial spin-spin interactions between magnetic phases in dissimilar layers lead to emergent and controllable magnetic behavior. However, crystallographic incommensurability and atomic-scale interfacial disorder can severely limit the types of materials amenable to this strategy, as well as the performance of these systems.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Saclay, 91400 Orsay, France.
Ni(II) complexes with an integer spin = 1 that behave as clock transition spin qubits at zero magnetic field are resilient to magnetic fluctuations of the spin bath, while Co(II) complexes with a half-integer spin ( = 3/2) lose their coherence when they are subject to the same fluctuating magnetic field as the Ni(II) ones. These findings demonstrate that adequately designed Ni(II) complexes are excellent candidates for spin qubits.
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