Spin crossover (SCO) complexes have been extensively explored as bistable materials and recently used as molecular modules for the development of new multifunctional molecular magnetic materials. Herein, we present the synthesis, crystal structure, magnetic, and electrical properties of a mononuclear cobalt complex constructed by a halogen-functionalized terpyridine derivative and organosulfonate. A complete and gradual spin transition with the T =200 K was observed for the Co ions through both the magnetic measurement and dynamic crystallographic experiments. Interestingly, considerable room temperature proton conductivity of 6.9×10 S cm under 98% relative humidity was evidenced because of the presence of sulfonate-assisted hydrogen-bonded proton hopping pathways. The forgoing results not only provide an unprecedented proton-conducting cobalt(II) SCO complex but also a promising way for the design and construction of bifunctional SCO molecular conductors via the incorporation of SCO transition and proton conduction.
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http://dx.doi.org/10.1002/asia.202200949 | DOI Listing |
J Phys Condens Matter
January 2025
Department of Physics and Astronomy, University of Nebraska, 855 North 16th Street, Lincoln , 68588-0299, UNITED STATES.
From a comparison of the known molecular stoichiometry and X-ray photoemission spectroscopy (XPS), it is evident that the Fe(III) spin crossover salt [Fe(qsal)2Ni(dmit)2], where qsal = N(8quinolyl)salicylaldimine, and dmit2- = 1,3-dithiol-2-thione-4,5-dithiolato has a preferential surface termination with the Ni(dmit)2 moiety. This preferential surface termination leads to a significant surface to bulk core level shift for the Ni 2p X-ray photoemission core level, not seen in the corresponding Fe 2p core level spectra. A similar surface to bulk core level shift is seen in Pd 3d in the related [Fe(qsal)2]2Pd(dmit)2, ], where qsal = N(8quinolyl)salicylaldimine, and dmit2- = 1,3-dithiol-2-thione-4,5-dithiolato.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
Laboratoire de Chimie de Coordination, CNRS & Université de Toulouse (UPS, INP), 31077 Toulouse, France.
Spin crossover (SCO) iron (II) coordination compounds in the form of nanohybrid SCO@SiO particles were prepared using a reverse micelles technique based on the TritonX-100/cyclohexane/water ternary system. Tetraethyl orthosilicate (TEOS) acts as precursor of both the SiF counter-anion and SiO to obtain Fe(NHtrz)(BF)(SiF)@SiO nanoparticles with different sizes and morphologies while modifying the TEOS concentration and reaction time. The adjustable mixed-anion strategy leads to a range of quite scarce abrupt spin crossover behaviors with hysteresis just above room temperature (ca.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
An modelling workflow is used to predict the thermoelectric properties and figure of merit of the lanthanide cobalates LaCoO, PrCoO and NdCoO in the orthorhombic phase with the low-spin magnetic configuration. The LnCoO show significantly lower lattice thermal conductivity than the widely-studied SrTiO, due to lower phonon velocities, with a large component of the heat transport through an intraband tunnelling mechanism characteristic of amorphous materials. Comparison of the calculations to experimental measurements suggests the p-type electrical properties are significantly degraded by the thermal spin crossover, and materials-engineering strategies to suppress this could yield improved .
View Article and Find Full Text PDFJ Chem Phys
January 2025
Université Paris-Saclay, UVSQ, CNRS, GEMaC, 45 Avenue des Etats Unis, 78035 Versailles, France.
Among the large family of spin-crossover (SCO) solids, recent investigations focused on polynuclear SCO materials, whose specific molecular configurations allow the presence of multi-step transitions and elastic frustration. In this contribution, we develop the first elastic modeling of thermal and dynamical properties of trinuclear SCO solids. For that, we study a finite SCO open chain constituted of successive elastically coupled trinuclear (A=B=C) blocks, in which each site (A, B, and C) may occupy two electronic configurations, namely, low-spin (LS) and high-spin (HS) states, accompanied with structural changes.
View Article and Find Full Text PDFChemistry
January 2025
School of Chemistry, University College Dublin, Belfield, Dublin 4, D04 N2E5, Ireland.
Symmetry breaking spin state transitions in two of three isostructural salts of Mn spin crossover cations, [Mn(3-OMe-5-NO-sal323)], with heavy anions are reported. The ReO (1) salt undergoes two-step spin crossover which is coupled with a re-entrant symmetry breaking structural phase transition between a high temperature phase (S=2, C2/c), an intermediate ordered phase (S=1/S=2, P2/c), and a low temperature phase (S=1, C2/c). The AsF (2) complex undergoes an abrupt transition between a high temperature phase (S=2, C2/c) and a low temperature ordered phase (S=1/S=2, P ).
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