Molecular Spin Crossover Materials: Recent Trends, Emerging Properties and Applications

A special issue of Magnetochemistry (ISSN 2312-7481). This special issue belongs to the section "Spin Crossover and Spintronics".

Deadline for manuscript submissions: closed (20 July 2023) | Viewed by 18968

Special Issue Editor

Foundation for Research and Technology, Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Department of Chemistry, University of Patras, GR-26504 Patras, Greece
Interests: molecular inorganic chemistry; spin crossover phenomenon; raman spectroscopy; metal organic frameworks
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Although spin crossover has constituted a well-known phenomenon for over a century, it still attracts the interest of researchers from various fields. The SCO phenomenon refers to the exchange between two well-defined high-spin (HS) and low-spin (LS) states, mainly occurring in six-coordinate first-row transition metal complexes with d4–d7 configurations. SCO materials have been considered ideal candidates for various applications, being active components in nanotechnological devices, for example, in sensors, memory storage units, displays or actuators. Several research efforts are dedicated to SCO materials, since it is a quite delicate process which is fairly affected by several influencing factors, including intraligand substitution, particle size, cooperativity/intermolecular interactions, and the presence of counter-anions/solvent molecules in the lattice.

In this context, this Special Issue will compile recent developments in SCO materials concerning their applications, key features, and future trends. The main goal of this attempt is to highlight cutting-edge research activities focusing on the synthesis, characterization and implementation of SCO mononuclear and polynuclear coordination complexes and polymers (including Metal Organic Frameworks). The new findings, the persisting bottlenecks and future perspectives concerning the topic shall be elaborated.  

We encourage the submission of Original Research, Communications, Review, Mini Review and Perspective articles on this topic.

Dr. Zoi G. Lada
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Magnetochemistry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Spin Crossover Phenomenon
  • coordination chemistry
  • nanomaterials
  • Metal Organic Frameworks
  • Fe(II) coordination complexes
  • sensors
  • data storage

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

12 pages, 2078 KiB  
Article
Single-Molecule Magnets Based on Heteroleptic Terbium(III) Trisphthalocyaninate in Solvent-Free and Solvent-Containing Forms
by Maxim A. Faraonov, Alexander G. Martynov, Marina A. Polovkova, Salavat S. Khasanov, Yulia G. Gorbunova, Aslan Yu. Tsivadze, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa and Dmitri V. Konarev
Magnetochemistry 2023, 9(2), 36; https://doi.org/10.3390/magnetochemistry9020036 - 19 Jan 2023
Cited by 3 | Viewed by 1651
Abstract
Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H [...] Read more.
Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H4Cl2 (2). In the crystal structure of 2, the Tb-N(Pc) distances to the nitrogen atoms in the outer and inner decks are 2.350–2.367(4) and 2.583–2.598(4) Å, respectively, and the Tb–Tb distance is 3.4667(3) Å. The twist angle between the outer and the inner decks is 42.6°. The magnetic properties were studied for both 1 and 2. The χMT magnitude of 23.3 emu⋅K/mol at 300 K indicates a contribution of two TbIII centers with the 7F6 ground state. The χMT product increases with decreasing temperature to reach 38.5 emu⋅K/mol at 2 K. This is indicative of ferromagnetic coupling between TbIII spins in accordance with previous data for triple-decker lanthanide phthalocyaninates of a dipolar nature. Both forms show a single-molecule magnet (SMM) behavior manifesting the in-phase (χ′) and out-of-phase (χ″) AC susceptibility signals in an oscillating field of 3 Oe with estimated effective spin-reversal energy barriers (Ueff) of 222(9) and 93(7) cm−1 for 1 and 2, respectively. The compounds show narrow hysteresis loops in the −1 – +1 kOe range, and the splitting between the zero-field-cooling and field-cooling curves is observed below 6 K. Thus, in spite of similar static magnetic characteristics, each form of the Tb(III) complex shows a different dynamic SMM behavior. Full article
Show Figures

Graphical abstract

15 pages, 2463 KiB  
Article
The Halogen Effect on the Magnetic Behaviour of Dimethylformamide Solvates in [Fe(halide-salEen)2]BPh4
by Rafaela T. Marques, Frederico F. Martins, Deniz F. Bekiş, Ana I. Vicente, Liliana P. Ferreira, Clara S. B. Gomes, Sónia Barroso, Varun Kumar, Yann Garcia, Nuno A. G. Bandeira, Maria José Calhorda and Paulo N. Martinho
Magnetochemistry 2022, 8(12), 162; https://doi.org/10.3390/magnetochemistry8120162 - 22 Nov 2022
Cited by 2 | Viewed by 1739
Abstract
Complexes [Fe(X-salEen)2]BPh4·DMF, with X = Br (1), Cl (2), and F (3), were crystallised from N,N′-dimethylformamide with the aim of understanding the role of a high boiling point N, [...] Read more.
Complexes [Fe(X-salEen)2]BPh4·DMF, with X = Br (1), Cl (2), and F (3), were crystallised from N,N′-dimethylformamide with the aim of understanding the role of a high boiling point N,N′-dimethylformamide solvate in the spin crossover phenomenon. The counter ion was chosen for only being able to participate in weak intermolecular interactions. The compounds were structurally characterised by single crystal X-ray diffraction. Complex 1 crystallised in the orthorhombic space group P212121, and complexes 2 and 3 in the monoclinic space group P21/n. Even at room temperature, low spin was the predominant form, although complex 2 exhibited the largest proportion of the high-spin species according to both the magnetisation measurements and the Mössbauer spectra. Density Functional Theory calculations were performed both on the periodic solids and on molecular models for complexes 13 and the iodide analogue 4. While all approaches reproduced the experimental structures very well, the energy balance between the high-spin and low-spin forms was harder to reproduce, though some calculations pointed to the easier spin crossover of complex 2, as observed. Periodic calculations with the functional PBE led to very similar ΔEHS-LS values for all complexes but showed a preference for the low-spin form. However, the single-point calculations with B3LYP* showed, for the model without solvate, that the Cl complex should undergo spin crossover more easily. The molecular calculations also reflected this fact, which was more clearly defined when the cation–anion–solvate model was used. In the other models there was not much difference between the Cl, Br, and I complexes. Full article
Show Figures

Figure 1

13 pages, 2704 KiB  
Article
A Generalized Ising-like Model for Spin Crossover Nanoparticles
by Catherine Cazelles, Jorge Linares, Pierre-Richard Dahoo and Kamel Boukheddaden
Magnetochemistry 2022, 8(5), 49; https://doi.org/10.3390/magnetochemistry8050049 - 04 May 2022
Cited by 1 | Viewed by 1700
Abstract
Cooperative spin crossover (SCO) materials exhibit first-order phase transitions in the solid state, between the high-spin (HS) and low-spin (LS) states. Elastic long-range interactions are the basic mechanism for this particular behavior and are described well by the Ising-like model, which allows the [...] Read more.
Cooperative spin crossover (SCO) materials exhibit first-order phase transitions in the solid state, between the high-spin (HS) and low-spin (LS) states. Elastic long-range interactions are the basic mechanism for this particular behavior and are described well by the Ising-like model, which allows the reproduction of most of the experimental results in the literature. Until now, this model has been applied with an interaction parameter between the molecules, which is considered to be independent of the states. In this contribution, we extend the Ising-like model to include interaction energy that depends on the spin states and apply it to study SCO nanoparticles. Our research shows that following this new hypothesis, the equilibrium temperature shifts toward higher values. Full article
Show Figures

Figure 1

16 pages, 4401 KiB  
Article
Tuning the Spin-Crossover Behaviour in Fe(II) Polymeric Composites for Food Packaging Applications
by Zoi G. Lada, Konstantinos S. Andrikopoulos, Georgios N. Mathioudakis, Zoi Piperigkou, Nikos Karamanos, Spyros P. Perlepes and George A. Voyiatzis
Magnetochemistry 2022, 8(2), 16; https://doi.org/10.3390/magnetochemistry8020016 - 25 Jan 2022
Cited by 5 | Viewed by 2834
Abstract
Although the spin-crossover (SCO) phenomenon is well documented, tuning the SCO behaviour remains a challenging task. This could be mainly attributed to the ‘delicate’ nature of the phenomenon; cooperativity expressed through differences in particle size and morphologies, and electrostatic interactions could significantly affect [...] Read more.
Although the spin-crossover (SCO) phenomenon is well documented, tuning the SCO behaviour remains a challenging task. This could be mainly attributed to the ‘delicate’ nature of the phenomenon; cooperativity expressed through differences in particle size and morphologies, and electrostatic interactions could significantly affect the process. The goal of the present effort is dual bearing both scientific and technological interest. Firstly, to examine the technological potential of SCO complexes by incorporating them into polymers, and secondly—and most importantly—to investigate if polymer-SCO complex interactions could occur and could affect the SCO behaviour, depending on the structural properties of both the polymer matrix and the SCO complex. In this context, two different polymers, polylactic acid (PLA) and polysulphone (PSF), which are capable of developing different interactions with the inclusions, and the SCO complexes [Fe(abpt)2{N(CN)2}2] and [Fe(abpt)2(SCN)2] were examined; abpt is the N,N’-bidentate chelating ligand 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole. The composites were characterised through scanning electron microscopy (SEM), attenuated total reflectance infrared (ATR/FTIR), and Raman spectroscopy. In addition, the potential migration release of the SCO compounds from the polymeric matrices and their toxicity evaluation were also studied. In addition, the potential migration release of the SCO compounds from the polymeric matrices was evaluated, and their insignificant toxicity was also verified. Temperature-dependent Raman spectra were collected in situ for the monitoring of the SCO behaviour after the incorporation of the Fe(II) complexes into the polymers; an upshift of the T1/2 transition and a hysteretic behaviour was detected for PSF-SCO composites, compared with the non-hysteretic behaviour of the pristine SCO complexes. Full article
Show Figures

Figure 1

20 pages, 6998 KiB  
Article
Steric Quenching of Mn(III) Thermal Spin Crossover: Dilution of Spin Centers in Immobilized Solutions
by Komala Pandurangan, Anthony B. Carter, Paulo N. Martinho, Brendan Gildea, Tibebe Lemma, Shang Shi, Aizuddin Sultan, Tia E. Keyes, Helge Müller-Bunz and Grace G. Morgan
Magnetochemistry 2022, 8(1), 8; https://doi.org/10.3390/magnetochemistry8010008 - 10 Jan 2022
Cited by 7 | Viewed by 2759
Abstract
Structural and magnetic properties of a new spin crossover complex [Mn(4,6-diOMe-sal2323)]+ in lattices with ClO4, (1), NO3, (2), BF4, (3), CF3SO3, (4), and Cl (5) [...] Read more.
Structural and magnetic properties of a new spin crossover complex [Mn(4,6-diOMe-sal2323)]+ in lattices with ClO4, (1), NO3, (2), BF4, (3), CF3SO3, (4), and Cl (5) counterions are reported. Comparison with the magnetostructural properties of the C6, C12, C18 and C22 alkylated analogues of the ClO4 salt of [Mn(4,6-diOMe-sal2323)]+ demonstrates that alkylation effectively switches off the thermal spin crossover pathway and the amphiphilic complexes are all high spin. The spin crossover quenching in the amphiphiles is further probed by magnetic, structural and Raman spectroscopic studies of the PF6 salts of the C6, C12 and C18 complexes of a related complex [Mn(3-OMe-sal2323)]+ which confirm a preference for the high spin state in all cases. Structural analysis is used to rationalize the choice of the spin quintet form in the seven amphiphilic complexes and to highlight the non-accessibility of the smaller spin triplet form of the ion more generally in dilute environments. We suggest that lattice pressure is a requirement to stabilize the spin triplet form of Mn3+ as the low spin form is not known to exist in solution. Full article
Show Figures

Figure 1

9 pages, 1807 KiB  
Article
Investigation of the Effect of Spin Crossover on the Static and Dynamic Properties of MEMS Microcantilevers Coated with Nanocomposite Films of [Fe(Htrz)2(trz)](BF4)@P(VDF-TrFE)
by José Elías Angulo-Cervera, Mario Piedrahita-Bello, Fabrice Mathieu, Thierry Leichle, Liviu Nicu, Lionel Salmon, Gábor Molnár and Azzedine Bousseksou
Magnetochemistry 2021, 7(8), 114; https://doi.org/10.3390/magnetochemistry7080114 - 09 Aug 2021
Cited by 8 | Viewed by 2062
Abstract
We used a spray-coating process to cover silicon microcantilevers with ca. 33 wt% [Fe(Htrz)2(trz)](BF4)@P(VDF70-TrFE30) nanocomposite thin films of 1500 nm thickness. The bilayer cantilevers were then used to investigate the thermomechanical properties of the composites [...] Read more.
We used a spray-coating process to cover silicon microcantilevers with ca. 33 wt% [Fe(Htrz)2(trz)](BF4)@P(VDF70-TrFE30) nanocomposite thin films of 1500 nm thickness. The bilayer cantilevers were then used to investigate the thermomechanical properties of the composites through a combined static and dynamic flexural analysis. The out-of-plane flexural resonance frequencies were used to assess the Young’s modulus of the spray-coated films (3.2 GPa). Then, the quasi-static flexural bending data allowed us to extract the actuation strain (1.3%) and an actuation stress (7.7 MPa) associated with the spin transition in the composite. Full article
Show Figures

Figure 1

Review

Jump to: Research

14 pages, 2988 KiB  
Review
Variability of the Conductance Changes Associated with the Change in the Spin State in Molecular Spin Crossover Complexes
by M. Zaid Zaz, Thilini K. Ekanayaka, Ruihua Cheng and Peter A. Dowben
Magnetochemistry 2023, 9(11), 223; https://doi.org/10.3390/magnetochemistry9110223 - 29 Oct 2023
Viewed by 1271
Abstract
Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz) [...] Read more.
Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state. Full article
Show Figures

Figure 1

29 pages, 19657 KiB  
Review
The Investigation of Spin-Crossover Systems by Raman Spectroscopy: A Review
by Zoi G. Lada
Magnetochemistry 2022, 8(9), 108; https://doi.org/10.3390/magnetochemistry8090108 - 18 Sep 2022
Cited by 5 | Viewed by 3348
Abstract
Spin-crossover (SCO) is a well-documented phenomenon, being intensely investigated by a respectable number of researchers during the last decades. The conventional method for the investigation of SCO properties is by performing magnetic susceptibility measurements. On the other hand, Raman has also been proposed [...] Read more.
Spin-crossover (SCO) is a well-documented phenomenon, being intensely investigated by a respectable number of researchers during the last decades. The conventional method for the investigation of SCO properties is by performing magnetic susceptibility measurements. On the other hand, Raman has also been proposed as a promising characterization method since it is a non-bulk technique and allows, along with the monitoring of the SCO behavior, the parallel deep characterization of structure and molecular structure modifications, while it can also facilitate the determination of the entropy change related to the SCO event. There are several review articles focused on the analysis of the SCO phenomenon, the emerging applications of SCO materials and the importance of SCO/polymer composites, and elaborating on the vibrational effects on the investigation of SCO complexes; however, there has been no attempt to review solely the existing research efforts of the investigation of SCO phenomenon based on Raman spectroscopy. The main scope of this review is to focus on the main features, the challenges, and the key role of Raman spectroscopy in the investigation of 3d mononuclear complexes (comprising mainly of iron(II) complexes) and Hofmann-type metal organic frameworks (MOFs) exhibiting the SCO behavior. In addition, special focus is devoted to the research studies in which in situ Raman measurements are performed for the investigation of SCO systems. Finally, novelties, current challenges, future perspectives, and the contribution of Raman spectroscopy toward the practical application of SCO complexes are discussed. Full article
Show Figures

Figure 1

Back to TopTop