Molecule-based magnets (MBMs) or molecular magnets are magnetic materials composed of discrete molecules, typically either an organic molecule or a coordination compound. They typically have much lower Curie points than classical magnets, but remain ferro- or ferrimagnetic at the temperatures of interest (typically, room temperature). Essentially all common magnetic phenomena associated with conventional transition-metal and rare-earth magnets can be found in molecule-based magnets. Other properties are more favorable for industrial application: they can exhibit much lower density than classical magnets, and need be neither electrically conductive nor opaque.
History
editThe first synthesis and characterization of MBMs was accomplished by Wickman and co-workers in 1967. This was a diethyldithiocarbamate-Fe(III) chloride compound.[1][2]
In February 1992, Gatteschi and Sessoli published on MBMs with particular attention to the fabrication of systems in which stable organic radicals are coupled to metal ions.[3] At that date, the highest Tc on record was measured by SQUID magnetometer as 30K.[4]
The field exploded in 1996 with the publication of the book "Molecular Magnetism: From Molecular Assemblies to the Devices".[5]
In February 2007, de Jong et al. grew thin-film TCNE MBM in situ,[6] while in September 2007, photoinduced magnetism was demonstrated in a TCNE organic-based magnetic semiconductor.[7]
By 2011, MBMs were known with a Curie point above room temperature.[8][9] Essentially all of the common magnetic phenomena associated with conventional transition-metal magnets and rare-earth magnets could be found in molecule-based magnets, but also low density, transparency, low-temperature fabrication, and photoresponse.[10][8]
Theory
editAll magnets generate a stable net magnetic moment through unpaired electrons at identical crystallographic sites. These electrons generally prefer to adopt identical spins because of the quantum-mechanical exchange interaction. In classical magnets, the unpaired electrons are either located in nonbonding metal d- or f-type orbitals (in the case of metal alloys) or in metal-ligand bonds (in the case of complex salts; the so-called superexchange interaction).[citation needed]
In molecule-based magnets, the unpaired electrons may still locate in non- or weakly bonding metal orbitals or half-fill a main-group element's lone pair orbital, but are generally isolated within the molecule. Consequently, they have lower number density than a classical magnet, and poor geometric overlap between half-filled orbitals substantially reduces the exchange constant. Molecular solids also have much more flexible crystal lattices, and often strong local anisotropy. These properties reduce phonon-mediated coupling between the spin centers. As a result, magnetic ordering temperatures are much lower than metal/alloy-type magnets.[citation needed]
Nevertheless, in a molecule-based magnet, the exchange interaction is sufficiently large to achieve ferro- or ferrimagnetism at the temperatures of interest. In the related single-molecule magnets (SMMs), the exchange interaction is practically zero and the material is paramagnetic. Some industrial applications are the same, because the timescale for SMM thermal fluctuations exceeds many human activities (superparamagnetism).[citation needed]
Examples
editLike conventional magnets, they may be classified as hard or soft, depending on the magnitude of the coercive field.[citation needed]
Specific materials include purely organic magnets made of organic radicals for example p-nitrophenyl nitronyl nitroxides,[11] decamethylferrocenium tetracyanoethenide,[12] mixed coordination compounds with bridging organic radicals,[13] Prussian blue related compounds,[14] and charge-transfer complexes.[15]
In 2015 oxo-dimeric Fe(salen)-based magnets ("anticancer nanomagnets") in a water suspension were shown to demonstrate intrinsic room temperature ferromagnetic behavior, as well as antitumor activity, with possible medical applications in chemotherapy,[16][17][18][19] magnetic drug delivery, magnetic resonance imaging (MRI), and magnetic field-induced local hyperthermia therapy.
References
edit- ↑ Wickman, H. H.; Trozzolo, A. M.; Williams, H. J.; Hull, G. W.; Merritt, F. R. (1967-03-10). "Spin-3/2 Iron Ferromagnet: Its Mössbauer and Magnetic Properties". Physical Review. 155 (2). American Physical Society (APS): 563–566. Bibcode:1967PhRv..155..563W. doi:10.1103/physrev.155.563. ISSN 0031-899X.
- ↑ Wickham, H. H.; Trozzolo, A. M.; Williams, H. J.; Hull, G. W.; Merritt, F. R. (1967-11-10). "Spin-3/2 Iron Ferromagnet: Its Mossbauer and Magnetic Properties". Physical Review. 163 (2). American Physical Society (APS): 526. Bibcode:1967PhRv..163..526W. doi:10.1103/physrev.163.526. ISSN 0031-899X.
- ↑ Gatteschi, Dante; Sessoli, Roberta (1992). "Molecular based magnetic materials". Journal of Magnetism and Magnetic Materials. 104–107: 2092–2095. Bibcode:1992JMMM..104.2092G. doi:10.1016/0304-8853(92)91683-K.
- ↑ Codjovi, Epiphane; Bergerat, Pierre; Nakatani, Keitaro; Pei, Yu; Kahn, Olivier (1992). "Molecular-based magnets studied with an ultrasensitive SQUID magnetometer". Journal of Magnetism and Magnetic Materials. 104–107: 2103–2104. Bibcode:1992JMMM..104.2103C. doi:10.1016/0304-8853(92)91687-O.
- ↑ Coronado, Eugenio; Delhaès, Pierre; Gatteschi, Dante; Miller, Joel S, eds. (1996). Molecular Magnetism: From Molecular Assemblies to the Devices. doi:10.1007/978-94-017-2319-0. ISBN 978-90-481-4724-3.
- ↑ De Jong, M. P.; Tengstedt, C.; Kanciurzewska, A.; Carlegrim, E.; Salaneck, W. R.; Fahlman, M. (2007). "Chemical bonding inV(TCNE)x(x~2)thin-film magnets grownin situ". Physical Review B. 75 (6) 064407. Bibcode:2007PhRvB..75f4407D. doi:10.1103/PhysRevB.75.064407.
- ↑ Yoo, Jung-Woo; Edelstein, R. Shima; Raju, N. P.; Lincoln, D. M.; Epstein, A. J. (2008). "Novel mechanism of photoinduced magnetism in organic-based magnetic semiconductor V(TCNE)x, x~2". Journal of Applied Physics. 103 (7): 07B912. Bibcode:2008JAP...103gB912Y. doi:10.1063/1.2830960.
- 1 2 Miller, Joel S.; Gatteschi, Dante (2011). "Molecule-based magnets". Chemical Society Reviews. 40 (6): 3065–3066. doi:10.1039/C1CS90019F. PMID 21552607.
- ↑ Weber, Birgit; Jäger, Ernst-G. (2009). "Structure and Magnetic Properties of Iron(II/III) Complexes with N2O22-Coordinating Schiff Base Like Ligands (Eur. J. Inorg. Chem. 4/2009)". European Journal of Inorganic Chemistry. 2009 (4): 455. Bibcode:2009EJIC.2009..455W. doi:10.1002/ejic.200990003.
- ↑ [dead link] Molecule-Based Magnets Materials Research Society Retrieved on 20 December 2007
- ↑ Bulk ferromagnetism in the β-phase crystal of the p-nitrophenyl nitronyl nitroxide radical Chemical Physics Letters, Volume 186, Issues 4-5, 15 November 1991, Pages 401-404 Masafumi Tamura, Yasuhiro Nakazawa, Daisuke Shiomi, Kiyokazu Nozawa, Yuko Hosokoshi, Masayasu Ishikawa, Minuro Takahashi, Minoru Kinoshita doi:10.1016/0009-2614(91)90198-I
- ↑ Chittipeddi, Sailesh; Cromack, K. R.; Miller, Joel S.; Epstein, A. J. (1987-06-22). "Ferromagnetism in molecular decamethylferrocenium tetracyanoethenide (DMeFc TCNE)". Physical Review Letters. 58 (25). American Physical Society (APS): 2695–2698. Bibcode:1987PhRvL..58.2695C. doi:10.1103/physrevlett.58.2695. ISSN 0031-9007. PMID 10034821.
- ↑ Caneschi, Andrea; Gatteschi, Dante; Sessoli, Roberta; Rey, Paul (1989). "Toward molecular magnets: the metal-radical approach". Accounts of Chemical Research. 22 (11). American Chemical Society (ACS): 392–398. doi:10.1021/ar00167a004. ISSN 0001-4842.
- ↑ Ferlay, S.; Mallah, T.; Ouahès, R.; Veillet, P.; Verdaguer, M. (1995). "A room-temperature organometallic magnet based on Prussian blue". Nature. 378 (6558). Springer Nature: 701–703. Bibcode:1995Natur.378..701F. doi:10.1038/378701a0. ISSN 0028-0836. S2CID 4261137.
- ↑ Miller, Joel S.; Epstein, Arthur J.; Reiff, William M. (1988). "Ferromagnetic molecular charge-transfer complexes". Chemical Reviews. 88 (1). American Chemical Society (ACS): 201–220. doi:10.1021/cr00083a010. ISSN 0009-2665.
- ↑ Eguchi, Haruki; Umemura, Masanari; Kurotani, Reiko; Fukumura, Hidenobu; Sato, Itaru; Kim, Jeong-Hwan; Hoshino, Yujiro; Lee, Jin; Amemiya, Naoyuki; Sato, Motohiko; Hirata, Kunio; Singh, David J.; Masuda, Takatsugu; Yamamoto, Masahiro; Urano, Tsutomu; Yoshida, Keiichiro; Tanigaki, Katsumi; Yamamoto, Masaki; Sato, Mamoru; Inoue, Seiichi; Aoki, Ichio; Ishikawa, Yoshihiro (2015). "A magnetic anti-cancer compound for magnet-guided delivery and magnetic resonance imaging". Scientific Reports. 5 9194. Bibcode:2015NatSR...5.9194E. doi:10.1038/srep09194. PMC 4361848. PMID 25779357.
- ↑ Sato, Itaru; Umemura, Masanari; Mitsudo, Kenji; Fukumura, Hidenobu; Kim, Jeong-Hwan; Hoshino, Yujiro; Nakashima, Hideyuki; Kioi, Mitomu; Nakakaji, Rina; Sato, Motohiko; Fujita, Takayuki; Yokoyama, Utako; Okumura, Satoshi; Oshiro, Hisashi; Eguchi, Haruki; Tohnai, Iwai; Ishikawa, Yoshihiro (2016). "Simultaneous hyperthermia-chemotherapy with controlled drug delivery using single-drug nanoparticles". Scientific Reports. 6 24629. Bibcode:2016NatSR...624629S. doi:10.1038/srep24629. PMC 4840378. PMID 27103308.
- ↑ Ohtake, Makoto; Umemura, Masanari; Sato, Itaru; Akimoto, Taisuke; Oda, Kayoko; Nagasako, Akane; Kim, Jeong-Hwan; Fujita, Takayuki; Yokoyama, Utako; Nakayama, Tomohiro; Hoshino, Yujiro; Ishiba, Mai; Tokura, Susumu; Hara, Masakazu; Muramoto, Tomoya; Yamada, Sotoshi; Masuda, Takatsugu; Aoki, Ichio; Takemura, Yasushi; Murata, Hidetoshi; Eguchi, Haruki; Kawahara, Nobutaka; Ishikawa, Yoshihiro (2017). "Hyperthermia and chemotherapy using Fe(Salen) nanoparticles might impact glioblastoma treatment". Scientific Reports. 7 42783. Bibcode:2017NatSR...742783O. doi:10.1038/srep42783. PMC 5316938. PMID 28218292.
- ↑ Kim, Jeong-Hwan; Eguchi, Haruki; Umemura, Masanari; Sato, Itaru; Yamada, Shigeki; Hoshino, Yujiro; Masuda, Takatsugu; Aoki, Ichio; Sakurai, Kazuo; Yamamoto, Masahiro; Ishikawa, Yoshihiro (2017). "Magnetic metal-complex-conducting copolymer core–shell nanoassemblies for a single-drug anticancer platform". NPG Asia Materials. 9 (3): e367. doi:10.1038/am.2017.29.