China
Africa
Explore chapters and articles related to this topic
P
Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
The main differences between the organic molecule-based and inorganic atom-based magnetism are simply summarized in Table 1. Whereas inorganic atom-based magnets are comprised of transition metal elements such as Fe, Co, Ni, Nd, Sm, and Eu, organic molecule-based magnets are comprised of nonmetallic light elements such as H, C, N, O, and S. Accordingly, while the unpaired electron spins in inorganic atom-based magnets occupy the 3d and 4f orbitals, the unpaired electron spins in organic molecule-based magnets occupy the 2s and 2p orbitals (or 3s and 3p).
Hydrostatic pressure induced transformation of magnetism in a trimetallic CuMnFe Prussian blue analogue
Published in Journal of Coordination Chemistry, 2019
Yanfang Xia, Min Liu, Duxin Li
Molecular magnetic compounds are materials capable of displaying ferromagnetic, ferromagnetic, and other magnetic behaviors [1]. Molecular materials possessing reversible switchable physical properties attract interest on account of their potential applications as multifunctional devices [2–8]. In the last two decades, molecule-based magnets are predicted to be the smart functionalized magnets of the future [9–13]. In particular, Prussian blue analogues display room temperature magnetic ordering, photoinduced magnetization and magnetic pole inversion properties [2–6]. One of the targets in the field of Prussian blue analogues is to develop a functionalized magnet [7–22]. The reversible change of the spontaneous magnetization can also be observed as a response to an external stimulus, such as humidity [18], pressure [3, 4], heating [12], and light irradiation [2]. The application of hydrostatic pressure is a powerful tool to modulate the properties of molecular magnets, including Prussian blue analogues, which showed various responses, such as spin state transitions, internal electron transfer, and linkage isomerism of the cyanide bridge [14–16]. Some Mn2+ cyanides show pressure-induced magnetic transformation with increasing pressure [3, 4].
Solvent-dependent structures of lanthanide–TCNQ coordination networks and their magnetic properties
Published in Journal of Coordination Chemistry, 2018
Chihiro Kachi-Terajima, Norihisa Kimura, Yuka Tomori, Daisuke Akahoshi, Toshiaki Saito
The design and synthesis of lanthanide complexes are of growing interest in the field of molecule-based magnets because of their large magnetic moments and magnetic anisotropies. Accordingly, the introduction of lanthanide ions into molecule-based magnets has expanded their magnetic properties, particularly in terms of the superparamagnetic chemistry of nano-sized clusters such as single-molecule magnets (SMMs) [1,2]. Since the discovery of the first single-ion magnet (SIM), [Pc2Tb]− [3], lanthanide-based SMMs have been extensively studied to achieve the high-performance SMMs that have high energy barriers, high blocking temperatures, and suppressed quantum tunneling of magnetization (QTM). It is a crucial issue for the design of SMMs to understand the coordination symmetry for suppressing QTM in lanthanide-based complexes and to control it on the assembled structure because that can be readily influenced by even a slight distortion of the coordination sphere around lanthanide ions. Some typical local coordination symmetries which are advantageous for suppression of QTM have been reported, such as D4d symmetry for [Pc2Tb]− SIMs and D5h symmetry for Dy SIMs [4–8]. The DAPBH2 analogs (DAPBH2 = 2,6-diacetylpyridine bis(benzoylhydrazone)) are potentially five-coordinate occupying the equatorial sites and well suited to make D5h local symmetry. Indeed, SIM behaviors based on DAPBH2 analog ligands with a pseudo D5h symmetry have been reported on Ln complexes [5]. Furthermore, the combination of lanthanide ions and 4f–2p (i.e. organic radical) [9–22], 4f–3d [23–27], or 4f–3d–2p [28,29] spin carriers is an attractive strategy for the construction of molecule-based magnets with high-spin ground states and for the facilitation of studies on the magnetic exchange interactions in such systems. It also led to the development of lanthanide-radical based 4f-2p SCMs, where the lanthanide ions are connected by a substantial intrachain magnetic interaction [30–32]. The organic radical 7,7,8,8-tetracyano-p-quinodimethanide (TCNQ•−) (Srad = 1/2) is suitable for the connection of spin carriers through significant magnetic interactions [18–20,28,32–35]. Although the diamagnetism due to the strong π–π stacking between TCNQ•− radicals, as is often the case, is a disadvantage, the use of TCNQ•− radical still holds great promise as a building block for magnetic materials. Successful examples include the GdIII–TCNQ•− magnets [18], conducting DyIII nanomagnets [20], TbIII–TCNQ•− SMM [19], TbIII–TCNQ•− SCM [32], and MnIII–TCNQ•− SCM [35].