A Needed Dose of Competition …

Kahn, Alfred E.

doi:10.1080/05775132.1984.11470905

Cited by 8 publications

(11 citation statements)

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“…Thus, the SCO materials are particularly attractive for potential applications in molecular sensing, switching, data storage, display, and other electronic devices at nanometric scale. [38][39][40][41][42][43][44][45][46][47] In the solid state, temperature-dependent SCO shows any one of the five behaviors-gradual, abrupt, stepwise, incomplete, or one with hysteresis (Fig. 1) 48 -of which abrupt and sometimes hysteresis are vital if the compounds are to have any real technological impact.…”

Section: Chem Soc Revmentioning

confidence: 99%

Polymorphism in spin-crossover systems

et al. 2012

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The occurrence of spin-crossover (SCO) highly depends on external influences, i.e. temperature, pressure, light irradiation or magnetic field, this electronic switching phenomenon is accompanied by drastic changes in magnetic and optical properties, dielectric constants, colour and structures. Thus, SCO materials are particularly attractive for potential applications in molecular sensing, switching, data storage, display, and other electronic devices at nanometric scale. Polymorphism is widely encountered in the studies of crystallization, phase transition, materials synthesis, biomineralization, and in the manufacture of drugs. Because different crystal forms of the same substance can possess very different properties and behave as different materials, so they are particularly meaningful for investigating SCO phenomena. Studying polymorphism of SCO compounds is therefore important for better understanding the structural factors contributing to spin transition and the structure-function relationship. This critical review is aimed to provide general readers with a comprehensive view of polymorphism in SCO systems. The article is generally structured according to specific metal ions and the dimensionality of compounds in the field. This paper is addressed to readers who are interested in multifunctional materials and tuning magnetic properties through supramolecular chemistry principles (129 references).

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Section: Chem Soc Revmentioning

confidence: 99%

Polymorphism in spin-crossover systems

et al. 2012

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“…The LS state is enthalpically favoured (better bonding, greater CFSE) so stable at lower temperatures, whereas the HS state is entropically favoured (greater electronic and vibrational contributions) so is favoured at higher temperatures (DG = DH À TDS). 33 Iron(II), d 6 , is by far the most commonly studied metal ion in SCO research (usually with 6N donors), in large part due to the fact that it has the largest possible change in magnetic response, from a diamagnetic LS state to 4 unpaired electrons in the HS state ( Fig. 1).…”

Section: Introduction To Basics Of Spin Crossover (Sco)mentioning

confidence: 99%

Spin crossover with thermal hysteresis: practicalities and lessons learnt

2015

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The observation of spin crossover with thermal hysteresis loops of more than a few Kelvin remains relatively uncommon and unpredictable, so is a relatively underdeveloped, but important, area of spin crossover, particularly for memory applications. Lessons learnt regarding the origins, and the practicalities of the proper study and reporting, of thermal hysteresis loops are considered and explained, from a synthetic chemists perspective, after a general introduction to the field of spin crossover.

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“…The precipitate (K 2 SO 4 ) was filtered off and a colorless solution of Fe(NCS) 2 was obtained. Fe(NCSe) 2 and Fe(NCBH 3 ) 2 were prepared similarly with KNCSe and NaNCBH 3 , respectively.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…8−10 Whereas the early studies on SCO were focused on monounclear Fe II complexes, recently more attention has been drawn in the design and synthesis of coordination polymers (CPs) incorporating SCO active centers in a framework that may enhance the communication through them and may thus result in abrupt and hysteretic spin-sate conversion. 11,12 The first polymeric SCO system belongs to the one-dimensional (1D) triazole-based complexes [Fe(Htrz) 2 (trz)]·(BF 4 ) and [Fe(4-Rtrz) 2 ]·(anion) 2 (trz − is 1,2,4-triazolate anion, and R is the substituted group), some of which display large thermal hysteresis at high temperature. 13−15 Since then, more and more 1D, two-dimensional (2D), and three-dimensional (3D) polymeric SCO Fe II complexes with a variety of bridging ligands based on triazoles, 16−19 tetrazoles, 20−24 and pyridines, 25−29 respectively, have been reported.…”

Section: ■ Introductionmentioning

confidence: 99%

Coligand and Solvent Effects on the Architectures and Spin-Crossover Properties of (4,4)-Connected Iron(II) Coordination Polymers

Shi

Wei

et al. 2015

Inorg. Chem.

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The self-assemblies of 1,4-bis(pyrid-4-yl)benzene (bpb) and Fe(NCX)2 (X = S, Se, BH3) afforded six coordination polymers with the general formula of [Fe(bpb)2(NCX)2]·Y (X = S and Y = 3C2H5OH·2.5H2O for complex 4, X = S and Y = 2C2H5OH for 5, X = Se and Y = 2C2H5OH·H2O for 6, X = Se and Y = 0.67CH2Cl2·1.33C2H5OH·0.67H2O for 7, X = BH3 and Y = 3C2H5OH·2H2O for 8, X = BH3 and Y = 2CH2Cl2·2C2H5OH for 9). The frameworks of complexes 4 and 5 with the NCS(-) anion as coligand are supramolecular isomers, of which complex 4 features a threefold self-interpenetrated three-dimensional (3D) CdSO4-type topological structure with a Schläfli symbol of 6(5)·8, and complex 5 is a two-dimensional (2D) 4(4) rhombic grid network. These two complexes are purely high-spin systems. Complexes 6 and 7 with the NCSe(-) anion as coligand, both having the 3D 6(5)·8 CdSO4-type framework, show gradual and incomplete spin-crossover behaviors with transition temperature T1/2 being equal to 86 and 96 K, respectively. The usage of NCBH3(-) anion as coligand leads to the formation of 2D 4(4) rhombic grid networks for both complexes 8 and 9, which undergo relatively abrupt, complete spin crossover with T1/2 being equal to 247 and 189 K, respectively. The structural divergences are attributed to the coligands NCX(-) (X = S, Se, BH3) and solvent molecules. Meanwhile, a significant coligand effect is observed on the spin-crossover behaviors of these complexes, and the completeness and transition temperature of spin-state conversion depends on the nature of the coligand, that is, T1/2(NCS(-)) < T1/2(NCSe(-)) < T1/2(NCBH3(-)). These results further facilitate the design and synthesis of spin-crossover complexes with spin-state conversion.

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A Needed Dose of Competition …

Cited by 8 publications

References 0 publications

Polymorphism in spin-crossover systems

Polymorphism in spin-crossover systems

Spin crossover with thermal hysteresis: practicalities and lessons learnt

Coligand and Solvent Effects on the Architectures and Spin-Crossover Properties of (4,4)-Connected Iron(II) Coordination Polymers

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