High-spin versus spin-crossover versus low-spin: geometry intervention in cooperativity in a 3D polymorphic iron(ii)–tetrazole MOFs system

Zheng, Yan; Li, Mian; Gao, Huiling; Huang, Xiao‐Chun; Li, Dan

doi:10.1039/c2cc18140a

Cited by 71 publications

(47 citation statements)

References 35 publications

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“…Such an interlocked architecture was first reported for the 3D CPs [Fe(btzb) 3 ]A 2 ·Solv, (A = ClO 4 − , PF 6 − ; Solv = MeOH, H 2 O) (btzb = 1,2-bis(tetrazole-1-yl)butane) [349–351]. An abrupt SCO behavior is observed in contrast to the 3D bis-tetrazolate SCO polymer [Fe 2 (H 0.67 bdt) 3 ]·13H 2 O with H 2 bdt = 5,5′-(1,4-phenylene)bis(1 H -tetrazole) [352–353]. Another bidentate ligand based on a pyridine conjugated Schiff base, afforded a CP with a diamond-like 3D network made of FeN 4 O 2 sites and displaying a gradual spin conversion [354].…”

Section: Reviewmentioning

confidence: 99%

Spin state switching in iron coordination compounds

Gütlich¹,

Gaspar²,

Garcia³

2013

Beilstein J. Org. Chem.

640

589

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SummaryThe article deals with coordination compounds of iron(II) that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors as well as optical devices.The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the chemical nature that is important for the occurrence of spin crossover will be made. A subsequent section describes the molecular consequences of spin crossover and the variety of physical techniques usually applied for their characterization. The effects of light irradiation (LIESST) and application of pressure are subjects of two separate sections. The major part of this account concentrates on selected spin crossover compounds of iron(II), with particular emphasis on the chemical and physical influences on the spin crossover behavior. The vast variety of compounds exhibiting this fascinating switching phenomenon encompasses mono-, oligo- and polynuclear iron(II) complexes and cages, polymeric 1D, 2D and 3D systems, nanomaterials, and polyfunctional materials that combine spin crossover with another physical or chemical property.

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Section: Reviewmentioning

confidence: 99%

Spin state switching in iron coordination compounds

Gütlich¹,

Gaspar²,

Garcia³

2013

Beilstein J. Org. Chem.

640

589

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“…Because of their intriguing structures and unique properties, the investigation of MOFs has attracted considerable interest, and their potential applications have been explored in various fields, such as gas storage, catalysis, molecular sensing, separation, and nonlinear optical materials. By virtue of this strategy, a variety of energetic MOFs with diverse structures and topologies have been synthesized and utilized as energetic materials for commercial and military applications, [6][7][8][9] although they have not been called "energetic MOFs" in the literature. [4,5] Although they remain to be systematically exploited, the exceptional energetic performance of several reported energetic MOFs has revealed their great potential as new-generation high explosives.…”

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confidence: 99%

“…By virtue of this strategy, a variety of energetic MOFs with diverse structures and topologies have been synthesized and utilized as energetic materials for commercial and military applications, [6][7][8][9] although they have not been called "energetic MOFs" in the literature. In the field of energetic materials, a great number of metal-based explosives, including metal salts and complexes, have been used as initiating primary explosives for many decades; many are composed of metal ions (including Pb 2+ and Ag + ) and energetic anions (such as N 3 À and NO 3 À ) or energetic ligands (e.g., hydrazine).…”

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Metal–Organic Frameworks as High Explosives: A New Concept for Energetic Materials

2014

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In memory of Malcolm M. Renfrew coordination polymers · energetic materials · heat of detonation · metal-organic frameworks · porous structures Metal-organic frameworks (MOFs) represent a fascinating class of porous crystalline materials with ordered pores and channels. [1] In general, they can be readily prepared by the self-assembly of metal ions or metal-containing clusters with organic ligands through coordination bonds between metal center and organic linker. Because of their intriguing structures and unique properties, the investigation of MOFs has attracted considerable interest, and their potential applications have been explored in various fields, such as gas storage, catalysis, molecular sensing, separation, and nonlinear optical materials. [2,3] Recently, several investigators have demonstrated the possibility of using nitrogen-rich MOFs as high explosives. [4,5] Although they remain to be systematically exploited, the exceptional energetic performance of several reported energetic MOFs has revealed their great potential as new-generation high explosives.The concept of energetic metal-organic polymers is not strictly new. In the field of energetic materials, a great number of metal-based explosives, including metal salts and complexes, have been used as initiating primary explosives for many decades; many are composed of metal ions (including Pb 2+ and Ag + ) and energetic anions (such as N 3 À and NO 3 À ) or energetic ligands (e.g., hydrazine). In the case of energetic bidentate or multidentate ligands, many energetic metalorganic frameworks can be formed through coordination interactions between metal ions and energetic ligands. By virtue of this strategy, a variety of energetic MOFs with diverse structures and topologies have been synthesized and utilized as energetic materials for commercial and military applications, [6][7][8][9] although they have not been called "energetic MOFs" in the literature. Depending upon the metal ion geometry and the binding mode of the bridging energetic ligands, the network structures of energetic MOFs can be designed in one, two, or three dimensions (1D, 2D, or 3D; Figure 1). Apart from metal ions and ligand geometries, other factors, such as temperature, solvent, pH, and stoichiometry, may also play a significant role in modulating the network topologies and the dimensionalities of the target energetic MOFs. In this sense, the concept of designing energetic MOFs as high explosives has provided a unique architectural platform for developing new-generation energetic materials.Recently, in pursuit of greener energetic materials, an interesting energetic metal-organic coordination polymer of zinc(II) hydrazine azide, [Zn(N 2 H 4 ) 2 (N 3 ) 2 ] n , was reported. [10] This material has a 1D framework structure, in which the Zn II ion is hexacoordinated with two azido ligands by m 1 -azido bridges and four hydrazine molecules, which act as bidentate ligands. The nitrogen content of this energetic 1D MOF material is 65.6 %, and its heat of combustion is 5.45 MJ kg À1 . By ...

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“…From the SCXRD analysis, we encountered a dilemma that we could not find any obvious differences between the reddish-purple crystals and the blackish-purple ones except that the helices in the structures of the reddish-purple single crystals are all right-handed opposite to 1M-NH 3 . We presume that the terminal coordinated solvent molecules in the reddish-purple crystals are H 2 O molecules based on the following reasons: (1) the value of atomic scattering factor for N and O is close, so it is difficult to distinguish NH 3 and H 2 O by crystallographic structural determination; (2) the magnetic properties 1M-NH 3 and the reddish-purple ones are very similar, excluding the probabilities that their different colors are caused by spin-crossover or different valence state of the Co atoms (vide infra); 14 (3) from elemental analysis the content of N element of the reddish-purple crystalline solids decreases by ca. 1.2 wt% ; (4) according to Hans Bethe's crystal field theory (CFT), 15 H 2 O is weaker field ligand than NH 3 , resulting in Δ (NH3) > Δ (H2O) (Δ denotes the crystal field splitting energy).…”

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confidence: 99%