scholarly journals High-temperature Spin Crossover of a Solvent-Free Iron(II) Complex with the Linear Hexadentate Ligand [Fe(L2-3-2Ph)](AsF6)2 (L2-3-2Ph = bis[N-(1-Phenyl-1H-1,2,3-triazol-4-yl)methylidene-2-aminoethyl]-1,3- propanediamine)

2019 ◽  
Vol 5 (1) ◽  
pp. 10 ◽  
Author(s):  
Hiroaki Hagiwara
Keyword(s):  
Room Temperature ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Three Dimensional ◽  
Solvent Free ◽  
Supramolecular Network ◽  
Scanning Calorimetry ◽  
Mononuclear Iron ◽  
3D Network

A novel mononuclear iron(II) complex with a linear hexadentate N6 ligand, containing two 1,2,3-triazole moieties, [Fe(L2-3-2Ph)](AsF6)2 (1), was synthesized (L2-3-2Ph = bis[N-(1-Phenyl-1H-1,2,3-triazol-4-yl)methylidene-2-aminoethyl]-1,3-propanediamine). Variable-temperature magnetic susceptibility measurements revealed a gradual one-step spin crossover (SCO) between the high-spin (HS, S = 2) and low-spin (LS, S = 0) states above room temperature (T1/2 = 468 K). The spin transition was further confirmed by differential scanning calorimetry (DSC). A single-crystal X-ray diffraction study showed that the complex was in the LS state (S = 0) at room temperature (296 K). In the crystal lattice, a three-dimensional (3D) supramolecular network was formed by intermolecular CH⋯ and – interactions of neighboring complex cations [Fe(L2-3-2Ph)]2+. AsF6− ions were located interstitially in the 3D network of complex cations, with no solvent-accessible voids. The crystal structure at 448 K (mixture of HS and LS species) was also successfully determined thanks to the thermal stability of the solvent-free crystal.

scholarly journals Spin-Crossover 2-D Hofmann Frameworks Incorporating an Amide-Functionalized Ligand: N-(pyridin-4-yl)benzamide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 360-372
Author(s):  
Xandria Ong ◽  
Manan Ahmed ◽  
Luonan Xu ◽  
Ashley T. Brennan ◽  
Carol Hua ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Spin State ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Single Step ◽  
Amide Group ◽  
State Transitions ◽  
Structure Property ◽  
Scanning Calorimetry

Two analogous 2-D Hofmann-type frameworks, which incorporate the novel ligand N-(pyridin-4-yl)benzamide (benpy) [FeII(benpy)2M(CN)4]·2H2O (M = Pd (Pd(benpy)) and Pt (Pt(benpy))) are reported. The benpy ligand was explored to facilitate spin-crossover (SCO) cooperativity via amide group hydrogen bonding. Structural analyses of the 2-D Hofmann frameworks revealed benpy-guest hydrogen bonding and benpy-benpy aromatic contacts. Both analogues exhibited single-step hysteretic spin-crossover (SCO) transitions, with the metal-cyanide linker (M = Pd or Pt) impacting the SCO spin-state transition temperature and hysteresis loop width (Pd(benpy): T½↓↑: 201, 218 K, ∆T: 17 K and Pt(benpy): T½↓↑: 206, 226 K, ∆T: 20 K). The parallel structural and SCO changes over the high-spin to low-spin transition were investigated using variable-temperature, single-crystal, and powder X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. These studies indicated that the ligand–guest interactions facilitated by the amide group acted to support the cooperative spin-state transitions displayed by these two Hofmann-type frameworks, providing further insight into cooperativity and structure–property relationships.

scholarly journals Iron(II) Spin Crossover Complex with the 1,2,3-Triazole-Containing Linear Pentadentate Schiff-Base Ligand and the MeCN Monodentate Ligand

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 276 ◽  
Author(s):  
Tomoe Matsuyama ◽  
Keishi Nakata ◽  
Hiroaki Hagiwara ◽  
Taro Udagawa
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Ligand Field ◽  
X Ray Diffraction ◽  
Monodentate Ligand ◽  
X Ray ◽  
Mononuclear Iron

A mononuclear iron(II) complex bearing the linear pentadentate N5 Schiff-base ligand containing two 1,2,3-triazole moieties and the MeCN monodentate ligand, [FeIIMeCN(L3-Me-3Ph)](BPh4)2·MeCN·H2O (1), have been prepared (L3-Me-3Ph = bis(N,N′-1-Phenyl-1H-1,2,3-triazol-4-yl-methylideneaminopropyl)methylamine). Variable-temperature magnetic susceptibility measurements revealed an incomplete one-step spin crossover (SCO) from the room-temperature low-spin (LS, S = 0) state to a mixture of the LS and high-spin (HS, S = 2) species at the higher temperature of around 400 K upon first heating, which is irreversible on the consecutive cooling mode. The magnetic modulation at around 400 K was induced by the crystal-to-amorphous transformation accompanied by the loss of lattice MeCN solvent, which was evident from powder X-ray diffraction (PXRD) studies and themogravimetry. The single-crystal X-ray diffraction studies showed that the complex is in the LS state (S = 0) between 296 and 387 K. In the crystal lattice, the complex-cations and B(1)Ph4− ions are alternately connected by intermolecular CH···π interactions between the methyl group of the MeCN ligand and phenyl groups of B(1)Ph4− ions, forming a 1D chain structure. The 1D chains are further connected by P4AE (parallel fourfold aryl embrace) interactions between two neighboring complex-cations, constructing a 2D extended structure. B(2)Ph4− ions and MeCN lattice solvents exist in the spaces of the 2D layer. DFT calculations verified that the 1,2,3-triazole-containing ligand L3-Me-3Ph gives a stronger ligand field around the octahedral coordination environment of the iron(II) ion than the analogous imidazole-containing ligand H2L2Me (= bis(N,N′-2-methylimidazol-4-yl-methylideneaminopropyl)methylamine) of the known compound [FeIIMeCN(H2L2Me)](BPh4)1.5·Cl0.5·0.5MeCN (2) reported by Matsumoto et al. (Nishi, K.; Fujinami, T.; Kitabayashi, A.; Matsumoto, N. Tetrameric spin crossover iron(II) complex constructed by imidazole⋯chloride hydrogen bonds. Inorg. Chem. Commun. 2011, 14, 1073–1076), resulting in the much higher spin transition temperature of 1 than that of 2.

scholarly journals Symmetry breaking above room temperature in an Fe(ii) spin crossover complex with an N4O2 donor set

2017 ◽  
Vol 53 (8) ◽  
pp. 1374-1377 ◽  
Author(s):  
Wasinee Phonsri ◽  
Casey G. Davies ◽  
Guy N. L. Jameson ◽  
Boujemaa Moubaraki ◽  
Jas S. Ward ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Room Temperature ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Temperature Variable

An halogen-substituted salicylaldimine iron(ii) complex shows an abrupt two-step spin transition above room temperature, variable temperature crystallography showing symmetry breaking.

scholarly journals Thermal and near-infrared light induced spin crossover in a mononuclear iron(ii) complex with a tetrathiafulvalene-fused dipyridophenazine ligand

2016 ◽  
Vol 45 (28) ◽  
pp. 11267-11271 ◽  
Author(s):  
F. Pointillart ◽  
X. Liu ◽  
M. Kepenekian ◽  
B. Le Guennic ◽  
S. Golhen ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Near Infrared ◽  
Spin Transition ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Mononuclear Iron

A thermal and photo-induced spin transition in a tetrathiafulvalene-based Fe(ii) complex.

One Shot Laser Pulse Induced Reversible Spin Transition in the Spin-Crossover Complex [Fe(C4H4N2){Pt(CN)4}] at Room Temperature

2005 ◽  
Vol 117 (26) ◽  
pp. 4137-4141 ◽  
Author(s):  
Sébastien Bonhommeau ◽  
Gábor Molnár ◽  
Ana Galet ◽  
Antoine Zwick ◽  
José-Antonio Real ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition

The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2]

2019 ◽  
Vol 75 (6) ◽  
pp. 1144-1151
Author(s):  
Tamara J. Bednarchuk ◽  
Wolfgang Hornfeck ◽  
Vasyl Kinzhybalo ◽  
Zhengyang Zhou ◽  
Michal Dušek ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Room Temperature ◽  
Variable Temperature ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Hybrid Compound ◽  
Space Group ◽  
X Ray

The organic–inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling–heating cycles over the temperature ranges 290–100–290 K. In the room-temperature phase (I), space group C2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinic X2/c(α,0,γ)0s superspace group (where X is ½, ½, 0, ½) with modulation wavevectors q = (0.2943, 0, 0.5640) and q = (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinic P{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.

Evidence for room temperature mesomorphism in a mixed-valent diruthenium(II,III) quintapalmitoleate polymer

1998 ◽  
Vol 76 (11) ◽  
pp. 1520-1523
Author(s):  
Jennifer F Caplan ◽  
Christopher A Murphy ◽  
Susan Swansburg ◽  
Robert P Lemieux ◽  
T Stanley Cameron ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Powder Diffraction ◽  
Strong Evidence ◽  
Room Temperature ◽  
Variable Temperature ◽  
Mixed Valence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystal Transition

The synthesis of Ru2(μ-O2CR)4(μ´-O2CR) (1), R = -CH2(CH2)6CH=CH(CH2)5CH3, has been achieved and characterization using elemental analysis and FTIR and UV-Vis spectroscopies undertaken. Strong evidence for a hexagonal discotic mesophase has been found using differential scanning calorimetry, variable-temperature polarizing optical microscopy, and X-ray powder diffraction. A solid to liquid crystal transition was found upon heating at 128°C and the mesophase is found to persist to room temperature upon cooling from 150°C. This is the first report of room temperature mesomorphism in a mixed-valent metallomesogen. Key words: ruthenium carboxylate, liquid crystal, metallomesogen, mixed valence, polymer.

Synthesis, Structure, and Properties of a New ErIII Iodate

2014 ◽  
Vol 67 (5) ◽  
pp. 763 ◽  
Author(s):  
Chun-Yang Pan ◽  
Hai-Deng Mai ◽  
Wu-Zhou Chen ◽  
Feng-Hua Zhao ◽  
Hong-Mei Yang
Keyword(s):  
Three Dimensional ◽  
Luminescence Spectroscopy ◽  
Supramolecular Network ◽  
Structure And Properties ◽  
Dsc Analysis ◽  
Hydrothermal Conditions ◽  
Scanning Calorimetry ◽  
One Dimensional ◽  
X Ray ◽  
Triclinic System

A new iodate Er(IO3)3·2H2O was synthesized under mild hydrothermal conditions. The structure has been confirmed by single-crystal X-ray analysis. It crystallizes in the triclinic system with space group P-1 (No.2), a = 7.338(4) Å, b = 7.506(4) Å, c = 9.409(5) Å, α = 79.698(5)°, β = 85.245(4)°, γ = 71.934(4)°, V = 484.5(5) Å3, Z = 2. Some characterizations were performed such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric–differential scanning calorimetry (TG-DSC) analysis, luminescence spectroscopy, and magnetic property measurements. The overall framework of Er(IO3)3·2H2O is based on one-dimensional chains. The adjacent chains are further linked with each other by hydrogen bonds to form a three-dimensional supramolecular network. The luminescent and magnetic properties of Er(IO3)3·2H2O were studied.

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