One-Dimensional Iron(II) Compounds Exhibiting Spin Crossover and Liquid Crystalline Properties in the Room Temperature Region
摘要:
A novel series of 1D Fe(II) metallomesogens have been synthesized using the ligand 5-bis(alkoxy)-N-(4H-1,2,4-triazol-4-yl)benzamide (C-n-tba) and the Fe(X)(2) center dot sH(2)O salts. The polymers obey the general formula [Fe(C-n-tba)(3)]-(X)(2) center dot sH(2)O [X = CF3SO3-, BF4-; n = 4, 6, 8, 10, 12]. The derivatives with n = 4, 6 exhibit spin transition behavior like in crystalline compounds, whereas those with n = 8, 10, 12 present a spin transition coexisting with the mesomorphic behavior in the room-temperature region. A columnar mesophase has been found for the majority of the metallomesogens, but also a columnar lamellar mesophase was observed for other derivatives. [Fe(C-12- tba)(3)](CF3SO3)(2) represents a new example of a system where the phase transition directly influences the spin transition of the Fe(II) ions but is not the driving energy of the spin crossover phenomenon. The compounds display drastic changes of color from violet (low-spin state, LS) to white (high-spin state, HS). The compounds are fluid, and it is possible to prepare thin films from them.
Switching of Spin States Triggered by a Phase Transition: Spin-Crossover Properties of Self-Assembled Iron(II) Complexes with Alkyl-Tethered Triazole Ligands
作者:Tsuyohiko Fujigaya、Dong-Lin Jiang、Takuzo Aida
DOI:10.1021/ja038088e
日期:2003.12.1
self-assembled structure of polynuclear iron(II) species. According to DSC, VT-IR, and VT-XRD profiles, the spin-state transition is triggered by melting of the interdigitating alkyl chains, which is likely responsible for the "lock-and-release" feature of the spin state. By virtue of the thermoreversibility of the phasetransition, the spincrossover could be repeated without deterioration.
Spin-Crossover Dendrimers: Generation Number-Dependent Cooperativity for Thermal Spin Transition
作者:Tsuyohiko Fujigaya、Dong-Lin Jiang、Takuzo Aida
DOI:10.1021/ja050275k
日期:2005.4.1
Poly(benzyl ether) dendrons having a focal triazole unit (Gntrz: trz = triazole; n = generation knumber = 0-2) were found to react with (MeSO3)(2)Fe to form dendritic coordination polymers ([Fe(Gntrz)3]-(MeSO3)(2)center dot 2H(2)O) that undergo the thermal spin transition. When the generation number of the dendritic unit was larger (n = 0 -> 1 -> 2), the average degree of polymerization (D-p = 20 -> 10 -> 3) and spin-crossover temperature (T-c = 335 - 315 - 300 K) of the resulting polymer were lower. However, the abruptness of the spin transition was not monotonically dependent on the generation number; (G1trz)Fe exhibited an abrupt spin transition with a temperature width of only 10 K, while the smallest and largest members of the (Gntrz)Fe family both displayed a rather broad spin-transition temperature width (30 (n = 0) and 50 K (n = 2)). X-ray diffraction and calorimetric analyses indicated the presence of a discotic columnar core-shell assembly with a crystal lattice best occupied by a C3v symmetric array of medium-sized (G1trz)-Fe.
One-Dimensional Iron(II) Compounds Exhibiting Spin Crossover and Liquid Crystalline Properties in the Room Temperature Region
作者:M. Seredyuk、A. B. Gaspar、V. Ksenofontov、Y. Galyametdinov、M. Verdaguer、F. Villain、P. Gütlich
DOI:10.1021/ic8006266
日期:2008.11.17
A novel series of 1D Fe(II) metallomesogens have been synthesized using the ligand 5-bis(alkoxy)-N-(4H-1,2,4-triazol-4-yl)benzamide (C-n-tba) and the Fe(X)(2) center dot sH(2)O salts. The polymers obey the general formula [Fe(C-n-tba)(3)]-(X)(2) center dot sH(2)O [X = CF3SO3-, BF4-; n = 4, 6, 8, 10, 12]. The derivatives with n = 4, 6 exhibit spin transition behavior like in crystalline compounds, whereas those with n = 8, 10, 12 present a spin transition coexisting with the mesomorphic behavior in the room-temperature region. A columnar mesophase has been found for the majority of the metallomesogens, but also a columnar lamellar mesophase was observed for other derivatives. [Fe(C-12- tba)(3)](CF3SO3)(2) represents a new example of a system where the phase transition directly influences the spin transition of the Fe(II) ions but is not the driving energy of the spin crossover phenomenon. The compounds display drastic changes of color from violet (low-spin state, LS) to white (high-spin state, HS). The compounds are fluid, and it is possible to prepare thin films from them.