Hai-Xia Zhao

Synthesis, characterization and property of a mixed-valent AgI/AgII coordination polymer

A novel mixed-valent Ag(I)/Ag(II) coordination polymer {[Ag(I)(2)Ag(II)(0.5)(SO(4))(HSO(4))(pyz)(2.5)]·H(2)O}(n) (1, pyz = pyrazine) was synthesized and characterized. The results show it presents semiconducting and photoluminescent properties.

Two Three-Dimensional 2p−3d−4f Heterometallic Frameworks Featuring a Ln6Cu24Na12 Cluster as a Node

Two three-dimensional 2p-3d-4f heterometallic frameworks featuring a nanosized Ln(6)Cu(24)Na(12) (Ln = Gd, Dy) cluster as a node have been obtained under microwave irradiation conditions through the reaction of H(2)ANMA (H(2)ANMA = L-alanine-N-monoacetic acid), Cu(NO(3))(2), and Ln(NO(3))(3) (Ln = Gd for 1, Dy for 2) with NaOH in deionized water. Investigations on the magnetic properties show that 1 exhibits ferrimagnetic behavior. The electrical conductivity measurements reveal that 1 behaves as a proton conductor.

Magnetic and thermal properties of three ionothermally synthesized metal–carboxylate frameworks of [M3(ip)4][EMIm]2 (M = Co, Ni, Mn, H2ip = isophthalic acid, EMIm = 1-ethyl-3-methyl imidazolium)

Three metal-organic frameworks, [M(3)(ip)(4)][EMIm](2) (M = Co 1, Ni 2, Mn 3, H(2)ip = isophthalic acid, EMIm = 1-ethyl-3-methyl imidazolium) were prepared from an ionic liquid medium. All the compounds feature the same (4(24))(6(4)) topology based on linear trinuclear clusters as eight-connected nodes. Compounds 1 and 2 are isostructural, while compound 3 exhibits a different structure due to the slight difference in the arrangement of M(3)(OOCR)(8) SBUs. Magnetic property measurements reveal that all the compounds display anti-ferromagnetic coupling, where compounds 2 and 3 show isotropic exchange interactions of -0.10 cm(-1) for 2 and -1.6 cm(-1) for 3. Investigation of the thermal diffusivity shows that the thermal diffusivity of 1 is higher than that of 3, while that of 3 is higher than that of 2.

The influence of water on dielectric property in cocrystal compound of [orotic acid][melamine]·H2O

An organic cocrystal compound consisting of melamine, orotic acid and water molecules was synthesized under hydrothermal conditions. Investigation of its temperature- and frequency-dependent dielectric behaviors reveals that the fluctuation of hydrogen atoms of water molecules between the layers plays a key role in its dielectric anomaly.

An insight into the magnetoelectric coupling effect in the MOF of [NH2(CH3)2]n[FeIIIFeII(HCOO)6]n

Understanding the microscopic mechanism of magnetoelectric coupling is of fundamental importance for the rational design of multiferroics. Herein, the magnetoelectric coupling effect in the metal-organic frameworks of [NH2(CH3)2]n[FeIIIFeII(HCOO)6]n (1) was investigated, respectively, through measuring the dielectric properties and ferroelectric polarization of single-crystal 1 along different crystal axes under external magnetic fields. Analysis on the magnetic structure of 1 reveals that the defect in the FeII-FeIII sublattices plays a key contribution to the magnetoelectric coupling of 1, providing a unique insight into the magnetoelectric coupling effect of MOFs-based multiferroics.

An above-room-temperature switchable molecular dielectric with a large dielectric change between high and low dielectric states

Dielectric anisotropy of anilinium perchlorate is investigated at various temperatures. Crystal structures at different temperatures reveal that significant dielectric change between low and high dielectric states is closely related to the disorder of the anilinium cation and perchlorate anion at high dielectric state; meanwhile, the conductivity after phase transition also contributes a lot to the high dielectric state.

Giant Room-Temperature Magnetodielectric Response in a MOF at 0.1 Tesla

A giant room-temperature magnetodielectric (MD) response upon the application of a small magnetic field is of fundamental importance for the practical application of a new generation of devices. Here, the giant room-temperature magnetodielectric response is demonstrated in the metal-organic framework (MOF) of [NH2 (CH3 )2 ]n [FeIII FeII(1-x) NiIIx (HCOO)6 ]n (x ≈ 0.63-0.69) (1) with its MD coefficient remaining between -20% and -24% in the 300-410 K temperature range, even at 0.1 T. Because a room-temperature magnetodielectric response has never been observed in MOFs, the present work not only provides a new type of magnetodielectric material but also takes a solid step toward the practical application of MOFs in a new generation of devices.

Thermal energy storage in a supramolecular assembly of [C6H11NH3]+[CF3COO]−(C6H11 = cyclohexyl)

A supramolecular compound [C6H11NH3]+[CF3COO]− was synthesized. Investigation on the structure of 1 at different temperatures reveals that it is the disorder of the anions that plays a key role in thermal energy storage. Studies on the thermal and physical properties of 1 indicate that utilization of the sensible heat in 1 can significantly enhance its ability to store thermal energy.