The Cobalt(II) Oxidotellurate(IV) Hydroxides Co₂(TeO₃)(OH)₂ and Co₁₅(TeO₃)₁₄(OH)₂

Previously unknown Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2 were obtained under mild hydrothermal reaction conditions (210 °C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co2(TeO3)(OH)2 (Z = 2, P1¯, a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) Å, α = 101.539(2), β = 100.036(2), γ = 104.347(2)°, 2120 independent reflections, 79 parameters, R[F2 > 2σ(F2)] = 0.017) crystallizes in a unique structure comprised of undulating 2∝[Co2(OH)6/3O3/3O2/2O1/1]4− layers. Adjacent layers are linked by TeIV atoms along the [001] stacking direction. Co2(TeO3)(OH)2 is stable up to 450 °C and decomposes under the release of water into Co6Te5O16 and CoO. Magnetic measurements of Co2(TeO3)(OH)2 showed antiferromagnetic ordering at ≈ 70 K. The crystal structure of Co15(TeO3)14(OH)2 (Z = 3, R3¯, a = 11.6453(2), c = 27.3540(5) Å, 3476 independent reflections, 112 parameters, R[F2 > 2σ(F2)] = 0.026) is isotypic with Co15(TeO3)14F2. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO6], [CoO5(OH)], [CoO5] and [TeO3] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures

The Cobalt(II) Oxidotellurate(IV) Hydroxides Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2

Previously unknown Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2 were obtained under mild hydrothermal reaction conditions (210 °C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co2(TeO3)(OH)2 (Z = 2, P1¯, a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) Å, α = 101.539(2), β = 100.036(2), γ = 104.347(2)°, 2120 independent reflections, 79 parameters, R[F2 > 2σ(F2)] = 0.017) crystallizes in a unique structure comprised of undulating 2∝[Co2(OH)6/3O3/3O2/2O1/1]4− layers. Adjacent layers are linked by TeIV atoms along the [001] stacking direction. Co2(TeO3)(OH)2 is stable up to 450 °C and decomposes under the release of water into Co6Te5O16 and CoO. Magnetic measurements of Co2(TeO3)(OH)2 showed antiferromagnetic ordering at ≈ 70 K. The crystal structure of Co15(TeO3)14(OH)2 (Z = 3, R3¯, a = 11.6453(2), c = 27.3540(5) Å, 3476 independent reflections, 112 parameters, R[F2 > 2σ(F2)] = 0.026) is isotypic with Co15(TeO3)14F2. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO6], [CoO5(OH)], [CoO5] and [TeO3] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures

Ultrasonic Implantation and Imaging of Sound-Sensitive Theranostic Agents for the Treatment of Arterial Inflammation

For site-specific diseases such as atherosclerosis, it is desirable to noninvasively and locally deliver therapeutics for extended periods of time. High-intensity focused ultrasound (HIFU) provides targeted drug delivery, yet remains unable to sustain delivery beyond the HIFU treatment time. Furthermore, methods to validate HIFU-enhanced drug delivery remain limited. In this study, we report on HIFU-targeted implantation of degradable drug-loaded sound-sensitive multicavity PLGA microparticles (mcPLGA MPs) as a theranostic agent for the treatment of arterial lesions. Once implanted into the targeted tissue, mcPLGA MPs eluted dexamethasone for several days, thereby reducing inflammatory markers linked to oxidized lipid uptake in a foam cell spheroid model. Furthermore, implanted mcPLGA MPs created hyperechoic regions on diagnostic ultrasound images, and thus noninvasively verified that the target region was treated with the theranostic agents. This novel and innovative multifunctional theranostic platform may serve as a promising candidate for noninvasive imaging and treatment for site-specific diseases such as atherosclerosis

CoTeO4 : a wide-bandgap material adopting the dirutile structure type

High-quality crystals of CoTeO4 were grown by application of chemical vapor transport reactions in closed silica ampoules, starting from polycrystalline material in a temperature gradient 640 °C → 580 °C with TeCl4 as transport agent. Crystal structure analysis of CoTeO4 from single crystal X-ray data revealed a dirutile-type structure with CoII and TeVI atoms at crystallographically distinct sites, each with point group symmetry . The statistical significance and accuracy of the previously reported structural model based on powder data with the ordered arrangement of Co and Te cations was noticeably improved. CoTeO4 does not undergo a structural phase transition upon heating, but decomposes stepwise (Co2Te3O8 as intermediate phase) to Co3TeO6 as the only crystalline phase stable above 770 °C. Temperature-dependent magnetic susceptibility and dielectric measurements suggest antiferromagnetic ordering at ∼50 K. Optical absorption spectroscopy and computational studies reveal wide-band semiconductive behavior for CoTeO4. The experimentally determined band gap of ∼2.42 eV is also found for CdS, which is frequently used in photovoltaic systems but is hazardous to the environment. Hence, CoTeO4 might be a possible candidate to replace CdS in this regard

Phase Stability and Magnetic Properties of Compositionally Complex <i>n</i> = 2 Ruddlesden–Popper Perovskites

Four new compositionally complex perovskites with multiple (four or more) cations on the B site of the perovskites have been studied. The materials have the general formula La0.5Sr2.5(M)2O7−δ (M = Ti, Mn, Fe, Co, and Ni) and have been synthesized via conventional solid-state synthesis. The compounds are the first reported examples of compositionally complex n = 2 Ruddlesden–Popper perovskites. The structure and properties of the materials have been determined using powder X-ray diffraction, neutron diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and magnetometry. The materials are isostructural and adopt the archetypal I4/mmm space group with the following unit cell parameters: a ∼ 3.84 Å, and c ∼ 20.1 Å. The measured compositions from energy dispersive X-ray spectroscopy were La0.51(2)Sr2.57(7)Ti0.41(2)Mn0.41(2)Fe0.39(2)Co0.38(1)Ni0.34(1)O7−δ, La0.59(4)Sr2.29(23)Mn0.58(5)Fe0.56(6)Co0.55(6)Ni0.42(4)O7−δ, La0.54(2)Sr2.49(13)Mn0.41(2)Fe0.81(5)Co0.39(3)Ni0.36(3)O7−δ, and La0.53(4)Sr2.55(19)Mn0.67(6)Fe0.64(5)Co0.31(2)Ni0.30(3)O7−δ. No magnetic contribution is observed in the neutron diffraction data, and magnetometry indicates a spin glass transition at low temperatures