A pH-Sensitive Zwitterionic Iron Complex Probe with High Biocompatibility for Tumor-Specific Magnetic Resonance Imaging

Accurate diagnosis of tumor characteristics, including its location and boundary, is of immense value to subsequent therapy. Activatable magnetic resonance imaging (MRI) contrast agents that respond to tumor-specific microenvironments, such as the redox state, pH, and enzyme activity, enable better mapping of tumor tissue. However, the practical application of most reported activatable agents is hampered by problems including potential toxicity, inefficient elimination, and slow activation. In this study, we developed a zwitterionic iron complex (Fe-ZDS) as a positive MRI contrast agent for tumor-specific imaging. Fe-ZDS could dissociate in weakly acidic solution rapidly, accompanied by clear longitudinal relaxivity (r₁) enhancement, which enabled the complex to act as a pH-sensitive contrast agent for tumor-specific MR imaging. In vivo experiments showed that Fe-ZDS rapidly enhanced the tumor-to-normal contrast ratio by >40 %, which assisted in distinguishing the tumor boundary. Furthermore, Fe-ZDS circulated freely in the bloodstream and was excreted relatively safely via kidneys owing to its zwitterionic nature. Therefore, Fe-ZDS is an ideal candidate for a tumor-specific MRI contrast agent and holds considerable potential for clinical translation.     

自由基浓度测定方法的再验证及其在煤化学中应用

对前人建立的标准曲线法测煤中自由基浓度进行优化,以DPPH标准样品和基准样品的二次积分面积比值为新参数,结果显示新参数标准曲线法的实测值与理论值相对误差都在5%以内;重复性、复现性实验的相对标准偏差都小于3%。将新参数标准曲线法用于分析不同煤化程度煤和新疆黑山煤(HS)沥青质的自由基浓度,发现随着煤化程度增加,其煤中自由基浓度逐渐增大,从低阶褐煤的8.531×10~(17)/g上升到高阶无烟煤3.37899×10~(19)/g;而在HS煤液化过程中,随着加氢液化温度的升高,其沥青质自由基浓度逐渐下降,从290℃的1.5793×10~(18)/g降到450℃的7.410×10~(17)/g,沥青质自由基浓度变化趋势与其产率变化趋势相一致。     

Exploration of Nano-Saturns: A Spectacular Sphere–Ring Supramolecular System

Saturn-like systems consisting of nanoscale rings and spheres are fascinating motifs in supramolecular chemistry. Several ring molecules are known to include spherical molecules at the center of the cavity via noncovalent attractive interactions. In this Minireview, we generalize the molecular design, the structural features, and the supramolecular chemistry of such “nano-Saturns”, which consist of monocyclic rings and fullerene spheres (mainly C₆₀), on the basis of previous experimental and theoretical studies. Ring molecules are classified into three types (loop, belt, and disk) according to their shapes and possible interactions. Whereas typical belt-shaped rings tend to form tight complexes due to the wide contact area via π–π interactions, flat disk-shaped rings generally form weak complexes due to the narrow contact area mainly via CH–π interactions. In spite of the small association energies, disk-shaped rings are attractive because such rings can mimic the planet Saturn precisely as exemplified by an anthracene cyclic hexamer–C₆₀ complex.     

Effective Application of Microwave Resonant Cavity System to Flow Chemistry

By applying advanced telecommunication solid state devices to microwave (MW) resonant cavity system for flow chemistry, it becomes possible to heat up low polarity solvents higher than 250 C, that are considered impossible to heat up by MW until now. The resonant cavity system is opening new process windows to production processes of specialty chemicals which require low cost, high yield and high productivity.     

Novel tantalum phosphate Na13Sr2Ta2(PO4)9: synthesis,crystal structure,DFT calculations and Dy3+‐activated fluorescence performance

A new tantalum phosphate, tridecasodium distrontium ditantalum nonaphosphate, Na₁₃Sr₂Ta₂(PO₄)₉, was prepared using the high‐temperature flux method. The structure can be described as a three‐dimensional open framework containing isolated [Ta^V₂(PO₄)₉]¹⁷⁻ units that are interlocked by Na and Sr ions. Band structure studies by the first‐principles method revealed that Na₁₃Sr₂Ta₂(PO₄)₉ is an insulator with an indirect band gap of 4.78 eV, which makes it suitable as a luminescent host matrix. A series of solid solutions, i.e. Na₁₃Sr_2–xTa₂(PO₄)₉:xDy³⁺ (x = 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12 and 0.14), were prepared and their photoluminescence properties studied. Under 350 nm light excitation, these emit two typical emissions of the Dy³⁺ ion, i.e. the ⁴F_9/2→⁶H_15/2 transition centred at 476 nm and the ⁴F_9/2→⁶H_13/2 transition centred at 570 nm.     

Critical Assessment of the DFT + U Approach for the Prediction of Vanadium Dioxide Properties

In a previous study (Stahl and Bredow, Chem. Phys. Lett. 2018, 695, 28–33), we have studied structural, energetic, and electronic properties of two vanadium dioxide VO₂ polymorphs with modified global and range-separated hybrid functionals. Since hybrid methods are computationally demanding, we evaluate the computationally more efficient DFT + U method in the present study. We assessed the widely used Dudarev PBE + U approach with a literature value of the effective Hubbard parameter U_eff = 3.4 eV. We compared the PBE + U results for the two VO₂ polymorphs with our previous results, a self-consistent hybrid functional sc-PBE0, and the meta-GGA functional SCAN. It was found that the PBE + U method yields a strongly distorted monoclinic phase and does not reproduce the metal-to-insulator transition of VO₂ correctly, even with modified values of U_eff. On the other hand, sc-PBE0 and SCAN describe the relative stability and the electronic structure of both polymorphs correctly and also provide reasonable lattice parameters. The functional SCAN yields the optimal balance between computational efficiency and accuracy. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.     

Caesium carbonate supported on hydroxyapatite‐encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst for the one‐pot synthesis of pyrazolo[1,2‐b]phthalazine‐5,10‐diones

A novel nanomagnetic basic catalyst of caesium carbonate supported on hydroxyapatite‐coated Ni_0.5Zn_0.5Fe₂O₄ magnetic nanoparticles (Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃) was prepared. This new catalyst was fully characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, X‐ray diffraction and vibrating sample magnetometry techniques, and then the catalytic activity of this catalyst was investigated in the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives. Also, Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃ could be reused at least five times without significant loss of activity and could be recovered easily by applying an external magnet. Thus, the developed nanomagnetic catalyst is potentially useful for the green and economic production of organic compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Yolk‐Shell Porous Microspheres of Calcium Phosphate Prepared by Using Calcium L‐Lactate and Adenosine 5′‐Triphosphate Disodium Salt: Application in Protein/Drug Delivery

A facile and environmentally friendly approach has been developed to prepare yolk‐shell porous microspheres of calcium phosphate by using calcium L ‐lactate pentahydrate (CL) as the calcium source and adenosine 5′‐triphosphate disodium salt (ATP) as the phosphate source through the microwave‐assisted hydrothermal method. The effects of the concentration of CL, the microwave hydrothermal temperature, and the time on the morphology and crystal phase of the product are investigated. The possible formation mechanism of yolk‐shell porous microspheres of calcium phosphate is proposed. Hemoglobin from bovine red cells (Hb) and ibuprofen (IBU) are used to explore the application potential of yolk‐shell porous microspheres of calcium phosphate in protein/drug loading and delivery. The experimental results indicate that the as‐prepared yolk‐shell porous microspheres of calcium phosphate have relatively high protein/drug loading capacity, sustained protein/drug release, favorable pH‐responsive release behavior, and a high biocompatibility in the cytotoxicity test. Therefore, the yolk‐shell porous microspheres of calcium phosphate have promising applications in various biomedical fields such as protein/drug delivery.     

Structure determination of KScS2, RbScS2 and KLnS2 (Ln = Nd,Sm, Tb,Dy, Ho,Er, Tm and Yb) and crystal–chemical discussion

The title structures of KScS₂ (potassium scandium sulfide), RbScS₂ (rubidium scandium sulfide) and KLnS₂ [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS₂, RbScS₂ and KTbS₂) or redetermined. All of them belong to the α‐NaFeO₂ structure type in agreement with the ratio of the ionic radii r³⁺/r⁺. KScS₂, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S—S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S²⁻) and the bond‐valence sums.