Power and thermal characteristics of up-conversion luminescence in Er3+/Yb3+-doped Nb2O5 nano-powder

Nb2O5 nano-powder doped with Er3+ and Yb3+ ion can emit strong up-conversion emissions under infrared (975 and 1550nm) excitation. The intensities of the up-conversion emissions is very sensitive to temperature. Based on luminescence intensity ration, the thermal sensitivity had been studied. Under 1550nm excitation, the relative sensitivity SR1 is higher at 300-460K range, whose maximal value is 9.13%/K

Galactose-based Thermosensitive Nanogels for Targeted Drug Delivery of Iodoazomycin Arabinofuranoside (IAZA) for Theranostic Management of Hypoxic Hepatocellular Carcinoma

In this study, galactose-based nanogels were prepared by reversible addition–fragmentation chain transfer process to facilitate the targeted delivery of iodoazomycin arabinofuranoside (IAZA), a clinical drug for imaging solid hypoxic tumors, and evaluate its role in hypoxia-selective (radio)­theranostic (therapy + diagnostic) management of therapy-resistant cancer cells. The nanogels have a cross-linked temperature-responsive core and a dense carbohydrate shell. Their thermoresponsive nature allowed the controlled encapsulation of IAZA drug for targeted delivery and release in hypoxic hepatocellular carcinoma via asialoglycoprotein receptor-mediated uptake. The synthesized nanogel-IAZA delivery systems demonstrated a stable, nonburst release of IAZA over 10 h with up to 0.6 mM loading capacity of IAZA within the nanogel. The cytotoxicity evaluations of the nanogels demonstrated that they are relatively nontoxic in multiple cell lines. The radiosensitization studies indicated that IAZA in encapsulated form offers a superior radiosensitization of hypoxic cells (sensitizer enhancement ratio for IAZA alone, 1.33; 1.62 for nanogel encapsulated IAZA). These studies suggest that galactose-based nanogels may serve as a versatile drug delivery system for IAZA (and other azomycin-based agents) and enable its hypoxia-selective multimodal theranostic applications to manage hypoxic solid (hepatocellular) tumors by facilitating position/single photon emission tomography-based imaging, external beam radiation therapy, and <i>in situ</i> molecular radiotherapy

Making Flavone Thioethers Using Halides and Powdered Sulfur or Na₂S₂O₃

The method for constructing C–S bonds is very important in organic synthesis. Here a new sulfenylation method to generate flavone thioether derivatives was developed by employing aromatic or alkyl halides, S powder and Na₂S₂O₃ as reactants. Good yields of regioselective C_alkyl–S and C_aryl–S-substituted flavones were generated under relatively environmentally friendly and simple conditions. This method might be potentially applicable to large scale production, and it enriches current sulfenylation methods

Diversity-Oriented Syntheses: Coupling Reactions Between Electron-Deficient Olefins and Aryl Aldehydes via C(sp²)–H Functionalization

A diversity-oriented syntheses by coupling three electron-deficient olefins (vinyl sulfonamides, methacrylamides, and methyl acrylates, respectively) with aryl aldehydes via C­(sp²)–H functionalization were reported. These reactions gave four different skeletal products respectively under environment-friendly and mild conditions. All these reactions are highly regioselective and effective, very suitable for the preparation of synthetic building blocks and compound library, the results will enrich current coupling chemistry of olefins with aldehydes and can be applied to other chemistry areas as well

Parallel Syntheses of Eight-Membered Ring Sultams via Two Cascade Reactions in Water

From vinyl sulfonamides as precursors to vinyl sulfonamide epoxides, two cascade reaction protocols were developed to synthesize eight-membered ring sultams in water. These protocols employ intermolecular Michael addition by NaOH or NaHS in water, followed by rapid proton transfer and intramolecular 8-<i>endo-tet</i> epoxide ring-opening to give medium-size sultams selectively in one-pot. Novel core structures and high synthetic efficiency make these cascade reactions highly suitable for sultam library production. Both reactions proceeded well and afforded the respective sultams in good yields under environmentally friendly conditions

Selective Synthesis of Seven- and Eight-Membered Ring Sultams via Two Tandem Reaction Protocols from One Starting Material

From one starting material, two tandem reaction protocols to synthesize seven- and eight-membered ring sultams were developed. One protocol employs intermolecular epoxide ring-opening by NaN₃, followed by an intramolecular 7-<i>endo-trig</i> oxa-Michael addition reaction. The second protocol applies to intermolecular aza-Michael addition of a primary amine, followed by 8-<i>endo-tet</i> intramolecular epoxide ring-opening of the resultant amine intermediate. Both protocols afforded the respective sultams in good yields under mild reaction conditions

Ammonium Iodide Induced Nonradical Regioselective Sulfenylation of Flavones via a C–H Functionalization Process

A novel and highly regioselective ammonium iodide-induced nonradical sulfenylation method for the construction of a C–S bond was developed via C–H functionalization. With DMSO or R¹SO₂NHNH₂ as a sulfenylating agent, MeS- and R¹S-substituted flavone derivatives were obtained in good yields. This method enriches current C–S bond formation chemistry, making it a highly valuable and practical method in pharmaceutical industry

Cascade Couplings of <i>N</i>‑Alkyl‑<i>N</i>‑methacryloyl Benzamides with Ethers and Benzenesulfonohydrazides To Generate Isoquinoline-1,3(2<i>H</i>,4<i>H</i>)‑dione Derivatives

Two radical-mediated cascade couplings of <i>N-</i>alkyl<i>-N-</i>methacryloylbenzamides with different ethers and arylsulfonohydrazides to generate ether- and arylsulfonyl-substituted isoquinoline-1,3­(2<i>H</i>,4<i>H</i>)-dione derivatives were developed. Both casccades proceeded via initially triggered functionalization of the alkene functions of the <i>N-</i>alkyl<i>-N-</i>methacryloylbenzamides, followed by ortho radical cyclizations onto the aromatic ring to give isoquinoline-1,3­(2<i>H</i>,4<i>H</i>)-dione derivatives in good yields. These highly functionalized drug-like molecules will be valuable in drug discovery in the future