Guanghui An

Charge-Convertible Carbon Dots for Imaging-Guided Drug Delivery with Enhanced in Vivo Cancer Therapeutic Efficiency

Carbon dots (CDs) are remarkable nanocarriers due to their promising optical and biocompatible capabilities. However, their practical applicability in cancer therapeutics is limited by their insensitive surface properties to complicated tumor microenvironment in vivo. Herein, a tumor extracellular microenvironment-responsive drug nanocarrier based on cisplatin(IV) prodrug-loaded charge-convertible CDs (CDs-Pt(IV)@PEG-(PAH/DMMA)) was developed for imaging-guided drug delivery. An anionic polymer with dimethylmaleic acid (PEG-(PAH/DMMA)) on the fabricated CDs-Pt(IV)@PEG-(PAH/DMMA) could undergo intriguing charge conversion to a cationic polymer in mildly acidic tumor extracellular microenvironment (pH ∼ 6.8), leading to strong electrostatic repulsion and release of positive CDs-Pt(IV). Importantly, positively charged nanocarrier displays high affinity to negatively charged cancer cell membrane, which results in enhanced internalization and effective activation of cisplatin(IV) prodrug in the reductive cytosol. The in vitro experimental results confirmed that this promising charge-convertible nanocarrier possesses better therapeutic efficiency under tumor extracellular microenvironment than normal physiological condition and noncharge-convertible nanocarrier. The in vivo experiments further demonstrated high tumor-inhibition efficacy and low side effects of the charge-convertible CDs, proving its capability as a smart drug nanocarrier with enhanced therapeutic effects. The present work provides a strategy to promote potential clinical application of CDs in the cancer treatment.

Palladium-Catalyzed Tandem Diperoxidation/C−H Activation Resulting in Diperoxy-oxindole in Air

A highly efficient and facile palladium-catalyzed tandem diperoxidation and C-H activation process was reported, which provides a new pathway for the synthesis of biologically active diperoxides as well as oxindole derivatives from readily available starting materials in excellent chemical yields.

Au25 cluster functionalized metal–organic nanostructures for magnetically targeted photodynamic/photothermal therapy triggered by single wavelength 808 nm near-infrared light

Near-infrared (NIR) light-induced cancer therapy has gained considerable interest, but pure inorganic anti-cancer platforms usually suffer from degradation issues. Here, we designed metal-organic frameworks (MOFs) of Fe3O4/ZIF-8-Au25 (IZA) nanospheres through a green and economic procedure. The encapsulated Fe3O4 nanocrystals not only produce hyperthemal effects upon NIR light irradiation to effectively kill tumor cells, but also present targeting and MRI imaging capability. More importantly, the attached ultrasmall Au25(SR)18(-) clusters (about 2.5 nm) produce highly reactive singlet oxygen ((1)O2) to cause photodynamic effects through direct sensitization under NIR light irradiation. Furthermore, the Au25(SR)18(-) clusters also give a hand to the hyperthemal effect as photothermal fortifiers. This nanoplatform exhibits high biocompatibility and an enhanced synergistic therapeutic effect superior to any single therapy, as verified by in vitro and in vivo assay. This image-guided therapy based on a metal-organic framework may stimulate interest in developing other kinds of metal-organic materials with multifunctionality for tumor diagnosis and therapy.

Immobilization of Polyoxometalate in the Metal-Organic Framework rht-MOF-1: Towards a Highly Effective Heterogeneous Catalyst and Dye Scavenger

A series of three remarkable complexes [PMo12O40]@[Cu6O(TZI)3(H2O)9]4·OH·31H2O (H3TZI = 5-tetrazolylisophthalic acid; denoted as HLJU-1, HLJU = Heilongjiang University), [SiMo12O40]@[Cu6O(TZI)3(H2O)9]4·32H2O (denoted as HLJU-2), and [PW12O40]@[Cu6O(TZI)3(H2O)6]4·OH·31H2O (denoted as HLJU-3) have been isolated by using simple one-step solvothermal reaction of copper chloride, 5-tetrazolylisophthalic acid (H3TZI), and various Keggin-type polyoxometalates (POMs), respectively. Crystal analysis of HLJU 1−3 reveals that Keggin-type polyoxoanions have been fitted snuggly in the cages of rht-MOF-1 (MOF: metal−organic framework) with large cell volume in a range of 87968−88800 Å3 and large pore volume of about 68%. HLJU 1–3 exhibit unique catalytic selectivity and reactivity in the oxidation of alkylbenzene with environmental benign oxidant under mild condition in aqueous phase as well as the uptake capacity towards organic pollutants in aqueous solution.

Ligand-free palladium-catalyzed intramolecular Heck reaction of secondary benzylic bromides.

A facile ligand-free palladium-catalyzed intramolecular Heck reaction of β-hydrogen-containing secondary benzylic bromides was developed, which affords pyrroline derivatives with good regioselectivities.

Hydrogen-bonding self-assembly of two dimensional (2D) layer structures generating metal–organic nanotubes

Two metal–organic nanotubular architectures are built from 2D layer structures with big windows through hydrogen-bonding self-assembly of a thiourea group, representing a strategy for the preparation of metal–organic nanotubes generated from 2D layer structures.

2D l-Di-toluoyl-tartaric acid Lanthanide Coordination Polymers: Toward Single-component White-Light and NIR Luminescent Materials.

A series of five l-di-p-toluoyl-tartaric acid (l-DTTA) lanthanide coordination polymers, namely {[Ln4 K(4)  L6 (H2O)x ]⋅yH2 O}n , [Ln=Dy (1), x=24, y=12; Ln=Ho (2), x=23, y=12; Ln=Er (3), x=24, y=12; Ln=Yb (4), x=24, y=11; Ln=Lu (5), x=24, y=12] have been isolated by simple reactions of H2L (H2 L= L-DTTA) with LnCl3 ⋅6 H2O at ambient temperature. X-ray crystallographic analysis reveals that complexes 1-5 feature two-dimensional (2D) network structures in which the Ln(3+) ions are bridged by carboxylate groups of ligands in two unique coordinated modes. Luminescent spectra demonstrate that complex 1 realizes single-component white-light emission, while complexes 2-4 exhibit a characteristic near-infrared (NIR) luminescence in the solid state at room temperature.

NIR luminescence of a series of benzoyltrifluoroacetone erbium complexes

A series of five β-diketone erbium complexes with various azacyclo-auxiliary ligands, namely, Er(Hbta)3(H2O)2 (1), Er(Hbta)3(bpy) (2), Er(Hbta)3(phen) (3), Er(Hbta)3(dpq) (4) and Er(Hbta)3(dppz) (5) (Hbta = benzoyltrifluoroacetone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dpq = pyrazino[2,3-f][1,10]phenanthroline, dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been isolated and characterized by X-ray crystallographic analysis. Near-infrared luminescence analysis reveals that all complexes 1–5 exhibit strong NIR luminescence of Er(III) ions around 1535 nm with the highest lifetime of 4.532 μs, quantum yield of 3.24 × 10−4 and broadband emission around 1.5 μm for complex 5, in which the azacyclo-auxiliary ligand absorbs and transfers the energy leading to complete quenching of the ligand-associated visible emission. The energy transfer processes among benzoyltrifluoroacetone, the Er(III) ion and the auxiliary ligands in complexes 1–5 have been investigated.

Ultrasound-Promoted Ligand-Free Heck Reaction in Water

Abstract An ultrasound irradiation–promoted Heck reaction catalyzed by ligand-free palladium acetate was described. The ultrasound-promoted Heck reaction was carried out under mild and environmentally friendly conditions, resulting in the corresponding products with good to excellent chemical yields (up to 96% yield) and high regioselectivities and stereoselectivities (E/Z > 99:1). Acrylamide and acrylic acid were used for the first time as substrates in the ultrasound-promoted Heck reaction. It was found that the reaction could be finished within 20 min.

The racemate-to-homochiral approach to crystal engineering via chiral symmetry breaking

The racemate-to-homochiral approach is a method to transform or separate a racemic mixture into homochiral compounds. This protocol, if without an external chiral source, is categorized into chiral symmetry breaking. The resolution processes without chiral induction are highly important for the investigation of the origin of homochirality in life, pharmaceutical synthesis, the chemical industry and materials science. Besides the studies on the models and mechanisms used to explain the racemate-to-homochiral approach which may give the probable origin of homochirality in life, recent developments in this field have been plotted towards the separation of enantiomers for the synthesis of pharmaceuticals and chiral chemicals. Direct synthesis of chiral metal–organic framework (MOF) coordination polymers has been achieved as well. In this highlight, we will disclose the comparison of spontaneous resolution and chiral symmetry breaking resolution, and describe the evolution of models and mechanisms for chiral symmetry breaking resolution and its applications in enantiomer resolution and materials science.