Copper(I) complexes of tris(thioimidazolyl)borates (R′Tm), including [Cu(Tm)(PR″)] (R″ = Ph, Cu1; Cy, Cu2) and [Cu(R′Tm)(PR″)] (R′ = N-methylimidazole; R″ = Ph, Cy) were prepared and characterized by spectroscopic methods. The X-ray crystal structures of Cu1 and Cu2 feature a tripodal Tm ligand coordinated in κ-S,S,S mode. Using Cu2 as a catalyst (loading: 1 mol %), the aziridination of styrenes and sulfimidation of thioanisoles with PhI=NTs at RT for 3 and 0.5 h, respectively, both resulted in product yields of up to 99%. Cu2 also catalyzed intramolecular amination of the aryl C-H bond of vinyl azides with up to 98% yield. DFT calculations were performed to gain insight into the mechanism of the Cu2-catalyzed aziridination reaction.

Lam Tsz Lung    Tso Ken Chi-Hang    Bei Cao    Yang Chen    Chen Daqing    Chang Xiaoyong    Jie sheng Huang    支志明    

Inorganic Chemistry

2017

A series of luminescent cyclometalated gold(III) complexes having alkyls as auxiliary ligands has been prepared. The alkyl ligand was found to effectively increase the emission quantum yields and lifetimes of luminescent cyclometalated gold(III) complexes by circumventing the population of LLCT excited states that are found in complexes supported by arylacetylide ligands. These gold(III) alkyl complexes exhibit emission quantum yields and lifetimes of up to 0.40 and 180 μs, respectively, in solution at room temperature. The triplet emission color of these complexes is tunable from yellow to sky blue by modifying the cyclometalating ligand.

Wai pong To    Glenna so ming Tong    Cheung Chi Wah    Yang Chen    Zhou Dongling    支志明    

Inorganic Chemistry

2017

Cobalt(II)-porphyrin catalyzed intramolecular Buchner reaction and arene cyclopropanation of alkyl diazomethanes generated in situ from N-tosylhydrazones gave a range of bicyclic cycloheptatriene fused pyrrolidines and tetracyclic cyclopropane fused pyrrolidines in good to high yields and with high chemo- and regioselectivities. The obtained cyclopropane fused pyrrolidines can be readily converted into other N-heterocycles with potential synthetic and biological interest. (Figure presented.).

Wang Haixu    Congying Zhou    支志明    

Advanced Synthesis and Catalysis

2017

Reprogramming of intracellular metabolism is common in liver cancer cells. Understanding the mechanisms of cell metabolic reprogramming may present a new basis for liver cancer treatment. In our previous study, we reported that a novel oncogene eukaryotic translation initiation factor 5A2 (EIF5A2) promotes tumorigenesis under hypoxic condition. Here, we aim to investigate the role of EIF5A2 in cell metabolic reprogramming during hepatocellular carcinoma (HCC) development. In this study, we reported that the messenger RNA (mRNA) level of EIF5A2 was upregulated in 59 of 105 (56.2%) HCC clinical samples (P = 0.015), and EIF5A2 overexpression was significantly associated with shorter survival time of patients with HCC (P = 0.021). Ectopic expression of EIF5A2 in HCC cell lines significantly promoted cell growth and accelerated glucose utilization and lipogenesis rates. The high rates of glucose uptake and lactate secretion conferred by EIF5A2 revealed an abnormal activity of aerobic glycolysis in HCC cells. Several key enzymes involved in glycolysis including glucose transporter type 1 and 2, hexokinase 2, phosphofructokinase liver type, glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase M2 isoform, phosphoglycerate mutase 1 and lactate dehydrogenase A were upregulated by overexpression of EIF5A2. Moreover, EIF5A2 showed positive correlations with FASN and ACSS2, two key enzymes involved in the fatty acid de novo biosynthetic pathway, at both protein and mRNA levels in HCC. These results indicated that EIF5A2 may regulate fatty acid de novo biosynthesis by increasing the uptake of acetate. In conclusion, our findings demonstrate that EIF5A2 has a critical role in HCC cell metabolic reprogramming and may serve as a prominent novel therapeutic target for liver cancer treatment.

Cao Ting-Ting    Shuhai Lin    Fu Li    Tang Zhi    支志明     Zhang Li-Yi    Ming Xiaoyan    Liu Tengfei    Tang Xu Ming    Tan Bin Bin    Xiang Di    Li Feng    Chan On Yee    Dan Xie    Zongwei Cai    关新元   

Carcinogenesis

2017

A series of charge-neutral Au complexes, which comprise a dicarbanionic C-deprotonated biphenyl ligand and bidentate ancillary ligands ([Au(C^C)(L^X)]; L^X=β-diketonate and relatives (O^O), quinolinolate and relatives (N^O), and diphosphino (P^P) ligands), were prepared. All the complexes are emissive in degassed CHCl solutions and in thin-film samples with Φ up to 18 and 35 %, respectively, except for 5 and 6, which bear (N^O)-type ancillary ligands. Variation of the electronic characteristics of the β-diketonate ancillary ligand was demonstrated to be a viable route for tuning the emission color from blue-green (peak λ at ca. 466 nm for 1 and 2; 501 nm for 4 a and 4 b) to orange (peak λ at 585 nm for 3), in contrast to the common observations that the ancillary ligand has a negligible effect on the excited-state energy of the Au complexes reported in the literature. DFT/time-dependent (TD) DFT calculations revealed that the energies of the ππ*(C^C) and the ILCT(O^O) excited states (ILCT=intraligand charge transfer) switch in order on going from O^O=acetylacetonate (acac) to aryl-substituted β-diketonate ligands. Solution-processed and vacuum-deposited organic light-emitting diode (OLED) devices of selected complexes were prepared. The vacuum-deposited OLED fabricated with 2 displays a sky-blue emission with a maximum external quantum efficiency (EQE) of 6.71 % and CIE coordinates of (0.22, 0.40). The crystal structures of 7 and 9 reveal short intermolecular Au⋅⋅⋅Au contacts, with intermetal distances of 3.408 and 3.453 Å, respectively. DFT/TDDFT calculations were performed on 7 and 9 to account for the noncovalent interactions. Solid samples of 1, 3, and 9 exhibit excimeric emission at room temperature, which is rarely reported in Au complexes.

Chan Kaai-Tung    Glenna so ming Tong    Wan Qingyun    Cheng G.    Yang Chen    支志明    

Chemistry - An Asian Journal

2017

The platinum(ii) photo-catalyzed difluoroalkylation of cinnamic acids and alkynes for selective construction of E-,Z-difluoroalkyl alkenes and difluoroalkyl alkenyl iodides, respectively, were achieved under mild conditions. The high efficiency, good substrate scope and high selectivity altogether highlight the prospect of Pt(ii) photocatalysts in visible-light-driven organic transformation reactions.

Jianji Zhong    Yang Chen    Chang Xiaoyong    Zou Chao    Wei Lu    支志明    

Chemical Communications

2017

The development of high-efficiency and low-cost catalysts for hydrogen release from chemical hydrogen-storage materials is essential for the hydrogen-economy paradigm. Herein, we report a facile and controllable method to fabricate a series of Co-doped nickel phosphides and their corresponding nanohybrids with graphene oxide (GO) as highly efficient, robust and noble-metal-free catalysts for ammonia borane hydrolysis. The incorporation of Co into NiP effectively optimizes the electronic structures of NiCoP catalysts to enhance their interaction with AB and simultaneously facilitate the hydroxyl activation of AB, resulting in the reduction of the reaction energy barrier and thus substantial improvement of the catalytic rate.

Hou Chun-Chao    Li Qiang    Chuanjun Wang    Peng Cheng-Yun    Chen Qian-Qian    Ye Hui-Fang    Wenfu Fu    支志明     López Núria    Yong Chen   

Energy and Environmental Science

2017

Ovarian cancer is a nearly uniform lethal disease and its highly aggressive metastatic phenotype portends a poor prognosis. Lack of a well-controlled, relevant experimental model has been a major obstacle to identifying key molecules causing metastasis. Here we describe the creation of a new isogenic model of spontaneous human ovarian cancer metastasis exhibiting opposite phenotypes - highly metastatic (HM) and non-metastatic (NM) - both in vitro and in vivo. HM was unique in its ability to metastasize consistently to the peritoneum, mimicking the major dissemination route of human ovarian cancer. In contrast, NM failed to form detectable metastases, although it was equally tumorigenic. Using comparative label-free quantitative liquid chromatography tandem mass spectrometry (LC-MS/MS), we identified β-catenin, which we demonstrated for the first time as having a direct role in the pathogenesis of ovarian cancer metastasis. Our studies also revealed a previously unrecognized role of β-catenin in the downregulation of multiple microRNAs (miRNAs) through attenuating miRNA biogenesis by targeting Dicer, a key component of the miRNA-processing machinery. One such downregulated miRNAs was miR-29s involved in epithelial-to-mesenchymal transition and subsequent stem cell traits. Silencing β-catenin or overexpressing Dicer or miR-29 mimics in HM significantly reduced the ability of these cells to migrate. β-catenin-knockdown cells also failed to metastasize in an orthotopic model of ovarian cancer. Meta-analysis revealed an increase in CTNNB1 and a decrease in DICER1 expression levels in the high-risk group. These results uncover β-catenin as a critical factor in promoting ovarian cancer aggressiveness and a new mechanism linking between β-catenin and miRNA downregulation underlying this process.

To S. K.Y.    Mak Abby Sin Chi    Eva Fung Y. M.    支志明     Li Shan-Shan    Wen Deng    Ru Beibei    Jiangwen Zhang    Alice sze tsai Wong   

Oncogene

2017

Herein are described the synthesis, photophysical properties and applications of a series of luminescent cyclometalated Au complexes having an auxiliary aryl ligand. These complexes show photoluminescence with emission quantum yields of up to 0.79 in solution and 0.84 in thin films (4 wt % in PMMA) at room temperature, both of which are the highest reported values among Au complexes. Thermally activated delayed fluorescence (TADF) is the emission origin for some of these complexes. Solution-processed OLEDs made with these complexes showed sky-blue to green electroluminescence with external quantum efficiencies (EQEs) of up to 23.8 %, current efficiencies of up to 70.4 cd A, and roll-off of down to 1 %, highlighting the bright prospect of Au-TADF emitters in OLEDs.

Wai pong To    Zhou Dongling    Glenna so ming Tong    Cheng G.    Yang Chen    支志明    

Angewandte Chemie - International Edition

2017

Homo-metallic metal alkynyl complexes exhibit interesting catenane structures, but their hetero-metallic catenane counterparts are under-developed. In this work, we report rare examples of bimetallic Au-Cu (DtbpCC ligand; Dtbp = 3,5-di-tert-butylphenyl), Au-Ag (BuCC ligand), and Au-Cu, Au-Ag (C6-FluoCC ligand; C6-Fluo = 9,9-dihexyl-9H-fluoren-2-yl) complexes as well as a trimetallic Au-Ag-Cu (C6-FluoCC ligand) complex, which feature [2]catenane structures. The formation of the [2]catenane structure is significantly affected by the coinage metal ion(s) and change of the structure of the alkynyl ligand. These hetero-metallic [2]catenane structures are strongly luminescent with tunable emission λ from 503 to 595 nm and Φ values up to 0.83.

Chang Xiaoyong    Xu Guang Tao    Bei Cao    Wang Juan-Yu    Jie sheng Huang    支志明    

Chemical Science

2017