Unveiling the anti-cancer mechanism for half-sandwich and cyclometalated Ir(iii)-based complexes with functionalized α-lipoic acid.

Alpha lipoic acid (LA) is a natural compound and coenzyme with sufficient safety information for serving as a promising anticancer agent. To further clarify the mechanism of action (MoA), two Ir(iii) complexes with the functionalized α-lipoic acid (N∧N-LA, N∧N, 2,2-bipyridine derivative), namely Ir1 and Ir2, were synthesized, where Ir1 possessed a half-sandwich structure with the formula [Ir(Cp*)(N∧N-LA)Cl]PF6 (Cp* = 1,2,3,4,5-pentamethyl-cyclopentadiene) and Ir2 possessed the cyclometalated structure with the formula [Ir(C∧N)2(N∧N-LA)]PF6 (C∧N = 2-phenylpyridine). Even though both complexes were constructed based on the same N∧N-LA ligand, Ir1 showed no cytotoxicity (IC50 > 200 µM), which was due to its low lipophilicity for hard penetration into the cancer cells, easy hydrolysis, and reaction with GSH. Ir2 exhibited excellent cytotoxicity (IC50 = 3.43-6.74 µM) toward diverse cancer cell lines in vitro and a promising ability to overcome the cisplatin-resistance in A549R cells. The anticancer mechanism of Ir2 in A549 cells was investigated in detail, and it was found it could localize and accumulate in the lysosomes of A549 cells, induce ROS, arrest the cycle at G0/G1, and lead to cell death by autophagy. Comparison with Ir-NH2 ([Ir(C∧N)2(N∧N-NH2)]PF6) demonstrated that introduction of the LA ligand to Ir2 could highly enhance the cytotoxicity and help to overcome the cisplatin-resistance. This study of the half-sandwich and cyclometalated Ir(iii)-based anticancer agents highlighted the different MoAs toward cancer cells and provided new insights for understanding their structure-property relationships.

Polyoxometalate-Decorated g-C3 N4 -Wrapping Snowflake-Like CdS Nanocrystal for Enhanced Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution technology is recognized as a promising approach to relieving the growing energy crisis. Therefore, the development of a stable high-performance photocatalyst has long been the focus of research. In this work, quaternary composite materials involving a snowflake-like CdS nanocrystal wrapped by different amounts of polyoxometalate-decorated g-C3 N4 and polypyrrole (GPP@CdS) have been synthesized as photocatalysts for hydrogen production under visible-light irradiation. It has been revealed that the best composite (40 % GPP@CdS composite) exhibits hydrogen production activity of 1321 µmol, which exceeds that of CdS by a factor of more than two, and can be used in at least seven cycles with negligible loss of activity. The enhanced photocatalytic performance has been primarily attributed to the efficient synergy of CdS, g-C3 N4 , polypyrrole (PPy), and the polyoxometalate Ni4 (PW9 )2 . It should be noted that the introduction of PPy and g-C3 N4 into the title composite simultaneously promotes electron/hole pair separation and photocatalytic stability, whereas Ni4 (PW9 )2 serves as an efficient electron modulator and extra catalytic active site.

Engineering Zn1-xCdxS/CdS Heterostructures with Enhanced Photocatalytic Activity.

Various porous Zn1-xCdxS/CdS heteorostructures were achieved via in situ synthesis method with organic amines as the templates. Because of the larger radius of Cd(2+) than that of Zn(2+), CdS quantum dots are formed and distributed uniformly in the network of Zn1-xCdxS. The Zn1-xCdxS/CdS heterostructure with small Cd content (10 at%) derived from ethylenediamine shows very high H2-evolution rate of 667.5 µmol/h per 5 mg photocatalyst under visible light (λ ≥ 420 nm) with an apparent quantum efficiency of 50.1% per 5 mg at 420 nm. Moreover, this Zn1-xCdxS/CdS heterostructure photocatalyst also shows an excellent photocatalytic stability over 100 h.

Engineering the Morphology and Configuration of Ternary Heterostructures for Improving Their Photocatalytic Activity.

Heteronanomaterials composed of suitable semiconductors enable the direct conversion from solar power into clean and renewable energy. Ternary heterostructures with appropriate configuration and morphology possess rich and varied properties, especially for improving the photocatalytic activity and stability synchronously. However, suitable ternary heterostructure prototypes and facile while effective strategy for modulating their morphology and configuration are still scarce. Herein, various ternary ZnS-CdS-Zn(1-x)Cd(x)S heterostructures with tunable morphology (0 to 2 D) and semiconductor configurations (randomly distributed, interface mediated, and quantum dots sensitized core@shell heterostructures) were facilely synthesized via one-pot hydrothermal method resulting from the different molecular structures of the amine solvents. Semiconductor morphology, especially configuration of the ternary heterostructure, shows dramatic effect on their photocatalytic activity. The CdS sensitized porous Zn(1-x)CdxS@ZnS core@shell takes full advantage of ZnS, Zn(1-x)Cd(x)S and CdS and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h. This study provides some guidelines for the design and synthesis of high-performance ternary heterostructure via modulation of semiconductor configuration and morphology using one-pot method.

Nitrogen-doped Fe/Fe3C@graphitic layer/carbon nanotube hybrids derived from MOFs: efficient bifunctional electrocatalysts for ORR and OER.

A novel nitrogen-doped Fe/Fe3C@graphitic layer/carbon nanotube hybrid derived from MOFs has been first fabricated by a facile approach. The hybrid exhibited outstanding bifunctional electrocatalytic activity for ORR and OER, due to the merits of graphitic layer/carbon nanotube structures with highly active N and Fe/Fe3C sites.

Self-assembly of a mesoporous ZnS/mediating interface/CdS heterostructure with enhanced visible-light hydrogen-production activity and excellent stability.

We designed and successfully fabricated a ZnS/CdS 3D mesoporous heterostructure with a mediating Zn1-x Cd x S interface that serves as a charge carrier transport channel for the first time. The H2-production rate and the stability of the heterostructure involving two sulfides were dramatically and simultaneously improved by the careful modification of the interface state via a simple post-annealing method. The sample prepared with the optimal parameters exhibited an excellent H2-production rate of 106.5 mmol h-1 g-1 under visible light, which was 152 and 966 times higher than CdS prepared using ethylenediamine and deionized water as the solvent, respectively. This excellent H2-production rate corresponded to the highest value among the CdS-based photocatalysts. Moreover, this heterostructure showed excellent photocatalytic stability over 60 h.

Heteroatoms ternary-doped porous carbons derived from MOFs as metal-free electrocatalysts for oxygen reduction reaction.

The nitrogen (N), phosphorus (P) and sulphur (S) ternary-doped metal-free porous carbon materials have been successfully synthesized using MOFs as templates (denoted as NPS-C-MOF-5) for oxygen reduction reaction (ORR) for the first time. The influences of porous carbons from carbonizing different MOFs and carbonization temperature on ORR have been systematically investigated. Due to the synergistic effect of N, P and S ternary-doping, the NPS-C-MOF-5 catalyst shows a higher onset potential as a metal-free electrocatalyst for ORR among the currently reported metal-free electrocatalysts, very close to the commercial Pt-C catalyst. In particular, the kinetic limiting current density of NPS-C-MOF-5 catalyst at -0.6 V is up to approximate -11.6 mA cm(-2), which is 1.2 times higher than that of the commercial Pt-C catalyst. Furthermore, the outstanding methanol tolerance and excellent long-term stability of NPS-C-MOF-5 are superior to those of the commercial Pt-C catalyst for ORR in alkaline media.