Selective Electrocatalytic Oxidation of Ammonia by Ru-dpp Complexes Containing Aromatic Nitrogen Donor as Axial Ligand.

Inspired by the rapid growth of Ru-based complexes as molecular ammonia oxidation catalysts, we propose novel Ru-dpp complexes bearing a nitrogen donor as the axial ligand into the ammonia oxidation catalysts family. Herein, a series of Ru-dpp complexes [Ru(-,',″-dpp)(bpy)(L)]·PF (where Hdpp = 2-[5-(pyridin-2-yl)-1-pyrrol-2-yl]pyridine; bpy = 2,2'-bipyridine; L = pyridine (); 4-methylpyridine (); pyrimidine (); isoquinoline ()) containing aromatic nitrogen donor axial ligand are synthesized and fully characterized by NMR, IR, and ESI-MS. The structural analysis displays that dpp as a pincer ligand coordinates to ruthenium, and nitrogen donor L binds to ruthenium at an axial ligand.

Neutral mononuclear indium(III) photosensitizers for CO photoreduction.

Herein, neutral mononuclear indium(III) complexes (In-1-In-3) containing 2,6-di(1-pyrrol-2-yl)pyridine and substituted dipyridylpyrrole pincer ligand were employed as photosensitizers (PS) in photocatalytic CO reduction. In-2 exhibits good photo-activity and selectivity, which is superior to the classic PS Ru(bpy). The amount of CO generation is 28.

Mononuclear indium(III) photosensitizers for photo-dehalogenation and olefin reduction.

Photoactive main-group complexes have been relatively underexplored in photocatalytic applications. Herein, we report a family of indium(III) complexes (In-1-In-4) containing pyridylpyrrolide ligands with different amounts of methyl groups, which all exhibit intense visible-light absorption as well as blue-green emission with nanosecond emission lifetimes and emission quantum yields of 6.7-12.

N-Site Regulation of Pyridyltriazole in Cp*Ir(N̂N)(HO) Complexes Achieving Catalytic FA Dehydrogenation.

A series of novel Cp*Ir complexes with nitrogen-rich N̂N bidentate ligands were developed for the catalytic dehydrogenation of formic acid in water under base-free conditions. These complexes were synthesized by using pyridyl 1,2,4-triazole, methylated species, or pyridyl 1,2,3-triazole as a N-site regulation ligand and were fully characterized. Complex bearing 1,2,4-triazole achieved a high turnover frequency of 14192 h at 90 °C in 4 M FA aqueous solution.

Stepwise assembly of thiacalix[4]arene-protected Ag/Ti bimetallic nanoclusters: accurate identification of catalytic Ag sites in CO electroreduction.

The accurate identification of catalytic sites in heterogeneous catalysts poses a significant challenge due to the intricate nature of controlling interfacial chemistry at the molecular level. In this study, we introduce a novel strategy to address this issue by utilizing a thiacalix[4]arene (TC4A)-protected Ti-oxo core as a template for loading Ag ions, leading to the successful synthesis of a unique Ag/Ti bimetallic nanocluster denoted as TiAg. This nanocluster exhibits multiple surface-exposed Ag sites and possesses a distinctive "core-shell" structure, consisting of a {Ti@Ag(TC4A)} core housing a {TiO@Ag(TC4A)} motif and two {Ti@Ag(TC4A)} motifs.

Unveiling the Remarkable Stability and Catalytic Activity of a 6-Electron Superatomic Ag Nanocluster for CO Electroreduction.

Nanocluster catalysts face a significant challenge in striking the right balance between stability and catalytic activity. Here, we present a thiacalix[4]arene-protected 6-electron [Ag(TC4A)(PrS)] nanocluster that demonstrates both high stability and catalytic activity. The nanocluster features a metallic core, Ag, consisting of two Ag triangles and one Ag square, shielded by four {Ag@(TC4A)} staple motifs.

Precisely Controlling Ancillary Ligands to Improve Catalysis of Cp*Ir Complexes for CO Hydrogenation.

The regulation of ancillary ligands is critical to improve catalysis of Cp*Ir complexes for CO hydrogenation. Herein, a series of Cp*Ir complexes with N^N or N^O ancillary ligands were designed and synthesized. These N^N and N^O donors were derived from the pyridylpyrrole ligand.

Atomically accurate structural tailoring of thiacalix[4]arene-protected copper(II)-based metallamacrocycles.

Accurate manipulation of ligands at specific sites in robust clusters is attractive but difficult, especially for those ligands that coordinate in intricate binding patterns. By linking the shuttlecock-like {Cu(μ-Cl)TC4A} motif and the phenylphosphate (PhPO) ligand, we elaborately design and synthesize two Cu(II)-thiacalix[4]arene metallamacrocycles (MMCs), namely CuL and CuL, which have regular triangular and quadrilateral topologies, respectively. While keeping the core intact, the Cl and PhPO in those two MMCs, which coordinated in a μ-bridging fashion, can be accurately substituted with salicylate ligands.

Auxiliary Carboxylate-Induced Assembly of Calix[6]arene-Polyoxotitanate Hybrid Systems with Photocatalytic Activity in the Oxidation of Sulfides.

This study used the -butylcalix[6]arene (TBC[6]) as the ligand and successfully synthesized six TBC[6]-stabilized titanium-oxo clusters (TOCs) by the one-step solvothermal reaction. These six compounds were [TiO(TBC[6])] (), {Ti(TBC[6])(EtO)(SaH)} (, HSa = squaric acid), {Ti(TBC[6])(EtO)(Oa)} (, HOa = oxalic acid), [HTi(TBC[6])(BA)(EtO)] (, HBA = benzoic acid), [TiO(TBC[6])(BA)(OPr)] (), and [Ti(TBC[6])(Sal)(EtO)] (, HSal = salicylic acid). These clusters contain one or two TBC[6] ligands, with the biconical or monoconical configuration, greatly increasing the variety of TOCs it could support.

Homoleptic Al(III) Photosensitizers for Durable CO Photoreduction.

Exploiting noble-metal-free systems for high-performance photocatalytic CO reduction still presents a key challenge, partially due to the long-standing difficulties in developing potent and durable earth-abundant photosensitizers. Therefore, based on the very cheap aluminum metal, we have deployed a systematic series of homoleptic Al(III) photosensitizers featuring 2-pyridylpyrrolide ligands for CO photoreduction. The combined studies of steady-state and time-resolved spectroscopy as well as quantum chemical calculations demonstrate that in anerobic CHCN solutions at room temperature, visible-light excitation of the Al(III) photosensitizers leads to an efficient population of singlet excited states with nanosecond-scale lifetimes and notable emission quantum yields (10-40%).

Baicalein sensitizes triple negative breast cancer MDA-MB-231 cells to doxorubicin via autophagy-mediated down-regulation of CDK1.

Triple negative breast cancer (TNBC) is a kind of refractory cancer with poor response to conventional chemotherapy. Recently, the combination of baicalein and doxorubicin was reported to exert a synergistic antitumor effect on breast cancer. However, the underlying mechanism how baicalein sensitizes breast cancer cells to doxorubicin remains to be elucidated.

Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer.

Gastric cancer (GC) is one of the most common tumors worldwide, and cisplatin is a standard chemotherapeutic reagent for GC treatment. However, chemoresistance is an inherent challenge which limits its application and effectiveness in clinic. This study aims to investigate the mechanism of metformin-induced cisplatin resistance in GC.

Ancillary ligand-regulated Ti(IV)-based metallocalixarene coordination cages for photocatalytic H evolution.

High-valence Ti(IV)-based metallocalixarene coordination cages that are linked by oriented ancillary ligands are unknown so far. Herein, the first family of tunable calixarene-based coordination cages of Ti(IV) with a framework formula [Ti(OPr)(TBC[4])L] have been assembled from six {Ti(OPr)(TBC[4])} nodes and six pyridinedicarboxylic ligands. Furthermore, the {Ti12L6} cage showed strong photocatalytic H evolution activity, and DFT studies were performed to explore its electronic structure.

Heterometallic Polyoxotitanium Clusters as Bifunctional Electrocatalysts for Overall Water Splitting.

Incorporating heterometal into titanium-oxygen clusters (TOCs) is an effective way to improve its catalytic activity. Herein, we synthesize three novel heterometallic TOCs with the formula of [TiCuO(Dmg)(OAc)(PrO)][HTiCuO(Dmg)(OAc)(PrO)] (), [TiCuO(Dmg)(OAc)(PrO)] (), and [TiCoO(Dmg)(Pdc)(PrO)Cl] (, DmgH = dimethylglyoxime; PdcH = pyridine-2,3-dicarboxylic acid) using dimethylglyoxime and different carboxylates as the synergistic ligands. By depositing the clusters and on carbon cloth as electrodes, we investigated the electrocatalytic performance of TOCs for full water splitting for the first time.

An ultrastable Ti-based metallocalixarene nanocage cluster with photocatalytic amine oxidation activity.

Polyhedral metallocalixarene nanocage clusters based on pure Ti(IV) ions are to our knowledge unknown hitherto. Herein we report the first Ti(IV)-based metallocalixarene nanocage cluster by assembling a [TiO] cage with six -butylcalix[4]arene molecules. Notably, the cluster exhibits extraordinary stability in high-concentration acid/alkali solutions and can act as a stable photocatalyst to catalyze the oxidation of ammonia to imines.

Self-Assembly of Chiral Ferrocene-Functionalized Polyoxotitanium Clusters for Photocatalytic Selective Sulfide Oxidation.

Here, we systematically studied the self-assembly behavior of chiral polyoxytitanium clusters for the first time. Through the cooperative assembly of ferrocenecarboxylic acid and ketoxime ligands, we successfully incorporated the planar chirality of ferrocene (Fc) into the layered {Ti} building blocks. The resulting {TiFc} clusters can be used as structural units to assemble into large ordered structures in various ways; either a pair of {TiFc} enantiomers are bridged by organic adhesive to form sandwich structures or two homochiral {TiFc} units participate in the assembly to form the large clusters.

Metal-Directed Self-Assembly of {TiL} Cluster-Based Coordination Polymers with Enhanced Photocatalytic Alcohol Oxidation Activity.

Cooperative assembly of the neutral cluster {TiO(OEt)L} (L = pyrazine-2,3-dicarboxylic acid) with different metal units of Mn(NO), CuCl, Zn(OEt), Cd(NO), Ce(NO), Lu(NO), and Lu(NO)(OEt), or the [CuI] cluster, generates a family of titanium-oxygen cluster (TOC)-based coordination polymers. These one-dimensional (1D) linear structures contain the same {TiL} cluster but with variable bridging metal units. The regulation of the heterometal not only affects the chain geometries of the {MTi} but also affects the way the 1D chains are stacked in the crystal lattice.

Cd-Doped Polyoxotitanium Nanoclusters with a Modifiable Organic Shell for Photoelectrochemical Water Splitting.

Incorporating heterometal and chromogenic groups into the titanium oxo cluster (TOC) nanomaterials is one of the effective strategies for the development of new high-performance photoelectrically active materials. In this Article, we report the structures and photoelectrochemical (PEC) performances of a family of TOCs, including pure [TiO(OEt)L] () and six Cd-doped clusters formulated as [HCdTiO(OEt)(L)(HO)] (; L = salicylic acid and their derivatives). The six Cd-doped clusters are isostructural, containing the same {CdTiO} core, but are protected by salicylic ligands modified with different functional groups.

Metal-Ligand Cooperation in Cp*Ir-Pyridylpyrrole Complexes: Rational Design and Catalytic Activity in Formic Acid Dehydrogenation and CO Hydrogenation under Ambient Conditions.

Interconversion between CO + H and FA/formate is the most promising strategy for the fixation of carbon dioxide and reversible hydrogen storage; however, FA dehydrogenation and CO hydrogenation are usually studied separately using different catalysts for each reaction. This report describes of the catalysis of [Cp*Ir(N∧N)(X)] (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; X = Cl, = 0; X = HO, = 1) bearing a proton-responsive N∧N pyridylpyrrole ligand for both reactions. Complex catalyzes FA dehydrogenation at 90 °C with a TOF of 45 900 h.

Efficient Electrochemical Water Oxidation Mediated by Pyridylpyrrole-Carboxylate Ruthenium Complexes.

Spurred by the rapid growth of Ru-based complexes as molecular water oxidation catalysts (WOCs), we propose novel ruthenium(II) complexes bearing pyridylpyrrole-carboxylate (Hppc) ligands as members of the WOC family. The structure of these complexes has 4-picoline (pic)/dimethyl sulfoxide (DMSO) in and pic/pic in as axial ligands. Another ppc ligand and one pic ligand are located at the equatorial positions.

An Iridium Complex as an AIE-active Photosensitizer for Image-guided Photodynamic Therapy.

Image-guided photodynamic therapy (PDT) has received growing attention due to its non-invasiveness and precise controllability. However, the PDT efficiency of most photosensitizers are decreased in living system due to the aggregation-caused singlet oxygen ( O ) generation decreasing. Herein, we present an Iridium (III) pyridylpyrrole complex (Ir-1) featuring of aggregation-induced emission (AIE) and O generation characteristics for image-guided PDT of cancer.

Neutral Cyclometalated Ir(III) Complexes with Pyridylpyrrole Ligand for Photocatalytic Hydrogen Generation from Water.

To explore structure-activity relationships with respect to light-harvesting behavior, a family of neutral iridium complexes [Ir(ppy)(L)] - (where ppy = 2-phenylpyridine, and N̂N = 2-(1-pyrrol-2-yl)pyridine and its functionalized derivatives) were designed and synthesized. The structural modifications in metal complexes are accomplished through the attributions of electron-donating CH in , OCH in , and electron-withdrawing CF in . The structural analysis displays that the pyridylpyrrole acts as one-negative charged bidentated ligand to chelate the iridium center.

3D Uranyl Organic Frameworks Supported by Rigid Octadentate Carboxylate Ligand: Synthesis, Structure Diversity, and Luminescence Properties.

Seven three dimensional (3D) uranyl organic frameworks (UOFs), formulated as [NH ][(UO ) (HTTDS)(H O)] (1), [(UO ) (HTTDS) ](HIM) (2, IM=imidazole), [(UO ) (TTDS)(H O) (Phen) ] (3, Phen=1,10-phenanthroline), [Zn(H O) ] [(UO ) (HTTDS)(H O) ] (4), and {(UO ) [Zn(H O) ] (TTDS)} (5), {Zn(UO ) (H O)(Dib) (HDib)(HTTDS)} (6, Dib=1,4-di(1H-imidazol-1-yl)benzene) and [Na]{(UO ) [Cu (u -OH)(H O) ](TTDS) } (7) have been hydrothermally prepared using a rigid octadentate carboxylate ligand, tetrakis(3,5-dicarboxyphenyl)silicon(H TTDS). These UOFs have different 3D self-assembled structures as a function of co-ligands, structure-directing agents and transition metals. The structure of 1 has an infinite ribbon formed by the UO pentagonal bipyramid bridged by carboxylate groups.

Accurate assembly of ferrocene-functionalized {Ti22Fc4} clusters with photocatalytic amine oxidation activity.

We report here the synthesis of a ferrocene-functionalized {Ti22Fc4} cluster with a 'dimer-of-clusters' topology, which represents the largest Ti-oxo cluster (TOC) modified with organometallic groups ever reported. The exact assembly path of {Ti22Fc4} can be inferred from its two substructures, {Ti11Fc2} and {Ti5Fc}, which can also be synthesized independently through subtle changes in reaction conditions. Furthermore, we used these clusters as photocatalysts, and have studied, for the first time, the photocatalytic activity of TOCs in the oxidative coupling of amines.