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Selective cleavage of C–C bonds can be a valuable tool for various applications including polymer degradation and biomass utilization. Performing chemical transformations involving C–C bond cleavag...

Deep eutectic solvents (DESs) are effective solvents for biomass conversion and have been proposed as alternatives to ionic liquids (ILs). Herein, we first report an effective pretreatment of woody...

Transition-metal ions doped nanocrystals (NCs), specifically Mn-doped NCs, hold great potential in the field of photocatalysis, especially, to improve photocatalytic performance for singlet oxygen (1O2) generation. Here, we report the design of a novel Mn-doped NC-based nanocomposites, specifically, silica-coated Mn-doped CdS/ZnS NCs decorated with Pt NCs (denoted as Mn-NCs@SiO2-Pt), which enhance photocatalytic 1O2 generation. Owing to the long-lived Mn excited state (on the order of ms), the energy-transfer between Mn-NCs and molecular oxygen is facilitated with the assistance of the Pt NCs adhered to the Mn-NC@SiO2 surface. Therefore, the Mn-NCs@SiO2-Pt composites, integrate the advantages of Mn-doped NCs, a protective silica layer, and Pt NCs to exhibit excellent catalytic activity and selectivity for the selective oxidation of primary benzylic alcohols to aldehydes through an 1O2 engaged oxidation process under visible-light irradiation. This work paves the way for enhancing catalytic performance via facilitated energy transfer relaxation by utilizing the long-lived excited-state of Mn2+ dopant ions in nanocomposites.

As a green synthetic approach, visible light-driven photosynthesis is highly desirable in arylation of inert alkyl halides, as they are important precursors in the total synthesis of natural products and pharmaceuticals. However, the high bond dissociation energy of aryl halides is typically out of the range of a single visible-light photon. Here, we propose an essential initiation and subsequent electron-transfer step process for visible light-driven aryl halide reduction, and identify the key pyrrole radical anion intermediate, that acts as the strong reduction species. We propose a photoinduced disproportionation (PDP) approach without the addition of any photocatalysts or additives to afford radical anions of pyrrole derivatives, which have enough reduction power to transfer an electron to aryl halide, giving rise to the corresponding aryl radical to afford the desired C–H arylated heterocyclic product. Once generated, the heterocyclic product can undergo the same photoinduced disproportionation (PDP) process to activate aryl halides, thereby promoting the reaction rate. This unprecedented initiation step, which was carried out in the absence of photocatalysts and additives under ambient conditions, can also be used for coupling a wide range of (hetero)aryl halides and pyrrole derivatives, as well as the synthesis of drug intermediates and biorelevant compounds.

The organic chromophore 2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(thiophene-3-carboxylic acid), T2-BTD, was prepared and investigated along with metal complex [Ru(bda)(pyP)2] (bda = 2,2′-bipyridine-6,6′-dicarboxylate; pyP = 3-(pyridine-4-yloxy)propyl)phosphonic acid), RuC, for light-driven water splitting in dye-sensitized photoelectrochemical cells. The resulting co-loaded organic chromophore plus catalyst surface assembly was evaluated by photocurrent transient measurement and direct O2 detection using a collector–generator cell. The complete SnO2/TiO2 core–shell-based photoanode exhibited an enhanced photocurrent (∼38 μA cm–2) compared to that with only the chromophore (∼24 μA cm–2). A modest Faradaic efficiency of 12% was recorded for O2 generation under 1 sun illumination in pH 3.9, 0.1 M acetate buffer solutions.

The trimeric perfluoro-o-phenylene mercury compound Hg3 and poly(2-methoxy,5-(2′-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) interact strongly in solution and the solid state. The interaction is attributed to electron donor–acceptor complex formation, where MEH-PPV is the donor, and the Lewis acid Hg3 is the acceptor. The study reported herein explores the effects of the donor–acceptor complex formation on the properties of MEH-PPV in solution and in the solid state. Addition of Hg3 to MEH-PPV solution or films leads to a distinct color change, and the change in the visible absorption spectrum and fluorescence of MEH-PPV is consistent with the formation of polymer aggregates. In the solid state, Hg3 induced aggregation is suggested to lead to formation of crystalline domains of the conjugated polymer. Transmission electron microscopy and grazing incidence X-ray scattering results support the hypothesis that the complex formation with Hg3 induces aggregation of the polymer. Transient absorption spectros...

A polystyrene-based chromophore-catalyst assembly (poly-2) has been synthesized and assembled at a mesoporous metal oxide photoanode. The assembly contains water oxidation catalyst centers based on [Ru(trpy) (phenq)]2+ (Ru-Cat) and [Ru(bpy)3]2+ derivatives (Ru-C) as chromophores (trpy= 2,2′;6,2″- terpyridine, phenq = 2-(quinol-8′-yl)-1,10-phenanthroline and bpy = 2,2′-bipyridine). The photophysical and electrochemical properties of the polychromophore-oxidation catalyst assembly were investigated in solution and at the surface of mesoporous metal oxide films. The layer-by-layer (LbL) method was utilized to construct multilayer films with cationic poly-2 and anionic poly(acrylic acid) (PAA) for light-driven photochemical oxidations. Photocurrent measurements of (PAA/poly-2)10 LbL films on mesoporous TiO2 demonstrate light-driven oxidation of phenol and benzyl alcohol in aqueous solution. Interestingly, illumination of (PAA/poly-2)5 LbL films on a fluorine doped SnO2/TiO2 core/shell photoanode in aqueous so...

Because of the importance of hydrogen atom transfer (HAT) in biology and chemistry, there is increased interest in new strategies to perform HAT in a sustainable manner. Here, we describe a sustainable, net redox-neutral HAT process involving hydrosilanes and alkali metal Lewis base catalysts — eliminating the use of transition metal catalysts — and report an associated mechanism concerning Lewis base-catalysed, complexation-induced HAT (LBCI-HAT). The catalytic LBCI-HAT is capable of accessing both branch-specific hydrosilylation and polymerization of vinylarenes in a highly selective fashion, depending on the Lewis base catalyst used. In this process, earth abundant, alkali metal Lewis base catalyst plays a dual role. It first serves as a HAT initiator and subsequently functions as a silyl radical stabilizing group, which is critical to highly selective cross-radical coupling. EPR study identified a potassiated paramagnetic species and multistate density function theory revealed a high HAT character, yet multiconfigurational nature in the transition state of the reaction., Graphical Abstract

Layer-by-Layer (LbL) polyelectrolyte self-assembly occurs by the alternate exposure of a substrate to solutions of oppositely charged polyelectrolytes or polyions. Here, we report the application of LbL to construct chromophore–catalyst assemblies consisting of a cationic polystyrene-based Ru polychromophore (PS-Ru) and a [Ru(tpy)(2-pyridyl-N-methylbenzimidazole) (OH2)]2+ water oxidation catalyst (RuC), codeposited with poly(acrylic acid) (PAA) as an inert polyanion. These assemblies are deposited onto planar indium tin oxide (ITO, Sn:In2O3) substrates for electrochemical characterization and onto mesoporous substrates consisting of a SnO2/TiO2 core/shell structure atop fluorine doped tin oxide (FTO) for application to light-driven water oxidation in a dye-sensitized photoelectrosynthesis cell. Cyclic voltammetry and ultraviolet–visible absorption spectroscopy reveal that multilayer deposition progressively increases the film thickness on ITO glass substrates. Under an applied bias, photocurrent measureme...

As a result of our continuous research, new 3,4-dihydroquinazoline derivative containing ureido group, KCP10043F was synthesized and evaluated for T-type Ca(2+) channel (Cav3.1) blockade, cytotoxicity, and cell cycle arrest against human non-small cell lung (A549) cells. KCP10043F showed both weaker T-type Ca(2+) channel blocking activity and less cytotoxicity against A549 cells than parent compound KYS05090S [4-(benzylcarbamoylmethyl)-3-(4-biphenylyl)-2-(N,N',N'-trimethyl-1,5-pentanediamino)-3,4-dihydroquinazoline 2 hydrochloride], but it exhibited more potent G1-phase arrest than KYS05090S in A549 cells. This was found to be accompanied by the downregulations of cyclin-dependent kinase (CDK) 2, CDK4, CDK6, cyclin D2, cyclin D3, and cyclin E at the protein levels. However, p27(KIP1) as a CDK inhibitor was gradually upregulated at the protein levels and increased recruitment to CDK2, CDK4 and CDK6 after KCP10043F treatment. Based on the strong G1-phase cell cycle arrest of KCP10043F in A549 cells, the combination of KCP10043F with etoposide (or cisplatin) resulted in a synergistic cell death (combination index=0.2-0.8) via the induction of apoptosis compared with either agent alone. Taken together with these overall results and the favorable in vitro ADME (absorption, distribution, metabolism, and excretion) profiles of KCP10043F, therefore, it could be used as a potential agent for the combination therapy on human lung cancer.

The synthesis of polymer-based assemblies for light harvesting has been motivated by the multi-chromophore antennas that play a role in natural photosynthesis for the potential use in solar conversion technologies. This review describes a general strategy for using polymer-based chromophore–catalyst assemblies for solar-driven water oxidation at a photoanode in a dye-sensitized photoelectrochemical cell (DSPEC). This report begins with a summary of the synthetic methods and fundamental photophysical studies of light harvesting polychormophores in solution which show these materials can transport excited state energy to an acceptor where charge-separation can occur. In addition, studies describing light harvesting polychromophores containing an anchoring moiety (ionic carboxylate) for covalent bounding to wide band gap mesoporous semiconductor surfaces are summarized to understand the photophysical mechanisms of directional energy flow at the interface. Finally, the performance of polychromophore/catalyst assembly-based photoanodes capable of light-driven water splitting to oxygen and hydrogen in a DSPEC are summarized.

A polychromophoric light-harvesting assembly featuring a polystyrene (PS) backbone with ionic carboxylate-functionalized Ru(II) polypyridyl complexes as pendant groups (PS-Ru-A) was synthesized and successfully anchored onto mesoporous structured TiO2 films (TiO2 //PS-Ru-A). Studies of the resulting TiO2 //PS-Ru-A films carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) confirmed that the ionic carboxylated Ru(II) complexes from PS-Ru-A led to the surface immobilization on the TiO2 film. Monochromatic light photocurrent spectroscopy (IPCE) and white light (AM1.5G) current-voltage studies of dye-sensitized solar cells using the TiO2 //PS-Ru-A photoanode give rise to modest photocurrent and white light efficiency (24 % peak IPCE and 0.33 % PCE, respectively). The photostability of surface-bound TiO2 //PS-Ru-A films was tested and compared to a monomeric Ru(II) complex (TiO2 //Ru-A), showing an enhancement of ∼14 % in the photostability of PS-Ru-A. Transient absorption measurements reveal that electron injection from surface-bound pendants occurs on the picosecond time scale, similar to TiO2 //Ru-A, while time-resolved emission measurements reveal delayed electron injection occurring in TiO2 //PS-Ru-A on the nanosecond time scale, underscoring energy transport from unbound to surface-bound complexes. Additionally, charge recombination is delayed in PS-Ru-A, pointing towards intra-assembly hole transport to complexes away from the surface. Molecular dynamics simulations of PS-Ru-A in fluid solution indicate that a majority of the pendant Ru(II) complexes lie within 10-20 A of each other, facilitating efficient energy- and charge transport among the pendant complexes.