Construction of a Dye-Sensitized and Gold Plasmon-Enhanced Cathodic Photoelectrochemical Biosensor for Methyltransferase Activity Assay.

DNA methyltransferases may function as important biomarkers of cancers and genetic diseases. Herein, we develop a dye-sensitized and gold plasmon-enhanced cathodic photoelectrochemical (PEC) biosensor on the basis of p-type covalent organic polymers (COPs) for the signal-on measurement of M.SssI methyltransferase (M.SssI MTase). The cathodic PEC biosensor is constructed by the in situ growth of p-type COP films onto a glass coated with indium tin oxide and the subsequent assembly of biotin- and HS-labeled double-stranded DNA (dsDNA) probes onto the COP film via biotin-streptavidin interaction. The dsDNA probe contains the recognition sequence of M.SssI MTase. The COP thin films possess a porous ultrathin nanosheet structure with abundant active sites, facilitating the generation of a high photocurrent compared with the hydrothermally synthesized ones. The presence of DNA methyltransferases can prevent the digestion of restriction endonuclease HpaII, consequently inducing the introduction of gold nanoparticles (AuNPs) to the dsDNA probes via the S-Au bond and the intercalation of rhodamine B (RhB) into the DNA grooves to produce a high photocurrent due to the dye-photosensitized enhancement and AuNP-mediated surface plasmon resonance. However, in the absence of M.SssI MTase, HpaII digests the dsDNA probes, and neither AuNPs nor RhB can be introduced onto the electrode surface, leading to a low photocurrent. This cathodic PEC biosensor possesses high sensitivity and good selectivity, and it can screen the inhibitors and detect M.SssI MTase in serum as well.

Cobalt-Based Metal-Organic Frameworks for Adsorption of CO2 and C2 Hydrocarbons: Effect of Auxiliary Ligands with Different Functional Groups.

Recently, metal-organic frameworks (MOFs) have been investigated as potential materials for CO2 capture and light hydrocarbon storage/separation due to their high porosity, large surface area, and tunable skeleton structures. In this work, the six cobalt-based MOFs 1-6 were successfully synthesized under solvothermal conditions by a mixed-ligand strategy. 1 and 2 have the same framework structure with a topology of {42·5}2{44·510·67·76·8}, while the structures of the 3-6 frameworks are the same with a topology of {42·5}2{44·510·69·74·8}. The adsorption properties of these MOFs for CO2 and C2 hydrocarbons were then investigated, and the effect of the functional groups was discussed. The results revealed that the introduction of amino and bromo groups could effectively strengthen the adsorption performance.

Rhodium(III)-Catalyzed C(sp2)-H Chemoselective Annulation to O-Cyclized Isochromen-imines from Benzamides.

Through the development of ligands and reaction conditions, the Rh(III)-catalyzed selective annulation of benzamides with internal alkynes has been achieved to the formation of O-cyclized isochromen-imines. Various substituents are well-tolerated under mild reaction conditions. Density functional theory calculations indicate that silver carbonate could act as a Lewis acid to assist the ligand to improve the chemical selectivity of the reaction in a catalytic system.

Two series of Ln-MOFs by solvent induced self-assembly demonstrating the rapid selective sensing of Mg2+ and Fe3+ cations.

Two series of lanthanide-based metal-organic frameworks, namely {[Ln(BIPA-TC)0.5(DMA)2(NO3)]·DMA·H2O}n (1-Ln, Ln = Eu, Dy, Sm, Nd) and {[Ln2(BIPA-TC)1.5(DMA)3(H2O)2]·2DMA·2H2O}n (2-Ln, Ln = Eu, Dy, Sm, Nd), were successfully constructed via a solvent regulation strategy based on a π-electron rich tetra-carboxylate ligand (H4BIPA-TC). 1-Ln shows a 4-connected lvt topology with the point symbol of {42·84}, but 2-Ln displays a new 4,4,6-connected wxk1 topology with the point symbol of {43·83}4{46·66·83}2{86}. The solid-state luminescence property and the microporous nature of Eu-MOFs (1-Eu and 2-Eu) indicate that they can potentially be used as luminescent sensors. Fluorescence measurements indicate that Fe3+ exhibits the quenching effect for 1-Eu with the quenching efficiency of 93.1%. 2-Eu is the first MOF sensor for Mg2+ with the lowest detection limit of 1.53 × 10-10 mol L-1 and displays good recyclable capability. Simultaneously, in the presence of other metal ions (Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pd2+, Al3+, Cr3+and Fe3+), 2-Eu can maintain the selective sensing of Mg2+, indicating its potential for Mg2+ turn-on sensing.

Zinc(II) and Copper(II) Hybrid Frameworks via Metal-Ion Metathesis with Enhanced Gas Uptake and Photoluminescence Properties.

The fabrication of metal-organic frameworks with controlled structure and desired properties is important but still a challenge. In this work, a zinc(II) framework, {[Zn3(L)2(DABCO)(H2O)]·9DMF} (named as Zn-1), has been synthesized based on [1,1':3',1″-terphenyl]-4,4″,5'-tricarboxylic acid (H3L) and 1,4-diazabicyclo[2.2.2]octane (DABCO), which is isostructural to the previously reported copper(II) analogue, {[Cu3(L)2(DABCO)(H2O)]·15H2O·9DMF} (named as Cu-1). Interestingly, hybrid zinc(II) and copper(II) bimetallic frameworks have been obtained via metal-ion metathesis and found to show enhanced adsorption and photoluminescence properties. Such a post-metal-ion metathesis method can be used to synthesize new and desired frameworks that could not be obtained by direct synthesis.

Ligand-Promoted Rh(III)-Catalyzed Coupling of Aryl C-H Bonds with Arylboron Reagents.

Rhodium(III)-catalyzed C-H arylation of arenes with phenylboronic acid pinacol esters has been achieved using a readily removable N-pentafluorophenylbenzamide directing group for the first time. The use of a bidentate phosphine ligand (Binap) significantly increased the yield of the cross-coupling of C-H bonds with organoboron reagents.

Synthesis, structure and adsorption properties of lanthanide-organic frameworks with pyridine-3,5-bis(phenyl-4-carboxylate).

Under solvothermal conditions, reactions of pyridine-3,5-bis(phenyl-4-carboxylic acid) (H2L) with lanthanide metal salts give rise to three new metal-organic frameworks (MOFs) with the formula {[Ln4(L)3(µ3-OH)4(H2O)4]·(NO3)2·solvent}n [Ln = Er (1), Yb (2) and Lu (3)]. The complexes were characterized by single crystal and powder X-ray diffraction, IR and thermogravimetric analyses. They have the same two-fold interpenetrating three-dimensional (3D) framework structures with [Ln4(COO)6(µ3-OH)4(H2O)4] clusters as secondary building units (SBUs) and a rare 6-connected lcy topology with the point (Schläfli) symbol of {3(3)·5(9)·6(3)}. Interestingly, 1-3 show selective and hysteretic sorption of CO2 over N2, and the photoluminescence properties of the complexes were also investigated.

Rh(iii)-catalyzed C-H olefination of N-pentafluoroaryl benzamides using air as the sole oxidant.

The oxidative olefination of a broad array of arenes and heteroarenes with a variety of activated and unactivated olefins has be achieved via a rhodium(iii)-catalyzed C-H activation reaction. The use of an N-pentafluorophenyl benzamide directing group is crucial for achieving catalytic turnovers in the presence of air as the sole oxidant without using a co-oxidant.