An Ultra-Microporous Metal–Organic Framework with Exceptional Xe Capacity

Molecular confinement plays a significant effect on trapped gas and solvent molecules. A fundamental understanding of gas adsorption within the porous confinement provides information necessary to design a material with improved selectivity. In this regard, metal–organic framework (MOF) adsorbents are ideal candidate materials to study confinement effects for weakly interacting gas molecules, such as noble gases. Among the noble gases, xenon (Xe) has practical applications in the medical, automotive and aerospace industries. In this Communication, we report an ultra-microporous nickel-isonicotinate MOF with exceptional Xe uptake and selectivity compared to all benchmark MOF and porous organic cage materials. The selectivity arises because of the near perfect fit of the atomic Xe inside the porous confinement. Notably, at low partial pressure, the Ni–MOF interacts very strongly with Xe compared to the closely related Krypton gas (Kr) and more polarizable CO₂. Further ¹²⁹Xe NMR suggests a broad isotropic chemical shift due to the reduced motion as a result of confinement.     

Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Treatment of [Cp*RuCl₂]₂, 1 , [(COD)IrCl]₂, 2 or [(p-cymene)RuCl₂]_2, 3 (Cp*=η⁵-C₅Me_5, COD= 1,5-cyclooctadiene and p-cymene=η⁶-ⁱPrC₆H₄Me) with heterocyclic borate ligands [Na[(H₃B)L], L₁ and L₂ ( L₁ : L=amt, L₂ : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L₁ and L₂ afforded dihydridoborate species [L^AM(μ-H)₂BHL] 4 – 6 ( 4 : L^A=Cp*, M=Ru, L=amt; 5 : L^A=Cp*, M=Ru, L=mp; 6 : L^A=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L₂ yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)₂BH(mp)}₂], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)₂BH(mp)}{(μ-H)BH(mp)₂}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d .     

Amperometric sandwich-type aptasensor based on peroxidase mimetic Au@Pt for the carcinoembryonic antigen

For sensitive analysis of cancer biomarker carcinoembryonic antigen (CEA), an amperometric sandwich-type aptasensor is proposed based on a signal amplification strategy of Au@Pt bimetallic nanoprobes. As the excellent catalytic activity to hydrogen peroxide (H₂O₂), core-shell Au@Pt nanoparticles are employed as nanoprobes by conjugating directly with the secondary aptamer of CEA (Apt-II). Due to the synergic recognition effect of dual aptamers and the excellent catalytic activity of nanoprobes, this amperometric sandwich-type aptasensor for CEA exhibits high specificity and good sensitivity with a limit of detection of 0.31 ng/mL, along with a wide linear range from 0.1 ng/mL to 100 ng/mL.     

Titanium Salalen Catalyzed Enantioselective Benzylic Hydroxylation

The titanium complex of the cis-1,2-diaminocyclohexane (cis-DACH) derived Berkessel-salalen ligand is a highly efficient and enantioselective catalyst for the asymmetric epoxidation of terminal olefins with hydrogen peroxide (“Berkessel-Katsuki catalyst”). We herein report that this epoxidation catalyst also effects the highly enantioselective hydroxylation of benzylic C−H bonds with hydrogen peroxide. Mechanism-based ligand optimization identified a novel nitro-salalen Ti-catalyst of the highest efficiency ever reported for asymmetric catalytic benzylic hydroxylation, with enantioselectivities of up to 98 % ee, while overoxidation to ketone is marginal. The novel nitro-salalen Ti-catalyst also shows enhanced epoxidation efficiency, as evidenced by e.g. the conversion of 1-decene to its epoxide in 90 % yield with 94 % ee, at a catalyst loading of 0.1 mol-% only.     

Synthesis,Characterization of Cr Doped TeO2 Nanostructures and its Application as EGFET pH Sensor

In the present work, Cr doped tellurium dioxide nanostructures (CTO NS)(1 wt %, 6 wt %, 8 wt % and 12 wt %) synthesized by co precipitation method and characterized by CV, UV-Visible, SEM, XRD, XPS spectroscopic analysis. Electron beam deposited thin film of CTO NS having 12 wt % of Cr exhibited EGFET-pH sensitivity of 62.03 mV/pH at 250 °C in buffer solutions of pH 6–12, linearity 0.9345, drift rate of 1.12 mV/h and deviation of 0.01145 as compared with 1 wt %, 6 wt % and 8 wt % of CTO NS.     

A green route towards substituted 2-amino-4H-chromenes catalyzed by an organobase (TBD) functionalized mesoporous silica nanoparticle without heating

Research on Chemical Intermediates - 1,5,7-Triazabicyclo-[4,4,0]-dec-1-ene functionalized mesoporous silica nanoparticle promoted one-pot multicomponent synthesis of 2-amino-4H-chromenes from a...     

Further results on the Drazin inverse of even‐order tensors

The notion of the Drazin inverse of an even‐order tensors with the Einstein product was introduced, very recently [J. Ji and Y. Wei. Comput. Math. Appl., 75(9), (2018), pp. 3402‐3413]. In this article, we further elaborate this theory by establishing a few characterizations of the Drazin inverse and $\mathrm{??}$‐weighted Drazin inverse of tensors. In addition to these, we compute the Drazin inverse of tensors using different types of generalized inverses and full rank decomposition of tensors. We also address the solution of multilinear systems by using the Drazin inverse and iterative (higher order Gauss‐Seidel) method of tensors. Besides these, the convergence analysis of the iterative technique is also investigated within the framework of the Einstein product.     

Ethynylation of Cysteine Residues: From Peptides to Proteins in Vitro and in Living Cells

Current approaches to introduce terminal alkynes for bioorthogonal reactions into biomolecules still present limitations in terms of either reactivity, selectivity, or adduct stability. We present a method for the ethynylation of cysteine residues based on the use of ethynylbenziodoxolone (EBX) reagents. The acetylene group is directly introduced onto the thiol group of cysteine and can be used for copper‐catalyzed alkyne‐azide cycloaddition (CuAAC) without further processing. Labeling proceeded with reaction rates comparable to or higher than the most often used iodoacetamide on peptides or maleimide on the antibody trastuzumab, and high cysteine selectivity was observed. The reagents were also used in living cells for cysteine proteomic profiling and displayed improved coverage of the cysteinome compared to previously reported iodoacetamide or hypervalent iodine reagents. Fine‐tuning of the EBX reagents allows optimization of their reactivity and physical properties.     

Surfactant-promoted enhancement in bioremediation of hexavalent chromium to trivalent chromium by naturally occurring wall algae

Research on Chemical Intermediates - The discharge of hexavalent chromium [Cr(VI)] has resulted in significant pollution because of the presence of Cr(VI) oxyanions. They are highly water-soluble,...