High-temperature carbon dioxide capture in a porous material with terminal zinc hydride sites.

Carbon capture can mitigate point-source carbon dioxide (CO) emissions, but hurdles remain that impede the widespread adoption of amine-based technologies. Capturing CO at temperatures closer to those of many industrial exhaust streams (>200°C) is of interest, although metal oxide absorbents that operate at these temperatures typically exhibit sluggish CO absorption kinetics and instability to cycling. Here, we report a porous metal-organic framework featuring terminal zinc hydride sites that reversibly bind CO at temperatures above 200°C-conditions that are unprecedented for intrinsically porous materials.

Metal-Halide Covalency, Exchange Coupling, and Slow Magnetic Relaxation in Triangular (Cp)UX (X = Cl, Br, I) Clusters.

The actinide elements are attractive alternatives to transition metals or lanthanides for the design of exchange-coupled multinuclear single-molecule magnets. However, the synthesis of such compounds is challenging, as is unraveling any contributions from exchange coupling to the overall magnetism. To date, only a few actinide compounds have been shown to exhibit exchange coupling and single-molecule magnetism.

Coercive Fields Exceeding 30 T in the Mixed-Valence Single-Molecule Magnet (Cp)HoI.

Mixed-valence dilanthanide complexes of the type (Cp)LnI (Cp = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy) featuring a direct Ln-Ln σ-bonding interaction have been shown to exhibit well-isolated high-spin ground states and, in the case of the Tb and Dy variants, a strong axial magnetic anisotropy that gives rise to a large magnetic coercivity. Here, we report the synthesis and characterization of two new mixed-valence dilanthanide compounds in this series, (Cp)LnI (; Ln = Ho, Er). Both compounds feature a Ln-Ln bonding interaction, the first such interaction in any molecular compounds of Ho or Er.

Synthesis and Structural Characterization of Macrocyclic α-ABpeptoids and Their DNA-Encoded Library.

The first synthesis of macrocyclic α-ABpeptoids with varying lengths is described. X-ray crystal structures reveal that cyclic trimer displays a chair-like conformation with a amide sequence and cyclic tetramer has a saddle-like structure with an uncommon amide arrangement. The creation of a DNA-encoded combinatorial library of macrocyclic α-ABpeptoids is described.

Selective Adsorption of Oxygen from Humid Air in a Metal-Organic Framework with Trigonal Pyramidal Copper(I) Sites.

High or enriched-purity O is used in numerous industries and is predominantly produced from the cryogenic distillation of air, an extremely capital- and energy-intensive process. There is significant interest in the development of new approaches for O-selective air separations, including the use of metal-organic frameworks featuring coordinatively unsaturated metal sites that can selectively bind O over N electron transfer. However, most of these materials exhibit appreciable and/or reversible O uptake only at low temperatures, and their open metal sites are also potential strong binding sites for the water present in air.

Reactive high-spin iron(IV)-oxo sites through dioxygen activation in a metal-organic framework.

In nature, nonheme iron enzymes use dioxygen to generate high-spin iron(IV)=O species for a variety of oxygenation reactions. Although synthetic chemists have long sought to mimic this reactivity, the enzyme-like activation of O to form high-spin iron(IV) = O species remains an unrealized goal. Here, we report a metal-organic framework featuring iron(II) sites with a local structure similar to that in α-ketoglutarate-dependent dioxygenases.

A Trinuclear Gadolinium Cluster with a Three-Center One-Electron Bond and an = 11 Ground State.

The recent discovery of metal-metal bonding and valence delocalization in the dilanthanide complexes (Cp)LnI (Cp = pentaisopropylcyclopentadienyl; Ln = Y, Gd, Tb, Dy) opened up the prospect of harnessing the 4f5d electron configurations of non-traditional divalent lanthanide ions to access molecules with novel bonding motifs and magnetism. Here, we report the trinuclear mixed-valence clusters (Cp)LnHI (, Ln = Y, Gd), which were synthesized via potassium graphite reduction of the trivalent clusters (Cp)LnHI. Structural, computational, and spectroscopic analyses support valence delocalization in resulting from a three-center, one-electron σ bond formed from the 4d and 5d orbitals on Y and Gd, respectively.

Divalent Lanthanide Metallocene Complexes with a Linear Coordination Geometry and Pronounced 6s-5d Orbital Mixing.

A small but growing number of molecular compounds have been isolated featuring divalent lanthanides with 4f5d electron configurations. While the majority of these possess trigonal coordination geometries, we previously reported the first examples of linear divalent metallocenes Ln(Cp) (Ln = Tb, Dy; Cp = pentaisopropylcyclopentadienyl). Here, we report the synthesis and characterization of the remainder of the Ln(Cp) () series (including Y and excluding Pm).

Programmable Synthesis of Silver Wheels.

The synthesis of sandwich-shaped multinuclear silver complexes with planar penta- and tetranuclear wheel-shaped silver units and a central anion, [Ag()(A)](OTf), , = 4 or 5 and A = OH or F or Cl, is reported, along with complete spectroscopic and structural characterization. An NMR mechanistic study reveals that silver complexes were formed in the following order: → → → . The central hydroxides in and exhibit exotic physical properties due to the confined environment inside the complex.

Dinitrogen activation by a penta-pyridyl molybdenum complex.

A new dinitrogen (N) molybdenum(0) complex supported exclusively by pyridine ligands was synthesized. The X-ray crystal structure of the complex elucidated the activated nature of the N ligand, consistent with a low N-N IR stretching frequency. Natural bond orbital (NBO) analyses on this system confirmed a strong π-backdonation arising from the large p orbital character in molybdenum lone pairs.

Facile Synthesis of α-Boryl-Substituted Allylboronate Esters Using Stable Bis[(pinacolato)boryl]methylzinc Reagents.

Reported herein is the utilization of bis[(pinacolato)boryl]methylzinc halides, whose structures are characterized via single-crystal X-ray analysis, as solid storable reagents for copper-catalyzed coupling with vinyliodonum salts. The reaction proceeds under mild conditions and shows broad scope with respect to vinyliodonium salts, affording various α-boryl-substituted allylboronate esters in good yields. Synthetic applications of the obtained products are also demonstrated.

Effect of fermented spent instant coffee grounds on milk productivity and blood profiles of lactating dairy cows.

Objective: This study was conducted to evaluate the fermentation characteristics under low mesophilic temperature of spent instant coffee ground (SICG) and to estimate the effect of fermented SICG (FSICG) as alternative feed ingredient on milk productivity of dairy cows.

Methods: In the fermentation trial, fermentation of SICG was performed to investigate changes in characteristics using the microbial mixture (Lactobacillus plantarum, Saccharomyces cerevisiae, and Bacillus subtilis = 1:1:1) for 21 days at 20°C under anaerobic conditions. Molasses was added at 5% of dry mass.

Fluxional motion in a dinuclear copper(i) complex with a propeller-type ligand: metal hopping on both sides.

The first study of fluxional motion in [Cu(2-HPB)(MeCN)Cl] (1,2-HPB = hexa(2-pyridyl)benzene) is presented. For detailed examination of the fluxional motion mechanism, a monofluorinated derivative of the ligand (MFHPB) and its copper(i) complexes were synthesized and characterized. The solution NMR studies of monofluoro copper(i) complex 1a suggest the existence of five species in equilibrium.

Static and dynamic coordination behaviours of copper(i) ions in hexa(2-pyridyl)benzene ligand systems.

Two hexaarylbenzenes having six pyridine substituents (LH and LM) were prepared and six corresponding coordination complexes with copper(i) chloride were synthesized. Monomeric complexes (1, 2a and 2b) and 1D coordination polymers (3, 4 and 5) were synthesized via the judicious concentration control of copper(i) ions and characterized fully by X-ray crystal analysis. The binding modes of the ligands to copper(i) ions in the coordination polymers were dependent on steric effects and solvents to determine the morphology of the coordination polymers.