Microclimate predicts kelp forest extinction in the face of direct and indirect marine heatwave effects.

Marine heatwaves threaten the persistence of kelp forests globally. However, the observed responses of kelp forests to these events have been highly variable on local scales. Here, we synthesize distribution data from an environmentally diverse region to examine spatial patterns of canopy kelp persistence through an unprecedented marine heatwave.

Promoting Proton Transfer and Stabilizing Intermediates in Catalytic Water Oxidation via Hydrophobic Outer Sphere Interactions.

The outer coordination sphere of metalloenzyme often plays an important role in its high catalytic activity, however, this principle is rarely considered in the design of man-made molecular catalysts. Herein, four Ru-bda (bda=2,2'-bipyridine-6,6'-dicarboxylate) based molecular water oxidation catalysts with well-defined outer spheres are designed and synthesized. Experimental and theoretical studies showed that the hydrophobic environment around the Ru center could lead to thermodynamic stabilization of the high-valent intermediates and kinetic acceleration of the proton transfer process during catalytic water oxidation.

Comparison of [PdL][BF] cages for binding of -octyl glycosides and nitrate (L = isophthalamide or dipicolinamide linked dipyridyl ligand).

Two dipyridyl ligands were synthesized, where the pyridyl donor fragments were separated by an isophthalamide (1) or a dipicolinamide moiety (2). Both ligands formed [Pd2(Ligand)4][BF4]4 complexes in CD2Cl2 containing 5% dmso-d6. It was found that while [Pd2(1)4][BF4]4 readily binds to n-octyl glycosides and to nitrate anions, [Pd2(2)4][BF4]4 did not.

Anion binding properties of a hollow PdL-cage.

The hollow [PdL][BArF]2 complex 1 of a tetra-pyridyl (py) ligand (L) has a [Pd(py)4]2+ coordination environment. Addition of coordinating anions resulted in the formation of a neutral species with Pd(py)2(anion)2 coordination environment (12A). These species bind further to the coordinating anions in the order Cl- > N3- > Br- > I- > AcO- with Ka1 : 1 ≤ 414 M-1.

A Synthetic Galectin Mimic.

Galectins are a galactoside specific subclass of carbohydrate binding proteins (lectins) involved in various cellular activities, certain cancers, infections, inflammations, and many other biological processes. The molecular basis for the selectivity of galectins is well-documented and revolves around appropriate interaction complementarity: an aromatic residue for C-H⋅⋅⋅π interactions and polar residues for (charge assisted) hydrogen bonds with the axial hydroxyl group of a galactoside. However, no synthetic mimics are currently available.

Off-Set Interactions of Ruthenium-bda Type Catalysts for Promoting Water-Splitting Performance.

O-O bond formation with Ru(bda)L -type catalysts is well-known to proceed through a bimolecular reaction pathway, limiting the potential application of these catalysts at low concentrations. Herein, we achieved high efficiencies with mononuclear catalysts, with TOFs of 460±32 s at high catalyst loading and 31±3 s at only 1 μM catalyst concentration, by simple structural considerations on the axial ligands. Kinetic and DFT studies show that introduction of an off-set in the interaction between the two catalytic units reduces the kinetic barrier of the second-order O-O bond formation, maintaining high catalytic activity even at low catalyst concentrations.

Intermolecular π-π Stacking Interactions Made Visible.

Mixing the liquids hexafluorobenzene () and 1,3,5-trimethylbenzene (mesitylene, ) results in a crystalline solid with a melting point of 34 °C. The solid consists of alternating π-π stacked pillars of both aromatics. This simple experiment can be used to visually demonstrate the existence and the effect of noncovalent intermolecular π-π stacking interactions.

Electronic Influence of the 2,2'-Bipyridine-6,6'-dicarboxylate Ligand in Ru-Based Molecular Water Oxidation Catalysts.

Water provides an ideal source for the production of protons and electrons required for generation of renewable fuels. Among the most-prominent electrocatalysts capable of water oxidation at low overpotentials are -type catalysts. Although many studies were dedicated to the investigation of the influence of structural variations, the true implication of the bda backbone on catalysis remains mostly unclarified.

Molecular Functionalization of NiO Nanocatalyst for Enhanced Water Oxidation by Electronic Structure Engineering.

Tuning the local environment of nanomaterial-based catalysts has emerged as an effective approach to optimize their oxygen evolution reaction (OER) performance, yet the controlled electronic modulation around surface active sites remains a great challenge. Herein, directed electronic modulation of NiO nanoparticles was achieved by simple surface molecular modification with small organic molecules. By adjusting the electronic properties of modifying molecules, the local electronic structure was rationally tailored and a close electronic structure-activity relationship was discovered: the increasing electron-withdrawing modification readily decreased the electron density around surface Ni sites, accelerating the reaction kinetics and improving OER activity, and vice versa.

Differences in δ N and δ C between embryonic and maternal tissues of the ovoviviparous bluntnose sixgill shark Hexanchus griseus.

Stable nitrogen (δ N) and carbon (δ C) isotope ratios from muscle, liver and yolk were analysed from the mother and embryos of an ovoviviparous shark, Hexanchus griseus. Embryonic liver and muscle had similar δ N and δ C ratios or were depleted in heavy isotopes, compared to the same maternal somatic and reproductive yolk tissues, but no relationship existed between δ N or δ C and embryo length, as expected, because a switch to placental nourishment is lacking in this species. This study expands the understanding of maternal nourishment and embryonic stable isotope differences in ovoviviparous sharks.

Acid-Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water.

The ability to use unprotected carbohydrates in olefin metathesis reactions in aqueous media is demonstrated. By using water-soluble, amine-functionalized Hoveyda-Grubbs catalysts under mildly acidic aqueous conditions, the self-metathesis of unprotected alkene-functionalized α-d-manno- and α-d-galactopyranosides could be achieved through minimization of nonproductive chelation and isomerization. Cross-metathesis with allyl alcohol could also be achieved with reasonable selectivity.

QCM sensing of multivalent interactions between lectins and well-defined glycosylated nanoplatforms.

Quartz crystal microbalance (QCM) methodology has been adopted to unravel important factors contributing to the "cluster glycoside effect" observed in carbohydrate-lectin interactions. Well-defined, glycosylated nanostructures of precise sizes, geometries and functionalization patterns were designed and synthesized, and applied to analysis of the interaction kinetics and thermodynamics with immobilized lectins. The nanostructures were based on Borromean rings, dodecaamine cages, and fullerenes, each of which carrying a defined number of carbohydrate ligands at precise locations.

Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source.

The use of water as an oxygen and hydrogen source for the paired oxygenation and hydrogenation of organic substrates to produce valuable chemicals is of utmost importance as a means of establishing green chemical syntheses. Inspired by the active Ni intermediates involved in electrocatalytic water oxidation by nickel-based materials, we prepared NiB as a catalyst and used water as the oxygen source for the oxygenation of various organic compounds. NiB was further employed as both an anode and a cathode in a paired electrosynthesis cell for the respective oxygenation and hydrogenation of organic compounds, with water as both the oxygen and hydrogen source.

Resolving a Reactive Organometallic Intermediate from Dynamic Directing Group Systems by Selective C-H Activation.

Catalyst discovery from systems of potential precursors is a challenging endeavor. Herein, a new strategy applying dynamic chemistry to the identification of catalyst precursors from C-H activation of imines is proposed and evaluated. Using hydroacylation of imines as a model reaction, the selection of an organometallic reactive intermediate from a dynamic imine system, involving many potential directing group/metal entities, is demonstrated.

Formal Synthesis of Solanoeclepin A: Enantioselective Allene Diboration and Intramolecular [2+2] Photocycloaddition for the Construction of the Tricyclic Core.

An enantioselective synthesis of an intermediate in the Tanino total synthesis of solanoeclepin A has been developed. The key step was an intramolecular [2+2] photocycloaddition, which led to the tricyclo[5.2.

Preorganized frustrated Lewis pairs.

Geminal frustrated Lewis pairs (FLPs) are expected to exhibit increased reactivity when the donor and acceptor sites are perfectly aligned. This is shown for reactions of the nonfluorinated FLP tBu(2)PCH(2)BPh(2) with H(2), CO(2), and isocyanates and supported computationally.