Highly Efficient and Selective N-Formylation of Amines with CO2 and H2 Catalyzed by Porous Organometallic Polymers.

The valorization of carbon dioxide (CO2 ) to fine chemicals is one of the most promising approaches for CO2 capture and utilization. Herein we demonstrated a series of porous organometallic polymers could be employed as highly efficient and recyclable catalysts for this purpose. Synergetic effects of specific surface area, iridium content, and CO2 adsorption capability are crucial to achieve excellent selectivity and yields towards N-formylation of diverse amines with CO2 and H2 under mild reaction conditions even at 20 ppm catalyst loading. Density functional theory calculations revealed not only a redox-neutral catalytic pathway but also a new plausible mechanism with the incorporation of the key intermediate formic acid via a proton-relay process. Remarkably, a record turnover number (TON=1.58×106 ) was achieved in the synthesis of N,N-dimethylformamide (DMF), and the solid catalysts can be reused up to 12 runs, highlighting their practical potential in industry.

Iridium-Catalyzed Selective Cross-Coupling of Ethylene Glycol and Methanol to Lactic Acid.

An atom-economic approach that has an unprecedented high selectivity for the synthesis of lactic acid (LA) based on a catalytic dehydrogenative cross-coupling by using inexpensive bulk ethylene glycol and methanol is described. This method relies on the synthesis and utilization of a novel iridium catalyst bearing three N-heterocyclic carbenes derived from 1,3-dimethylbenzimidazolium salts, and exhibits outstanding activity in the production of LA [turnover frequency (TOF) up to 3660 h-1 ] owing to an elegant metal-ligand cooperation.

Selective Catalytic Dehydrogenative Oxidation of Bio-Polyols to Lactic Acid.

The global demand for lactic acid (LA) is increasing due to its successful application as monomer for the manufacture of bioplastics. Although N-heterocyclic carbene (NHC) iridium complexes are promising molecular catalysts for LA synthesis, their instabilities have hindered their utilization especially in commercial applications. Here, we report that a porous self-supported NHC-iridium coordination polymer can efficiently prevent the clusterization of corresponding NHC-Ir molecules and can function as a solid molecular recyclable catalyst for dehydrogenation of bio-polyols to form LA with excellent activity (97 %) and selectivity (>99 %). A turnover number of up to 5700 could be achieved in a single batch, due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol. Our findings demonstrate a potential route for the industrial production of LA from cheap and abundant bio-polyols, including sorbitol.

The Energetic Significance of Metallophilic Interactions.

Metallophilic interactions are increasingly recognized as playing an important role in molecular assembly, catalysis, and bio-imaging. However, present knowledge of these interactions is largely derived from solid-state structures and gas-phase computational studies rather than quantitative experimental measurements. Here, we have experimentally quantified the role of aurophilic (AuI ⋅⋅⋅AuI ), platinophilic (PtII ⋅⋅⋅PtII ), palladophilic (PdII ⋅⋅⋅PdII ), and nickelophilic (NiII ⋅⋅⋅NiII ) interactions in self-association and ligand-exchange processes. All of these metallophilic interactions were found to be too weak to be well-expressed in several solvents. Computational energy decomposition analyses supported the experimental finding that metallophilic interactions are overall weak, meaning that favorable dispersion and orbital hybridization contributions from M⋅⋅⋅M binding are largely outcompeted by electrostatic or dispersion interactions involving ligand or solvent molecules. This combined experimental and computational study provides a general understanding of metallophilic interactions and indicates that great care must be taken to avoid over-attributing the energetic significance of metallophilic interactions.

A porous metal-organic framework constructed from carboxylate-pyrazolate shared heptanuclear zinc clusters: synthesis, gas adsorption, and guest-dependent luminescent properties.

A three-dimensional porous structure of [Zn7O2(bpdc)4(dmpp)2]·6DEF·10H2O (MAC-7, H2bpdc = 4,4'-biphenyldicarboxylic acid, Hdmpp = 3,5-dimethyl-4-(4'-pyridyl)pyrazole), built of 12-bridged carboxylate-pyrazolate shared Zn7O2 clusters, has been synthesized. Because of the presence of 12-bridged carboxylate-pyrazolate shared building block, MAC-7 is a double-linked pcu-type framework and shows reversible phase transformation. Photoluminescent property studies indicate that MAC-7 could sense nitrobenzene over toluene, p-xylene, and mesitylene by luminescent quenching.

Self-assembled aggregates originated from the balance of hydrogen-bonding, electrostatic, and hydrophobic interactions.

Rich phase behavior was observed in salt-free cationic and anionic (catanionic) mixtures of a double-tailed surfactant, di(2-ethylhexyl)phosphoric acid (abbreviated as DEHPA), and tetradecyldimethylamine oxide (C(14)DMAO) in water. At a fixed C(14)DMAO concentration, phase transition from L(1) phase to L(α) phase occurs with increasing amounts of DEHPA. Moreover, in the L(α) phase, with the increase in DEHPA concentration, a gradual transition process from vesicle phase (L(αv)) to stacked lamellar phase (L(αl)) was determined by cryo- and FF-TEM observations combining with (2)H NMR measurements. The rheological data show that the viscosity increases with DEHPA amounts for L(αv) phase samples because of the increase in vesicle density. At a certain molar ratio of DEHPA to C(14)DMAO, i.e., 80:250, the samples are with the highest viscoelasticity, indicating the existence of densely packed vesicles. While for L(αl) phase samples, with increasing DEHPA amount, a decrease of bilayer curvature was induced, leading to a decrease of viscosity obviously. Compared with general catanionic surfactant mxitures, in addition to the electrostatic interaction of ion pairs, the transition of the microstructures is also ascribed to the formation of the hydrogen bonding (-N(+)-O-H···O-N-) between C(14)DMAO molecules and protonated C(14)DMAOH(+), which induces the growth of aggregates and the decrease of aggregate curvatures.

Instantaneous High-Resolution Visual Imaging of Latent Fingerprints in Water Using Color-Tunable AIE Pincer Complexes.

Instant visualization of latent fingerprints is developed by using a series of water-soluble terpyridine zinc complexes as aggregation-induced emission probes in pure water, under UV light or ambient sunlight. By simply soaking, or spraying with an aqueous solution of the probe, bright yellow fluorescence images with high contrast and resolution are readily developed on various surfaces including tinfoil, glass, paper, steel, leather, and ceramic tile. Remarkably, latent fingerprints can be visualized within seconds including details of whorl and sweat pores. The color of emission can be tuned from blue to orange by modifying the pincer ligands, allowing direct imaging under sunlight. These inexpensive, water-resistant, and color-tunable probes provide a practical approach for latent fingerprints recording and analysis, security protection, as well as criminal investigation in different scenarios.

Rare-Earth-Catalyzed Transsulfinamidation of Sulfinamides with Amines.

A rare-earth-catalyzed transsulfinamidation of primary sulfinamides with alkyl, aryl, and heterocyclic amines for the synthesis of diverse secondary and tertiary sulfinamides has been realized. Unlike transition metal-catalyzed cross-coupling approaches restricted to non-commercially available disubstituted O-benzoyl hydroxylamines, this newly developed protocol is suitable for diverse readily available primary and secondary amines without any modifications. Excellent catalytic activity and selectivity are achieved with Eu(OTf)3 under mild reaction conditions, which extends the applicability of rare-earth catalysis.

Nickel-Catalyzed Amination of Aryl Chlorides with Amides.

A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single-Site Catalysts with Enhanced Activity.

Porous organometallic polymers (POMPs) with hierarchical pore structures, high specific surface areas, and atomically dispersed metal (Ir, Pd, Ru) centers are successfully fabricated by a facile one-pot method through direct knitting of diverse N-heterocyclic carbene metal (NHC-M) complexes. These polymers can function as recyclable solid single-site catalysts and exhibit excellent catalytic activity and selectivity in both dehydrogenation and hydrogenation reactions even at ppm-level catalyst loadings. Remarkably, a record turnover number (TON) of 1.01 × 106 is achieved in the hydrogenation of levulinic acid to γ-valerolactone, which is 750 times higher than that attained with corresponding bis-NHC-Ir complex.

Reversible stimuli-responsive chromism of a cyclometallated platinum(II) complex.

We report the reversible chromism and luminescence of a cyclometalated platinum(ii) complex that forms dimers, with close PtPt interactions that can be modulated by solvent and temperature. The precise reversible control may be exploited in future stimuli-responsive chemosensing or optoelectronic devices.

Cobalt substitution in a flexible metal-organic framework: modulating a soft paddle-wheel unit for tunable gate-opening adsorption.

Developing feasible ways to achieve tunable gate-opening pressure (Pgo) while minimizing the side effects on the adsorption capacity and enthalpy is greatly desired for flexible MOFs. In this work, we focused on solving this issue by cobalt substitution. We showed the successful modulation of the energy required for the reversible transformation of a soft paddle-wheel so that the whole framework presented a substitution-dependent Pgo for CO2 adsorption.