Deoxygenation is an important pathway for adding value to biomass-derived feedstocks in both the commodity and fine chemical sectors, and benzylic aldehydes and ketones serve as useful model compounds for these substrates. In this work, we demonstrate that the reductive deoxygenation of benzylic aldehydes and ketones can be achieved using [Co₂(CO)₈] and syngas (H₂/CO) in alcoholic media, in the absence of additional ligands or additives. The simplicity of this system contrasts with other methodologies, which often require bases and/or stoichiometric reagents, as well as expensive second- and third-row transition metal complexes. Notably, isopropanol emerges as the most suitable solvent and represents an environmentally friendly option. The protocol is effective for a range of benzylic aldehydes and ketones bearing different electron-donating groups on the aromatic ring, as well as for indole derivatives containing an aldehyde functionality at the β-position.
The integration of organometallic and enzymatic catalysis in one pot is often limited by mutual inhibition between metal complexes and enzymes, particularly in NAD(P)⁺-dependent redox cascades that require efficient cofactor regeneration. Here we report a family of IrCp* pyridinium-amidate (PYA) complexes that regenerate NAD(P)H in aqueous media. Systematic tuning of the pyridinium and phenolate substituents identified Ir4 containing an acetamide substituent at the pyridinium unit as the most active catalyst (turnover frequency TOF = 5.6 h−1), which reduces both NAD⁺ and NADP⁺ alike, making it compatible with both cofactors. The catalyst was successfully paired with ene-reductase mcOYE and ketoreductase cgKR1. While mcOYE proved intrinsically compatible and supported productive cascades under simple monophasic conditions, cgKR1 showed co-aggregation with the iridium catalyst in aqueous buffer. However, switching to Ir2 and a simple biphasic set-up largely overcame mutual inhibition, raising the regeneration TOF threefold (to 17.6 h−1) and restoring cascade activity. Computational surface analysis across six oxidoreductases showed that the inhibition is not correlated to any single surface descriptor. This work establishes phase separation as a low-effort strategy for combining molecular transition metal catalysts with enzymes when mutual inhibition in water is stronger than their sensitivity to the liquid–liquid interface.
The integration of acidic zeolites with Fe-based catalysts provides a promising strategy to overcome the broad hydrocarbon distribution of CO2-modified Fischer-Tropsch synthesis (FTS) through in situ product upgrading. In this work, a 5 wt% Na-Fe3O4 catalyst is combined with commercial BETA zeolites having nominal SiO2/Al2O3 ratios of 25, 38, and 360 to investigate the effects of zeolite acidity and catalyst configuration at 360 °C and 2.3 MPa. CO2 conversion remains within 37–44%, whereas BETA markedly alters hydrocarbon selectivity by promoting cracking, isomerization, and H-transfer reactions. Mössbauer spectroscopy and STEM-EDS show that close contact between the catalytic functions modifies the iron-phase distribution and promotes Na migration toward the zeolite. Physical separation in the dual-bed configuration reduces the Na content detected on BETA-38 from 1.02 to 0.20 mmolNa gzeolite−1. NH3-TPD reveals a substantial loss of acidity after reaction, although the residual acid sites remained sufficient to sustain secondary upgrading. Detailed Hydrocarbon Analysis (DHA) and GC-MS show a strong depletion of linear olefins and enrichment in branched and cyclic hydrocarbons. For the layered BETA-38 system, the reconstructed liquid product contains 71.3 vol% naphtha-range and 21.7 vol% kerosene-range hydrocarbons, with only 7.0 vol% gasoil and heavier residue. The dual-bed configuration promotes more extensive cracking and an almost entirely naphtha-range liquid. Despite the wide initial acidity range, product distributions are similar, identifying catalyst architecture as the dominant parameter for tuning CO2-derived fuel composition.
Cellulose solubilization and homogeneous conversion into industrial products and advanced materials through one-pot processes remain major challenges for the biorefinery industry since conventional cellulose derivatization generally requires heterogeneous alkaline activation and multiple processing steps. In this study, we report the ultrarapid carboxymethylation of cellulose in a homogeneous medium using zinc chloride trihydrate (ZnCl2·3 H2O) as a green solvent through a complex-mediated autocatalytic process without NaOH activation. The novelty of this approach lies in the simultaneous use of ZnCl2·3 H2O as a cellulose-dissolution medium and a source of Zn2 + coordination centers, integrating dissolution, derivatization, metal coordination, and nanoparticle formation in a single reaction system. Carboxymethylation was achieved within 10 min, resulting in a novel water-soluble nanoscale coordination polymer formed through the coordination of zinc cations by carboxylate groups of carboxymethylcellulose, the nanoZnCMC. Dynamic light scattering and electron microscopy revealed particle sizes of 10–36 nm, while complementary spectroscopic analyses confirmed cellulose carboxymethylation and Zn2+ coordination by carboxylate groups. NanoZnCMC nanoparticles assembled into cubic supracrystals through Coulombic interactions between charged Zn-O clusters and ions provided by excess NaCl. The water solubility, nanoscale dimensions, metal-carboxylate coordination, fluorescence and supracrystalline organization of nanoZnCMC support its potential for further application in nanotechnology, sensing, and photonics. Thus, this study introduces a previously unexplored one-pot strategy for homogeneous cellulose derivatization and the production of a bio-based nanoscale coordination material.
Two dimensional (2D) copper-carboxylate frameworks (MOFs) have become increasingly important in modern science and technology due to their unique properties broad-spectrum applications. Two 2D Cu-isophthalate frameworks (Cu-MOF1 and Cu-MOF2) were synthesized via solvothermal and ambient-condition synthetic methods, respectively, employing the relatively less-explored isophthalic acid linker. Multiple analytical techniques (FTIR, TGA, PXRD, SEM-EDX, and BET) were applied for characterization of synthesized materials. Single crystal X-ray diffraction (SC-XRD) analysis confirmed the SBUs self-assembled structure resulted nanosized bowls which in turn form 2D MOF layers. Considering the interesting structural characteristics and facile bulk scale synthesis of Cu-MOF, it was selected as a potential catalyst for the chemical fixation of CO₂ with epichlorohydrin (ECH) to produce the corresponding cyclic carbonate. A comprehensive optimization of the reaction parameters, including temperature, CO₂ pressure, reaction time, catalyst and/or co-catalyst loading, was performed for achieving maximum ECH conversion. The chemical fixation of CO2 to epoxide revealed promising catalytic efficiency of Cu-MOF: with ⁓97% conversion and > 99% selectivity to organic cyclic carbonate at room temperature to 120 °C under 1–3 bar gas pressure for 3–24 h by applying ~0.3 mol% catalyst and ~0.1 mol% co-catalyst. The scope of the epoxides was extended for assessing the catalytic potential of Cu-MOF towards five different substrates. Theoretical investigations revealed interesting energy profiling for efficient conversion of CO2. The structural stability of Cu-MOF was investigated by performing post-catalytic characterizations (SEM, PXRD, TGA). 2D Cu-MOF appeared to be a promising catalyst for valorization of CO2 in production of valued cyclic carbonates.
