Metalated nanoporous organic polymers (M-POPs) combine covalent bonds and open metal sites to enable structural stability and single-site catalysis. In this work, we constructed two single-site Pd-metalated knitting aromatic polymers (Pd@KAP-1 and Pd@KAP-2) and explored their catalytic activity in lignocellulosic biomass-derived furfural (FFR) upgrading to tetrahydrofurfuryl alcohol (THFAL), a green industrial solvent. Pd@KAP-1 exhibits superior catalytic performance compared to Pd@KAP-2 toward FFR conversion, resulting in 80% conversion with a 95% selectivity toward THFAL. Using in situ DRIFTS analysis, we find that FFR strongly adsorbs on Pd@KAP-1, which is a key determining factor in its higher catalytic efficiency. Our X-ray photoelectron spectroscopic (XPS) measurements show a lower (∼0.3 eV) binding energy displacement of Pd-3d5/2 in Pd@KAP-1 compared to Pd@KAP-2. We attribute this to the presence of a biphenyl ring that enables partial charge transfer between the P and the Pd atoms inside the nanocavity of Pd@KAP-1 to facilitate catalytic hydrogenation. We also carried out a kinetic analysis showing that Pd@KAP-1 has a lower activation barrier than Pd@KAP-2 for the FFR hydrogenation process. Our study demonstrates a novel concept for designing efficient, robust, and sustainable metalated porous organic polymer-based heterogeneous nanocatalysts in biomass refinery industries.
The rational synthesis of durable, earth-abundant efficient electrocatalysts for the oxygen evolution reaction (OER) from water is one of the most significant routes for storing renewable energy and minimizing fossil...
The development of efficient metal‐free photocatalysts for the generation of reactive oxygen species (ROS) for sulfur mustard (HD) decontamination can play a vital role against the stockpiling of chemical warfare agents (CWAs). Herein, one novel concept is conceived by smartly choosing a specific ionic monomer and a donor tritopic aldehyde, which can trigger linker‐independent regioselective protonation/deprotonation in the polymeric backbone. In this context, the newly developed vinylene‐linked ionic polymers (TPA/TPD‐Ionic) are further explored for visible‐light‐assisted detoxification of HD simulants. Time‐resolved‐photoluminescence (TRPL) study reveals the protonation effect in the polymeric backbone by significantly enhancing the life span of photoexcited electrons. In terms of catalytic performance, TPA‐Ionic outperformed TPD‐Ionic because of its enhanced excitons formation and charge carrier abilities caused by the donor‐acceptor (D‐A) backbone and protonation effects. Moreover, the formation of singlet oxygen (1O2) species is confirmed via in‐situ Electron Spin Resonance (ESR) spectroscopy and density functional theory (DFT) analysis, which explained the crucial role of solvents in the reaction medium to regulate the (1O2) formation. This study creates a new avenue for developing novel porous photocatalysts and highlights the crucial roles of sacrificial electron donors and solvents in the reaction medium to establish the structure‐activity relationship.
In recent times, a self-complementary balanced characteristic feature with the combination of both covalent bonds (structural stability) and open metal sites (single-site catalysis) introduced an advanced emerging functional nanoarchitecture termed metalated porous organic polymers (M-POPs). However, the development of M-POPs in view of the current interest in catalysis has been realized still in its infancy and remains a challenge for the years to come. In this work, we built benzothiazolelinked Fe-metalated porous organic polymer (Fc-Bz-POP) using ferrocene dicarboxaldehyde (FDC), 1,3,5-tris(4-aminophenyl) benzene (APB), and elemental sulfur (S 8 ) via a template-free, multicomponent, cost-effective one-pot synthetic approach. This Fc-Bz-POP is endowed with unique features including an extended network unit, isolated active sites, and catalytic pocket with a possible local structure, in which convergent binding sites are positioned in such a way that substrate molecules can be held in close proximity. Prospective catalytic application of this Fc-Bz-POP has been explored in executing catalytic allylic "C−H" bond functionalization of cyclohexene (CHX) in water at room temperature. Catalytic screening results identified that a superior performance with a CHX conversion of 95% and a 2-cyclohexene-1-ol selectivity (COL) of 80.8% at 4 h and 25 °C temperature has been achieved over Fc-Bz-POP, thereby addressing previous shortcomings of the other conventional catalytic systems. Comprehensive characterization understanding with the aid of synchrotron-based extended X-ray absorption fine structure (EXAFS) analysis manifested that the Fe atom with an oxidation state of +2 in our Fc-Bz-POP catalytic system encompasses a sandwich structural environment with the two symmetrical eclipsed cyclopentadienyl (Cp) rings, featuring nearestneighbor (NN) Fe−C (≈2.05 Å) intramolecular bonds, as validated by the Fe L 3 -edge EXAFS fitting result. Furthermore, in situ attenuated total reflection-infrared spectroscopy (ATR-IR) analysis data for liquid-phase oxidation of cyclohexene allow for the formulation of a molecular-level reaction mechanistic pathway with the involvement of specific reaction intermediates, which is initiated by the radical functionalization of the allyl hydrogen. A deep insight investigation from density functional theory (DFT) calculations unambiguously revealed that the dominant pathway from cyclohexene to 2-cyclohexene-1-ol is initiated by an allyl-H functionalization step accompanied by the formation of 2-cyclohexene-1-hydroperoxide species as the key reaction intermediate. Electronic properties obtained from DFT simulations via the charge density difference plot, Bader charge, and density of state (DOS) demonstrate the importance of the organic polymer frame structure in altering the electronic properties of the Fe site in Fc-Bz-POP, resulting in its high activity. Our contribution has great implications for the precise design of metalated porous organic polymer-based robust catalysts, which will open a new av...
Cobalt complexes (1-2) were synthesized from ligands L1 (1,2-bis(2-phenyl-2-(pyridin- 2-yl) hydrazineylidene) ethane)) and L2 (1,2-bis(2-(pyridin-2-yl) hydrazineylidene) ethane)) in moderate yields. These complexes were characterized by UV–visible, IR and ESI-MS spectroscopic...
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