Unprecedented POSS-linked 3D Covalent Organic Frameworks with scu or sqc Topology Regulated by Porphyrin Center for Photocatalytic CO2 Reduction.

The synthesis and characterization of porphyrin center regulated three-dimensional covalent organic frameworks with 2-fold interpenetrated scu or sqc topology have been investigated. These COFs exhibit unique structural features and properties, making them promising candidates for photocatalytic applications in CO2 reduction and artemisinin synthesis. The porphyrin center serves as an anchor for metal ions, allowing precise control over structures and functions of the frameworks. Furthermore, the metal coordination within the framework imparts desirable catalytic properties, enabling their potential use in photocatalytic reactions. Overall, these porphyrin center regulated metal-controlled COFs offer exciting opportunities for the development of advanced materials with tailored functionalities.

Constructing 2D Phthalocyanine Covalent Organic Framework with Enhanced Stability and Conductivity via Interlayer Hydrogen Bonding as Electrocatalyst for CO2 Reduction.

Fabricating COFs-based electrocatalysts with high stability and conductivity still remains a great challenge. Herein, 2D polyimide-linked phthalocyanine COF (denoted as NiPc-OH-COF) is constructed via solvothermal reaction between tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(II) and 2,5-diamino-1,4-benzenediol (DB) with other two analogous 2D COFs (denoted as NiPc-OMe-COF and NiPc-H-COF) synthesized for reference. In comparison with NiPc-OMe-COF and NiPc-H-COF, NiPc-OH-COF exhibits enhanced stability, particularly in strong NaOH solvent and high conductivity of 1.5 × 10-3  S m-1 due to the incorporation of additional strong interlayer hydrogen bonding interaction between the O-H of DB and the hydroxy "O" atom of DB in adjacent layers. This in turn endows the NiPc-OH-COF electrode with ultrahigh CO2 -to-CO faradaic efficiency (almost 100%) in a wide potential range from -0.7 to -1.1 V versus reversible hydrogen electrode (RHE), a large partial CO current density of -39.2 mA cm-2 at -1.1 V versus RHE, and high turnover number as well as turnover frequency, amounting to 45 000 and 0.76 S-1 at -0.80 V versus RHE during 12 h lasting measurement.

Enhanced Photocatalytic CO2 Reduction through Hydrophobic Microenvironment and Binuclear Cobalt Synergistic Effect in Metallogels.

Assemblies that mimic natural lipid bilayers are theoretically efficient for photocatalytic CO2 reduction; however, such an approach has not been yet explored. Herein, metallogels (LG/Nico-Co) based on the co-assembly of L-glutamic acid lipid (LG/Nico) and cobalt ions exhibited excellent photocatalytic CO2 reduction, with 208 724 µmol g-1 CO production within 24 h and 90 % CO/H2 selectivity, or 166 826 µmol g-1 CO production within 12 h and 46 % CO/H2 selectivity, depending on the water content of the solvent. The alkyl chains of LG/Nico provide a hydrophobic microenvironment for efficient gas transfer, and the assembled bilayers induce a synergistic effect between two adjacent Co ions for catalyzing the CO2 reduction reaction. These architectures present new alternatives for the development of highly efficient photocatalytic soft matter based on the assembly of small amphiphilic molecules.

Mechanistic insights into ring cleavage of hydroquinone by PnpCD from quantum mechanical/molecular mechanical calculations.

PnpCD is a mononuclear non-heme iron(ii) dioxygenase containing an unusual 2His-1Glu-1Asn metal-binding motif. To gain insights into the catalytic mechanism of the ring opening of hydroquinone by PnpCD, hybrid quantum mechanics/molecular mechanics calculations have been performed by using two models with different protonation states of the substrate (nonionized and ionized forms of the Fe-bound hydroxyl group of hydroquinone). In both cases, the structure of the reactive Fe-O2 species reveals a trigonal bipyramidal complex, in which Asn258 is no longer coordinated to the iron center. The catalytic process mainly involves the attack of the superoxo radical, O-O bond cleavage, three-membered ring closure and opening, attack of the Fe-bound oxyl radical, and ring-opening of the seven-membered ring. The transition state for the peroxo O-O bond cleavage was found to be the rate-determining transition state. The second-sphere Glu248 serves as a proton acceptor to deprotonate the unbound substrate hydroxyl group, thereby facilitating the electron transfer between the substrate and dioxygen. The first-sphere Glu262 can act as an acid-base catalyst to lower the rate-limiting barrier, thus providing a useful clue for improving catalytic efficiency.

Mn-complex modified NaDyF4:Yb@NaLuF4:Yb,Er@polydopamine core-shell nanocomposites for multifunctional imaging-guided photothermal therapy.

Upconversion nanoparticles (UCNPs) have been used as building blocks in the construction of multimodal contrast agents for theranostics, that is, the combination of diagnostics and therapies. Upconversion luminescence (UCL) imaging is widely used for cell and tissue imaging while magnetic resonance imaging (MRI) is well-suited for in vivo imaging. Photothermal therapy (PTT) using (near-infrared) NIR laser radiation constitutes a minimally invasive alternative to the conventional surgical treatment of cancer. As such, multifunctional Mn-complex modified NaDyF4:Yb@NaLuF4:Yb,Er@polydopamine (PDA) nanocomposites (Dy@Lu@PDA-Mn) were synthesized, which was based on the fact that Yb3+ and Er3+ induce UCL, Dy3+ and Mn2+ interferes with T2 and T1 in MRI, and PDA strongly absorbs in the NIR region for PTT. Through tri-modal UCL, T1-, T2-weighted MRI guiding, an outstanding photothermal therapeutic efficacy with tumour elimination was obtained in a mice breast cancer model, by injection of Dy@Lu@PDA-Mn upon laser irradiation. A strategy for multimodal imaging-guided PTT was formulated and the potential of multifunctional nanostructures for use in cancer theranostics was demonstrated.