Post-Modification Approach for Self-Exfoliated Synthesis of Pyridinium Sulfobetaine Covalent Organic Frameworks for Enhanced Lithium-Ion Conductivity.

While covalent organic frameworks (COFs) have been extensively investigated in the field of organic electrolyte materials, there is potential for further enhancement of their room-temperature ionic conductivity. This study introduces a novel methodology to induce self-exfoliation in the parent COF during synthesis through a postmodification technique. This process yields covalent organic nanosheets that feature pyridinium sulfobetaine groups, referred to as PS-CON. Due to the strategic arrangement of pyridinium cations and sulfobetaine anions, the charge distribution in PS-CON varies substantially, leading to a significant enhancement in lithium-ion dissociation. The methodically organized one-dimensional pore channels, along with the linear structure of the pyridinium sulfobetaine groups, facilitate the lithium-ion transport. PS-CON demonstrated a remarkable ionic conductivity of 2.19 × 10-4 S cm-1and a low activation energy (0.26 eV) coupled with a broad electrochemical stabilization window (4.05 V). Furthermore, the symmetrical cell (Li|Li@PS-CON|Li) demonstrates stable Li plating/stripping for more than 1200 h, which highlights the vast potential of pyridinium-sulfobetaine based zwitterionic nanosheets as high-performance organic electrolytes.

TiO2@UiO-68-CIL: A Metal-Organic-Framework-Based Bifunctional Composite Catalyst for a One-Pot Sequential Asymmetric Morita-Baylis-Hillman Reaction.

A chiral ionic liquid (CIL) moiety of a l-pyrrolidin-2-ylimidazole-decorated homochiral UiO-68-type metal-organic framework, UiO-68-CIL (1), was successfully prepared by the combination of a new premodified chiral CIL ligand (H2L-CIL) and ZrCl4 via a solvothermal method. The TiO2-loaded TiO2@UiO-68-CIL (2) was prepared by impregnating 1 in a toluene solution of Ti(OPri)4 and sequential in situ hydrolysis. The obtained 2 can be a bifunctional asymmetric heterogeneous catalyst to successfully promote the one-pot Morita-Baylis-Hillman reaction starting from aromatic alcohols in a tandem way.

Smart pH-Responsive Polymer-Tethered and Pd NP-Loaded NMOF as the Pickering Interfacial Catalyst for One-Pot Cascade Biphasic Reaction.

A Pd nano particle (NP)-loaded and nano metal-organic framework (NMOF)-based Pickering emulsifier is reported. The poly[2-(diethylamino)ethyl methacrylate)] (PDEAEMA) chains were grafted onto UiO-66-type NPs via a postsynthetic approach to generate PDEAEMA-g-UiO-66 NMOF (termed as MOF-3). The Pd NPs-loaded Pd@MOF-3 was synthesized via solution impregnation. Stable toluene-in-water Pickering emulsion was prepared with emulsifier Pd@MOF-3. Notably, the obtained Pd@MOF-3 is pH-responsive, and it is able to trigger the emulsification (at neutral condition) and demulsification (at acidic condition) of toluene droplets. Furthermore, it can be a highly active interfacial catalyst to effectively promote one-pot Knoevenagel condensation-hydrogenation cascade reaction at ambient conditions. The pH-responsive property allowed it to be in situ separated and recycled by demulsifying via simply tuning the pH value at the end of the reaction. This smart Pickering emulsion catalytic system is robust, and it can be recycled at least five times without loss of its catalytic activity.