ILs with reversible construction of ionic networks, which mainly consist of cooperative hydrogen bonds (CHBs) were designed for sigmoidal ammonia (NH3) absorption isotherm, which leads to efficient absorption, energy-saving desorption, and high reversibility. Combined with NH3 absorption–desorption experiments, spectroscopic investigations, NH3–TPD measurement, and quantum-chemical calculations, NH3 absorption mechanism was proposed as the hydrogen bond interaction with IL by overcoming the heat for disorganizing ionic networks, including CHBs breakage and the phase change of IL from solid to liquid. Reversely, the NH3 desorption would be promoted by the heat release for the reformation of ionic networks. Thereinto, [BzAm]­[Tf2N] with ionic networks showed NH3 absorption with threshold pressure at 0.28 bar and NH3 capacity of 2.8 mol NH3/mol IL at 1 bar as well as be desorpted completely just through pressure swing, calorimetric test indicated the exothermic reformation of ionic networks provided 31.8% of energy for NH3 desorption from [BzAm]­[Tf2N]. Furthermore, the ammonia capacity as well as the threshold pressure would be changed by varying the CHBs interaction in IL, that [2PyH]­[Tf2N] with weaker interaction of CHBs indicating decreased threshold pressure at 0.04 bar and enhanced NH3 capacity of 3.8 mol NH3/mol IL at 1 bar. We believe this highly efficient and reversible process by reversible construction of absorbents can provide a potential alternative for NH3 as well as other gas absorption.

Hyper-crosslinking polymers and its immobilized acid ionic liquid catalyst were prepared using cheap pitch, as a monomer, through hyper-crosslinking reactions and allyl chloride, as a chlorine source, for chloromethylation and further grafting with imidazole and functionalizing with sulfonic acid. The polymers were characterized by FE-SEM, FTIR, TG, and nitrogen sorption. The grafting ratios of the chloromethylated pitch-based hyper-crosslinked polymer (HCPpitch–CH2–Cl) and immobilized acid ionic liquid [HCPpitch–Im–Pros][Tos] were 3.5 mmol/g and 3.0 mmol/g, and the BET specific surface areas were 520 m2/g and 380 m2/g, respectively. This strategy provides an easy approach to preparing highly stable and acid functionalized mesoporous catalysts. The immobilized acidic ionic liquid was used as a catalyst for the esterification of oleic acid and methanol to synthesize biodiesel. The results demonstrated that under the optimal conditions of an alcohol to acid molar ratio of 7:1, ionic liquid to oleic acid molar ratio of 0.12, and a reaction time of 3 h at atmospheric pressure, the yield of methyl oleate can reach up to 93%. Moreover, the catalyst was reused five times without the yield decreasing significantly. This study shows that [HCPpitch–Im–Pros][Tos] is a robust catalyst for the synthesis of biodiesel.

In this work, flexible hydrogen-bonded frameworks composed of amino pyridinium-based protic ionic liquids (ILs) marked as [X-PyH]­[Tf2N] were designed as NH3 absorption agents. Interestingly, NH3 absorption isotherm of these ILs present sigmoidal absorption isotherm (S mode), and the threshold pressure (TP) decreases from 75 to 6 mbar with the tunable of hydrogen bonded frameworks by varying the substituted group X. Combined with XRD characterizations, Fourier transform infrared and 1H NMR spectroscopies, thermometric analyses, and theory calculations, it indicates NH3 fixed by these ILs via acid–base interaction as well as hydrogen bonding based on the activation of sites through the fracture of the hydrogen-bonded frameworks, which would reform along with heat release when NH3 desorption. Therefore, S mode NH3 absorption with [3NH2-PyH]­[Tf2N] presents low TP of 6 mbar (6000 ppm) at 30 °C, and its NH3 capacity increases sharply and followed by a continuous increase to 3.85 mol/mol IL (175 mg/g IL) at 1.0 bar, which is higher than that of the reported ILs. The fixed NH3 could be desorbed completely in vacuum at 80 °C and 1 mbar. [3NH2-PyH]­[Tf2N] maintained its high capacity within 20 time recycles. The sigmoidal NH3 absorption would be considered as one of the potential approaches for its simultaneous efficient absorption and energy-saving separation at low concentrations.

Cooperative CO2 absorption by anion functionalized ILs with dual sites including amino acid group (AA) and basic anion (R) could be achieved through regulating the relative activation of two sites.

An efficient strategy for enhancing CO2 capture performance based on 2-hydroxyl pyridium anion-functionalized ILs was reported via the reduction of cation–anion interactions in ILs.

Under the assistance of the state‐of‐the‐art meta‐dynamics simulations, in this contribution, we report a push‐pull‐type acylhydrazone 4(Z) ([Z)‐2‐(naphthalen‐2‐yloxy)‐N'‐(pyridine‐2‐ylmethylene)acetohydrazide] connecting an electron‐donating naphthalene ether group with an accepting pyridyl unit, which could be thermally converted to its configurational isomer 4(E) ([E)‐2‐(naphthalen‐2‐yloxy)‐N'‐(pyridine‐2‐ylmethylene)acetohydrazide]. The thermally triggered Z‐to‐E configurational isomerization not only involves up to five chemical bonds undergoing 180° rotation in the backbone of acylhydrazone, but changes the crystal packing symmetry from a centrosymmetric space group to a non‐centrosymmetric one. Most impressively, the acentric crystal arrangement of 4(E) exhibits a second‐harmonic generation (SHG) active response, about 2.5 times than that of KH2PO4 (KDP) standard.