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An aromatic porous polymer incorporated with carbonyl functionality (APP) was prepared via a facile route of Friedel-Crafts reaction. Subsequent reaction with diethylenetriamine via Schiff-base chemistry produced the amine-functionalized porous polymer (DETA-APP), which was used as a solid backbone to stabilize Pd nanoparticles with sizes of 1–3 nm. The prepared multifunctional Pd/DETA-APP catalyst showed high catalytic activity and selectivity towards the cascade reaction of Knoevenagel condensation-transfer hydrogenation using HCOOH as a hydrogen source. The positive influence of the amine functionality on the Pd/DETA-APP in the hydrogenation step was established after comparing the catalytic performance with that of the Pd/APP. The catalyst could be reused without any loss in reaction efficiency and selectivity for at least 5 times. Finally, a plausible mechanistic pathway for the cascade reaction over Pd/DETA-APP catalyst was proposed.

A new nanoporous N-heterocyclic carbene-based cross-linked aromatic polymer (NHC-CAP-1) incorporated with highly nucleophilic bromide anions and with a large surface area was synthesized by a simple Friedel-Crafts reaction of imidazolium salt, triphenylbenzene, and formaldehyde dimethyl acetal. Subsequently, ZnBr2 was grafted onto the NHC-CAP-1 to obtain NHC-CAP-1(Zn2+) with enhanced Lewis acidity. After systematic evaluation of the structural and chemical properties using different analytical techniques, these were explored for CO2 adsorption and CO2 chemical fixation to cyclic carbonates. Whilst NHC-CAP-1 showed a high CO2 capture capacity (188.2 mg g−1 at 273 K/1 bar) with a moderate CO2/N2 selectivity, NHC-CAP-1(Zn2+) displayed significantly enhanced CO2/N2 selectivity (100/80 at 273/298 K) at the expense of diminished CO2 capture (123.0 mg g−1 at 273 K/1 bar). These values are among the highest reported so far for porous cross-linked organic polymers. As a catalyst, NHC-CAP-1(Zn2+) showed high catalytic activities for CO2 cycloaddition to a series of epoxides to form cyclic carbonates in the absence of co-catalyst and solvent, producing a high turnover frequency (TOF) of 2202 h−1 at 100 °C. The effect of reaction parameters including temperature, reaction time, and catalyst loading was examined. NHC-CAP-1(Zn2+) could be separated readily and reuse for a minimum of 10 runs while maintaining high activity and stability owing to the strong covalent bonding of Lewis acidic Zn2+ to the NHC-CAP-1 backbones. This work demonstrated that NHC-CAP-1 and NHC-CAP-1(Zn2+) are viable porous materials that are highly efficient for both CO2 capture and catalytic conversion of CO2 to cyclic carbonates.

A new porphyrinic porous organic polymer (PPOP) with high stability and excellent textural properties (929 m2/g surface area with 0.73 cm3/g pore volume) was made via the Friedel-Crafts reaction and applied for bisphenol A (BPA) adsorption in water. The material was examined by X-ray diffraction, N2 adsorption-desorption isotherms, scanning electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, and solid-state 13C CP-MAS nuclear magnetic resonance spectroscopy. PPOP was proven highly effective for capturing BPA among the many adsorbent materials investigated. The Langmuir model could closely match the adsorption isotherm data with a high adsorption amount of ca. 653 mg/g at 25 °C. Approximately 95% of BPA was adsorbed in 50 min, and the pseudo-second-order kinetic model satisfactorily described the adsorption behavior. This adsorption process was exothermic (ΔH° = −39.10 kJ/mol), and the capacity gradually decreased with increasing pH. Spectroscopic analyses indicated that the BPA adsorption on PPOP was affected by (1) π-π interaction between BPA and the aromatic constituents of PPOP, (2) hydrogen bonding between the N sites of porphyrin units in PPOP and the hydroxyl group of BPA and, and (3) hydrophobic interactions. PPOP was easily regenerated after acetone washing, and >98% efficiency was observed throughout the five repeated adsorption-desorption cycles.

The direct synthesis of cyclic carbonates from olefins involves epoxidation and CO2 cycloaddition reactions in series. It is, however, a challenging task to devise single catalyst with the multiple functions for one-pot reaction. Herein, an imidazolium bromide ionic liquid-functionalized metalloporphyrin ImBr-MOF-545(Mn) was proposed as an effective catalyst for the reaction. The effects of temperature, pressure, catalyst loading, and time were examined for individual reactions and finally for one-pot reaction. ImBr-MOF-545(Mn) was efficient under solvent-free condition of 60 °C, 5/5 bar (O2/CO2), and 10 h. The Mn(III) ions with the dual functions of oxidation and acting as Lewis acid catalyst with strong nucleophilic/leaving bromide anion in an adjacent position of mesoporous MOF-545 resulted in high efficiency and selectivity to the cyclic carbonates. The catalyst also showed sufficient stability for up to 5 runs with little decline in catalytic activity. A radical mechanism for the epoxidation step and a plausible reaction pathway was proposed.

The metal-organic frameworks MOF-525 and MOF-545 comprised of Zr-oxide clusters and porphyrin moieties in different geometries were synthesized solvothermally and applied for the adsorptive removal of the broadly used organic contaminant sulfamethoxazole (SMX) from water. Both MOFs were found highly efficient for the adsorption of SMX with the maximum adsorption capacities of 585 and 690 mg/g for MOF-525 and MOF-545, respectively. The latter value is the highest adsorption capacity reported so far for the adsorption of SMX molecules on any adsorbent. The adsorption equilibrium could be modeled successfully by the Langmuir model, which showed close to matching with the experimental data. Their adsorption equilibriums were attained within 120 and 30 min for MOF-525 and MOF-545, respectively. MOF-545 with mesopores demonstrated superior adsorption kinetics to MOF-525 with micropores, and the simulation by the pseudo-second-order kinetic model indicated ca. 20 times faster adsorption by MOF-545 than MOF-525. Both showed pH-dependent adsorption of SMX with a gradual reduction at high pH due to the repulsion between negatively charged adsorbent and SMX. The adsorption of SMX conducted over a group of representative MOFs with different physicochemical properties and detailed characterization confirmed that the high adsorption capacity of the porphyrin MOFs is achieved by H-bonding between the SMX molecule and the N-sites of the porphyrin units in the MOFs, π-π interaction, and the high surface area. The adsorbents were easily regenerated by simple washing with acetone and reusable with >95% efficiency during 4 repeated adsorption-desorption cycles.