Constructing novel hyper-crosslinked conjugated polymers through molecular expansion for enhanced gas adsorption performance.

The porous organic polymers have been considered as effective materials for gas storage and adsorption. Herein, we synthesized highly crystalline nitrogen-rich covalent triazine frameworks (CTFs) by polycondensation for preparing the novel hyper-cross-linked conjugated polymers (HCCPs) with tunable specific surface area and pore volume through coupling Friedel-Crafts reaction, in which 1,4-Bis(chloromethyl)benzene and 4,4-Bis(chloromethyl)biphenyl as the expansion molecules were pillared between the layers of CTF-HUST. This technology not only increased the specific surface area and total pore volume of CTF-HUST by 2.56 and 4.68 times, but also greatly enhanced the utilization of adsorption sites of CTF-HUST. The HCCP2-1.25 exhibited the highest surface area (1349.29 m2g-1) among these HCCPs and demonstrated excellent adsorption performance for ethyl acetate (1605.14 mg/g), ethanol (1371.49 mg/g), 1,2-Dichloroethane (1971.68 mg/g), benzene (1151.77 mg/g) and toluene (1024.28 mg/g) due to the multiple C-H…O, C-H…Cl, O-H…N and C-H…π interactions between volatile organic compounds (VOCs) and HCCPs framework. Moreover, CO2 and H2 storage capacities of the HCCP2-1.25 were 8.02 wt% and 1.54 wt%, 1.66 and 1.67 times higher than CTF-HUST, respectively. This study developed a simple and effective molecular expansion strategy to synthesize a series of novel high-surface-area porous polymers for potential applications in the environmental field.

Two pure MOF-photocatalysts readily prepared for the degradation of methylene blue dye under visible light.

Two 3D metal-organic frameworks (MOFs) with different structures, [Cu(4,4'-bipy)Cl]n (1) and [Co(4,4'-bipy)·(HCOO)2]n (2), were synthesized by means of a hydrothermal method using a typical ligand (4,4'-bipyridine), and characterized by elemental analyses, thermal analyses and single crystal X-ray diffraction. As MOF materials, the two complexes showed active performance for the photodegradation of methylene blue (MB) dye under visible light. MB degradation over the two MOF-based photocatalysts follows first-order kinetics. The addition of an H2O2 electron acceptor can markedly enhance the photocatalytic MB degradation performance via a ligand-to-metal charge transfer mechanism, especially in complex 1. Complex 1 is better than complex 2 in MB photodegradation performance under the same conditions. Moreover, complex 1 showed a stable activity for MB degradation after four consecutive usages. Owing to the advantages of the visible light response, stable structure, low cost and high yield, these MOF-based photocatalysts will facilitate new efforts in environmental purification.