基于偶氮桥连卟啉的共轭微孔聚合物的制备及其表征

Azo-bridged porphyrin-based conjugated microporouspolymer:synthesis and gases storage properties

以卟啉作为基本构筑单元,通过偶氮键的链接制备得到基于偶氮链接卟啉的共轭微孔聚合物。通过红外(FT-IR)表征,偶氮键(—NN—)的特征吸收峰(1 597cm-1)证明该材料中大量偶氮键的生成。利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对其形貌进行分析,发现该材料表面粗糙且具有很明显的孔结构。热重分析(TGA)表明其在N2中具有很好的热稳定性(195℃失重5%)。利用N2、CO2和H2对该材料进行气体吸脱附实验,结果显示该材料的比表面积达到571m2/g;CO2吸附量可达94.2mg/g(273K);H2吸附量可达8.6mg/g(77K)。CO2和H2的吸附焓(ΔH)经计算分别达到37和7kJ/mol。

A novel conj ugated microporous polymer (Azo-1 )based on porphyrin block and azo (-N -N-) bridge was successfully synthesized by potassium hydroxide assisted nitrogen-nitrogen coupling reaction.The new prepared materials Azo-1 was characterized by Fourier transform infrared spectroscopy (FT-IR),scanning electron microscopy (SEM),transmission electron microscopy (TEM),thermogravimetric analysis (TGA). Besides,the surface area of Azo-1 was measured by N2 sorption/desorption at 77 K.CO2 (273 and 298 K)and H2 (77 K and 87 K)physisorption properties at different temperatures were also studied to further look into the gases storage properties of Azo-1 .FT-IR spectroscopy was useful for probing the structure of such kind of in-soluble networks.The peak at 1 5 9 7 cm-1 in the FT-IR spectrum indicates that there are plenty of azo bonds in this material.The SEM image of Azo-1 exhibits a typical amorphous morphology.Simultaneously,the enlarged TEM image of Azo-1 shows obvious porous structure.The thermal stability of Azo-1 was analyzed by TGA un-der nitrogen flow.This material shows its onset weight loss (about 5% weight loss)at 1 9 5 ℃,which suggests that this material possesses high thermal stability.The N2 sorption isotherms were measured at 77 K to charac-terize the porosity of this network.The specific BET surface area of Azo-1 was high up to 5 7 1 m2/g.The calcu-lated pore size distribution based on non-local density functional theory (NL-DFT)indicates that Azo-1 has two very narrow pores at 1.6 and 4.0 nm.Besides,the CO2 uptake of Azo-1 under 273 K was up to 94.2 mg/g,and the H2 uptake under 77 K was up to 8.6 mg/g.Based on the CO2 and H2 sorption/desorption isotherms,the isosteric heat for adsorption of CO2 and H2 was calculated as high as 37 and 7 kJ/mol,respectively.