乙酸水溶液pH对CuBDC形貌和结构可逆性转变的影响

Effect of pH of acetic acid solution on the reversible transformation of CuBDC morphology and structure

以Cu^(2+)为金属离子,对苯二甲酸(BDC)为配体,利用简便的滴加法合成了二维纳米片状铜基金属有机骨架(CuBDC),将CuBDC分别浸泡在pH梯度变化的乙酸水溶液中,合适的酸度值会促使CuBDC晶体发生溶解,然后重结晶生成另一种棒状形貌金属有机骨架(CuBDC-T),实现了CuBDC形貌和结构的转变。通过扫描电子显微镜、傅里叶变换红外光谱仪、X射线衍射仪等表征手段对2种材料的组分、结构、形貌及转变过程进行了研究;通过CO_(2)环加成反应研究了2种材料的催化反应活性。结果表明:2种材料形貌的差异可能是晶体的成核速率和生长速率不同导致;反应时间达到4h时,在CuBDC作用下环状碳酸酯产物的产率达到62%,相较于棒状CuBDC-T,CuBDC纳米片显示出更好的催化性能。

Two-dimensional nanosheets copper-based metal-organic framework(CuBDC)was synthesized by a simple distribution droplets method using Cu^(2+)as the metal ion and terephthalic acid(BDC)as the ligand.The CuBDC was immersed into acetic aqueous solutions with pH gradient respectively,and the appropriate acidity value promoted the dissolution and recrystallization process of the CuBDC crystal and thus produced another rod-shaped MOF(CuBDC-T),achieving morphology and structure invertible transformation of CuBDC.The composition,structure and morphology and the transformation process of two materials were studied by scanning electron microscope,Fourier transform infrared spectrometer,X-ray diffractometer and other characterization methods.The catalytic reaction activities of the two materials were investigated by CO_(2)cycloaddition reaction.The results showed that the difference of morphology between the two materials might be caused by the difference of nucleation rates and growth rates of the crystals.The yield of cyclic carbonate product reached 62%under the action of CuBDC at the reaction time of 4h.CuBDC nanosheets exhibited better catalytic performance compared with the rod-shaped CuBDC-T.