Stegmann Niklas, Dai Yitao, Nürenberg Edward, Schmidt Wolfgang
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim a.d. Ruhr, Germany.
Inorg Chem. 2021 Dec 20;60(24):18957-18963. doi: 10.1021/acs.inorgchem.1c02769. Epub 2021 Dec 2.
Herein, we present a novel bottom-up preparation route for heptazine-based polymers (melon), also known as graphitic carbon nitride. The growth characteristics of isolated 1D melon strings in microporous templates are presented and studied in detail. Removal of the microporous silicate template via etching is accompanied by the self-assembly of a 1D melon to stacked 3D structures. The advantages and limitations of the bottom-up approach are shown by using microporous templates with different pore sizes (ETS-10, ZSM-5, and zeolite Y). In accordance with the molecular size of the heptazine units (0.67 nm), a 1D melon can be deposited in ETS-10 with a pore width of about 0.78 nm, whereas its formation in the smaller 0.47 nm pores of ZSM-5 is sterically impeded. The self-assembly of isolated 1D melon to stacked 3D structures offers a novel experimental perspective to the controversial debate on the polymerization degree in 2D sheets of graphitic carbon nitride as micropore sizes below 1 nm confine the condensation degree of heptazine to isolated 1D strands at a molecular level. The growth characteristics and structural features were investigated by X-ray diffraction, N physisorption, scanning transmission electron microscopy/energy-dispersive X-ray analysis, C CP-NMR spectroscopy, and attenuated total reflection-infrared spectroscopy.
在此，我们展示了一种用于制备基于七嗪的聚合物（蜜勒胺）的新型自下而上的制备路线，蜜勒胺也被称为石墨相氮化碳。详细介绍并研究了微孔模板中孤立的一维蜜勒胺链的生长特性。通过蚀刻去除微孔硅酸盐模板的同时，一维蜜勒胺会自组装成堆叠的三维结构。使用不同孔径的微孔模板（ETS-10、ZSM-5和Y型沸石）展示了自下而上方法的优点和局限性。根据七嗪单元的分子大小（0.67纳米），一维蜜勒胺可以沉积在孔径约为0.78纳米的ETS-10中，而在孔径较小的0.47纳米的ZSM-5中，其形成受到空间位阻的阻碍。孤立的一维蜜勒胺自组装成堆叠的三维结构，为关于石墨相氮化碳二维片层聚合度的争议性辩论提供了一个新的实验视角，因为小于1纳米的微孔尺寸在分子水平上将七嗪的缩合程度限制为孤立的一维链。通过X射线衍射、N物理吸附、扫描透射电子显微镜/能量色散X射线分析、C CP-NMR光谱和衰减全反射红外光谱研究了生长特性和结构特征。
