Synthesizing Cr‐Based Two‐Dimensional Conjugated Metal‐Organic Framework Through On‐Surface Substitution Reaction
Weiliang Zhong, Tingfeng Zhang, Dan Chen, Nuoyu Su, Guangyao Miao, Jiandong Guo, Long Chen, Zhengfei Wang, Weihua Wang
Abstract
Abstract A single‐layer Cr 3 (HITP) 2 (HITP = 2,3,6,7,10,11‐hexaiminotriphenylene) conjugated metal‐organic framework ( c ‐MOF) is synthesized under ultrahigh vacuum conditions by substituting Cr for Ni in Ni 3 (HITP) 2 template. As revealed by low‐temperature scanning tunneling microscopy and scanning tunneling spectroscopy, while codeposition of Cr atoms and 2,3,6,7,10,11‐hexaaminotriphenylene precursors produces irregular branches, crystalline Cr 3 (HITP) 2 frameworks are obtained by depositing Cr atoms to the Ni 3 (HITP) 2 templates. The density functional theory calculations reveal that the binding energy between Cr and HITP ligands is much higher than that for Ni, which hampers the growth of crystalline Cr 3 (HITP) 2 frameworks through direct coordination assembly but makes the substitution reaction energetically favorable. This work demonstrates a new strategy to prepare high‐quality early‐transition‐metal‐based c ‐MOFs under ultrahigh vacuum conditions.