Single-Molecule Investigations of Conformation Adaptation of Porphyrins on Surfaces

• Published in: The journal of physical chemistry letters Vol. 8; no. 6; pp. 1241 - 1247
• Main Authors: Zhang, Qiushi, Zheng, Xiaoyan, Kuang, Guowen, Wang, Weihua, Zhu, Lizhe, Pang, Rui, Shi, Xingqiang, Shang, Xuesong, Huang, Xuhui, Liu, Pei Nian, Lin, Nian
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16.03.2017
• Subjects: Adsorption; Microscopy, Scanning Tunneling; Models, Molecular; Molecular Conformation; Nanotechnology; Porphyrins - chemistry; Surface Properties
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.7b00007

The porphyrin macrocyclic core features dynamic conformational transformations in free space because of its structural flexibility. Once attached to a substrate, the molecule–substrate interaction often restricts this flexibility and stabilizes the porphyrin in a specific conformation. Here using molecular dynamic and density-functional theory simulations and scanning tunneling microscopy and spectroscopy, we investigated the conformation relaxation and stabilization processes of two porphyrin derivatives (5,15-dibromophenyl-10,20-diphenylporphyrin, Br2TPP, and 5,15-diphenylporphyrin, DPP) adsorbed on Au(111) and Pb(111) surfaces. We found that Br2TPP adopts either dome or saddle conformations on Au(111) but only the saddle conformation on Pb(111), whereas DPP deforms to a ruffled conformation on Au(111). We also resolved the structural transformation pathway of Br2TPP from the free-space conformations to the surface-anchored conformations. These findings provide unprecedented insights revealing the conformation adaptation process. We anticipate that our results may be useful for controlling the conformation of surface-anchored porphyrin molecules.