@article{Wu2021, 
author = {Rongting Wu and De-Liang Bao and Linghao Yan and Junhai Ren and Yanfang Zhang and Qi Zheng and Ye-Liang Wang and Qing Huan and Shixuan Du and Hong-Jun Gao},
title = {Construction of poly-naphthalocyanine linked by [4]-radialene-like structures on silver surfaces},
year = {2021},
journal = {Nano Research},
volume = {14},
number = {12},
pages = {4563-4568},
keywords = {density functional theory calculation, polymerization, scanning tunneling microscope, naphthalocyanine, π-interaction extension},
url = {https://www.sciopen.com/article/10.1007/s12274-021-3374-3},
doi = {10.1007/s12274-021-3374-3},
abstract = {Cyclic-conjugated linkages between planar-macrocyclic molecules contribute to the robustness of the two-dimensional (2D) polymerization and extension of π-interactions. The fabrication of such linkages in 2D polymers remains challenging. Combining scanning tunneling microscope (STM) measurements and density functional theory (DFT) calculations, we demonstrate a linear polymerization of metal-free naphthalocyanine (NPc) molecules with [4]-radialene-like linkages on silver surfaces. Experimentally, by depositing NPc molecules on the Ag(110) surface and subsequent annealing up to 750 K, one-dimensional polymers are constructed along the [11(_)0] direction. High-resolution STM images show a stem-leaf-like feature. STM simulations based on a linear polymer of NPc molecules linked by four-membered carbon rings, [4]-radialene-like structure, agree well with the experimental observations. DFT calculations reveal that the polymerization process includes detaching two-terminal H atoms of NPc molecules along [11(_)0] direction, then bonding with a neighboring dehydrogenated NPc molecule by forming a four-membered ring. The dehydrogenation process can be promoted by on-surface impurities such as additional H atoms. Similar polymerizations have been achieved on Ag(111) surfaces in an amorphous way. Moreover, the energy gap of the NPc molecule decreases after linear polymerization, suggesting a red-shift for its optical absorption/scattering spectrum. Our study offers a new route to polymerize conjugated molecules with extended planar π-interactions.}
}