Double hydrogen bond mediating self-assembly structure of cyanides on metal surface

Cyanides with different numbers of –C≡N, 1,2,4,5-Tetracyanobenzene (TCNB) and 2,3-Dicyanonaphthalene (2,3-DCN) deposited on Ag(111) and Ag(110) surfaces, have been investigated by room temperature scanning tunneling microscopy (RTSTM), respectively. High resolution STM images show double hydrogen bond is the main driving force to form variety of self-assembly structures, indicating the double hydrogen bond affects the electron distribution of cyanides and leads to a more stable structure with lower energy. In addition, the difference between Ag(111) and Ag(110) surfaces in their lattice structure induces a bigger assembly structural change of 2,3-DCN than that of 1,2,4,5-TCNB, which confirms the fact that the opposite double hydrogen bond formation formed by 1,2,4,5-TCNB is more stable than the neighboring double hydrogen bond formation formed by molecule 2,3-DCN.