Figure 1
From: Theoretical study on the polar hydrogen-π (Hp-π) interactions between protein side chains
The Hp-π interaction structures and HOMOs of three small interaction pairs. (A) Structure of Hp-π interaction pair CH3OH-H2CO. The polar hydrogen atom of CH3OH points to the carbon atom of H2CO perpendicularly. (B) The HOMO of Hp-π interaction pair CH3OH-H2CO. The polar hydrogen atom is in close touching with the π-orbital of H2CO. (C) Structure of Hp-π interaction pair NMA-C2H4. The polar hydrogen atom of NMA (n-methyl acetamide) points to the center of double bond. (D) The HOMO of Hp-π interaction pair NMA-C2H4. (E) Structure of Hp-π interaction pair CH3OH-C2H4. The polar hydrogen atom of CH3OH points to the center of double bond perpendicularly. (F) The HOMO of Hp-π interaction pair CH3OH-C2H4. The ghost hydrogen atom H-Bq is attached to the polar hydrogen atoms, and the distance to polar hydrogen is 0.90 Å.