The Cyclic Hydrogen-Bonded 6-Azaindole Trimer and its Prominent Excited-State Triple-Proton-Transfer Reaction
Journal
Angewandte Chemie (International ed. in English)
Date Issued
2018-04-23
Author(s)
Tu, Ting-Hsun
Chen, Yi-Ting
Chen, Yi-An
WEI-YU CHEN
Chen, You-Hua
Chen, Chi-Lin
Shen, Jiun-Yi
Chen, Yi-Han
Ho, Ssu-Yu
Cheng, Kum-Yi
Lee, Shern-Long
Abstract
The compound 6-azaindole undergoes self-assembly by formation of N(1)-H⋅⋅⋅N(6) hydrogen bonds (H bonds), forming a cyclic, triply H-bonded trimer. The formation phenomenon is visualized by scanning tunneling microscopy. Remarkably, the H-bonded trimer undergoes excited-state triple proton transfer (ESTPT), resulting in a proton-transfer tautomer emission maximized at 435 nm (325 nm of the normal emission) in cyclohexane. Computational approaches affirm the thermodynamically favorable H-bonded trimer formation and the associated ESTPT reaction. Thus, nearly half a century after Michael Kasha discovered the double H-bonded dimer of 7-azaindole and its associated excited-state double-proton-transfer reaction, the triply H-bonded trimer formation of 6-azaindole and its ESTPT reaction are demonstrated.
Subjects
H-bonded trimers; azaindole; excited-state triple proton transfer; hydrogen bonding; self-assembly
SDGs
Type
journal article