101084-17-7Relevant articles and documents
The Excited-State Triple Proton Transfer Reaction of 2,6-Diazaindoles and 2,6-Diazatryptophan in Aqueous Solution
Chung, Kun-You,Chen, Yi-Han,Chen, Yi-Ting,Hsu, Yen-Hao,Shen, Jiun-Yi,Chen, Chi-Lin,Chen, Yi-An,Chou, Pi-Tai
, p. 6396 - 6402 (2017)
3-Me-2,6-diazaindole ((2,6-aza)Ind) was strategically designed and synthesized to probe water molecule catalyzed excited-state proton transfer in aqueous solution. Upon electronic excitation (λmax ～ 300 nm), (2,6-aza)Ind undergoes N(1)-H to N(6) long-distance proton transfer in neutral H2O, resulting in normal (340 nm) and proton-transfer tautomer (480 nm) emissions with an overall quantum yield of 0.25. The rate of the water-catalyzed proton transfer shows a prominent H/D kinetic isotope effect, which is determined to be 8.3 × 108 s-1 and 4.7 × 108 s-1 in H2O and D2O, respectively. Proton inventory experiments indicate the involvement of two water molecules and three protons, which undergo a relay type of excited-state triple proton transfer (ESTPT) in a concerted, asynchronous manner. The results demonstrate for the first time the fundamental of triple proton transfer in pure water for azaindoles as well as pave a new avenue for 2,6-diazatryptophan, an analogue of tryptophan exhibiting a similar ESTPT property with (2,6-aza)Ind, to probe biowaters in proteins.
