Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
Phys Chem Chem Phys. 2018 Oct 31;20(42):27131-27139. doi: 10.1039/c8cp03835j.
The double excited state intramolecular proton transfer (ESIPT) of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole (bis-HPTA), a molecule possessing two intramolecular hydrogen bonded donor-acceptor pairs, has been investigated. The molecule undergoes not only a single ESIPT, but also a rare twin ESIPT. The most interesting fact is that initially, only one acid-base pair is ESIPT active and the other pair is ESIPT inactive. The first proton transfer triggers the proton transfer in the second acid-base pair by creating appropriate conditions. This new type of sequential proton transfer is labeled as 'proton transfer triggered proton transfer' (PTTPT). The PTTPT has been demonstrated by steady state and time resolved fluorescence techniques. It was further substantiated by theoretical data and using a chemically modified system 3-(2-hydroxyphenyl)-5-(2-methoxyphenyl)-1H-1,2,4-triazole.
3,5-双(2-羟基苯基)-1H-1,2,4-三唑（双-HPTA）分子具有两个分子内氢键供体-受体对，其双激发态分子内质子转移（ESIPT）已被研究。该分子不仅经历了单一的 ESIPT，还经历了罕见的双 ESIPT。最有趣的事实是，最初只有一个酸碱对是 ESIPT 活性的，而另一个酸碱对是非 ESIPT 活性的。第一个质子转移通过创造适当的条件触发第二个酸碱对中的质子转移。这种新类型的顺序质子转移被标记为“质子转移触发质子转移”（PTTPT）。通过稳态和时间分辨荧光技术证明了 PTTPT。通过理论数据和使用化学修饰的系统 3-(2-羟基苯基)-5-(2-甲氧基苯基)-1H-1,2,4-三唑进一步证实了这一点。
