Schulke Simon, Nolten Melinda, Schwaab Gerhard, Havenith Martina
Physical Chemistry 2, Ruhr-Univeristy Bochum, Universitaetsstraße 150, 44801, Bochum, Germany.
Chemphyschem. 2024 Jan 2;25(1):e202300389. doi: 10.1002/cphc.202300389. Epub 2023 Nov 30.
In a previous study we could show that a large amplitude mode of the zwitterion glycine can serve as a sensitive probe for protonation and allows to deduce local pK values. Here we show that the underlying concept is more general: We present the results of a pH dependent measurement of Terahertz-FTIR (THz-FTIR) spectra of solvated amines, i. e. Diethylamine (DEA), Triethylamine (TEA), and Diisopropylamine (DiPA). We show that amines serve as a sensitive, label free probe for local protonation. Protonation of the amines yield intensity changes which can be quantified by precise THz spectroscopy (30 cm -450 cm ). A detailed analysis allows us to correlate the titration spectra of solvated amines in the THz range with pK values. This demonstrates the potential of THz spectroscopy to probe the charge state of biomolecules in water in a label free manner.
在之前的一项研究中，我们能够证明两性离子甘氨酸的一种大幅度模式可作为质子化的灵敏探针，并能据此推断局部pK值。在此我们表明，其基本概念更为通用：我们展示了对溶剂化胺（即二乙胺（DEA）、三乙胺（TEA）和二异丙胺（DiPA））的太赫兹傅里叶变换红外光谱（THz-FTIR）进行pH依赖性测量的结果。我们表明，胺可作为局部质子化的灵敏、无标记探针。胺的质子化会产生强度变化，可通过精确的太赫兹光谱（30 cm - 450 cm）对其进行量化。详细分析使我们能够将太赫兹范围内溶剂化胺的滴定光谱与pK值相关联。这证明了太赫兹光谱以无标记方式探测水中生物分子电荷状态的潜力。
