Effect of amino group protonation on the carboxyl group in aqueous glycine observed by O 1s X-ray emission spectroscopy

被引：12

作者：

Horikawa, Y. ^{[1
]}

Tokushima, T. ^{[1
]}

Takahashi, O. ^{[2
]}

Harada, Y. ^{[3
,4
]}

Hiraya, A. ^{[5
]}

Shin, S. ^{[3
]}

机构：

[1] RIKEN SPring 8 Ctr, Kouto, Hyogo 6795148, Japan

[2] Hiroshima Univ, Grad Sch Sci, Dept Chem, Higashihiroshima, Hiroshima 7398526, Japan

[3] Univ Tokyo, Inst Solid State Phys, Kashiwa, Chiba 2778581, Japan

[4] Univ Tokyo, Synchrotron Radiat Res Org, Koto Ku, Shingu Cho, Tatsuno, Hyogo 6795165, Japan

[5] Hiroshima Univ, Dept Phys Sci, Higashihiroshima, Hiroshima 7398526, Japan

来源：

PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 2018年 / 20卷 / 36期

基金：

日本学术振兴会;

关键词：

ELECTRONIC-STRUCTURE; LIQUID WATER; ABSORPTION; SCATTERING; BEAMLINE; ACIDS;

D O I：

10.1039/c7cp08305j

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The valence electronic structures of the amino acid glycine in aqueous solution were investigated in detail through X-ray emission spectroscopy at O 1s excitation under selective excitation conditions of the C=O site in the carboxyl group. The X-ray emission spectra of glycine were similar to that of acetic acid (CH3COOH), suggesting a resemblance between the molecular orbitals associated with the carboxyl groups in the two molecules. The changes of O 1s X-ray emission spectra as a function of pH were investigated in detail. In addition to spectral changes due to protonation/deprotonation of the carboxyl group for lower pH-values around the pK(a) value (similar to 2.3), the spectra of glycine exhibited further changes in the higher-pH region near the pK(b) value of glycine (dissociation constant of amino group similar to 9.5). These results show the effects of amino group protonation on the electronic state around the carboxyl group. X-ray emission spectroscopy might be a tool to investigate intramolecular interactions between functional groups in a molecule.

引用

页码：23214 / 23221

页数：8

共 31 条

[1]

[Anonymous], ANGEW CHEM

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