Zenobi María C, Luengo Carina V, Avena Marcelo J, Rueda Elsa H
Departamento de Química, Universidad Nacional del Sur, Avda. Alem 1253, (B8000CPB) Bahía Blanca, Argentina.
Spectrochim Acta A Mol Biomol Spectrosc. 2008 Jul;70(2):270-6. doi: 10.1016/j.saa.2007.07.043. Epub 2007 Aug 2.
An ATR-FIR study of the vibrational spectra of 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP) and N,N-bis(2-hydroxyethyl)aminomethylphosphonic acid (BHAMP) in aqueous solution is presented. The study was performed in the range of pH from 5 to 9, and bands assignments are given in the 2000-890 cm(-1) range. However, as phosphonates display bands due to the PO stretching vibration mainly in the 900-1200 cm(-1) range, the study is focused in this midinfrared region, which shows important changes as the pH changes, specially the nu(POH) at approximately 925 cm(-1) and nu(PO(3)(2-)) at approximately 970 cm(-1) vibrations. IR analyses give also evidences for the zwitterionic nature of BHAMP and NTMP in solution with a strong indication that the zwitterion in both compounds remains intact throughout the pH range investigated. The successive protonation steps with the decrease of pH were evidenced in the IR spectra of the three studied phosphonates.
本文介绍了在水溶液中对1-羟基乙烷-1,1'-二膦酸（HEDP）、次氮基三（亚甲基膦酸）（NTMP）和N,N-双（2-羟乙基）氨甲基膦酸（BHAMP）的振动光谱进行的衰减全反射傅里叶变换红外光谱（ATR-FIR）研究。该研究在pH值为5至9的范围内进行，并给出了2000 - 890 cm⁻¹范围内的谱带归属。然而，由于膦酸盐主要在900 - 1200 cm⁻¹范围内出现因PO伸缩振动产生的谱带，本研究聚焦于这个中红外区域，该区域随pH变化显示出重要变化，特别是在约925 cm⁻¹处的ν(POH)和约970 cm⁻¹处的ν(PO₃²⁻)振动。红外分析还为溶液中BHAMP和NTMP的两性离子性质提供了证据，有力表明这两种化合物中的两性离子在整个研究的pH范围内保持完整。在三种研究的膦酸盐的红外光谱中证实了随着pH降低的连续质子化步骤。
