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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >New infrared spectra and the tautomeric studies of purine and #alpha#L-alanine with an innovative sampling technique
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New infrared spectra and the tautomeric studies of purine and #alpha#L-alanine with an innovative sampling technique

机译：新的红外光谱和嘌呤和＃alpha＃L-丙氨酸的互变异构研究，采用创新的采样技术

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摘要

New infrared spectra of purine and #alpha#L-alanine in the mid-IR range (400-4000 cm~-1) were obtained with an innovative infrared sampling technique. The technique was directed at maximizing the separation of solid sample molecules at room temperature through a procedure of dissolution, spray, and deposition. The notoriously broad and overlapped bands inthe region 2500-3300 cm~-1, which are characteristic of the KBr pellet spectra of amino acids and nucleic acid bases, are now absent in all our new spectra. The spectra obtained from neutral and acidic aqueous solutions are different. For purine, these spectral differences are interpreted in terms of the existence of N(7)H or N(9)H tautomers; For alanine, the differences are ascribed to its two different structures, zwitterion and un-ionized neutral. It was found that with this new method, better resolved IR spectra of purine and alanine were obtained at room temperature. Furthermore, for the first time, a spectrum of zwitterionic alanine of largely monomeric form in the complete mid-IR range was obtained. IR spectra were predicted from self consistent reaction field (SCRF) molecular orbital calculations at the HF/6-311 + + G(d,p) level. The SCRF calculations were for purine and alanine present in a KBr continuum. Good agreement was found between the observed and calculated spectra.
机译：利用创新的红外采样技术，获得了中红外范围（400-4000 cm〜-1）的嘌呤和＃alpha＃L-丙氨酸的新红外光谱。该技术旨在通过溶解，喷雾和沉积过程在室温下最大程度地分离固体样品分子。现在，在我们所有的新光谱中都没有出现2500-3300 cm-1区域中众所周知的宽带和重叠带，这些带是氨基酸和核酸碱基的KBr沉淀光谱的特征。从中性和酸性水溶液获得的光谱不同。对于嘌呤，这些光谱差异是根据N（7）H或N（9）H互变异构体的存在来解释的。对于丙氨酸，差异归因于其两个不同的结构，两性离子和未电离的中性。发现使用这种新方法，在室温下可获得更好的分辨嘌呤和丙氨酸的红外光谱。此外，首次获得了完整的中红外范围内主要为单体形式的两性离子丙氨酸的光谱。红外光谱是通过自洽反应场（SCRF）分子轨道计算在HF / 6-311 + + G（d，p）水平预测的。 SCRF计算是针对KBr连续体中存在的嘌呤和丙氨酸。在观察到的光谱和计算的光谱之间发现了很好的一致性。

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