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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >Low-temperature FTIR spectra and hydrogen bonds in polycrystalline adenosine and uridine
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Low-temperature FTIR spectra and hydrogen bonds in polycrystalline adenosine and uridine

机译：多晶腺苷和尿苷的低温FTIR光谱和氢键

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摘要

FTIR spectra of polycrystalline samples of adenosine and uridine, pure and containing small (<10%) quantity of N(O)H or N(O)D groups, were measured in KBr pellets from 4000 to 400 cm(-1) at temperatures from 300 to 20 K. For the first time, the bands of narrow isotopically decoupled proton stretching vibration v, mode of NH- and OH- groups were found and assigned to ordered hydrogen bonds according to crystal structural data for both nucleosides. The FTIR adenosine spectra in the out-of-plane bending proton v(4) mode range (lower than 1000 cm(-1)) of N(O)H groups revealed at low temperature at least twice more bands, than in the v I range, which are influenced by isotopic exchange and (or) cooling. Almost all of them have their counterparts in the N(O)D substance spectrum with an isotopic frequency ratio of 1.30-1.40. These bands were assigned to the differently H-bound disordered NH and OH protons, which could not be seen with crystal structural methods. The energy and length of different H-bonds were estimated from peak positions of both mode bands (as the red shift of v, or blue shift of v(4) relatively free molecules) with well-established empirical correlations between spectral, thermodynamic and structural parameters of hydrogen bonds. The results were compared with independent experimental data. (C) 2004 Elsevier B.V. All rights reserved.
机译：在温度为4000至400 cm（-1）的KBr颗粒中测量了纯净且含有少量（<10％）N（O）H或N（O）D基团的腺苷和尿苷多晶样品的FTIR光谱从300到20K。首次发现窄的同位素解耦质子拉伸振动带v，NH-和OH-的模式，并根据两个核苷的晶体结构数据分配给有序的氢键。 N（O）H基团的面外弯曲质子v（4）模式范围（低于1000 cm（-1））的FTIR腺苷光谱在低温下显示的谱带比v至少多两倍I范围受同位素交换和（或）冷却的影响。它们几乎都在N（O）D物质光谱中具有对应物，其同位素频率比为1.30-1.40。这些条带被分配给不同的H结合的无序NH和OH质子，这在晶体结构方法中是看不到的。根据两个模态带的峰值位置（作为v的红移或v（4）相对自由的分子的蓝移）估算不同H键的能量和长度，并在光谱，热力学和结构之间建立起经验相关氢键的参数。将结果与独立实验数据进行比较。 （C）2004 Elsevier B.V.保留所有权利。

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