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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >A short hydrogen bond investigation by polarized Raman spectra of Co2+ and Zn2+ salts of pyromellitic acid
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A short hydrogen bond investigation by polarized Raman spectra of Co2+ and Zn2+ salts of pyromellitic acid

机译：均苯四酸的Co2 +和Zn2 +盐的极化拉曼光谱研究氢键

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摘要

Cobalt and zinc salts of 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), [C6H2(COO)(4)H-4], have been synthesized and investigate by polarized Raman spectroscopy. These compounds present short intramolecular hydrogen bonds (SHB) between adjacent carboxyl groups. Raman spectra indicate the presence of this interaction in both salts. Three specific vibrational of SHB modes have been investigated: O-H-O symmetric [v(sym)(OHO)] and asymmetric [v(asym)(OHO)] stretching modes and O-H stretching mode [v(O-H)], which they were observed around 300, 850 and 2500 cm(-1), respectively. In crystallographic point of view, the cobalt salt presents a symmetric SHB while the zinc salt presents an asymmetric SHB. In cobalt salt all three vibrational modes of O-H-O groups in polarized Raman spectra occur in Ag orientation although in zinc salts two of them are observed in Ag orientation and one in Bg. Spectra analysis indicate that vsym(OHO) mode is observed as Ag to cobalt salt and Bg to zinc salt. This mode occurs in a crowed spectral region and its identification was made by deconvolution techniques. Comparing spectra of the two salts, it is observed a small difference in relative intensity and wavenumber shift of vsym(OHO) (deviance of 43 cm(-1)) and v(OH) (deviance of 21 cm(-1)) modes due probably to differences in O center dot center dot center dot O distance between salts and in orientation of pyromellitate anion in unit cell. The v(asym)(OHO) mode does not present significant wavenumber shift due difference in SHB. The v(OH) band presents a great potential for hydrogen bond studies due to the fact that in its vibrational region (around 2500 cm-1) it is not observed other vibrational modes of these compounds. (C) 2006 Elsevier B.V. All rights reserved.
机译：合成了1,2,4,5-苯四甲酸（均苯四酸）的钴盐和锌盐[C6H2（COO）（4）H-4]，并通过偏振拉曼光谱研究。这些化合物在相邻的羧基之间具有短的分子内氢键（SHB）。拉曼光谱表明两种盐中都存在这种相互作用。 SHB模式的三种特定振动已被研究：OHO对称[v（sym）（OHO）]和非对称[v（asym）（OHO）]拉伸模式和OH拉伸模式[v（OH）]，它们在附近观察到300、850和2500 cm（-1）。从晶体学的观点来看，钴盐呈现出对称的SHB，而锌盐呈现出不对称的SHB。在钴盐中，极化拉曼光谱中O-H-O基团的所有三种振动模式均在Ag取向上发生，尽管在锌盐中，在Ag取向中观察到其中两个在Bg中发生。光谱分析表明，从Ag到钴盐和从Bg到锌盐观察到vsym（OHO）模式。这种模式发生在一个拥挤的光谱区域，其识别是通过反卷积技术进行的。比较这两种盐的光谱，可以观察到vsym（OHO）（距离为43 cm（-1））和v（OH）（距离为21 cm（-1））模式的相对强度和波数移位存在微小差异可能是由于盐之间的O中心点中心点中心点O的距离以及晶胞中均苯四酸根阴离子的取向不同。由于SHB的差异，v（asym）（OHO）模式没有出现明显的波数偏移。 v（OH）谱带具有很大的氢键研究潜力，因为在其振动区域（约2500 cm-1）没有观察到这些化合物的其他振动模式。 （C）2006 Elsevier B.V.保留所有权利。

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