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Impact of donor acidity and acceptor anharmonicity on vc=o spectral shifts in O-H···O=C H-bonded ketone-alcohol complexes: An IR spectroscopic investigation.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy ( IF 4.4 ) Pub Date : 2020-01-16 , DOI: 10.1016/j.saa.2020.118070
Binod Kumar Oram 1 , Monu 1 , Biman Bandyopadhyay 1
Affiliation  

O-H···O=C Hydrogen bonding (H-bonding) results in spectral shifts in both νO-H and νC=O modes. A large number of investigations exist in literature that focuses on how the spectral shifts vary with certain properties of the donors and acceptors. However information on how the magnitude of spectral shift is dictated individually by the donor and acceptor is not yet clear to us. Here, IR spectroscopy in room temperature CCl4 solution has been used to investigate how νC=O spectral shifts of ketones in H-bonded complexes with alcohols are influenced by change in donor and acceptor properties. For this purpose 25 number of O-H···O=C H-bonded complexes formed by 5 different ketones and 5 alcohols have been studied. The magnitude of red-shifts shown by the νC=O bands were found to show systematic trends with changing donor and acceptor species. It was found that for a particular ketone, the magnitude of shift increases monotonically with acidity of the alcohols. Spectral shifts were found to increase in a linear fashion with decreasing pKa of the donor alcohols. On the other hand, when the alcohol were kept fixed, the spectral shift was found to be dependent on the CO bond strength of the ketones. We found spectral shifts to linearly increase with increasing anharmonicity constant and decreasing dissociation energy of CO bond. Finally, it has been shown that there exist concomitant correlations of the spectral shifts with donor pKa and acceptor νC=O anharmonicity constant/bond dissociation energy. The relations have been validated for H-bonded complexes of 1,4-cyclohexanedione with the above mentioned five alcohols.

中文翻译:

供体酸度和受体非谐性对OH··O = C H键合的酮-醇络合物中vc = o光谱位移的影响:红外光谱研究。

OH··O = C氢键(H键)导致νO-H和νC= O模式的光谱偏移。文献中有大量研究集中在光谱位移如何随供体和受体的某些特性而变化。但是,我们尚不清楚有关供体和受体如何分别规定光谱位移幅度的信息。在这里,室温CCl4溶液中的IR光谱已被用于研究H与醇键合的配合物中酮的νC= O光谱位移如何受供体和受体性质变化的影响。为此,已经研究了由5种不同的酮和5种醇形成的25种OH··O = C H键合的配合物。发现由νC= O波段显示的红移幅度显示出随着供体和受体种类的变化而出现的系统趋势。已经发现,对于特定的酮,位移的幅度随醇的酸度单调增加。发现光谱变化随着供体醇的pKa降低而线性增加。另一方面,当将醇保持固定时,发现光谱位移取决于酮的CO键强度。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。位移的幅度随醇的酸度单调增加。发现光谱变化随着供体醇的pKa降低而线性增加。另一方面,当将醇保持固定时,发现光谱位移取决于酮的CO键强度。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。位移的幅度随醇的酸度单调增加。发现光谱变化随着供体醇的pKa降低而线性增加。另一方面,当将醇保持固定时,发现光谱位移取决于酮的CO键强度。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。发现光谱变化随着供体醇的pKa降低而线性增加。另一方面,当将醇保持固定时,发现光谱位移取决于酮的CO键强度。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。发现光谱变化随着供体醇的pKa降低而线性增加。另一方面,当将醇保持固定时,发现光谱位移取决于酮的CO键强度。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。我们发现,随着非谐常数的增加和CO键离解能的降低,光谱位移呈线性增加。最后,已经表明,光谱位移与施主pKa和受体vC = O非调和常数/键解离能同时存在相关性。对于1,4-环己二酮与上述五种醇的H-键合的配合物,已经验证了该关系。
更新日期:2020-01-17
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