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首页> 外文期刊>Environmental toxicology and chemistry >Noncovalent interactions between aromatic compounds and dissolved humic acid examined by nuclear magnetic resonance spectroscopy.
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Noncovalent interactions between aromatic compounds and dissolved humic acid examined by nuclear magnetic resonance spectroscopy.

机译：核磁共振波谱研究了芳香族化合物与溶解的腐殖酸之间的非共价相互作用。

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摘要

We examined the molecular-level interactions of aromatic compounds with a humic acid that was extensively characterized with one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy. Interactions of target compounds were evaluated by monitoring their NMR relaxation properties. Solid-state NMR revealed that the humic sample contains paraffinic carbon (31%), substituted aliphatic carbon (30%), and aromatic carbon (28%). The liquid-state experiments further identified amino acids, a range of carbohydrates, methoxylated aromatics (likely derived from lignin), and a series of aliphatic chains. The 13C spin-lattice relaxation time (T1) of site-specifically labeled naphthalene, 1-naphthol, and quinoline was found to decrease with increasing additions of humic acid. The 1H T1 values also were measured and demonstrated that the association with the humic acid was not specific because all the protons acquired the T1 value of the humic acid at the same rate. The lack of a chemical shift change and an increase in signal line broadening indicates that the interaction between these compounds and humic acid is noncovalent. These interactions were detected at low humic concentrations (5 mg C/L) and suggest that low concentrations of humic material, which are prevalent in both aquatic and terrestrial systems, will significantly affect the fate and transport of contaminants in the environment.
机译：我们检查了芳香族化合物与腐殖酸的分子水平相互作用，腐殖酸通过一维和二维核磁共振（NMR）光谱得到了广泛的表征。通过监测其NMR弛豫特性来评估目标化合物的相互作用。固态NMR显示腐殖质样品包含链烷烃碳（31％），取代脂肪族碳（30％）和芳族碳（28％）。液态实验进一步确定了氨基酸，一系列碳水化合物，甲氧基化的芳族化合物（可能源自木质素）和一系列脂族链。研究发现，随着腐殖酸添加量的增加，位点特异性标记的萘，1-萘酚和喹啉的13C自旋晶格弛豫时间（T1）降低。还测量了1H T1值，表明与腐植酸的缔合不是特异性的，因为所有质子均以相同的速率获得了腐殖酸的T1值。缺乏化学位移变化和信号线展宽的增加表明这些化合物与腐殖酸之间的相互作用是非共价的。这些相互作用是在低腐殖质浓度（5 mg C / L）下检测到的，表明在水生和陆地系统中普遍存在的低浓度腐殖质将显着影响环境中污染物的命运和运输。

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