相关实验视频
Updated: Jul 14, 2026
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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
在酸盐薄膜中对微环境酸度的单分子谱学研究
Yi Fu1, Maryanne M Collinson, Daniel A Higgins
1Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA.
Journal of the American Chemical Society
|October 21, 2004
概括
单分子光谱检测显示了酸膜酸度的变化. 酸度受到浸泡时间和pH值的影响,在pH值9附近观察到缓冲效应.
科学领域:
- 材料科学 材料科学 材料科学
- 频谱学是一种光谱学.
- 表面化学 表面化学
背景情况:
- 来自sol-gel的酸薄膜在各种应用中至关重要.
- 了解它们的表面酸度对于性能至关重要.
- 之前的研究缺乏薄膜酸度的单点分辨率.
研究的目的:
- 为了研究酸薄膜中的单位酸度变化.
- 为了将薄膜酸度与浸泡时间和外部pH相关联.
- 阐明表面西兰醇在薄膜缓冲中的作用.
主要方法:
- 采用单分子 (SM) 光谱学.
- 在纳米分子度下使用了pH敏感染料Carboxy SNARF-1 (C.SNARF-1).
- 测量了C.SNARF-1的光比,以确定局部膜的pH值.
主要成果:
- 薄膜中的光谱变异主要是由于局部矩阵酸度的静态变化.
- 较短的浸泡时间显示了更广泛的pH分布,表明了动力限制.
- 更长的浸泡时间产生了更窄的分布,特别是在pH8-9附近,这归因于西兰醇缓冲.
结论:
- 单分子光谱学提供了对酸薄膜酸度的高分辨率洞察.
- 薄膜酸度是一种动态性质,受浸泡条件和表面化学的影响.
- 表面的西拉诺缓冲显著影响到接近中性条件的膜pH值.
相关概念视频
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In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
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In ¹H NMR spectroscopy, acidic protons (–COOH) of carboxylic acids are highly deshielded and absorb far downfield, at around 9–12 ppm. The chemical shift value depends on the concentration and solvent used.
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While α protons of carboxylic acids absorb at 2–2.5 ppm, β protons absorb further upfield.
Carboxylic acids are easily identified by dissolving them in deuterium oxide, which results in a rapid exchange of the acidic protons with deuterium. This leads to the disappearance of the acidic...