通过一个金属的法稳定气相zwitterion稳定
Robert C Dunbar1, Nick C Polfer, Jos Oomens
1Chemistry Department, Case Western Reserve University, Cleveland, Ohio 44106, USA. rcd@po.cwru.edu
Journal of the American Chemical Society
|November 8, 2007
概括
气相氨基酸通常更喜欢规范结构,而不是zwitterions. 然而,这项研究通过实验证实了盐桥 (SB) 的特子形式在双重电荷的复合物中,排除了其他结构.
科学领域:
- 物理化学 物理化学
- 频谱学是一种光谱学.
- 生物物理化学 生物物理化学
背景情况:
- 氨基酸存在于溶液中的zwitterions,但通常在气相中采用正规形式.
- 金属离子复合可以稳定zwitterionic形式,但这通常不是单电荷复合体最稳定的配置.
- 计算研究表明,在双电荷复合体中增强了zwitterionic稳定性,但缺乏实验验证.
研究的目的:
- 实验性地研究气相双电荷金属-氨基酸复合物的结构.
- 为了验证zwitterionic (盐桥) 形式在这些复合体中预测的增强稳定性.
- 用红外光谱学来描述三丰复合物的结构.
主要方法:
- 使用多光子红外分离 (MP-IRPD) 光谱.
- 使用FELIX自由电子激光器进行精确的红外激发.
- 分析了特征的振动频率 (碳酸盐抗对称CO延伸和NH3模式) 来识别离子结构.
主要成果:
- 实验证实,酸的 (Ba2+) 复合物存在于盐桥 (SB) 型中.
- 绝对排除了非zwitterionic,电荷溶解形式的存在.
- 确定了SB结构的关键光谱特征,包括1600厘米-1的CO延伸和1400厘米-1的NH3模式.
结论:
- 双电荷金属复合物可以稳定氨基酸在气相中的zwitterionic (盐桥) 形式.
- 这种实验证据验证了关于增强SB稳定的计算预测.
- 红外光谱学提供了一个强大的工具,用于区分zwitterionic和nonzwitterionic气相离子结构.
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