Influence of Ions on Aqueous Acid-Base Reactions
Influence of Ions on Aqueous Acid-Base Reactions
复制标题
DOI：
10.1002/cphc.200800406
复制
发表时间：
2009-01-12
期刊：
影响因子：
2.9
通讯作者：
Bakker, Huib J.
中科院分区：
文献类型：
--
作者：
Cox, M. Jocelyn;Siwick, Bradley J.;Bakker, Huib J.
研究了溴化物对光酸8-羟基-1,3,6-芘三磺酸（HPTS）与碱乙酸酯之间质子/氘核转移反应速率和反应机理的影响。质子/氘核释放是由400 nm飞秒脉冲激发HPTS触发的。利用飞秒可见光和中红外脉冲探测光酸、共轭光碱、水合质子/氘核和接受碱的电子共振和振动共振，监测质子转移。确定了两种反应通道：1)通过连接酸和碱的氢键水桥直接远程质子转移；2)酸解离产生完全溶剂化的质子，然后醋酸盐从溶液中清除质子。我们观察到，盐的加入影响了远程反应途径，降低了HPTS向溶液中释放质子的速率和乙酸从溶液中清除溶剂化质子的速率。我们研究了这些影响与溶解盐的性质和浓度的关系。
We study the effects of bromide salts on the rate and mechanism of the aqueous proton/deuteron-transfer reaction between the photoacid 8-hydroxy-1,3,6-pyrenetrisulfonic acid (HPTS) and the base acetate. The proton/deuteron release is triggered by exciting HPTS with 400 nm femtosecond loser pulses. Probing the electronic and vibrational resonances of the photoacid, the conjugate photobase, the hydrated proton/deuteron and the accepting base with femtosecond visible and mid-infrared pulses monitors the proton transfer. Two reaction channels are identified: 1) direct long-range proton transfer over hydrogen-bonded water bridges that connect the acid and base and 2) acid dissociation to produce fully solvated protons followed by proton scavenging from solution by acetate. We observe that the addition of salt affects the long-range reaction pathway, and reduces both the rate at which protons are released to solution by HPTS and the rate at which solvated protons are scavenged from solution by acetate. We study the dependence of these effects on the nature and concentration of the dissolved salt.