The protonation/deprotonation equilibrium of a fluorescent pH probe (carboxy-seminaphthorhodafluor-1, SNARF-1) within the nanoscale water layer confined in common black films (CBFs) has been studied. We find that SNARF-1 molecules feel a more acidic environment in CBFs than when they are in the bulk micellar solution, using the base/acid peak area ratio of the dye to indicate its microenvironment pH. Three surfactants are used to study the dependence of the pH drop versus charge: cationic (cetyltrimethylammonium bromide, CTAB), anionic (sodium dodecylsulphate, SDS) and nonionic (Triton X-100) species. The decrease of CBFs pH versus the pH of the micellar solution is the following: ΔpH≈1.5 for CTAB (pH: 7.0-9.0), ΔpH≈0.8 for SDS, and ΔpH≈0.4 for Triton X-100. With the addition of electrolyte in CBFs, we observe large decrease the amplitude of the pH anomaly, thus suggesting an electrostatic origin of the pH change at nanoscale environment.

研究了局限在普通黑膜（CBF）中的纳米级水层中的荧光pH探针（羧基-seminaphthorhodafluor-1，SNARF-1）的质子/去质子平衡。我们发现，SNARF-1分子在CBF中的酸性环境比在散装胶束溶液中的酸性环境大，使用染料的碱/酸峰面积比来表明其微环境pH。三种表面活性剂用于研究pH下降对电荷的依赖性：阳离子型（十六烷基三甲基溴化铵，CTAB），阴离子型（十二烷基硫酸钠，SDS）和非离子型（Triton X-100）。CBFs pH相对于胶束溶液pH的降低如下：CTAB的ΔpH≈1.5（pH：7.0-9.0），SDS的ΔpH≈0.8，Triton X-100的ΔpH≈0.4。在CBF中添加电解质后，