液相近场红外纳米显微术研究离子交换反应
Liquid-Phase Near-Field Infrared Nanoscopy of Ion-Exchange Reactions
- Department of Physics and Astronomy, University of Georgia（佐治亚大学物理与天文系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用SiC膜液相近场红外纳米成像与光谱技术，原位监测Ca²⁺/Na⁺离子交换中CaTP配位相的形成，通过羧酸根振动模式变化及纳米沉淀成像，实现金属-配体相互作用的原位化学监测。
AI中文摘要：
在水相条件下以化学特异性和纳米级空间分辨率对反应进行原位监测，一直是一个长期存在的实验挑战。在此，我们利用薄SiC膜支撑的液相红外纳米成像和纳米光谱技术，监测对苯二甲酸二钠与CaCl$_2$溶液混合物中的Ca$^{2+}$/Na$^{+}$离子交换过程。在膜下方，我们追踪了对苯二甲酸钙（CaTP）的形成，这是一种金属有机框架（MOF）型配位相，其中对苯二甲酸配体连接Ca$^{2+}$中心。对称和不对称羧酸根伸缩振动模式作为化学特异性的近场探针，用于表征Ca$^{2+}$与对苯二甲酸配体的配位情况。纳米傅里叶变换红外光谱（nano-FTIR）显示这些振动模式出现显著的峰位移和线宽变化，表明在CaTP形成过程中羧酸根配位环境发生了改变。互补的近场纳米成像揭示了在注入CaCl$_2$后SiC膜下方纳米级沉淀物的出现，为CaTP配位框架的形成提供了空间分辨的证据。固相纳米成像和纳米光谱识别出明确的CaTP颗粒，进一步证明了结晶态CaTP的形成。我们证明了金属-配体相互作用的化学过程可以通过液相近场纳米显微术进行原位监测。这一能力可能有助于在天然水相条件下研究催化、电化学和生物过程。
英文摘要：
In situ monitoring of reactions with chemical specificity and nanometer-scale spatial resolution under aqueous conditions remains a long-standing experimental challenge. Here, we use thin SiC membrane-enabled liquid-phase infrared nanoimaging and nanospectroscopy to monitor Ca$^{2+}$/Na$^{+}$ ion exchange in a mixture of disodium terephthalate and CaCl$_2$ solution. Beneath the membrane, we follow the formation of calcium terephthalate (CaTP), a metal-organic framework (MOF)-type coordination phase in which terephthalate ligands link Ca$^{2+}$ centers. The symmetric and asymmetric carboxylate stretching modes serve as chemically specific near-field reporters of Ca$^{2+}$ coordination to the terephthalate linkers. Nano-FTIR spectra reveal pronounced peak shifts and linewidth changes in these vibrational modes, indicating modification of the carboxylate coordination environment during CaTP formation. Complementary near-field nanoimaging resolves the emergence of nanoscale precipitates beneath the SiC membrane following CaCl$_2$ injection, providing spatially resolved evidence of the formation of the CaTP coordination framework. Solid-phase nanoimaging and nanospectroscopy identify well-defined CaTP particles, providing further evidence for crystalline CaTP formation. We demonstrate that the chemistry of metal-ligand interactions can be monitored in situ via liquid-phase near-field nanoscopy. This capability could enable the study of catalytic, electrochemical, and biological processes under native aqueous conditions.
