Microchemical single droplet reaction analysis by online cavity ring-down spectroscopy

微流体为控制液滴分散体的产生及其在规定的流场中的操纵提供了一个特殊的环境。微通道位置和反应时间之间的时空对应使得能够以前所未有的时间分辨率和动态范围研究(化学和物理)过程的动力学。此外，少量液滴“反应器”与其组成的精确配方相结合，在化学合成中开辟了巨大的可能性，包括筛选、发现和优化。到目前为止，使用非侵入性探针实时监测反应仍然是微型化学反应器的一个主要缺点，因为样品体积小(Pl-NL)和运行速度快(1-1000 mm/S)。这项提议寻求开发、实施和验证一种新的实验方法，通过首次将腔衰荡光谱和耐溶剂微制造相结合来实时监测微化学反应。这种方法将允许模型催化反应的在线研究，具有前所未有的重复性和流动控制。腔衰荡光谱分析可以分析光致发光体积，有效地消除了微通道中路径长度的限制，具有纳秒到微秒的时间分辨率，与微反应液滴兼容。特别是，我们将阐明个体和全球反应群体的结果以及混合和流动的影响，并具有时空分辨率。这种方法适用于一系列有机化学反应，对于这项工作，我们将重点放在选定的基本和工业相关的模型系统(详细如下)。

Microfluidics provides an exceptional environment for the generation of controlled droplet dispersions and their manipulation in prescribed flow fields. The spatio-temporal correspondence between microchannel position and reaction 'time' permits the study of kinetics of (chemical and physical) processes with unprecedented time resolution and dynamic range. Further, the combination of the small volumes of droplet 'reactors' and the precise formulation of their composition opens vast possibilities in chemical synthesis, including screening, discovery and optimisation. Monitoring reactions in real-time with non-invasive probes remains, hitherto, a major shortcoming of microchemical reactors due to the minute sample volumes (pL-nL) and fast travel speeds (1-1000 mm/s). This proposal seeks to develop, implement and validate a novel experimental approach to monitor microchemical reactions in real-time by coupling, for the first time, cavity ring-down spectroscopy and solvent-resistant microfabrication. This approach will permit the online study of model catalytic reactions, with unprecedented reproducibility and flow control. Cavity ring-down spectroscopy will permit the analysis of pL volumes, effectively eliminating the restriction of path length in microchannels, with nanosecond to microsecond time resolution, compatible with microreaction drops. In particular, we will elucidate individual and global reaction population outcomes and the effect of mixing and flow, with spatiotemporal resolution. This approach is applicable to a range of organic chemical reactions and, for this work, we will focus on selected model systems (detailed below) of fundamental and industrial relevance.