Evolution of a Combined UV/Vis and NMR Setup with Fixed Pathlengths for Mass‐limited Samples

Abstract

The investigation of reaction mechanisms is a complex task that usually requires the use of several techniques. To obtain as much information as possible on the reaction and any intermediates ‐ possibly invisible to one technique ‐ the combination of techniques is a solution. In this work we present a new setup for combined UV/Vis and NMR spectroscopy and compare it to an established alternative. The presented approach allows a versatile usage of different commercially‐available components like mirrors and fiber bundles as well as different fixed pathlengths according to double transmission or single transmission measurements. While a previous approach is based on a dip‐probe setup for conventional NMR probes, the new one is based on a micro‐Helmholtz coil array (LiquidVoxel™). This makes the use of rectangular cuvettes possible, which ensure well‐defined pathlengths allowing for quantification of species. Additionally, very low quantities of compound can be analyzed due to the microfabrication and small cuvette size used. As proof‐of‐principle this new setup for combined UV/Vis and NMR spectroscopy is used to examine a well‐studied photochromic system of the dithienylethene compound class. A thorough comparison of the pros and cons of the two setups for combined UV/Vis and NMR measurements is performed.