Molecular modulation spectroscopy: Individual molecular spectra accurately deconvoluted from interfering systems via orthogonal reactions

Abstract

To accurately analyze strongly interfering species in a system, current analytical methodologies separate and purify each chemical species before individual characterization. Herein, we introduce a new concept to analyze individual molecules in interfering systems, provided the target molecules offer orthogonal modulation by external stimuli. Using optical and thermal modulation simultaneously, we demonstrated that two interfering molecules, one photoswitching while the other thermal switching, could be accurately identified in a mixture because they underwent orthogonal chemical reactions when stimulated by both light and heat. The broad impact of the newly developed molecular modulation spectroscopy (MMS) is significant because molecular species in interfering systems can be analyzed directly in situ and in detail without time-consuming chemical separation and purification. Conversely, such stimuli-induced switching molecules can function as molecular sensors, gauging the presence and magnitude of that specific external stimulus.