Kinetics of the Same Reaction Monitored over Nine Orders of Magnitude in Concentration: When Are Unique Subensemble and Single-Turnover Reactivity Displayed?

Essentially no information is known about the behavior of individual molecular catalysts under reaction conditions. This is a result of the averaging inherent to traditional analytical techniques. Herein, a combined fluorescence microscopy and 1 H NMR spectroscopy study reveals that unique (that is, non-ensemble averaged) distributions and time-variable kinetics from molecular ruthenium catalysts within growing polynorbornene occur and are detectable between 10-9 m and 10-6 m of substrate, surprisingly just 1000-fold less concentrated than a typical laboratory bench-scale reaction. The kinetic states governing single-turnover events are determinable by overlay of the signal arising from individual monomer insertion reactions with that from polymer growth from neighboring catalysts.