A "one pot" mass spectrometry technique for characterizing solution- and gas-phase photochemical reactions by electrospray mass spectrometry.

The characterization of new photochemical pathways is important to progress the understanding of emerging areas of light-triggered inorganic and organic chemistry. In this context, the development of platforms to perform routine characterization of photochemical reactions remains an important goal for photochemists. Here, we demonstrate a new instrument that can be used to characterise both solution-phase and gas-phase photochemical reactions through electrospray ionisation mass spectrometry (ESI-MS). The gas-phase photochemistry is studied by novel laser-interfaced mass spectrometry (LIMS), where the molecular species of interest is introduced to the gas-phase by ESI, mass-selected and then subjected to laser photodissociation in the ion-trap. On-line solution-phase photochemistry is initiated by LEDs prior to ESI-MS in the same instrument with ESI-MS again being used to monitor photoproducts. Two ruthenium metal carbonyls, [Ru(η 5 -C 5 H 5 )(PPh 3 ) 2 CO][PF 6 ] and [Ru(η 5 -C 5 H 5 )(dppe)CO][PF 6 ] (dppe = 1,2-bis(diphenylphosphino)ethane) are studied using this methodology. We show that the gas-phase photofragmentation pathways observed for the ruthenium complexes via LIMS ( i.e. loss of CO + PPh 3 ligands from [Ru(η 5 -C 5 H 5 )(PPh 3 ) 2 CO] + and loss of just CO from [Ru(η 5 -C 5 H 5 )(dppe)CO] + ) mirror the solution-phase photochemistry at 3.4 eV. The advantages of performing the gas-phase and solution-phase photochemical characterisations in a single instrument are discussed.