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

Cercola, Rosaria; Wong, Natalie G. K.; Rhodes, Christopher N.; Olijnyk, Lorna; Mistry, Neetisha S.; Hall, Lewis M.; Berenbeim, Jacob A.; Lynam, Jason M.; Dessent, Caroline E. H.

doi:10.1039/d1ra02581c

Cited by 7 publications

(14 citation statements)

References 57 publications

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“…While ion mobility detection is clearly complementary to the UV–vis laser photodissociation spectroscopy within the commercial mass spectrometer presented here, it is important to have a range of approaches available since what is crucial is that they can be applied in situ to identify deprotomeric species. This is of particular importance for the reaction studies discussed in the introduction, where the type of mass spectrometer available for ESI detection may vary. − …”

Section: Discussionmentioning

confidence: 99%

“…The influence of electrospray ionization (ESI) conditions on the location of protonation and deprotonation sites of electrosprayed ions is a topic of keen debate. − Acid–base reactions are of key importance throughout chemistry and biology, so correctly identifying the structures of protomers and deprotomers can be crucial to understanding reactive processes. While ESI has been successfully employed across analytical chemistry for many years, it is increasingly being used to probe solution-phase reactions and reactive intermediates for both chemical and biochemical systems. − The role of the electrospray process in determining the location of protonation and deprotonation sites is therefore of key chemical interest.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of the Population of Electrosprayed Deprotomers of Coumaric Acids Using UV–Vis Laser Photodissociation Spectroscopy

2021

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The measurement of deprotonation sites in multifunctional molecules following electrospray ionization is important to better inform a wide range of spectroscopic and photophysical studies that use electrospray to prepare molecular species for study in the gas phase. We demonstrate that low-resolution UV–vis laser photodissociation spectroscopy can be applied in situ to identify the deprotomers of three coumaric acids, trans-para -coumaric acid (CMA), trans- caffeic acid (CA), and trans- ferulic acid (FA), formed via electrospray. Electronic absorption spectra of the deprotonated coumaric acids are recorded via photodepletion and photofragmentation following electrospray from solutions of ethanol and acetonitrile. By comparing the experimental spectra to wave function theory calculations, we are able to confirm the presence of phenoxide and carboxylate deprotomers upon electrospray for all three coumaric acids, when sprayed from both protic and aprotic solvents. Ratios of the phenoxide:carboxylate deprotomers are obtained by generating summed theoretical absorption spectra that reproduce the experimental spectra. We find that choice of electrospray solvent has little effect on the ratio of deprotomers obtained for deprotonated CMA and CA but has a greater impact for FA. Our results are in excellent agreement with previous work conducted on deprotonated CMA using IR spectroscopy and demonstrate that UV photodissociation spectroscopy of electrosprayed ions has potential as a diagnostic tool for identifying deprotomeric species.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of the Population of Electrosprayed Deprotomers of Coumaric Acids Using UV–Vis Laser Photodissociation Spectroscopy

2021

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“…This report demonstrates that cold gas-phase UV spectroscopy is a useful method for identifying photochemical intermediates produced in solution. Very recently, Dessent and co-workers reported a MS study on characterization of photochemical reactions in solution and gas phase using an ESI source . In their paper, photochemistry of ruthenium metal carbonyls was initiated in solution and gas phase by introducing the light to the solution and a vacuum chamber, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Very recently, Dessent and co-workers reported a MS study on characterization of photochemical reactions in solution and gas phase using an ESI source. 37 In their paper, photochemistry of ruthenium metal carbonyls was initiated in solution and gas phase by introducing the light to the solution and a vacuum chamber, respectively. Spectroscopic information coupled with MS measurements would be very valuable to identify the electronic and geometric structures of chemical intermediates in solution.…”

Section: Discussionmentioning

confidence: 99%

Structural Investigation of Photochemical Intermediates in Solution by Cold UV Spectroscopy in the Gas Phase: Photosubstitution of Dicyanobenzenes by Allylsilanes

et al. 2021

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Electrospray ion sources with an in-line quartz cell were constructed to produce photochemical intermediates in solution. These ion sources can detect photochemical intermediates having lifetimes longer than a few seconds. Intermediates formed by photosubstitution of 1,4-dicyanobenzene (DCB) by allyltrimethylsilane (AMS) in acetonitrile using a Xe lamp were injected into the mass spectrometer. The cationic intermediate (C 11 H 10 N 2 •H + ) was observed at m/z = 171, but no anionic intermediate was found, although C 11 H 9 N 2 − was expected based on prior studies. Theoretical studies suggested that C 11 H 9 N 2 − was simultaneously converted to neutral C 11 H 10 N 2 and cationic C 11 H 10 N 2 •H + species, which can be stable intermediates in the photosubstitution reaction. The UV photodissociation (UVPD) spectrum of C 11 H 10 N 2 •H + under cold (∼10 K) gas-phase conditions determined the conformation of the C 11 H 10 N 2 unit of the C 11 H 10 N 2 •H + cation. This report demonstrates that cold gas-phase UV spectroscopy is a prospectively powerful tool for investigation of the electronic and geometric structures of photochemical intermediates produced in solution.

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“…We employ the technique of gas-phase laser photodissociation action spectroscopy on [RF−H] − through forming the anion as an isolated gas-phase species via electrospray ionization (ESI), and then obtaining the electronic absorption spectrum and action spectra of its resultant photofragment ions. Our gas-phase measurements are complemented by on-line photolysis in a UV-LED photolytic cell (365 nm) with ESI mass spectrometry (ESI-MS) [15]. This experimental approach which characterizes the gas-and solution-phase behavior of a chosen system provides a "one-pot" tool for approaching the understanding photochemistry.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of Riboflavin under Alkaline Conditions: What can Gas-Phase Photolysis Tell Us About What Happens in Solution?

Wong¹,

Rhodes²,

Dessent³

2021

Preprint

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The application of electrospray ionization mass spectrometry (ESI-MS) as a direct method for detecting reactive intermediates is a technique of developing importance in the routine monitoring of solution-phase reaction pathways. Here, we utilize a novel on-line photolysis ESI-MS approach to detect the photoproducts of riboflavin in aqueous solution under mildly alkaline conditions. Riboflavin is a constituent of many food products, so its breakdown processes are of wide interest. Our on-line photolysis setup allows for solution-phase photolysis to occur within a syringe using UVA LEDs, immediately prior to being introduced into the mass spectrometer via ESI. Gas-phase photofragmentation studies via laser-interfaced mass spectrometry of deprotonated riboflavin, [RFH], the dominant solution-phase species under the conditions of our study, are presented alongside the solution-phase photolysis. The results obtained illustrate the extent to which gas-phase photolysis methods can inform our understanding of the corresponding solution-phase photochemistry. We determine that the solution-phase photofragmentation observed for [RFH] closely mirrors the gas-phase photochemistry, with the m/z 241 ion being the only major condensed-phase photoproduct. Further gas-phase photoproducts are observed at m/z 255, 212, and 145. The value of exploring both the gas- and solution-phase photochemistry to characterize photochemical reactions is discussed.

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

Abstract: The solution and gas-phase dissociative photochemistry of two ruthenium half-sandwich complexes are analysed with electrospray ionisation mass spectrometry in a novel instrument.

Cited by 7 publications

References 57 publications

Measurement of the Population of Electrosprayed Deprotomers of Coumaric Acids Using UV–Vis Laser Photodissociation Spectroscopy

Measurement of the Population of Electrosprayed Deprotomers of Coumaric Acids Using UV–Vis Laser Photodissociation Spectroscopy

Structural Investigation of Photochemical Intermediates in Solution by Cold UV Spectroscopy in the Gas Phase: Photosubstitution of Dicyanobenzenes by Allylsilanes

Photodegradation of Riboflavin under Alkaline Conditions: What can Gas-Phase Photolysis Tell Us About What Happens in Solution?

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