Accelerated C–N Bond Formation in Dropcast Thin Films on Ambient Surfaces

Badu‐Tawiah, Abraham K.; Campbell, Dahlia I.; Cooks, R. Graham

doi:10.1007/s13361-012-0394-y

Cited by 104 publications

(125 citation statements)

References 37 publications

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“…58 The rapid desolvation of a droplet leads to increased reagent concentrations, a larger surface area to volume ratio, and a decrease in pH. Cumulatively, these factors can increase the rate of product formation within a rapidly desolvating droplet by between 1 and 3 orders of magnitude, 58 but the relative contributions of each of these factors are poorly characterized.…”

Section: Resultsmentioning

confidence: 99%

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Theta-Glass Capillaries in Electrospray Ionization: Rapid Mixing and Short Droplet Lifetimes

2014

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Double-barrel wire-in-a-capillary electrospray emitters prepared from theta-glass capillaries were used to mix solutions during the electrospray process. The relative flow rate of each barrel was continuously monitored with internal standards. The complexation reaction of 18-crown-6 and K+, introduced from opposite barrels, reaches equilibrium during the electrospray process, suggesting that complete mixing also occurs. A simplified diffusion model suggests that mixing occurs in less than a millisecond, and contributions of turbulence, estimated from times of coalescing ballistic microdroplets, suggest that complete mixing occurs within a few microseconds. This mixing time is 2 orders of magnitude less than in any mixer previously coupled to a mass spectrometer. The reduction of 2,6-dichloroindophenol by l-ascorbic acid was performed using the theta-glass emitters and monitored using mass spectrometry. On the basis of the rate constant of this reaction in bulk solution, an apparent reaction time of 274 ± 60 μs was obtained. This reaction time is an upper limit to the droplet lifetime because the surface area to volume ratio and the concentration of reagents increase as the droplet evaporates and some product formation occurs in the Taylor cone prior to droplet formation. On the basis of increases in reaction rates measured by others in droplets compared to rates in bulk solution, the true droplet lifetime is likely 1–3 orders of magnitude less than the upper limit, i.e., between 27 μs and 270 ns. The rapid mixing and short droplet lifetime achieved in these experiments should enable the monitoring of many different fast reactions using mass spectrometry.

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Section: Resultsmentioning

confidence: 99%

“…56,57 These factors can increase the rate of product formation in droplets by 1–3 orders of magnitude over bulk solution rates. 31,58−60 The relative contribution of each of these factors to the increased rate of product formation is unknown.…”

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confidence: 99%

Theta-Glass Capillaries in Electrospray Ionization: Rapid Mixing and Short Droplet Lifetimes

2014

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“…It is becoming well established that the reaction rate in microdroplets is remarkably faster than the same reaction in bulk solution (20,21,(37)(38)(39). Moreover, in some cases products are found in the droplet reactions that are different from those in the bulk (40).…”

Section: Discussionmentioning

confidence: 99%

Microdroplet fusion mass spectrometry for fast reaction kinetics

Lee

Kim

Nam

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

207

258

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We investigated the fusion of high-speed liquid droplets as a way to record the kinetics of liquid-phase chemical reactions on the order of microseconds. Two streams of micrometer-size droplets collide with one another. The droplets that fused (13 μm in diameter) at the intersection of the two streams entered the heated capillary inlet of a mass spectrometer. The mass spectrum was recorded as a function of the distance x between the mass spectrometer inlet and the droplet fusion center. Fused droplet trajectories were imaged with a high-speed camera, revealing that the droplet fusion occurred approximately within a 500-μm radius from the droplet fusion center and both the size and the speed of the fused droplets remained relatively constant as they traveled from the droplet fusion center to the mass spectrometer inlet. Evidence is presented that the reaction effectively stops upon entering the heated inlet of the mass spectrometer. Thus, the reaction time was proportional to x and could be measured and manipulated by controlling the distance x. Kinetic studies were carried out in fused water droplets for acid-induced unfolding of cytochrome c and hydrogen-deuterium exchange in bradykinin. The kinetics of the former revealed the slowing of the unfolding rates at the early stage of the reaction within 50 μs. The hydrogendeuterium exchange revealed the existence of two distinct populations with fast and slow exchange rates. These studies demonstrated the power of this technique to detect reaction intermediates in fused liquid droplets with microsecond temporal resolution.mass spectrometry | liquid microdroplets | reaction kinetics | protein unfolding | hydrogen-deuterium isotope exchange T ime-resolved measurements of reaction intermediates are crucial for understanding the fast kinetics of chemical reactions. Various approaches have been implemented to improve the temporal resolution of kinetic measurements in liquid reactions (1, 2), which are often limited by the mixing time. One approach for improving the mixing time involves the use of turbulent flow to increase the shear stress in fluid channels (3). Another approach is to stimulate the rapid initiation of a reaction by photo-triggered initiation (4), electron transfer (5), or temperature jump/rise (6). A small-size reactor was also used for rapid mixing so that the time required for diffusion-dependent mixing is minimized (7-10).Among various methods for detecting reaction intermediates, mass spectrometry has been a powerful tool for probing reaction products because it can discriminate similar species by their mass-to-charge ratio while simultaneously measuring multiple species. Time-resolved mass spectrometry (11) has been widely used for measuring the kinetics of protein-ligand complexation, organometallic compound formation, and enzyme-catalyzed processes. Despite these efforts for improving temporal resolution, time-resolved mass spectrometry has been limited to the millisecond timescale, with a recent achievement of 300 μs (12).A major obstacle for imp...

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“…Chemical reactions have been shown to proceed at greatly elevated rates in thin drop-cast layers [29] and in electrosprayed microdroplets [30] enabling derivatization to be completed during ionization and keeping total sample analysis times to a few seconds. Both ionization efficiency and molecular selectivity can be improved by chemical derivatization.…”

Section: Introductionmentioning

confidence: 99%

Biogenic aldehyde determination by reactive paper spray ionization mass spectrometry

Bag

Hendricks

Reynolds

et al. 2015

Analytica Chimica Acta

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Ionization of aliphatic and aromatic aldehydes is improved by performing simultaneous chemical derivatization using 4-aminophenol to produce charged iminium ions during paper spray ionization.Accelerated reactions occur in the microdroplets generated during the paper spray ionization event for the tested aldehydes (formaldehyde, n-pentanaldehyde, n-nonanaldehyde, n-decanaldehyde, ndodecanaldehyde, benzaldehyde, m-anisaldehyde, and p-hydroxybenzaldehyde). Tandem mass spectrometric analysis of the iminium ions using collision-induced dissociation demonstrated that straight chain aldehydes give a characteristic fragment at m/z 122 (shown to correspond to protonated 4-(methyleneamino)phenol), while the arylaldehydeiminium ions fragment to give a characteristic product ion at m/z 120. These features allow straightforward identification of linear and aromatic aldehydes. Quantitative analysis of n-nonaldehyde using a benchtop mass spectrometer demonstrated a linear response over 3 orders of magnitude from 2.5 ng -5 µg of aldehyde loaded on the filter paper emitter. The limit of detection was determined to be 2.2 ng for this aldehyde. The method had a precision of 22%, relative standard deviation. The experiment was also implemented using a portable ion trap mass spectrometer.3

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Accelerated C–N Bond Formation in Dropcast Thin Films on Ambient Surfaces

Cited by 104 publications

References 37 publications

Theta-Glass Capillaries in Electrospray Ionization: Rapid Mixing and Short Droplet Lifetimes

Theta-Glass Capillaries in Electrospray Ionization: Rapid Mixing and Short Droplet Lifetimes

Microdroplet fusion mass spectrometry for fast reaction kinetics

Biogenic aldehyde determination by reactive paper spray ionization mass spectrometry

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