The journal of physical chemistry letters, Jan 31, 2017
Gas phase protonated guanine-cytosine (CGH(+)) pair was generated using an electrospray ionizati... more Gas phase protonated guanine-cytosine (CGH(+)) pair was generated using an electrospray ionization source from solutions at two different pH (5.8 and 3.2). Consistent evidence from MS/MS fragmentation patterns and differential ion mobility spectra (DIMS) point toward the presence of two isomers of the CGH(+) pair, whose relative populations depend strongly on the pH of the solution. Gas phase infrared multiphoton dissociation (IRMPD) spectroscopy in the 900-1900 cm(-1) spectral range further confirms that the Watson-Crick isomer is preferentially produced (91%) at pH = 5.8, while the Hoogsteen isomer predominates (66%) at pH = 3.2). These fingerprint signatures are expected to be useful for the development of new analytical methodologies and to trigger isomer selective photochemical studies of protonated DNA base pairs.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in ... more Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries.
Differential Ion Mobility Spectrometry (DIMS) provides orthogonal separation to mass spectrometry... more Differential Ion Mobility Spectrometry (DIMS) provides orthogonal separation to mass spectrometry, and DIMS combined with the high sensitivity of a quadrupole ion trap is shown to be useful for the the separation and identification of saccharides. A comprehensive analysis of the separation of anomers (α- and β-methylated glucose) and epimers (α-methylated glucose and mannose) ionized with Li(+), Na(+), and K(+) is performed. DIMS separation is found to be better for saccharides cationized with the in the two latter species, and the corresponding resolving power for the two glucose anomers with Na(+) is found to be very close to the corresponding drift-tube IMS value. The lithiated complexes are investigated further using a combination of infrared spectroscopy integrated to ion-trap mass spectrometry and quantum chemical calculations. Together with DIMS, consistent results are obtained. It is found in particular that two competing structural motifs might be at play, depending on the ...
Chiral recognition in protonated cinchona alkaloid dimers has been studied in mass spectrometry e... more Chiral recognition in protonated cinchona alkaloid dimers has been studied in mass spectrometry experiments. The experimental setups involved a modified 7T FT-ICR (Fourier transform-ion cyclotron resonance) mass spectrometer (MS) and a modified Paul ion trap both equipped with an electrospray ionization source (ESI). The Paul ion trap has been coupled to a frequency-doubled dye laser. The fragmentation of protonated dimers made from cinchonidine (Cd) and the two pseudoenantiomers of quinine, namely, quinine (Qn) and quinidine (Qd), has been assessed by means of collision-induced dissociation (CID) as well as UV photodissociation (UVPD). Whereas CID fragmentation of the dimers only leads to the evaporation of the monomers, UVPD results in the additional loss of a neutral radical fragment corresponding to the quinuclidinyl radical. The effect of the excitation wavelength and of complexation with H(2)SO(4) has been studied to cast light on the reaction mechanism. Complexation with H(2)SO(4) modifies the photoreactivity of the dimers; only evaporation of the monomeric fragments, quinine, and cinchonidine is observed. Comparison between the mass spectra of the cinchona alkaloid (CdQnH(+)) or (CdQdH(+)) dimers resulting from the UVPD of (CdQnH(2)SO(4)H(+)) and that of bare (CdQnH(+)) helps propose a fragmentation mechanism, which is thought to involve fast proton transfer from the quinuclidine part of a molecular subunit to the quinoline ring. CID and UV fragmentation experiments show that the homochiral dimer is more strongly bound than the heterochiral adduct.
ABSTRACT The intracellular signal transductor cAMP, generated as a protonated species ([cAMP + H]... more ABSTRACT The intracellular signal transductor cAMP, generated as a protonated species ([cAMP + H]+) in an electrospray ionization source, has been assayed by infrared multiple photon dissociation (IRMPD) spectroscopy. IRMPD spectra have been recorded both in the 800–1800 cm−1 mid-IR range and in the N–H and O–H stretching region, between 3200 and 3700 cm−1. Extensive quantum chemical calculations have been performed at both B3LYP and MP2 levels of theory using the 6-311+G(2df,2p) basis set. At both levels of theory, the N7 protonated structures are predicted to be much higher in energy than the N1 and N3 protonated ones. Overall, the experimental spectrum is in very good agreement with the calculated IR spectra of the two lowest energy structures corresponding to protonation on either the N1 or the N3 adenine site. For both structures a syn conformation about the glycosidic bond is predicted at either level of theory. The NH stretching region appears to be the most structurally informative in terms of orientation about the glycosidic bond. It also suggests that the energetics derived at the MP2/6-311+G-(2df,2p) level are more reliable.
The journal of physical chemistry letters, Jan 31, 2017
Gas phase protonated guanine-cytosine (CGH(+)) pair was generated using an electrospray ionizati... more Gas phase protonated guanine-cytosine (CGH(+)) pair was generated using an electrospray ionization source from solutions at two different pH (5.8 and 3.2). Consistent evidence from MS/MS fragmentation patterns and differential ion mobility spectra (DIMS) point toward the presence of two isomers of the CGH(+) pair, whose relative populations depend strongly on the pH of the solution. Gas phase infrared multiphoton dissociation (IRMPD) spectroscopy in the 900-1900 cm(-1) spectral range further confirms that the Watson-Crick isomer is preferentially produced (91%) at pH = 5.8, while the Hoogsteen isomer predominates (66%) at pH = 3.2). These fingerprint signatures are expected to be useful for the development of new analytical methodologies and to trigger isomer selective photochemical studies of protonated DNA base pairs.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in ... more Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries.
Differential Ion Mobility Spectrometry (DIMS) provides orthogonal separation to mass spectrometry... more Differential Ion Mobility Spectrometry (DIMS) provides orthogonal separation to mass spectrometry, and DIMS combined with the high sensitivity of a quadrupole ion trap is shown to be useful for the the separation and identification of saccharides. A comprehensive analysis of the separation of anomers (α- and β-methylated glucose) and epimers (α-methylated glucose and mannose) ionized with Li(+), Na(+), and K(+) is performed. DIMS separation is found to be better for saccharides cationized with the in the two latter species, and the corresponding resolving power for the two glucose anomers with Na(+) is found to be very close to the corresponding drift-tube IMS value. The lithiated complexes are investigated further using a combination of infrared spectroscopy integrated to ion-trap mass spectrometry and quantum chemical calculations. Together with DIMS, consistent results are obtained. It is found in particular that two competing structural motifs might be at play, depending on the ...
Chiral recognition in protonated cinchona alkaloid dimers has been studied in mass spectrometry e... more Chiral recognition in protonated cinchona alkaloid dimers has been studied in mass spectrometry experiments. The experimental setups involved a modified 7T FT-ICR (Fourier transform-ion cyclotron resonance) mass spectrometer (MS) and a modified Paul ion trap both equipped with an electrospray ionization source (ESI). The Paul ion trap has been coupled to a frequency-doubled dye laser. The fragmentation of protonated dimers made from cinchonidine (Cd) and the two pseudoenantiomers of quinine, namely, quinine (Qn) and quinidine (Qd), has been assessed by means of collision-induced dissociation (CID) as well as UV photodissociation (UVPD). Whereas CID fragmentation of the dimers only leads to the evaporation of the monomers, UVPD results in the additional loss of a neutral radical fragment corresponding to the quinuclidinyl radical. The effect of the excitation wavelength and of complexation with H(2)SO(4) has been studied to cast light on the reaction mechanism. Complexation with H(2)SO(4) modifies the photoreactivity of the dimers; only evaporation of the monomeric fragments, quinine, and cinchonidine is observed. Comparison between the mass spectra of the cinchona alkaloid (CdQnH(+)) or (CdQdH(+)) dimers resulting from the UVPD of (CdQnH(2)SO(4)H(+)) and that of bare (CdQnH(+)) helps propose a fragmentation mechanism, which is thought to involve fast proton transfer from the quinuclidine part of a molecular subunit to the quinoline ring. CID and UV fragmentation experiments show that the homochiral dimer is more strongly bound than the heterochiral adduct.
ABSTRACT The intracellular signal transductor cAMP, generated as a protonated species ([cAMP + H]... more ABSTRACT The intracellular signal transductor cAMP, generated as a protonated species ([cAMP + H]+) in an electrospray ionization source, has been assayed by infrared multiple photon dissociation (IRMPD) spectroscopy. IRMPD spectra have been recorded both in the 800–1800 cm−1 mid-IR range and in the N–H and O–H stretching region, between 3200 and 3700 cm−1. Extensive quantum chemical calculations have been performed at both B3LYP and MP2 levels of theory using the 6-311+G(2df,2p) basis set. At both levels of theory, the N7 protonated structures are predicted to be much higher in energy than the N1 and N3 protonated ones. Overall, the experimental spectrum is in very good agreement with the calculated IR spectra of the two lowest energy structures corresponding to protonation on either the N1 or the N3 adenine site. For both structures a syn conformation about the glycosidic bond is predicted at either level of theory. The NH stretching region appears to be the most structurally informative in terms of orientation about the glycosidic bond. It also suggests that the energetics derived at the MP2/6-311+G-(2df,2p) level are more reliable.
Uploads