The structures and properties of anionic tryptophan complexes

The physicochemical properties of [Trpn–H]− and [Trpn⋯Cl]− (n = 1, 2) have been investigated in a combined computational and experimental infrared multiple dissociation (IRMPD) study. IRMPD spectra within the 850–1900 cm−1 region indicate that deprotonation is localized on the carboxylic acid moiety in [Trpn–H]− clusters. A combination of hydrogen bonding and higher order charge–quadrupole interactions appear to influence cluster geometries for all investigated systems. Calculated global minimum and low energy geometries of [Trp⋯Cl]− and [Trp2⋯Cl]− clusters favour coordination of the halide by the indole NH. [Trp2–H]− and [Trp2⋯Cl]− exhibit additional π–π interactions between the heterocyclic side chains.The authors would like to acknowledge the financial support provided by the Natural Sciences and Engineering Research Council (NSERC) of Canada

An IRMPD spectroscopic and computational study of protonated guanine-containing mismatched base pairs in the gas phase

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Gas phase structure and fragmentation of [Cytosine-Guanine] Ag + complex studied by mass-resolved IRMPD spectroscopy

The silver-mediated cytosine-guanine [CGAg]+ pair was characterized by mass-resolved IRMPD spectroscopy and electronic structure calculations at the DFT level. Three fragments were observed: [GAg]+ , [CAg]+ and [CH]+ . From the mass-resolved IRMPD spectra recorded on the mass of each fragment, two isomers of the [CGAg]+ complex were identified. The most populated isomer is a Hoogsteen structure [HooAg]+ between canonical cytosine (CKA(1)) and canonical guanine (GKA(9)), while the second isomer is an altered-Hoogsteen-like pair [*HooAg]+ in which guanine is in a non-canonical form (GKA(7)). The determined yields of each fragment are strongly dependent of the isomer of the precursor ion because of the fragmentation energy of the different channels. Finally, the [CH]+ is suggested to be produced by a metal-assisted proton transfer from guanine to cytosine preceded by an isomerization of the [HooAg]+ isomer.Fil: Cruz Ortiz, Andres Felipe. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Jara Toro, Rafael Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; ArgentinaFil: Berdakin, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; ArgentinaFil: Loire, Estelle. Université Paris-Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; Argentin

Convenient and Practical Alkynylation of Heteronucleophiles with Copper Acetylides

Copper acetylides, readily available reagents which are characterized by their lack of reactivity, can be simply activated by oxidation with oxygen in the presence of simple nitrogen ligands such as TMEDA or imidazole derivatives. Upon activation, these nucleophilic species undergo a formal umpolung and can transfer their alkyne subunit to a wide range of heteronucleophiles, including amides, oxazolidinones, imines, and dialkyl phosphites. This alkynylation, which provides one of the most practical entry to useful building blocks such as ynamides, ynimines, and alkynylphosphonates, proceeds under especially mild conditions and can be easily performed on a multigram scale.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Reactions of Thiiranium and Sulfonium Ions with Alkenes in the Gas Phase

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