We investigated collision-induced dissociation (CID) reactions of protonated Hoogsteen 9-methylguanine–1-methylcytosine base pair (HG-[9MG·1MC + H]+), which is aimed to address the mystery of the literature reported "anomaly" in product ion...

The structure of the title compound, C(17)H(16)OS, is primarily stabilized by T-shaped and parallel-displaced aromatic clusters. The distances between the centroids of the aromatic pairs are in the range 4.34-5.30 A. In the crystal packing, the molecules dimerize by means of pi-pi interactions of both face-to-face and edge-to-face types, and the aromatic rings associate in a cyclic edge-to-face tetrameric arrangement of the herring-bone type. These herring-bone interactions appear to insulate hydrogen-bond interactions in the crystal structure.

8-Bromoguanosine is generated in vivo as a biomarker for early inflammation. Its formation and secondary reactions lead to a variety of biological sequelae at inflammation sites, most of which are mutagenic and linked to cancer. Herein, we report the formation of radical cations of 8-bromoguanine (8BrG •+ ) and 8-bromoguanosine (8BrGuo •+ ) and their reactions toward the lowest excited singlet molecular oxygen ( 1 O 2 )a common reactive oxygen species generated in biological systems. This work aims to investigate synergistic, oxidatively generated damage of 8-brominated guanine and guanosine that may occur upon ionizing radiation, one-electron oxidation, and 1 O 2 oxidation. Capitalizing on measurements of reaction product ions and cross sections of 8BrG •+ and 8BrGuo •+ with 1 O 2 using guided-ion beam tandem mass spectrometry and augmented by computational modeling of the prototype reaction system, 8BrG •+ + 1 O 2 , using the approximately spin-projected ωB97XD/6-31+G(d,p) density functional theory, the coupled cluster DLPNO-CCSD(T)/aug-cc-pVTZ and the multireference CASPT2(21,15)/6-31G**, probable reaction products, and potential energy surfaces (PESs) were mapped out. 8BrG •+ and 8BrGuo •+ present similar exothermic oxidation products, and their reaction efficiencies with 1 O 2 increase with decreasing collision energy. Both single-and multireference theories predicted that the two most energetically favorable reaction pathways correspond to 1 O 2 -addition to the C8 and C5-positions of 8BrG •+ , respectively. The CASPT2-calculated PES represents the best quantitative agreement with the experimental benchmark, in that the oxidation exothermicity is close to the water hydration energy of product ions and, thus, is able to eliminate a water ligand in the product ions.

1998 magnetic resonance, nuclear quadrupole resonance magnetic resonance, nuclear quadrupole resonance (organic substances) K 2560 -023Two-Dimensional NMR Spectral Studies of Some 2,6-Diarylpiperidin-4-ones -[NOESY spectra of the title compounds; 13 C-1 H HETCOR, 1 H NMR spectrum and 13 C chemical shifts of (Ic)]. -(PANDIARAJAN, K.; JEGDISH, T. N.; BENNY, J. C. N.; Indian J. Chem., Sect. B: Org. Chem.

It has been shown previously in protonated, deprotonated and ionized guanine–cytosine base pairs that intra-base pair proton transfer from the N1-H at the Watson-Crick edge of guanine to the complementary...

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OneStep Synthesis of 3,4-Dihydro-2H-1,3-oxazines. -Under similar conditions p-chloro-and p-nitrobenzaldehydes do not give oxazines. However, prolonged refluxing yields tetrasubstituted pyrimidines. -(PANDIARAJAN, K.; BENNY, J. C. N.; J.

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