1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione reacts with ethyl bromoacetate under mild conditions to give 2-(ethoxycarbonylmethyl)-1-phenyl-6H-imidazo[1,5-c]quinazoline-3,5-dione (MEPIQ) and next 2,6-bis(ethoxycarbonylmethyl)-1-phenylimidazo[1,5-c]quinazoline-3,5-dione (BEPIQ). The products were isolated at high yield and identified on the basis of IR, 1H- and 13C-NMR, UV spectroscopy, an...

Pyrrolidinium-based ionic liquids with anions of the per(fluoroalkylsulfonyl)imide family are particularly interesting for their use as electrolytes in lithium batteries. These ions have several geometric isomers and the presence of different ion conformers and their distribution affects the ILs (Ionic liquids) physical and chemical properties. In the present work, we report the temperature dep...

The rotational spectrum of the natural amino acid tryptophan has been observed for the first time using a combination of laser ablation, molecular beams, and Fourier transform microwave spectroscopy. Independent analysis of the rotational spectra of individual conformers has conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers n...

An ab initio and density functional theory (DFT) study about conformational analysis of tripeptide model HCO−GLY−L−ILE−GLY−NH2 is presented. The tripeptide was scanned about initial, central, and final residues, separately while for every scanning procedure the two other residues had been kept in the β conformation and side chain (SC) dihedral angles were maintained on the gauche− (g‾) state (χ...

In a recent communication, [1] van Gunsteren et al. proposed that the folding of proteins is much easier than has been believed [2] because the number of accessible conformers in the denatured state is only on the order of 10 9 for a 100-residue protein, instead of on the order of 10 24 to 10 30 used in previous analyses. [3, 4] This would make it possible for a polypeptide chain to fold to the...

The conformational landscape of α-aminoglycine has been studied. A search first done using a set different low-cost computational methods. conformers obtained have finally optimized at MP2 and B3LYP-D3/6–311++G(2d,p) levels theory. 15 with relative energies lower than 2000 cm−1 obtained. For the global minimum (IIa) cooperative network formed by an OH···NH, NH···N NH···OC hydrogen bonds, closin...

The multiconformational landscape of the proteogenic amino acid aspartic acid, the simplest amino acid with two carboxylic groups, has been explored for the first time in the gas phase. Solid aspartic acid (m.p. > 300 degrees C) was vaporized by laser ablation and expanded in a supersonic jet where rotational spectra of various conformers were obtained by Fourier transform microwave spectroscop...

Standard free energies (DeltaGN degree) for formation of near attack conformers, those ground state conformers that can convert directly to the transition state, were calculated for the Claisen rearrangement of chorismate to prephenate in six different environments: water, wild-type enzymes from Bacillus subtilis and Escherichia coli, their Arg90Cit and Glu52Ala mutants, and the 1F7 catalytic a...

We have selected and spatially separated the two conformers of 3-aminophenol (C6H7NO) present in a molecular beam. Analogous to the separation of ions based on their mass-to-charge ratios in a quadrupole mass filter, the neutral conformers are separated based on their different mass-to-dipole-moment ratios in an ac electric quadrupole selector. For a given ac frequency, the individual conformer...