The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,N-trimethylammonium)-2-methylphenyl radical cations (m/z 149) with O2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce u...

The Michael addition of nitromethane to cinnamaldehyde has been computationally studied in the absence of a catalyst and the presence of a biotinylated secondary amine by a combined computational and experimental approach. The calculations were performed at the density functional theory (DFT) level with the M06-2X hybrid functional, and a polarizable continuum model has been employed to mimic t...

In this study, nuclear magnetic resonance spectroscopy and nuclear quadrupole resonance spectroscopy parameters of N (Nitrogen in imidazole ring) in N–H...O hydrogen bonding for Histidine hydrochloride monohydrate were calculated via density functional theory. We considered a five-molecule model system of Histidine hydrochloride monohydrate. Also we examined the trends of environmental effect o...

We describe, for the first time, the application of magnetic circular dichroism (MCD) spectroscopy and time-dependent density functional theory (TD-DFT) calculations using B3LYP and M06-2X functionals to characterize the electronic transitions of endohedral metallofullerenes (EMFs). Results revealed that the electronic transitions of La@C(2v)-C(82), La(2)@I(h)-C(80), and Sc(3)N@I(h)-C(80) can b...

We employ a variety of highly-correlated approaches including quantum Monte Carlo (QMC) and the n-electron valence state perturbation theory (NEVPT2) to compute the vertical excitation energies of retinal protonated Schiff base (RPSB) models in the gas phase. We find that the NEVPT2 excitation energies are in good agreement with the QMC values and confirm our previous findings that the complete...

A-type procyanidin trimers cinnamtannin B-1, cinnamtannin D-1, lindetannin, and aesculitannin B were studied in terms of their conformation and interaction with four solvents: methanol, acetone, DMSO and pyridine. The experiments demonstrated that for each trimer there are two principal conformers observable in the NMR. The ratio of the conformers (rotamers) depends on the structure of a given ...

The potential energy surfaces of stacked structures consisting of adenine (A) and 2-aminopurine (2AP) have been investigated in the gas phase. Both faceto-back (the double-ring system of one base exactly on top of that of the other one) and face-to-face (one base flipped by 180 ) A/A, 2AP/2AP and A/2AP stacks were considered. Minima and transition states were optimised at the counterpoise-corre...

A theoretical study based on (U)M06-2X/cc-pVTZ calculations has been used to investigate the [3 + 3] thermal dimerization of nitrones to 1,4,2,5-dioxadiazinanes in both the gas phase and in dichloromethane solution. Calculations suggest that dimerization of nitrones takes place through a concerted mechanism involving a formal disallowed [4π + 4π] cycloaddition with a free energy barrier of 30.8...

In this theoretical work we analyze the noncovalent interactions of molecular complexes formed between the hydrogen bonded HF dimer and single-walled carbon nanotubes (SWCNTs) of different diameters. In particular, the interaction energies of: (i) spatially confined hydrogen fluoride molecules and (ii) HF dimer and the exterior or interior of SWCNTs are investigated. The computations are carrie...

(S)-Proline-catalyzed nitro-Michael additions of aldehydes and ketones to β-nitrostyrene were investigated computationally (MP2/6-311+G**//M06-2X/6-31G**). Contrary to what is usually assumed in organocatalysis, the lowest-energy transition states of proline-catalyzed nitro-Michael reactions do not necessarily involve the carboxylic acid group of the proline moiety directing the incoming nitroa...