Halogens in Acetophenones Direct the Hydrogen Bond Docking Preference of Phenol via Stacking Interactions

Phenol is added to acetophenone (methyl phenyl ketone) and to six of its halogenated derivatives in a supersonic jet expansion to determine the hydrogen bonding preference of the cold and isolated 1:1 complexes by linear infrared spectroscopy. Halogenation is found to have a pronounced effect on the docking site in this intermolecular ketone balance experiment. The spectra unambiguously decide between competing variants of phenyl group stacking due to their differences in hydrogen bond strength. Structures where the phenyl group interaction strongly distorts the hydrogen bond are more difficult to quantify in the experiment. For unsubstituted acetophenone, phenol clearly prefers the methyl side despite a predicted sub-kJ/mol advantage that is nearly independent of zero-point vibrational energy, turning this complex into a challenging benchmark system for electronic structure methods, which include long range dispersion interactions in some way.

Halogens in Acetophenones Direct the Hydrogen Bond Docking Preference of Phenol via Stacking Interactions

Phenol is added to acetophenone (methyl phenyl ketone) and to six of its halogenated derivatives in a supersonic jet expansion to determine the hydrogen bonding preference of the cold and isolated 1:1 complexes by linear infrared spectroscopy. Halogenation is found to have a pronounced effect on the docking site in this intermolecular ketone balance experiment. The spectra unambiguously decide between competing variants of phenyl group stacking due to their differences in hydrogen bond strength. Structures where the phenyl group interaction strongly distorts the hydrogen bond are more difficult to quantify in the experiment. For unsubstituted acetophenone, phenol clearly prefers the methyl side despite a predicted sub-kJ/mol advantage which is nearly independent of zero point vibrational energy, turning this complex into a challenging benchmark system for electronic structure methods which include long range dispersion interactions in some way.

The torsional states of methyl hydroperoxide molecule calculated using anharmonic zero point vibrational energy

The 2D surfaces of potential energy, kinematic coefficients, components of the dipole moment, the heights of potential barriers, the energies of stationary torsional states, and the tunneling frequencies of hydroxyl and methyl groups in the methyl hydroperoxide molecule were calculated at MP2/CBS and CCSD(T)/Aug-cc-pVTZ levels of theory. Additionally, calculations of the 2D surface of zero point vibrational energy of the molecule in the harmonic and anharmonic approximations were performed at MP2/Aug-cc-pVTZ level of theory. The zero point vibrational energy calculated in two approximations is summed up with the potential energy of the methyl hydroperoxide molecule, calculated at two levels of theory, and the resulting four outcomes of the refined potential energy are used to calculate the energies of stationary torsional states and tunneling frequencies. The results obtained are compared with the experimental and theoretical data presented in the literature to evaluate the efficiency of taking into account the zero point vibrational energy when examining the internal rotation in molecules.

DFT study of new organic materials based on PEDOT and 4-[2-(2-N, N-dihydroxy amino thiophene) vinyl] benzanamine

In the present study, we theoretically determine the optoelectronic, electronic, nonlinear optical (NLO) and thermodynamic properties of new materials from the conjugated polymer poly (3,4-ethylenedioxythiophene) (PEDOT) doped with halogens (Fluorine and Chlorine) combined with the organic semiconductor 4-[2-(2-N, N-dihydroxy amino thiophene) vinyl] benzamine (DATVB). The molecular geometry of the ground state, the optoelectronics and electronics parameters have been calculated by combining the 6-311++G (d, p) basis set with functionals of the density functional theory (DFT). The functionals B3LYP and the CAM-B3LYP have been used for NLO parameters. The energy gaps obtains for all the compounds are less than 3.0 eV. These results clearly show that PEDOT and its derivatives can be considerated as good semiconductors. They can be tested for use in the manufacture of organic solar cells (OSC) and organic light emitting diodes (OLED). The first order hyperpolarisabilities of these PEDOT hybrid compounds are much higher than those of the reference compound for NLO applications, namely para-nitroaniline (p-NA), which opens up a new field of application of PEDOT in NLO devices. The thermodynamic parameters such as the zero point vibrational energy (ZPVE), the enthalpy (H), the heat capacity at constant volume (Cv), the entropy (S) and the free energy (G) have been calculated and reported herein.

QM/electrostatics scheme for predicting optical properties of molecular crystals

In this contribution it is shown that modest calculations combining first principles evaluations of the molecular properties with electrostatic interaction schemes to account for crystal environment are reliable for predicting and interpreting the experimentally-measured electric linear and second-order nonlinear optical susceptibilities within the experimental error bars. This is illustrated by considering two molecular crystals, namely: 2-methyl-4-nitroaniline (MNA) and 4-(N,N-dimethylamino)-3-acatamidonitrobenzene (DAN) [1]. A good agreement between theory and experiment (see figure below for DAN) is achieved providing the electric field effects originating from the electric dipoles of the surrounding molecules are accounted for. The presentation will also i) highlight the key role of the geometry on the χ(1) and χ(2) responses, ii) demonstrate the impact of electron correlation on the molecular and crystal properties, iii) assess the performance of exchange-correlation functionals, and iv) address the amplitude of the zero-point vibrational energy contributions [2]. A second illustration will deal with the χ(1) and χ(2) responses of two anil crystals, [N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) and N-(3,5-di-tert-butylsalicy-lidene)-4-aminopyridine, which can switch between a enol (E) and a keto (K) form [3].