A photoelectron circular dichroism (CD) study of the valence states of 2-amino-1-propanol (alaninol) in the gas phase is presented. The aim of the investigation is to reveal conformer population effects in the valence-state photoelectron spectrum. The experimental dispersion of the dichroic D parameter of valence states as a function of the photon excitation energy is compared with its theoretical value calculated by employing a multicentric basis set of B-spline functions and a Kohn-Sham Hamiltonian. The theoretical values are in very good agreement with the experimental data when the conformer population distribution is taken into account. Moreover, thanks to a comparison between experiment and theory, a clear assignment of the molecular orbital character and conformer geometry is given to the features of the photoelectron spectrum. This work indicates in a detailed experimental analysis that CD in photoelectron spectroscopy is an effective technique to disentangle the conformer assignment in photoelectron spectra.

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We have used density functional theory calculations, including a correction for the dispersive forces (DFT-D), to investigate the formation of a monolayer superstructure of uracil molecules adsorbed on the Au(100) surface. Our calculations provide insight into the interplay between lateral adsorbate adsorbate and vertical adsorbate substrate interactions, where we found that uracil adsorption to the surface is strongly dependent on the lateral interactions, particularly hydrogen bonding, although the first adsorbed molecule, before the formation of a uracil network, is covalently bonded to the surface. The self-assembly of the uracil network on the surface is mediated by proton transfer, and the ensuing charge separation stabilizes the geometry. Dispersive forces also play a role, and in particular, the introduction of a correction leads to flatter geometries with molecules lying parallel to the surface, thereby enhancing pi-pi stacking and hydrogen-bonding

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Valence band and C 1s core-level photoelectron spectra of S-(+)-2-amino-1-propanol (alaninol) and S-(+)-1-amino-2-propanol (isopropanolamine) have been studied by means of synchrotron radiation photoelectron spectroscopy in gas phase. The alaninol, the reduced derivative of the alanine, is a good test system of amino acid-like structures. The isopropanolamine, presenting the inversion of the two functional groups of the alaninol at the chiral carbon, offers the opportunity to study the effect of -OH and -NH(2) structural position on the photoelectron spectra. The influence of the conformational contribution on the electronic structure and the photoelectron spectra has been interpreted using density functional and ab initio theoretical calculations. Agreement has been achieved by taking into account the presence, in gas phase, of two conformers with different population ratios in both chiral systems. The C 1s core-level spectra of alaninol and isopropanolamine are reported and the peak positions of the three carbon atoms of the molecules are assigned.

We report the results of chemisorption in saturating conditions of D-alaninol on Cu(100) in term of the analysis of low-energy electron diffraction and scanning tunneling microscopy data. A large two-dimensional, single domain, ordered chiral structure of quadrangular tetrameric molecular units is formed. The four molecules interact differently with the surface in the two orthogonal directions.

The lattice energies of the experimental and several hypothetical crystal structures of the RNA base uracil derivative 5-formyluracil are calculated with a range of methods, based either on the electronic structure of the molecule or the lattice. The explicit modeling of the polarization within the crystal in the model intermolecular potential and the inclusion of an empirical dispersion correction to the periodic density functional energy (DFT-D2) were the only methods able to calculate the energy balance between different conformations, hydrogen bonding, and π-π stacking possibilities sufficiently accurately to give the observed structure as the most stable. Even these two methods underestimated the density of the room temperature structure, showing the need for improvement in the modeling of organic crystal structures.

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