Growth of regular nanometric molecular arrays on a functional 2D template based on a chemical guest-host approach

Coronene guest molecule selectivity in host templates formed by hydrogen bonding and van der Waals forces at liquid/solid interfaces

COR guest molecules are selectively adsorbed in the hexagonal cavities in both H6PDB and H6PAB self-assembled systems and preferentially adsorbed in the H6PAB host template in the H6PAB/HPB system.

Ba+2 ion trapping using organic submonolayer for ultra-low background neutrinoless double beta detector

If neutrinos are their own antiparticles the otherwise-forbidden nuclear reaction known as neutrinoless double beta decay can occur. The very long lifetime expected for these exceptional events makes its detection a daunting task. In order to conduct an almost background-free experiment, the NEXT collaboration is investigating novel synthetic molecular sensors that may capture the Ba dication produced in the decay of certain Xe isotopes in a high-pressure gas experiment. The use of such molecular detectors immobilized on surfaces must be explored in the ultra-dry environment of a xenon gas chamber. Here, using a combination of highly sensitive surface science techniques in ultra-high vacuum, we demonstrate the possibility of employing the so-called Fluorescent Bicolor Indicator as the molecular component of the sensor. We unravel the ion capture process for these molecular indicators immobilized on a surface and explain the origin of the emission fluorescence shift associated to the ion trapping.

Revealing the electronic properties of the B-B bond: the bis-catecholato diboron molecule

The electronic properties of a diboron molecule, namely bis(catecholato)diboron (2-(1,3,2-benzodioxaborol-2-yl)-1,3,2-benzodioxaborole) (B₂Cat₂), have been studied by comparing the results of photoemission (XPS) and near edge X-ray absorption spectroscopy (NEXAFS) experiments with the outcome of DFT calculations. The B 1s, C 1s and O 1s K-edges have been investigated for both the isolated gas phase molecule and the adsorbed one on the Au(111) surface. The main features of the polarized NEXAFS spectra at each of the three edges considered are not significantly affected by the presence of the substrate, with respect to the isolated molecule, indicating that the molecule-gold interaction is weak. Moreover, the comparison between the observed dichroism in the NEXAFS spectra of the adsorbed B₂Cat₂ and that in the NEXAFS spectra of the isolated molecule has confirmed the orbital symmetry assigned in the gas phase absorption spectra. The transitions to π(B-B) bonding and π*(B-B) anti-bonding final states represent the most relevant probe of the chemistry of the B₂Cat₂ molecule. We show that their theoretical description requires that the treatment of the relaxation changes among different excited state configurations, which we successfully implemented by using ΔSCF-DFT (ΔSCF) calculations.

On-surface trapping of alkali atoms by crown ethers in ultra high vacuum

Crown ethers, assembled into a regular 2D array via a chemical guest-host recognition process, have been successfully employed to trap sodium atoms on a surface, under ultra-high vacuum conditions.

On-surface synthesis of a 2D boroxine framework: a route to a novel 2D material?

The synthesis of a 2D boroxine covalent framework is described, which exhibits promising morphological and electronic properties.