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We explore a connection between the static molecular polarizability and the molecular conductance that arises naturally in the description of electrified molecular interfaces and that has recently been explored experimentally. We have tested this idea by using measured conductance of few different experimental design motifs for molecular junctions and relating them to the molecular polarizability. Our results show that for a family of structurally connected molecules the conductance decreases as the molecular polarizability increases. Within the limitations of our model, this striking result is consistent with the physically intuitive picture that a molecule in a junction behaves as a dielectric that is polarized by the applied bias, hence creating an interfacial barrier that hinders tunneling. The use of the polarizability as a descriptor of molecular conductance offers significant conceptual and practical advantages over a picture based on molecular orbitals. To further illustrate the plausibility of th...

NMR-based techniques are supposed to be incapable of distinguishing pure crystalline chemical enantiomers. However, through systematic studies of cross-polarization magic angle spinning (CP-MAS) NMR in a series of amino acids, we have found a rather unexpected behavior in the intensity pattern of optical isomers in hydrogen/nitrogen nuclear polarization transfer that would allow the use of CP NMR as a nondestructive enantioselective detection technique. In all molecules considered, the d isomer yields higher intensity than the l form, while the chemical shift for all nuclei involved remains unchanged. We attribute this striking result to the onset of electron spin polarization, accompanying bond charge polarization through a chiral center, a secondary mechanism for polarization transfer that is triggered only in the CP experimental setup. Electron spin polarization is due to the chiral-induced spin selectivity effect (CISS), which creates an enantioselective response, analogous to the one involved in molecular recognition and enantiospecific separation with achiral magnetic substrates. This polarization influences the molecular magnetic environment, modifying the longitudinal relaxation time T1 of 1H, and ultimately provoking the observed asymmetry in the enantiomeric response.

Hydrogen bonds (H-bonds) are relatively weak and result from non- covalent interactions. Despite their relatively low strength compared to other bonds of biochemical relevance, they play a vital role in determining the structure and function of biological molecules owing to their directionality and cooperativeness. This has led to an intense effort in harnessing the properties of these hydrogen bonds in developing organic electronic devices. Though a large number of theoretical investigations have devoted their attention to the structural andenergeticcharacteristicsofhydrogenbonds,therearerelativelyfewstudieson theelectronictransportcharacteristicsofhydrogenbonds.Inthisworkweevaluate the electrical conductance of a few model systems exhibiting the biologically important hydrogen bonds (N-H O, O-H O and N-H N). We find that the calculated conductance can be correlated to the magnitude of the polarisabilities of the atoms involved in the formation of the hydrogen bonds. The implications of the current work in understanding electron transfer in biological systems is highlighted.Wealsoaddresstheutilityofourworkinthedesignanddevelopment of novel sensors and electronic devices based on the formation of weak hydrogen bonds.