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Stabilizing ordered assemblies of molecules represents the first step towards the construction of molecular devices featuring hybrid (organic-inorganic) interfaces where molecules can be easily functionalized in view of specific applications. Molecular layers of planar metal-tetraphenylporphyrins (MTPP) grown on an ultrathin iron oxide [namely Fe(001)- p (1 × 1)O] show indeed a high degree of structural order. The generality of such a picture is tested by exploiting non-planar porphyrins, such as vanadyl-TPP (VOTPP). These molecules feature a VO 2+ ion in their center, with the O atom protruding out of the plane of the porphyrin ring. In this work, by employing diffraction, photoemission and X-ray absorption, we prove that non-planar VOTPP can nevertheless form a square and ordered superstructure, where porphyrin molecules lie flat with respect to the underlying substrate. Ab initio density functional theory simulations are used to elucidate the VO bond orientation with respect to the iron substrate.

Hybrid sp-sp 2 structures can be efficiently obtained on metal substrates via on-surface synthesis. The choice of both the precursor and the substrate impacts on the effectiveness of the process and the stability of the formed structures. Here we demonstrate that using anthracene-based precursor molecules on Au(111) the formation of polymers hosting sp carbon chains is affected by the steric hindrance between aromatic groups. In particular, by scanning tunneling microscopy experiments and density functional theory simulations we show that the de-metalation of organometallic structures induces a lateral separation of adjacent polymers that prevents the formation of ordered domains. This study contributes to the understanding of the mechanisms driving the on-surface synthesis processes, a fundamental step toward the realization of novel carbon-based nanostructures with perspective applications in nanocatalysis, photoconversion, and nano-electronics.

We present a joint experimental and theoretical characterization of the magnetic properties of coordination clusters with an antiferromagnetic core of four magnetic ions. Two different compounds are analyzed, with Co and Mn ions in the core. While both molecules are antiferromagnetic, they display different sensitivities to external magnetic field, according to the different atomic magnetic moments and strength of the intra-molecular magnetic couplings. In particular, the dependence of the magnetization versus field of the two molecules switches with temperature: at low temperature the magnetization is smaller in {Mn 4 } than in Co 4 , while the opposite happens at high temperature. Through a detailed analysis of the electronic and magnetic properties of the two compounds we identify a stronger magnetic interaction between the magnetic ions in {Mn 4 } with respect to {Co 4 }. Moreover {Co 4 } displays not negligible spin-orbit related effects that could affect the spin lifetime in future antiferromagnetic spintronic applications. We highlight the necessity to account for these spin-orbit effects together with electronic correlation effects for a reliable description of these compounds.

Glycodendron microarrays with defined valency have been constructed by on-chip synthesis on hydrophobic indium tin oxide (ITO) coated glass slides and employed in lectin-carbohydrate binding studies with several plant and human lectins. Glycodendrons presenting sugar epitopes at different valencies were prepared by spotwise strain-promoted azide-alkyne cycloaddition (SPAAC) between immobilised cyclooctyne dendrons and azide functionalised glycans. The non-covalent immobilisation of dendrons on the ITO surface by hydrophobic interaction allowed us to study dendron surface density and SPAAC conversion rate by in situ MALDI-TOF MS analysis. By diluting the dendron surface density we could study how the carbohydrate-lectin interactions became exclusively dependant on the valency of the immobilised glycodendron.

The recruitment of endogenous antibodies against cancer cells has become a reliable antitumoral immunotherapeutic alternative over the last decade. The covalent attachment of antibody and tumor binding modules (ABM and TBM) within a single, well-defined synthetic molecule was indeed demonstrated to promote the formation of an interacting ternary complex between both the antibodies and the targeted cell, which usually results in the simultaneous immune-mediated cellular destruction. In a preliminary study, we have described the first Antibody Recruiting Glycodendrimers (ARGs), combining cRGD as ligands for the αVβ3-expressing melanoma cell line M21 and Rha as ligand for natural IgM, and demonstrated that multivalency is an essential requirement to form this complex. In the present study, we synthesized a new series of ARGs composed of ABMs, i.e. self-condensed rhamnosylated cyclopeptide and polylysine dendrimer, which have been conjugated to the TBM with or without spacer. Flow cytometry and confocal microscopy experiments with human serum and different cell lines revealed that the ABM geometry significantly influences the ternary complex formation in M21, whereas no significant binding occurs in BT 549 having low integrin expression. In addition, we demonstrate with a cellular viability assay that ARGs induce high level of cytotoxicity against M21 which is also in close correlation with the ABM structure. In particular, we have shown that ARG combining cyclopeptide core and branches, with or without spacer, induce 40-57% of selective cytotoxicity against M21 cells in the presence of human serum as the unique source of immunity effectors. Finally, we also highlight that the spacer between ABM and TBM enables an increase of the immune-mediate cytotoxicity even with ABM of lower valency.

We analyse the spinterface formed by a C 60 molecular layer on a Fe(001) surface covered by a two-dimensional Cr 4 O 5 layer. We consider different geometries, by combining the high symmetry adsorption sites of the surface with three possible orientations of the molecules in a fully relaxed Density Functional Theory calculation. We show that the local hybridization between the electronic states of the Cr 4 O 5 layer and those of the organic molecules is able to modify the magnetic coupling of the Cr atoms. Both the intra-layer and the inter-layer magnetic interaction is indeed driven by O atoms of the two-dimensional oxide. We demonstrate that the C 60 adsorption on the energetically most stable site turns the ferromagnetic intra-layer coupling into an antiferromagnetic one, and that antiferromagnetic to ferromagnetic switching and spin patterning of the substrate could be possible by adsorption on other sites.

Antibody-recruiting molecules (ARMs) are one of the most promising tools to redirect the immune response towards cancer cells. In this review, we aim to highlight the recent advances in the field. We will illustrate the advantages of different ARM approaches and emphasize the importance of a multivalent presentation of the binding units., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The self-assembly of leucoquinizarin molecules on Au(111) surfaces is shown to be characterized by the molecules mostly being in their keto-enolic tautomeric form, with evidence of their temporary switching to other tautomeric forms. This reveals a metastable chemistry of the assembled molecules, to be considered for their possible employment in the formation of more complex hetero-organic interfaces.

The structure and electronic properties of carbon atom chains Cn in contact with Ag electrodes are investigated in detail with first principles means. The ideal Ag(100) surface is used as a model for binding, and electron transport through the chains is studied as a function of their length, applied bias voltage, presence of capping atoms (Si, S) and adsorption site. It is found that the metal-molecule bond largely influences electronic coupling to the leads. Without capping atoms the quality of the electric contact improves when increasing the carbon atom coordination number to the metal (1, 2 and 4 for adsorption on a top, bridge and hollow position, respectively) and this finding translates almost unchanged in more realistic tip-like contacts which present one, two or four metal atoms at the contact. Current-voltage characteristics show Ohmic behaviour over a wide range of bias voltages and the resulting conductances change only weakly when increasing the wire length. The effect of a capping species is typically drastic, and either largely reduces (S) or largely increases (Si) the coupling of the wire to the electrodes. Comparison of our findings with recent experimental results highlights the limits of the adopted approach, which can be traced back to the known gap problem of density-functional-theory.

The electronic and transport properties of graphene ribbons sandwiched between hydrogen dimer lines, of the kind recently realized by Nilsson et al., Carbon, 2012, 50, 2052, are investigated with the help of first principles methods. It is found that such lines of hydrogen atoms block conduction between neighboring channels and effectively allow the confinement of graphene charge carriers, thereby opening the possibility of imprinting nano-circuits in graphene by controlled hydrogenation.