The gelling ability of some geminal imidazolium salts was investigated both in organic solvents and in water solution. Organic salts differing either in the cation or anion structure were taken into account. In particular, the effects on the gel‐phase formation of isomeric substitution on the cation or anion as well as of the use of mono‐ or dianions were evaluated. As far as the cation structure is concerned, isomeric cations, such as 3,3′‐di‐n‐octyl‐1,1′‐(1,4‐phenylenedimethylene)diimidazolium and 3,3′‐di‐n‐octyl‐1,1′‐(1,3‐phenylenedimethylene)diimidazolium, were used. On the other hand, in addition to the bromide anion, isomeric dianions, such as the 1,5‐ and 2,6‐naphthalenedisulfonate anions, were also examined. After preliminary gelation tests, different factors affecting the obtained gel phases, such as the nature of the solvent, organogelator concentrations, and action of external stimuli, were analyzed. The gel‐phase formation was also studied as a function of time, by using resonance light scattering measurements. Gel morphologies were analyzed by scanning electron microscopy. To further support the understanding of the different behavior shown by the isomeric cations, some representative ion pairs were analyzed by DFT‐based investigations. The collected data underline the significant role played by isomeric substitution of both cation and anion structures in determining the gelling capability of the investigated salts, as well as the properties of the gel phases. Finally, DFT investigations were helpful in the identification of the structural features affecting the self‐assembly.

The processes of adsorption, fragmentation and diffusion of hydrogen on a small palladium cluster have been investigated by means of DFT and DFT/MM approaches. These studies have been performed by considering a D(3h) symmetry Pd(9) in the isolated state as well as when supported on a portion of single-walled armchair(6,6) carbon nanotube. The hydrogen fragmentation process easily occurs on the bare Pd(9) cluster, involving energy barriers of 25-35 kJ mol(-1) and the drop in spin multiplicity on passing from the reactant to the product. The atomic hydrogen diffuses through the cluster atoms with energy barriers, which do not exceed 20 kJ mol(-1), with some positions clearly identifiable as the most stable. In the case of the palladium supported system, which is a better model to simulate experimental conditions, calculations predict that the hydrogen fragmentation barrier is reduced by ca. 15 kJ mol(-1), with respect to that of the unsupported system, while the energetics of the diffusive process is not significantly affected by the support, if the reduction of the number of sites available in the same palladium cluster, as well as their geometry, are taken into account.

DFT calculations have been performed on a palladium cluster adsorbed on two different carbonaceous supports, namely, two stacked polycircumcoronene units mimicking a double layer of graphite and a portion of an armchair (6,6) carbon nanotube. All of the systems have been subjected to geometry optimization and electronic structure investigation. This work, which is part of an extensive computational study on heterogeneous catalytic systems, is devoted to identify electronic and geometrical changes in which metal clusters and supports are involved upon interaction. Such analysis is helpful in designing new heterogeneous metallic catalysts, namely, new metal-supported carbonaceous catalysts. Calculations reveal a major geometrical distortion occurring in the palladium cluster supported on both graphite and nanotubes, which is caused by strong Pd-C interactions. The curvature of the nanotube surface seems to provide the basis for a stronger interaction with respect to the flat surface of graphite. This evidence is also pointed out by the atomic orbital overlap occurring between the cluster and the nanotube, as revealed by the density of states analysis.

Density Functional Theory calculations were employed to investigate the nucleation and growth of small palladium clusters, up to Pd 9 , into a microcavity of the porous hypercrosslinked polystyrene (HPS). The geometries and the electronic structures of the palladium clusters inside the HPS cavity, following the one-by-one atom addition, are affected by a counterbalance between the Pd-phenyl (Pd-F) and Pd-Pd interactions. The analysis performed on energetics, cavity distortions and cluster geometries indeed suggest that the cluster growing is dominated by the Pd-F interactions up to the formation of Pd 4 aggregates, while the metal-metal interactions are actually ruling the growth of the larger clusters. The elasticity of the hypercrosslinked polystyrene matrix plays also an important role in the cluster development processes.

The Ge(II) complexes [GeX(2)(L-L)] (L-L = 1,10-phen (X = Cl, Br); L-L = Me(2)N(CH(2))(2)NMe(2), 2,2'-bipy (X = Cl)), [GeX(L-L)][GeX(3)] (L-L = 2,2'-bipy (X = Br); L-L = pmdta (MeN(CH(2)CH(2)NMe(2))(2)) (X = Cl, Br)) have been prepared and their crystal structures determined. The crystal structure of [GeCl(2){Me(2)N(CH(2))(2)NMe(2)}] shows a weakly associated centrosymmetric dimer based upon distorted square-pyramidal coordination at Ge(II) and containing asymmetrically chelating diamine ligands. The structure of [GeCl(2)(2,2'-bipy)] contains a chelating 2,2'-bipy ligand and forms a zig-zag chain polymer via long-range intermolecular Ge...Cl bridging interactions, leading to a very distorted six-coordinate environment at Ge. [GeCl(2)(1,10-phen)] adopts a weakly associated dimeric structure similar to that in [GeCl(2){Me(2)N(CH(2))(2)NMe(2)}], whereas [GeBr(2)(1,10-phen)] is again a zig-zag polymer similar to [GeCl(2)(2,2'-bipy)]. [GeBr(2,2'-bipy)][GeBr(3)] contains a pyramidal cation with a chelating 2,2'-bipy and a terminal Br ligand and with long-range contacts involving the three Br atoms in the anion. [GeX(pmdta)][GeX(3)] (X = Cl or Br) show discrete cations and anions, with no significant long-range interactions. The bonding in these systems can be described as covalent, with longer range interactions to other ligands involving the 4p orbitals of Ge. DFT calculations performed on [GeCl(2)(2,2'-bipy)] show that the geometry of the monomer unit in the experimental crystal structure does not correspond to the global minimum of the isolated molecule, but to a higher energy minimum. In contrast, the calculated structure of the tetramer shows some of the main structural characteristics observed in the crystal structure.

Different investigations, such as 1D and 2D NMR spectroscopy, resonance light scattering spectroscopy and molecular dynamics simulations, have been jointly used to achieve a deeper understanding of the degree of structural order in two geminal ionic liquids. In particular, 3,3'-di-n-butyl-1,1'-(1,3-phenylenedimethylene)diimidazolium and 3,3'-di-n-butyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis[bis(trifluoromethanesulfonyl)imide] have been studied. These geminal ionic liquids were chosen because of the presence of both a rigid phenylenedimethylene link between two imidazolium rings, which should give a high degree of order to the solvent system, and the different shapes of the two cations of the isomers, which could induce different properties and packing in the liquid state. Data collected here show that the two geminal ionic liquids are characterised by a different degree of structural order that induces, for example, a different sensitivity of the two solvent systems to temperature changes or to the presence of a co-solvent such as methanol.

The structure of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and that of urea containing AOT reversed micelles has been investigated by small-angle neutron scattering (SANS) and Fourier transform infrared (FT-IR) spectroscopy at different AOT concentrations and urea/AOT molar ratios. For the AOT/n-heptane system, SANS data analysis indicates that AOT molecules form prolate ellipsoidal aggregates, which grow asymmetrically along the major axis upon increasing the surfactant concentration. For the urea/AOT/ n-heptane system, the SANS results are consistent with the hypothesis that urea is encapsulated as small-sized ellipsoidal hydrogen-bonded clusters within the hydrophilic micellar core of the AOT reversed micelles. The insertion of urea in the micellar core causes a significant increase of the aggregate size along the minor-axis direction. FT-IR data indicates that, quite independently from the urea and AOT concentrations, the encapsulation of urea clusters in the AOT micellar core involves some changes of the H-bonded structure characterizing pure solid urea. This structural change was rationalized in terms of the specific interactions between the urea NH2 and the AOT SO3groups in small-sized urea clusters. Moreover, the CO stretching mode analysis suggests that within the cluster the urea CO groups interact with the urea NH 2 groups whereas the AOT CO groups do not.

We report on the application of three-coordinate organoboron polymers, inherently strong electron acceptors, in flexible photovoltaic (PV) cells. Poly[(1,4-divinylenephenylene)(2,4,6-triisopropylphenylborane)] (PDB) has been blended with poly(3-hexylthiophene-2,5-diyl) (P3HT) to form a thin film bulk heterojunction (BHJ) on PET/ITO substrates. Morphology may be modulated to give a high percentage of domains (10-20 nm in size) allowing exciton separation. The photoelectric properties of the BHJs in devices with aluminium back electrodes were imaged by light beam induced current (LBIC) and light beam induced voltage (LBIV) techniques. Open circuit voltages, short circuit currents and overall external quantum efficiencies obtained are among the highest reported for all-polymer PV cells.