The realization of molecule-based miniature devices with advanced functions requires the development of new and efficient approaches for combining molecular building blocks into desired functional structures, ideally with these structures supported on suitable substrates 1-4. Supramolecular aggregation occurs spontaneously and can lead to controlled structures if selective and directional non-covalent interactions are exploited. But such selective supramolecular assembly has yielded almost exclusively crystals or dissolved structures 5; the self-assembly of absorbed molecules into larger structures 6-8, in contrast, has not yet been directed by controlling selective intermolecular interactions. Here we report the formation of surface-supported supramolecular structures whose size and aggregation pattern are rationally controlled by tuning the non-covalent interactions between individual absorbed molecules. Using low-temperature scanning tunnelling microscopy, we show that substituted porphyrin molecules adsorbed on a gold surface form monomers, trimers, tetramers or extended wire-like structures. We find that each structure corresponds in a predictable fashion to the geometric and chemical nature of the porphyrin substituents that mediate the interactions between individual adsorbed molecules. Our findings suggest that careful placement of functional groups that are able to participate in directed non-covalent interactions will allow the rational design and construction of a wide range of supramolecular architectures absorbed to surfaces.

The Baeyer‐Villiger reaction of p‐anisaldehyde with peroxyacetic acid in nonpolar solvents to give p‐anisylformate was examined on the basis of ab initio molecular orbital calculations. To explain the experimental observations, the free‐energy change was evaluated for each case in the absence and in the presence of an acid catalyst. It was found that, without catalysts, the rate‐determining step corresponds to the carbonyl addition of peroxyacetic acid to p‐anisaldehyde and the reaction hardly occurs. Acetic acid was found to catalyze the carbonyl addition and change the rate‐determining step from the carbonyl addition to the migration of the carbonyl‐adduct intermediate. Trifluoroacetic acid was observed to catalyze both the carbonyl addition and migration, and the carbonyl addition was demonstrated to be a rate‐determining step. The results provided a convincing explanation of the complex kinetics seen experimentally. Further calculations were performed for the reaction of benzaldehyde with peroxyacetic acid to give phenylformate. Migratory aptitude was found to depend on the catalyst. Isotope effects were also investigated, and the exceptional isotope effect observed experimentally was shown to be due to the rate‐determining carbonyl addition caused by autocatalysis. It is concluded that the mechanism of the reaction varies with catalysis or substituent effects.

The mechanism of linear polyethylene formation catalyzed by palladium/phosphine−sulfonate and the effect of the ligand structure on the catalytic performance, such as linearity and molecular weight of the polyethylene, were reinvestigated theoretically and experimentally. We used dispersion-corrected density functional theory (DFT-D3) to study the entire mechanism of polyethylene formation from (R 2 PC 6 H 4 SO 3 )PdMe(2,6-lutidine) (R = Me, t-Bu) and elucidated the key steps that determine the molecular weight and linearity of the polyethylene. The alkylpalladium ethylene complex is the key intermediate for both linear propagation and β-hydride elimination from the growing polymer chain. On the basis of the key species, the effects of substituents on the phosphorus atom (R = t-Bu, i-Pr, Cy, Men, Ph, 2-MeOC 6 H 4 , biAr) were further investigated theoretically to explain the experimental results in a comprehensive manner. Thus, the experimental trend of molecular weights of polyethylene could be correlated to the ΔΔG ⧧ value between (i) the transition state of linear propagation and (ii) the transition state of the path for ethylene dissociation leading to β-hydride elimination. Moreover, the experimental behavior of the catalysts under varied ethylene pressure was well explained by our computation on the small set of key species elucidated from the entire mechanism. In our additional experimental investigations, [o-Ani 2 PC 6 H 4 SO 3 ]PdH[P(t-Bu) 3 ] catalyzed a hydrogen/ deuterium exchange reaction between ethylene and MeOD. The deuterium incorporation from MeOD into the main chain of polyethylene, therefore, can be explained by the incorporation of deuterated ethylene formed by a small amount of Pd−H species. These insights into the palladium/phosphine−sulfonate system provide a comprehensive understanding of how the phosphine−sulfonate ligands function to produce linear polyethylene.

The purpose of this study was to evaluate the immediate and long-term results in 63 patients who underwent transarterial embolization for control of hemoptysis. Overall immediate success rate was 86.1%. At long-term follow-up 50% of patients showed complete remission, 22% partial remission, and 28% recurrent hemoptysis. Hemoptysis remained controlled for a mean of 22 months and a median of 14 months. The long-term results among four disease groups differed substantially. Patients with bronchiectasis showed the best results, followed by those with idiopathic disease and with inflammation; patients with neoplasm showed the worst results.