Triangular exo-polydentate ligands have been frequently employed for the metal-directed assembly of coordination polyhedra. [1][2][3][4] By linking triangles at their corners or edges, a family of polyhedral structures can in principle be engaged at will. Here, we design a triangular panel-like ligand with four donor sites on the two edges of the triangle (two donor sites on each edge): namely, compound 1 in Scheme 1. Having two-point binding sites on its two edges, this triangular unit is expected to assemble into edgesharing polyhedral entity upon complexation with (en)Pd(NO 3 ) 2 (2), which is a versatile 90°coordination unit for metal-directed assembly. Whereas previous triangular ligands all possess C 3 symmetry, 1-4 panel 1 is C 2 -symmetric and hence can be linked in two different ways: parallel and antiparallel links. Interestingly, these two options were perfectly controlled by the guests. 5 We show that some large guests induce the parallel link of the triangles leading to open cone (tetragonal pyramidal) structure 3, whereas antiparallel link is selected by some small tetrahedral guests giving closed tetrahedron structure 4 (Scheme 1). Both assemblies have the same M 8 L 4 composition and, therefore, constitute a dynamic receptor library 6,7 from which each receptor is selected by its optimal guests.The quantitative assembly of M 8 L 4 open cone 3 was induced by large guest molecules such as dibenzoyl (5). Thus, ligand 1
Only one positional isomer is obtained from the assembly of 21 small components. A triangular molecular panel with five coordination sites is assembled upon complexation with [PdII(en)] (en=ethylenediamine) into a unique M15L6 hexahedral coordination capsule (see X‐ray structure). The capsule can encapsulate/exchange organic guests reversibly through the clefts at the nonbinding sites of the capsule.
Despite their structural similarity, triangular tetradentate ligands 2b and 2c experience different assembly pathways on complexation with (en)Pd(NO3)2 to give M8L4 tetrahedral (3) and open cone (4) structures, respectively, due to steric restriction by side chains at the corner or on the edge of the ligands.
The dehydrogenative polymerization of coniferyl alcohol by horseradish peroxidase was performed in 0.10 M phosphate buffer at 27 degrees C. Dehydrogenative polymer (DHP) from coniferyl alcohol was characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. The ratio of 8-O-4':8-5':8-8' linkages was determined by the 1H NMR spectrum of DHP acetate which had good solubility. In "end-wise like" polymerization (the slow addition of hydrogen peroxide), addition of alpha-cyclodextrin to the medium led to DHP with increased 8-O-4' content and a decrease in 8-5' linkages. Under higher pH conditions, DHP with higher 8-O-4' and 8-5' content was obtained in the presence of alpha-cyclodextrin. In the end-wise polymerization (the slow additions of coniferyl alcohol and hydrogen peroxide), using alpha-cyclodextrin also gave DHP with a 8-O-4' richer structure than that prepared in no additive system. The analysis of thioacidolysis products from DHP supported the results of the alpha-cyclodextrin effects on the 8-O-4'-rich structure of DHP. The 8-O-4' structure in DHP prepared in the presence of alpha-cyclodextrin had racemic form as shown by ozonation.
We use molecular dynamics (MD) simulations to investigate the wettability of AlO (0001) by organic molecules. Diffusion coefficients estimated for organic molecules are clearly correlated with the contact angles observed experimentally. The results of the MD simulations suggest that molecular flexibility influences wettability. In other words, wettability owing to flexible molecules, such as an epoxy tridecamer, improves with increasing temperature because the interaction between the droplet and the surface increases due to changes in molecular conformation. Conversely, for phenylene sulfide tetramer, wettability does not change with temperature because of the molecular rigidity. In addition, for epoxy monomers, we analyze the different molecular structures responsible for modifying the droplet-surface interaction. For hydrogens in aromatic rings and in methyl groups, the interaction with the surface clearly decreases with increasing temperature.
Ein einziges Positionsisomer wurde bei der Selbstorganisation von 21 Komponenten erhalten. Die Ligandenkomponente L ist ein „molekularer Dreispitz“ mit fünf Koordinationsstellen, der mit [PdII(en)] (en=Ethylendiamin) als Metallkomplexkomponente M das im Bild gezeigte hexaedrische M15L6‐Gerüst aufbaut. Dieser supramolekulare Komplex weist drei Spalten auf, in denen reversibel Gastmoleküle gebunden werden können.
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