Synthesis and Chiroptical Properties of Chiral Carbazole-Based BODIPYs

A series of carbazole-based boron dipyrromethenes (BODIPYs) 2 a – g bearing binaphthyl units have been synthesized by the Et₂AlCl-mediated reaction of the corresponding BODIPY difluorides 1 a – g with 1,1′-binaphthalene-2,2′-diol. Substituents such as halogen, nitrile, and amino groups were tolerated under the reaction conditions, and the reaction of the phenylethynyl-substituted 1 h gave (R,R)- 3 h bearing two binaphthyl units. The chiroptical properties of these dyes with different substituents were investigated by UV/Vis, CD, fluorescence, and circularly polarized luminescence (CPL) spectroscopy. The CD spectra showed Cotton effects in the absorption region of the BODIPY moieties. In addition, they showed CPL both in solution and in the solid state. Interestingly, several dyes recorded higher g_lum values in the solid state, probably due to intermolecular interactions. Because (R,R)- 3 h recorded relatively low g_lum values, the diastereomer (R,S)- 3 h was prepared. The (R,S) diastereomer showed intense CPL, which suggests a synergetic effect of the two binaphthyl groups. Finally, chiral carbazole-based BODIPY dimers have been synthesized for the first time and their chiroptical properties were investigated. They showed redshifted fluorescence and CPL, which reached the near-IR (NIR) region in the solid state.     

Ferroelectric Coordination Polymers Self‐Assembled from Mesogenic Zinc(II) Porphyrin and Dipolar Bridging Ligands

A new class of ferroelectric coordination‐based polymers has been developed by the self‐assembly of lipophilic zinc porphyrin ( ZnP ) and ditopic bridging ligands. The ligands contain dipolar benzothiadiazole or fluorobenzene units, which are axially coordinated to ZnP with the dipole moments oriented perpendicular to the coordination axes. The coordination‐based polymers show ferroelectric characteristics in the liquid crystalline state, as revealed by distinctive hysteresis in the polarization–electric field (P–E) loops and inversion current peaks in current–voltage (I–V) loops. The observed ferroelectric properties are explainable by flip–flop rotation of the dipolar axle ligands induced by the applied electric field, as demonstrated by the positive‐up–negative‐down (PUND) measurements. The present system provides a new operating principle in supramolecular ferroelectrics.     

Some Observations on the Impact of a Low-Solubility Ionic Solution on Drying Characteristics of a Model Porous Medium

Transport in Porous Media - We study the impact, on the drying rate, of the presence of suspended elements, such as calcium sulfate ions, in the interstitial fluid of a porous medium. In order to...     

Facile Fabrication of Concentrated Polymer Brushes with Complex Patterning by Photocontrolled Organocatalyzed Living Radical Polymerization

Photocontrolled surface‐initiated reversible complexation mediated polymerization (photo‐SI‐RCMP) was successfully applied to fabricate concentrated polymer brushes with complex patterning structures. Positive‐type patterned polymer brushes were obtained by photo‐SI‐RCMP under visible light (550(±50) nm) using photomasks. A particularly interesting finding was that negative‐type patterned polymer brushes were also obtainable in a facile manner. A nonspecial UV light (250–385 nm) enabled the preparation of pre‐patterned initiator surfaces in a remarkably short time (1 min), leading to negative‐type patterned polymer brushes. Based on this unique selectivity between visible and UV light, the combination of two patterning techniques enabled the preparation of complex patterned brushes, including diblock copolymers, binary polymers, and functional binary polymers, without multistep immobilization of one or more initiators on the surfaces.     

Bismuth-catalyzed intramolecular carbo-oxycarbonylation of 3-alkynyl esters

Borderline metal complexes, especially Bi(OTf)3, efficiently catalyze the carbo-oxycarbonylation of alkynyl esters to form multisubstituted lactones in moderate to high yields.     

Relative and absolute stereochemistry of quinadoline B, an inhibitor of lipid droplet synthesis in macrophages

New fungal metabolites, designated quinadolines A (1) and B (2), were isolated from culture broth of Aspergillus sp. FKI-1746, and their structures were elucidated by NMR spectroscopy. The complete relative and absolute stereochemistry of 2 was determined by X-ray crystallography and amino acid analysis using a chiral column. Quinadolines moderately inhibited lipid droplet synthesis in mouse macrophages.     

Nanomechanical properties of reversed surfactant bilayers formed in micrometre-sized holes

Nanomechanical properties of free-standing reversed surfactant bilayers, dried foam films (DFFs), were examined via AFM by fitting local force-indentation curves with a Hertzian model. The Young's moduli of four kinds of bilayers were in a range of 10-30 MPa.     

Lipid-packaged linear iron(II) triazole complexes in solution: controlled spin conversion via solvophobic self-assembly

Linear Fe(II) 1,2,4-triazole complexes with lipid counteranions are newly developed. These complexes show sharp and reversible spin conversion in toluene, with temperatures significantly higher (by 20-100 K) than the spin crossover temperatures observed in the crystalline states. This is accounted for in terms of increased metal-ligand interactions in organic media, which is caused by solvophobic compaction of charged coordination chains. In atomic force microscopy, developed nanowires are observed for low spin (LS) complexes. On the other hand, fragmented nanostructures are seen for high spin (HS) complexes, indicating that the spin conversion in solution is governed by a self-assembly process. The lipid packaging of charged coordination chains thus provides powerful means to improve and regulate their functions via solvophobic self-assembly.