Triple Linkage of Two Homooxacalix[3]arenes Creates Capsular Molecules and Self-Threaded Rotaxanes

Triple Linkage of Two Homooxacalix[3]arenes Creates Capsular Molecules and Self-Threaded Rotaxane

A General Semisynthetic Method for Fluorescent Saccharide-Biosensors Based on a Lectin

A General Semisynthetic Method for Fluorescent Saccharide-Biosensors Based on a Lecti

Silica Transcription in the Absence of a Solution Catalyst: The Surface Mechanism

Transcription of organic templates into shapely inorganic materials is generally believed to occur because of charge or hydrogen bonding interactions between the template and the inorganic precursor; the formation of the inorganic material is always promoted by a catalyst present in solution. In this paper, we prove for the first time the existence of a so-called surface mechanism, which allows the transcription process to take place via initiated formation of the inorganic material (here silica) exclusively on the template surface. Further growth of the inorganic material takes place solely on this surface, resulting in an inorganic product containing only templated silica and no granular (i.e., untemplated) product

A Stable Single Piece of Unimolecularly π-Stacked Porphyrin Aggregate in a Thixotropic Low Molecular Weight Gel: A One-Dimensional Molecular Template for Polydiacetylene Wiring up to Several Tens of Micrometers in Length

An amide-type copper porphyrin gelator having alkyldiacetylene tethers gives very transparent gel in Decalin, and the gel shows unique thixotropic behavior. One-dimensional aggregates generated in the gel act as templates for unimolecularly segregated polydiacetylene wiring upon UV irradiation on the surface. The polymerization along the aggregation goes to at least several micrometers long

[60]Fullerene-Motivated Organogel Formation in a Porphyrin Derivative Bearing Programmed Hydrogen-Bonding Sites

A tetraphenylporphyrin (1b) bearing amide groups at the 3,5-positions of the meso-phenyl groups is assembled into a two-dimensional sheetlike structure and acts as an organogelator. When [60]fullerene was added, the sheetlike structure was dramatically changed into a one-dimensional fibrous structure, and both the gelation ability and the gel stability were improved. The stoichiometry between [60]fullerene and 1b was determined to be 1:2. Examination utilizing SEM and TEM observations, UV−vis and ATR IR spectral analyses, and XRD analysis revealed that an amide−amide hydrogen-bonding interaction creates a cavity, the size of which is complementary to that of [60]fullerene, and these cavities are connected by another amide−amide hydrogen-bonding interaction to provide a one-dimensional multicapsular structure. This is a novel example that the superstructure constructed in an organogel system is drastically changed by added [60]fullerene

Selective Deposition of Metal Complex Nanocrystals onto the Surfaces of Organic Single Crystals Bearing Pyridine Moieties

Nanocrystals of a palladium complex 3 were deposited onto the specific surfaces of the single crystals of CT complex (CT1) between pyrene and naphthyldiimide bearing pyridine groups. They were characterized by X-ray powder diffraction (XRD) and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). Nanocrystals of 3 were deposited selectively onto {011̅} faces. Comparison between the crystal structures and deposition preference of the crystal faces revealed that deposition of 3 occurred on the most hydrophobic face of the single crystals of CT1 that exposed no pyridine moieties. This indicated that accessibility or coordination of metal complexes to the pyridine moieties apparently suppressed deposition of the nanocrystals. As a result, the nanocrystals were easily deposited onto the hydrophobic crystal surfaces, and rapid growth provides the thin-film decoration of the selective crystal faces

A Coordination Gelator That Shows a Reversible Chromatic Change and Sol−Gel Phase-Transition Behavior upon Oxidative/Reductive Stimuli

A novel coordination gelator exhibits reversible chromatic and sol−gel phase-transition phenomena triggered by thermal and chemical stimuli

Allosteric Silver(I) Ion Binding with Peripheral π Clefts of a Ce(IV) Double Decker Porphyrin

A cerium(IV) double decker porphyrin (1) bearing four 4-methoxyphenyl groups was synthesized. Compound 1 shows a positive, homotoropic allosteric effect in metal recognition of Ag+ ion, and the peripheral π clefts of 1 act as effective binding sites for Ag+ ion

Nano-Rod Structure of Poly(ethylenedioxythiophene) and Poly(pyrrole) As Created by Electrochemical Polymerization Using Anionic Porphyrin Aggregates as Template

It was found that a one-dimensional rodlike structure of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) in water acts as a powerful template for electrochemical polymerization of ethylenedioxathiophene (EDOT) and pyrrole on an ITO electrode. Examination using CV and UV−vis spectroscopic examinations established that J-aggregated TPPS molecules are entrapped in the resultant poly(EDOT) and poly(pyrrole) films. SEM observation established that these monomers are electrochemically oxidized to grow up to a nanosized rodlike structure, reflecting the aggregation structure of TPPS

Direct Observation of the Ferric-Porphyrin Cation Radical as an Intermediate in the Phototriggered Oxidation of Ferric- to Ferryl-Heme Tethered to Ru(bpy)₃ in Reconstituted Myoglobin

Using semisynthetic myoglobins (Ru(bpy)3-Mbs) with covalently appended Ru(bpy)3 (bpy = 2,2‘-bipyridine), an oxidized Mb is photoproduced through an intramolecular electron abstraction reaction as a key step. UV−vis spectra, electron paramagnetic resonance measurements, and reactivity tests identify the photooxidized Mb as a ferryl species (i.e., Fe4+-heme). By circular dichroism (CD) spectroscopy, high-performance liquid chromatography (HPLC), and SDS−polyacrylamide gel electrophoresis (SDS−PAGE), it was confirmed that the photooxidation proceeds without damage of the protein structure. Significantly, we report the first direct observation of ferryl-Mb photogeneration via the intermediate porphyrin cation radical. As a consequence of this observation and proposed mechanism, the rate constants for each step can be clearly determined. The photoexcited Ru2+(bpy)3 is oxidatively quenched by [Co(NH3)5Cl]2+, a sacrificial acceptor, to produce Ru3+(bpy)3, which then proceeds to abstract an electron from the porphyrin ring with a first-order rate constant of 7.1 × 105 s-1, in the first step. The electron transfer is followed by iron(III) oxidation by the porphyrin radical with concurrent deprotonation (a first-order rate constant of 4.0 × 104 s-1 at pH 7.5, and 2.0 × 105 s-1 at pH 9.0) in the second step. Consistent with this mechanism, it is demonstrated that the rate of the fast step of the porphyrin radical generation is independent of pH, whereas the slower step of ferryl-heme formation is dependent on pH. Simulation of the detailed pH dependence of the kinetics clearly shows that the deprotonation−protonation equilibrium of the protein matrix can control the ferryl-heme generation in a heme pocket of Mb