Soluble and processable thermoplastic hybrid polyimides containing POSS in main chains

The combination of 3,13-bis(3-aminopropyl)-double-decker-shaped-silsesquioxane and a fluorinated dianhydride produces a flexible polyimide with a low Tg, high heat resistance, and excellent solvent solubility. The fluorinated dianhydride loosened the interchain packing to suppress CT interactions, leading to the formation of a colorless polyimide.

Unsymmetric Dumbbell-Shaped Polyhedral Oligomeric Silsesquioxane (POSS) Compound as a Single-Component POSS Hybrid

Dumbbell-shaped polyhedral oligomeric silsesquioxane (POSS) derivatives, in which two POSS units are linked through a bridge, have attracted attention in the last decade. Here, we prepared an unsymmetric dumbbell-shaped POSS derivative (3_Ph-iBu) in which isobutyl- and phenyl-substituted POSS units are linked by a disiloxane unit and compared its thermal properties with those of the corresponding symmetric isobutyl- and phenyl-substituted dumbbell-shaped POSS derivatives (3_iBu-iBu and 3_Ph-Ph, respectively). The symmetric isobutyl- and phenyl-substituted dumbbell-shaped POSS derivatives, 3_iBu-iBu and 3_Ph-Ph, were almost completely phase-separated during a mixing process. This phase separation is due to the limited solubility of phenyl-substituted POSS compounds, which are only soluble in tetrahydrofuran (THF) and insoluble in hydrocarbons such as n-hexane and toluene, while the isobutyl-substituted POSS derivatives exhibit a wider spectrum of soluble solvents. The unsymmetric dumbbell-shaped POSS, 3_Ph-iBu, showed hybrid properties of solubility in solvents and thermal behaviors. Differential scanning calorimetric (DSC) analysis showed that enthalpy of the phase transition of 3_Ph-iBu was significantly lower than those of the mixture of 3_iBu-iBu and 3_Ph-Ph. No apparent melting behavior was observed above the phase transition. The thermal degradation of the weakest isobutyl substituents improves in the present single-component hybrid structure.

Tertiary arsine ligands for the Stille coupling reaction

The Stille coupling reaction is one of the most important coupling reactions. It is well known that the triphenylarsine ligand can accelerate the reaction rate of Stille coupling. However, other arsine ligands have never been investigated for the Stille coupling reaction so far. In this work, we prepared 13 kinds of C₃-symmetrical tertiary arsine ligands and discovered that tri(p-anisyl)arsine is the best ligand for the reaction of tributylvinyltin and p-iodoanisole. The reaction mechanism was studied by dispersion-corrected density functional theory calculations to demonstrate the energetic feasibility of the Stille coupling reactions mediated by tri(p-anisyl)arsine.

Synthesis and Optical Properties of Thiazolo-Chlorin and Porphyrin Skeletons

Macrocyclic π-skeletons containing a thiazole moiety were synthesized via MacDonald [3 + 1]-type condensation. The construction of thiazolochlorin 1a and thiazoloporphyrin 1b depended on the conformation of the thiazole moieties, and their 18π-systems expanded along the molecular y and x axes, respectively. In particular, the structure of thiazolochlorin 1a was studied in detail using 2D nuclear magnetic resonance methods. The optical properties in solution were measured and discussed based on both experimental data and computational studies.

Diarsine- vs diphosphine-protected Au13 clusters: Effect of subtle geometric differences on optical property and electronic structure

In the design of ligand-protected metal clusters, the choice of protecting ligands is a critical factor because they can profoundly affect the nuclearity, geometry, and electronic structures to afford a diverse range of cluster compounds. Here, we report the synthesis of two novel diarsine-protected Au₁₃ clusters ([Au₁₃L₅Cl₂]³⁺, L = diarsine) and compare these clusters with diphosphine analogs in terms of the core geometry and optical properties. In the crystal structure, the cluster bearing C3-bridged diarsines {[Au₁₃(dpap)₅Cl₂]³⁺, 3} had an apparently identical icosahedral Au₁₃ core to [Au₁₃(dppe)₅Cl₂]³⁺ (1) with C2-bridged diphosphines, but slight structural differences associated with the bridging unit of the ligands were found. Despite similar icosahedral Au₁₃ cores 1 and 3, their absorption and photoluminescence profiles were evidently different. Theoretical calculations revealed that the subtle deformation of the Au₁₃ icosahedron, rather than the coordinating atoms (As or P), notably influences the electronic structure to cause the difference in the absorption profiles.

Reversible pH Responsive Aggregation Behavior of Size-Controlled Calcium Carbonate Composite Nanoparticles by Phytic Acid in Aqueous Solution

Composite colloidal nanoparticles were prepared by a carbonate controlled-addition method in the presence of phytic acid, in which an aqueous ammonium carbonate solution was added into an aqueous solution of phytic acid and CaCl₂. The number-average particle size of the colloidal particles was 76 ± 18 nm formed by using the molar ratio [phytic acid]/[Ca²⁺] = 0.5 from the complexation time of 1 h. The composite nanoparticles were stable for more than 5 days in the suspension under the quiescent condition. After isolation of the nanoparticles by ultrafiltration, the dried samples could be redispersed in water. Effects of the complexation times of the aqueous solution of phytic acid and CaCl₂ and the molar ratio ([phytic acid]/[Ca²⁺]) were studied. Increasing the concentration of the calcium reagents as well as increasing the complexation times increased the particle sizes. The minimum and maximum average particle sizes of 29 and 142 nm were obtained. The plot of the transmittance at 350 nm of the aqueous solution of the dispersion against pH values after addition of 0.05 M HCl for 6 h showed that, by gradually increasing turbidity with decreasing pH from 9.6 to 7.3, precipitates were recognized at below pH 7.5, and turbidity decreased with further decreasing pH beyond 7.2. Dynamic light scattering analysis showed that the particle diameters increased from 90 to 200 nm with decreasing pH from 9.6 to 7.2. When increasing the pH from 6.2, the precipitate was redispersed and the turbidity increased to a pH of 7.4. No precipitates were observed above a pH of 7.4. These results suggest that the present phytic acid stabilized nanoparticles exhibit pH-dependent reversible precipitation and redispersion without degradation under slightly acidic conditions.

Drastic Enhancement of Photosensitized Energy Transfer Efficiency of a Eu(III) Complex Driven by Arsenic

In this study, we focused on arsenic as a new potential motif for the ligand design of high-efficiency, luminous lanthanide complexes. A Eu³⁺ complex bearing triphenylarsine oxide had a photosensitized energy-transfer efficiency 7.9 times higher than that of a Eu³⁺ complex bearing triphenylphosphine oxide. This is mainly due to the heavy-atom effect of arsenic, which was supported by evaluating the photoluminescence spectra of their corresponding Gd³⁺ complexes.

Turn-on type sensing of methanol vapor by a luminescent platinum(II) dichloride complex with 21-dibenzoarsacrown-7

The development of turn-on detection sensors for methanol vapor remains challenging in materials science. Methanol sensing materials are generally based on vapor-triggered color changes or are turn-off types. Additionally, in general, the selectivity for methanol is limited, and the recyclability is low. Turn-on type sensing, high selectivity, rapid response time, and recyclability are favorable for achieving real-time detection systems. Herein, platinum(ii) dihalide (PtX2, X = Cl, Br, and I) complexes with 21-dibenzoarsacrown-7 were synthesized and their structures were characterized by single-crystal diffraction analysis. The PtCl2 complex showed intense emission when capturing methanol molecules in the crystalline matrix. In addition, this sensing system possessed high selectivity for methanol vapor and required facile recycling procedures.

2,3-Diarylbenzo[b]arsole: Structural Modification and Polymerization for Tuning of Photophysical Properties

2,3-Diarylbenzo[b]arsoles were synthesized from zirconacycles and diiodophenylarsine. The structural modification to the luminophore was attained through diarylacetylene precursors, Suzuki-Miyaura coupling, and oxidation of the arsenic atom. The emission properties were controlled according to these modifications. The 2,3-diarylbenzo[b]arsoles showed aggregation-induced emission enhancement; the stronger emission was observed in the solid states than in solutions. In addition, Suzuki-Miyaura polycondensation and olefin metathesis polymerization produced main- and side-chain polymers, respectively. The resultant polymers showed different emission behaviors such as aggregation caused quenching and aggregation induced emission enhancement.

Dibenzoarsacrowns: an experimental and computational study on the coordination behaviors

Dibenzoarsacrowns have been synthesized as a novel class of heteroatom-fused crown ethers. The dibenzoarsacrowns can size-selectively capture alkali metal cations, and the arsenic atoms chemoselectively coordinated to gold(i) chloride (AuCl) due to the soft Lewis acid-base interaction. It is notable that the AuCl complex of 21-dibenzoarsacrown-7 further encapsulated Na⁺ with the enhanced association constant from bare 21-dibenzoarsacrown-7. The positive allosteric effect was studied computationally.

Superior light-resistant dithieno[3,2-b:2',3'-d]arsole-based polymers exhibiting ultrastable amplified spontaneous emission

Herein, by amplified spontaneous emission measurements, dithieno[3,2-b:2',3'-d]arsole (DTA)-bithiophene (DTA-BT) and DTA-ethynylbenzene (DTA-EB) polymer films exhibited considerable photostability under continuous pulsed pumping excitation for at least 15 h at the pumping energies, 28.9 and 20.7 μJ, respectively, showing an outstanding high light-resistance among the polymer-based gain media.

Homo- and hetero-metallophilicity-driven synthesis of highly emissive and stimuli-responsive Au(i)–Cu(i) double salts

Discrete complex salts having Au···Au and Au···Cu interactions were obtained as three crystalline polymorphs exhibiting various emission colors with high efficiency. Solvent vapor caused crystal-to-crystal transition, changing the emission color.

Hybrid polyurethanes composed of isobutyl-substituted open-cage silsesquioxane in the main chains: synthesis, properties and surface segregation in a polymer matrix

The resulting polyurethanes exhibited excellent optical transparency and surface hydrophobicity and acted as effective surface modifiers in poly(methyl methacrylate) (PMMA) by surface segregation.