In this paper we report the microwave assisted synthesis and characterization of a family of Na-Ln coordination polymers (CPs) of formula [NaDy2(MeCOO)2(SALOH)5(chpH)2] (1Ln, Ln = Eu, Gd, Tb, Dy, Ho, Y). The Na+ cations isolate Ln2 units in a one-dimensional polymer. By changing the lanthanoid ions, we attain Single Molecule Magnet properties (1Dy), luminescent properties (1Eu, 1Tb, 1Ho), a diamagnetic material (1Y) and a material that presents magnetocaloric effect (1Gd).
Long‐Term Heat‐Storage Ceramics based on Zr‐Substituted λ‐Ti3O5
Heat-storage materials are important for energy saving to protect the environment. Here, we show a long-term heat-storage material based on zirconium-substituted lambda-trititanium pentoxide (λ-ZrxTi3-xO5, 0 < x ≤ 0.06). λ-ZrxTi3-xO5 exhibits a phase transition to zirconium-substituted beta-trititanium pentoxide (β-ZrxTi3-xO5) upon application of pressure. The transition pressures were 600 MPa (x = 0.04) and about 1 GPa (x = 0.06). When the pressure-produced β-phase is heated, the β-phase transforms into λ-phase. The phase transition temperatures (i.e., heat-storage temperatures) were 185 °C (458 K) and 183 °C (453 K) for x = 0.04 and 0.06, respectively. These heat-storage temperatures are suitable for the reuse of low-temperature industrial waste heat, which are considered to be a difficult temperature region to be efficiently collected and reused. The present pressure-sensitive heat-storage ceramic, which can store the latent heat energy for a prolonged period, is effective for the sustainable reuse of heat energy that are wasted in power plants and industrial factories.
[ASAP] DNA-Coated Microspheres with Base Mismatches for Stepwise Programmed Assembly
Chemistry of Materials
DOI: 10.1021/acs.chemmater.4c00205
[ASAP] Supramolecular Chiral J-Aggregates of an Amphiphilic Boron-Azadipyrromethene Dye: Kinetic Pathway and Circularly Polarized Near-Infrared Luminescence
Chemistry of Materials
DOI: 10.1021/acs.chemmater.4c00031
[ASAP] Role of Dioleamide Formation during the Synthesis of Core@Shell@Shell Pt@NiPt@Pt Nanoparticles
Chemistry of Materials
DOI: 10.1021/acs.chemmater.3c03064
First Application of Non‐metallic A2B Type Silicon Corrole Complexes in Electrocatalytic Hydrogen Evolution
In this study, we have successfully synthesized two non-metallic-based silicon corrole complexes (F10C-Si, F10C-CN-Si) and used them as HER electrocatalysts for the first time. Electrochemical studies indicate the electrocatalytic HER may go via EE-CEEC (E: electron transfer step, C: chemical step) pathway. Notably, it can be seen that the introduction of electron-withdrawing cyano group on the meso-phenyl of the corrole macrocycle may enhance the catalytic activity of silicon corrole complexes. In DMF with TsOH as the proton source, F10C-CN-Si exhibits a turnover frequency (TOF) of 331.48 s-1 and a high catalytic efficiency (C.E) of 1.29. Furthermore, the catalytic prowess of the silicon corrole complexes extends to neutral aqueous solution, with F10C-CN-Si achieving a TOF of 52.72 h⁻¹ at an overpotential of 1188 mV. This study extends the application of non-metallic-based silicon corrole molecular catalysts in the electrocatalytic HER field.
Tailored Polymeric Carbon Nitride Coupled with Bi2O3 for Constructing Z‐Scheme Heterojunction with Enhanced Photocatalytic Activity
The great demand for visible-light-induced catalysts with high photocatalytic performance has stimulated extensive interest in constructing g-C3N4-based Z-scheme heterojunctions. In this research work, we constructed the g-C3N4/Bi2O3 Z-scheme heterojunction by precipitation-hydrothermal method, and confirmed the close contact interface between g-C3N4 and Bi2O3 to form the heterojunction by various characterization techniques, which facilitates the efficient separation of photogenerated electrons-holes. Compared to pure g-C3N4 and Bi2O3, the g-C3N4/Bi2O3-1 composite exhibited a transient photocurrent response approximately 7 and 5 times higher than that of g-C3N4 and Bi2O3, respectively, with stronger visible photocatalytic activity and degraded 99.8% methylene blue within 75 min. Ion trapping experiments showed that •OH free radical had the greatest effect on the degradation of methylene blue, while •O2- and h+ had less effect. According to the experimental test results, the possible photocatalytic degradation mechanism of g-C3N4/Bi2O3-1 catalyst was proposed. This study provides a new avenue for the development of novel g-C3N4-based Z heterojunction materials with application value.
[ASAP] Intersite Charge Transfer through Eu 4f Band Engineering in Eu1–xSrxVO2H Oxyhydride Films
Chemistry of Materials
DOI: 10.1021/acs.chemmater.4c00404
Substituent Effects in the Cationic Green Fluorescent Protein Chromophore: Ultrafast Excited‐State Proton Transfer or Twisting?
Understanding the structure-function relationships of the green fluorescent protein (GFP) chromophore is important in rationally developing new molecular tools for biological imaging and beyond. Herein, we systematically modified the GFP chromophore structure with electron-withdrawing and -donating groups (EWGs and EDGs) to investigate the substituent effects on the excited-state proton transfer (ESPT) and twisting dynamics of the cationic chromophore in solution. With key insights gained from femtosecond transient absorption and stimulated Raman spectroscopy, we reveal that the EWG substitution by –F increases photoacidity in an additive manner and leads to an ultrafast barrierless ESPT by difluorination, while the EDG substitution by –OCH3 also results in ultrafast ESPT despite the weak photoacidity as estimated by the Förster equation. We ascribe the unusually fast kinetics in methoxylated derivatives to the occurrence of a pre-existing chromophore-solvent complex that sets up the acceptor site for ESPT. Furthermore, the kinetic competition between ESPT and twisting pathways is crucial for the observation of ESPT in action, particularly for molecules undergoing efficient nonradiative decay in the excited state through torsional motions. Such flexible and highly engineerable molecules can enable more versatile photoswitches and sensors.
INVESTIGATION OF MORPHOLOGY, OPTICAL AND ELECTRONIC AC CONDUCTION OF THE OLIVINE MANGANITE COMPOUND: NaMnPO4
The development of multifunctional materials is an exceptional research area, which is aimed at enhancing the versatility of materials according to their wide fields of application. Special interest was devoted here to the orthophosphate compound, in particular, the olivine NaMnPO4 material. This compound was successfully synthesized by a solid-state method and characterized using various techniques. Preliminary room-temperature structural analysis evidences the sample formation in the orthorhombic structure and its phase purity. The material’s morphology, analyzed by scanning electron microscopy (SEM), is identified by a spherical grain size distribution. The average grain size of the sample was estimated to be around 420 nm. Moreover, the optical investigation of UV-visible spectroscopy has revealed that the band gap for our sample is (Eg = 2.28 eV), which shows that our compound is a potential candidate for optoelectronic applications. The electrical behavior study's main results confirm the ferroelectric character of the sample and support the aim of deepening the knowledge of the material according to its thermally stimulated conduction processes through impedance spectroscopy. Electrical studies revealed the dominant transport processes across various temperature and frequency ranges, leading to the NSPT model. The frequency dependency relates to frequency-dispersive dielectric spectra, conduction mechanisms, and relaxation phenomena.