Fast photocatalytic degradation of rhodamine B using indium-porphyrin based cationic MOF under visible light irradiation.

A broad light-harvesting range and efficient charge separation are two main ways to enhance the visible photocatalytic performance of semiconductors. Herein, an ionic porphyrin MOF [In(TPyP)]·(NO3) (1) (TPyP = 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin) was synthesized via in situ metalation. The orderly arranged porphyrin photosensitizer and the internal electric field between the MOF host and NO3- guests enable effective visible light response and electron-hole separation. Consequently, the as-synthesized MOF shows efficient photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) organic pollutants. It can degrade 99.07% of RhB within only 20 minutes under visible light irradiation (λ > 420 nm) with a high chemical reaction rate constant of 0.2400 min-1. The photocatalytic activity of the title MOF is more efficient than those of other reported MOFs, COFs and even inorganic semiconductors. The reusability, energy level, band gap, charge distribution and main degradation mechanisms of the photocatalyst were well studied.

Enhanced Activity of Enzyme Immobilized on Hydrophobic ZIF-8 Modified by Ni2+ Ions.

The development of efficient enzyme immobilization to promote their recyclability and activity is highly desirable. Zeolitic imidazolate framework-8 (ZIF-8) has been proved to be an effective platform for enzyme immobilization due to its easy preparation and biocompatibility. However, the intrinsic hydrophobic characteristic hinders its further development in this filed. Herein, a facile synthesis approach was developed to immobilize pepsin (PEP) on the ZIF-8 carrier by using Ni2+ ions as anchor (ZIF-8@PEP-Ni). By contrast, the direct coating of PEP on the surface of ZIF-8 (ZIF-8@PEP) generated significant conformational changes. Electrochemical oxygen evolution reaction (OER) was employed to study the catalytic activity of immobilized PEP. The ZIF-8@PEP-Ni composite attains remarkable OER performance with an ultralow overpotential of only 127 mV at 10 mA cm-2 , which is much lower than the 690 and 919 mV overpotential values of ZIF-8@PEP and PEP, respectively.

Acridine based metal-organic framework host-guest featuring efficient photoelectrochemical-type photodetector and white LED.

A novel metal-organic framework (MOF) host-guest material [Cd3(EtOIPA)4(HAD)2]·H2O has been successfully synthesized by the reaction of 5-ethoxyisophthalic acid (EtOIPA), acridine (AD) and Cd(II) salts under hydrothermal conditions. Structurally, the title MOF possesses a trinucleate Cd(II) based 2D double-layer with the protonated AD cations as the template encapsulated into the grids. The combination of experiments and theoretical calculations reveals that the orderly arrangement of EtOIPA dimers, protonated AD cations and trinucleate Cd(II) clusters generates highly delocalized π-electron channels with a prolonged exciton lifetime. The MOF powders show bright yellow emission with a long lifetime of 50.63 ns. Photoelectrochemical measurements reveal a high photocurrent density ratio of 290 between light and dark conditions at 0 V bias potential, making it a perfect self-driven photodetector. By coating the yellow phosphor on a commercially available blue LED, a high performance white LED with CIE, CCT and CRI values of (0.325, 0.336), 88.2 and 5844 K, respectively can be obtained.

Green-/NIR-light-controlled rapid photochromism featuring reversible thermally activated delayed fluorescence and photoelectronic switching.

Fluorescent dithienylethene-based photochromic materials have been attracting considerable attention owing to their wide applications in biological and materials sciences. However, the limitations of detrimental UV irradiation for photocyclization, short emission lifetime, and inefficient photoresponsive speed still need to be addressed. Herein, a novel dithienylethene photochromic molecule, BFBDTE, has been prepared by the incorporation of a difluoroboron ß-diketonate (BF2bdk) unit. The strong electron acceptor BF2bdk not only reduces the energy gap of the open isomer, ensuring visible light-controlled fluorescence switching, but also promotes intersystem crossing for the generation of thermally activated delayed fluorescence (TADF). Upon alternating irradiation with green and NIR light, BFBDTE presents a rare example of photochromism, fluorescence and TADF switching in various polar solvents and a poly(methyl methacrylate) (PMMA) film. Meanwhile, it shows rapid and well repeatable cyclization (12 s) and cycloreversion reactions (20 s) in PMMA, accompanied by fast TADF switching within 11 s. Furthermore, photo-electrochemical measurements reveal a remarkable on-off photoelectronic response (photocurrent density ratio: I light/I dark = 684) between the open- and closed-form of BFBDTE. These remarkable merits make BFBDTE promising for photoswitchable molecular devices, optical memory storage systems, NIR detectors, and photoelectric switching.

Red room temperature phosphorescence of lead halide based coordination polymer showing efficient angle-dependent polarized emission and photoelectric performance.

The development of organic-inorganic hybrid materials with long-lived room temperature phosphorescence (RTP) has attracted tremendous attention owing to their promising applications in the optoelectronic and anti-counterfeiting fields. In this work, by the selection of lead halide and electron-poor heteroaromatic molecule 1,10-phenanthroline (phen), a coordination polymer [Pb(phen)Cl2] has been synthesized under hydrothermal conditions. This complex shows an alternating arrangement of a long-range order of phen π-conjugated systems and lead halide inorganic chains as revealed by X-ray single-crystal structural analysis. This structural character and special chemical components endow this hybrid material with a rare example of red room temperature phosphorescence. Its electronic structure and electronic transition behavior were further examined by theoretical calculations. Meanwhile, the film of the complex features remarkable angle-dependent polarized emission and photoelectric performance.

Room-Temperature Phosphorescent Co-Crystal Showing Direct White Light and Photo-Electric Conversion.

The development of molecular crystalline materials with efficient room-temperature phosphorescence has been obtained much attention due to their fascinating photophysical properties and potential applications in the fields of data storage, bioimaging and photodynamic therapy. Herein, a new co-crystal complex [(DCPA) (AD)2] (DCPA = 9,10-di (4-carboxyphenyl)anthracene; AD = acridine) has been synthesized by a facile solvothermal process. Crystal structure analysis reveals that the co-crystal possesses orderly and alternant arrangement of DCPA donors and AD acceptors at molecular level. Fixed by strong hydrogen bonds, the DCPA molecule displays seriously twisty spatial conformation. Density functional theory (DFT) calculations show well separation of HOMO and LUMO for this co-crystal system, suggesting the efficient triplet excitons generation. Photoluminescence measurements show intensive cyan fluorescence (58.20 ns) and direct white phosphorescence (325 µs) emission at room-temperature. The transient current density-time curve reveals a typical switching electric response under the irradiation of simulated light, reveal that the [(DCPA) (AD)2] co-crystal has a high photoelectric response performance.