RESUMEN
Cost-effective and facile synthetic routes to organic ligands, along with porous materials that exhibit exceptional gas-storage properties, promise significant industrial applications. Here, a two-step synthesis of novel organophosphorus ligands without metal catalysts is reported. These ligands serve as versatile linkers for the construction of metal-organic frameworks (MOFs) incorporating various metal ions, including zinc and copper. One of the zinc-based MOFs demonstrates remarkable gas-storage properties, with a hydrogen (H2) capacity exceeding 2.5â wt% at 77â K and 100â kPa as well as a carbon dioxide (CO2) capacity exceeding 20â wt% at 298â K and 100â kPa. Furthermore, this zinc-based MOF can be synthesized through a solvothermal process on the gram scale that yields high-quality single crystals.
RESUMEN
Single crystals of alkoxy-functionalized hydroxamate/zinc metal-organic frameworks (MOFs) were obtained by fixating the hydroxamate moiety via intramolecular hydrogen bonding. The resulting MOF structures depend on the steric demand of the alkoxy groups, whereby the incorporation of bulky isopropyl groups affords porous hydroxamate/zinc MOFs. The topological structures of the isopropyl-substituted MOFs could be controlled by adding acid.
RESUMEN
Invited for the cover of this issue is the group of Koh Sugamata, Mao Minoura, and co-workers at Rikkyo University. The image depicts triptycene-based metal-organic frameworks with honeycomb structures that collect carbon dioxide and hydrogen, in an analogy to bees collecting honey in their honeycombs. Read the full text of the article at 10.1002/chem.202302080.
RESUMEN
A series of metal-organic frameworks (MOFs) based on zinc ions and two triptycene ligands of different size have been synthesized under solvothermal conditions. Structural analyses revealed that they are isostructural 3D-network MOFs. The high porosity and thermal stability of these MOFs can be attributed to the highly rigid triptycene-based ligands. Their BET specific surface areas depend on the size of the triptycene ligands. In contrast to these surface-area data, the H2 and CO2 adsorption of these MOFs is larger for MOFs with small pores. Consequently, we introduced functional groups to the bridge-head position of the triptycene ligands and investigated their effect on the gas-sorption properties. The results unveiled the role of the functional groups in the specific CO2 binding via an induced interaction between adsorbates and the functional groups. Excellent H2 and CO2 properties in these MOFs were achieved in the absence of open metal sites.
RESUMEN
To achieve an ultimate wide color gamut for ultrahigh-definition displays, there is great demand for the development of organic light-emitting diodes (OLEDs) enabling monochromatic, ultrapure blue electroluminescence (EL). Herein, high-efficiency and ultrapure blue OLEDs based on polycyclo-heteraborin multi-resonance thermally activated delayed fluorescence (MR-TADF) materials, BOBO-Z, BOBS-Z, and BSBS-Z, are reported. The key to the design of the present luminophores is the exquisite combination and interplay of multiple boron, nitrogen, oxygen, and sulfur heteroatoms embedded in a fused polycyclic π-system. Comprehensive photophysical and computational investigations of this family of MR-TADF materials reveal that the systematic implementation of chalcogen (oxygen and sulfur) atoms can finely modulate the emission color while maintaining a narrow bandwidth, as well as the spin-flipping rates between the excited singlet and triplet states. Consequently, OLEDs based on BOBO-Z, BOBS-Z, and BSBS-Z demonstrate narrowband and ultrapure blue EL emission, with peaks at 445-463 nm and full width at half maxima of 18-23 nm, leading to Commission Internationale de l'Éclairage-y coordinates in the range of 0.04-0.08. Particularly, for OLEDs incorporating sulfur-doped BOBS-Z and BSBS-Z, notably high maximum external EL quantum efficiencies of 26.9% and 26.8%, respectively, and small efficiency roll-offs are achieved concurrently.
RESUMEN
Establishing a simple and versatile design strategy to finely modulate emission colors while retaining high luminescence efficiency and color purity remains an appealing yet challenging task for the development of multi-resonance-induced thermally activated delayed fluorescence (MR-TADF) materials. Herein, we demonstrate that the strategic introduction of electron-withdrawing imine and electron-donating amine moieties into a versatile boron-embedded 1,3-bis(carbazol-9-yl)benzene skeleton enables systematic hypsochromic and bathochromic shifts of narrowband emissions, respectively. By this method, effective electroluminescence color tuning was accomplished over a wide visible range from deep-blue to yellow (461-571â nm), using the same MR molecular system, without compromising very narrow spectral features. Deep-blue to yellow organic light-emitting diodes with maximum external quantum efficiencies as high as 19.0-29.2 % and superb color purity could be produced with this family of color-tunable MR-TADF emitters.