Multifunctional Materials for High-Performance Double-Layer Organic Light-Emitting Diodes: Comparison of Isomers with and without Thermally Activated Delayed Fluorescence

Organic light-emitting diodes (OLEDs) with simple structures are attracting a lot of attention nowadays, though their performances are always inferior to those of the more complicated structures as multifunctional materials are rare. Here, we have designed and synthesized multifunctional isomers by combining electron-donating carbazole (Cz) and triphenylamine (TPA) units with electron-accepting triazine (Trz), namely, <i>N</i>-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)­phenyl]-<i>N</i>-[4-(9-phenyl-9<i>H</i>-carbazol-3-yl)­phenyl]-[1,1′-biphenyl]-4-amine (CzTPA-<i>p</i>-Trz) and <i>N</i>-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)­phenyl]-<i>N</i>-[4-(9-phenyl-9<i>H</i>-carbazol-3-yl)­phenyl]-[1,1′-biphenyl]-4-amine (CzTPA-<i>m</i>-Trz). The use of multiple electron-donating groups gives them suitable highest occupied molecular orbitals for hole injection and high mobilities for hole transport. Hole-only devices with CzTPA-<i>m</i>-Trz or CzTPA-<i>p</i>-Trz as the hole injection layers and hole transport layers show a higher hole current than the widely used 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile/4,4′-<i>N</i>,<i>N</i>′-bis­[<i>N</i>-(1-naphthyl)-<i>N</i>-phenylamino]­biphenyl system. Interestingly, CzTPA-<i>p</i>-Trz is a fluorescent material with a high photoluminescence quantum yield (PLQY), while CzTPA-<i>m</i>-Trz shows weak thermally activated delayed fluorescence (TADF). As expected, a CzTPA-<i>p</i>-Trz-based undoped double-layer green device achieved a higher external quantum efficiency (EQE) of 4.4% and a higher power efficiency (PE) of 11.8 lm/W. On the other hand, among double-layer devices doped with an orange phosphorescent dopant, a device based on TADF material, CzTPA-<i>m</i>-Trz, achieved higher peak EQE (23.5%) and PE (68.3 lm/W) than those of CzTPA-<i>p</i>-Trz (20.8% and 60.2 lm/W). Even at a high luminance of 5000 cd m^–2, a high EQE of 21.8% was retained for CzTPA-<i>m</i>-Trz-based devices. These results are even comparable to those for the state-of-the-art phosphorescent devices based on the same dopant with more complicated structures. The above results indicate that well-designed multifunctional materials are promising for high-performance OLEDs with simple structures

Asymmetric Catalytic 1,3-Dipolar Cycloaddition Reaction of Nitrile Imines for the Synthesis of Chiral Spiro-Pyrazoline-Oxindoles

A new 1,3-dipolar cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO₄)₂ complex of an <i>N</i>,<i>N</i>′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1,3-dipole in the construction of 2-pyrazoline subunit

Asymmetric Aerobic Oxidative Cross-Coupling of Tetrahydroisoquinolines with Alkynes

An efficient asymmetric aerobic oxidation of tetrahydroisoquinolines with terminal alkynes was realized under mild reaction conditions using O₂ as the sole oxidant. A chiral <i>N,N</i>′-dioxide/zinc­(II)/iron­(II) bimetallic cooperative catalytic system proves to be efficient for the formation of various α-alkynyl substituted tetrahydroisoquinolines in good to excellent yields and enantioselectivities. A primary mechanistic study supports an enantioselective electrophilic addition of zinc acetylide to the iminium intermediates, formed through a molecular O₂-involved oxidative process

Asymmetric Catalytic 1,3-Dipolar Cycloaddition Reaction of Nitrile Imines for the Synthesis of Chiral Spiro-Pyrazoline-Oxindoles

A new 1,3-dipolar cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO₄)₂ complex of an <i>N</i>,<i>N</i>′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1,3-dipole in the construction of 2-pyrazoline subunit

Materials by Design for Stiff and Tough Hairy Nanoparticle Assemblies

Matrix-free polymer-grafted nanocrystals, called assembled hairy nanoparticles (aHNPs), can significantly enhance the thermomechanical performance of nanocomposites by overcoming nanoparticle dispersion challenges and achieving stronger interfacial interactions through grafted polymer chains. However, effective strategies to improve both the mechanical stiffness and toughness of aHNPs are lacking given the general conflicting nature of these two properties and the large number of molecular parameters involved in the design of aHNPs. Here, we propose a computational framework that combines multiresponse Gaussian process metamodeling and coarse-grained molecular dynamics simulations to establish design strategies for achieving optimal mechanical properties of aHNPs within a parametric space. Taking poly­(methyl methacrylate) grafted to high-aspect-ratio cellulose nanocrystals as a model nanocomposite, our multiobjective design optimization framework reveals that the polymer chain length and grafting density are the main influencing factors governing the mechanical properties of aHNPs, in comparison to the nanoparticle size and the polymer–nanoparticle interfacial interactions. In particular, the Pareto frontier, that marks the upper bound of mechanical properties within the design parameter space, can be achieved when the weight percentage of nanoparticles is above around 60% and the grafted chains exceed the critical length scale governing transition into the semidilute brush regime. We show that theoretical scaling relationships derived from the Daoud–Cotton model capture the dependence of the critical length scale on graft density and nanoparticle size. Our established modeling framework provides valuable insights into the mechanical behavior of these hairy nanoparticle assemblies at the molecular level and allows us to establish guidelines for nanocomposite design

Asymmetric Catalytic 1,3-Dipolar Cycloaddition Reaction of Nitrile Imines for the Synthesis of Chiral Spiro-Pyrazoline-Oxindoles

A new 1,3-dipolar cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO₄)₂ complex of an <i>N</i>,<i>N</i>′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1,3-dipole in the construction of 2-pyrazoline subunit

Asymmetric Catalytic 1,3-Dipolar Cycloaddition Reaction of Nitrile Imines for the Synthesis of Chiral Spiro-Pyrazoline-Oxindoles

A new 1,3-dipolar cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO₄)₂ complex of an <i>N</i>,<i>N</i>′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1,3-dipole in the construction of 2-pyrazoline subunit

Changes of blood glucose on the 6^th and 10^th day after the intraperitoneal injection of LPS.

(A) Changes of blood glucose on day 6. (B) Changes of blood glucose on day 10. The data were shown as mean ± S.E.M with 5~9 rats in each group. ## compared with the normal group, P < 0.01. NS: no significance.</p

Changes of liver function (AST and ALT) and kidney function (BUN and CRE) on day 9 and day 12 after the intraperitoneal injection of LPS.

(A)—(D) Changes of liver function and kidney function on the 9th day. (E)—(H) Changes of liver function and kidney function on the 12th day. The data were shown as mean ± S.E.M with 5~9 rats in each group. # and ##, compared with normal groups, P P P P < 0.01. NS: no significance.</p

Changes of urinary total protein (uCSF) and urinary microalbumin (umALB) in hyperglycemia rats before and after the intraperitoneal injection of LPS.

(A)—(C) Changes of uCSF before and after LPS injection. (D)—(F) Changes of umALB before and after LPS injection. The data were shown as mean ± S.E.M from 3~14 rats in each group. # and ## compared with the normal groups, P P P P < 0.01. $ compared with normal groups, P = 0.057. NS: no significance.</p