19 research outputs found
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)Âphenyl]-<i>N</i>-[4-(9-phenyl-9<i>H</i>-carbazol-3-yl)Âphenyl]-[1,1′-biphenyl]-4-amine
(CzTPA-<i>p</i>-Trz) and <i>N</i>-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)Âphenyl]-<i>N</i>-[4-(9-phenyl-9<i>H</i>-carbazol-3-yl)Âphenyl]-[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>′-bisÂ[<i>N</i>-(1-naphthyl)-<i>N</i>-phenylamino]Âbiphenyl 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<sup>–2</sup>, 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(ClO<sub>4</sub>)<sub>2</sub> 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 O<sub>2</sub> as the sole oxidant. A chiral <i>N,N</i>′-dioxide/zincÂ(II)/ironÂ(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 O<sub>2</sub>-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(ClO<sub>4</sub>)<sub>2</sub> 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 polyÂ(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(ClO<sub>4</sub>)<sub>2</sub> 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(ClO<sub>4</sub>)<sub>2</sub> 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<sup>th</sup> and 10<sup>th</sup> 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