RESUMEN
Conventional fluorescent materials frequently exhibit narrow-band emissions with a small full width at half-maximum (fwhm) due to localized-state characteristics, but electroluminescence is less efficient owing to the utilization of only singlet excitons. In this work, taking advantage of naphthalimide (NAI)-acetylide derivatives with a rigid planar structure and localized transition characteristics, we elaborately designed two mononuclear Pt(II) complexes with weak double emissions of fluorescence and phosphorescence. Taking them as synthetic precursors, we prepared three PtAu2 heteronuclear clusters and successfully attained highly efficient narrow-band red phosphorescence with the fwhm below 30 nm. Both theoretical and experimental results suggest that the phosphorescence of PtAu2 clusters mainly originates from the naphthalimide-localized 3IL (intraligand) triplet state. Solution-processed organic light-emitting diodes (OLEDs) achieved highly efficient narrow-band red electroluminescence with an external quantum efficiency (EQE) of 16.7%. The CIE coordinates of the electroluminescence (0.69, 0.31) closely match the standard red emission for ultrahigh-definition display.
RESUMEN
As the simplest oligomeric acceptors, dimerized acceptors (DAs) are easier to synthesize, and more importantly, they can retain good intermolecular interaction and photovoltaic properties of their parent small-molecule acceptors (SMAs). Nevertheless, currently most efficient DAs are derived from banana-shaped acceptors and they might suffer from inferior device stability with high diffusion coefficients. Herein, we design and synthesize two planar DAs (DMT-FH and DMT-HF) by bridging two linear-shaped M-series SMAs with a thiophene unit. The effects of fluorination position on the diffusion coefficients, power conversion efficiencies (PCEs) and stability of the DAs are systematically studied. Our results suggest that DMT-HF with fluorination on the ending indanone groups shows enhanced intermolecular interactions, improved PCE and stability compared with the counterpart (DMT-FH) with fluorination on the central indanone groups. Further optimization on the DMT-HF-based devices yields an outstanding PCE of 17.17%, which is the highest among all linear-shaped SMA-based DAs. Notably, with the low diffusion coefficient (3.36×10-24 cm2 s-1) of DMT-HF, the resulting device retains over 93% of the initial PCE after 5000 h of continuous heating at 85 oC, suggesting its excellent thermal stability. The results highlight the importance of intermolecular interaction and fluorination for achieving efficient and stable polymer solar cells.
RESUMEN
Chiral 3D perovskites pose challenges compared to lower-dimensional variants due to limited chiral organic cation options. Here, we present a universal and controlled method for synthesizing chiral 3D lead halide perovskites using organic amines or alcohols as chiral templates. Introducing these templates to PbCl2 in N,N-dimethylformamide (DMF) under acidic conditions induces the crystallization of R/S [DMA]PbCl3 (DMA = dimethylamine). The resulting structure aligns with the templates used, stemming from the helical Pb2Cl95- chain as verified by single-crystal X-ray diffraction. Furthermore, the chiral perovskite exhibits absorption and circular dichroism (CD) signals in the high-energy band, enabling the circularly polarized light (CPL) detection in the UV spectrum. A CPL detector constructed by this chiral perovskite demonstrates excellent performance, boasting an anisotropy factor for photocurrent (gIph) of 0.296. Our work not only introduces a novel and controllable method for crafting chiral perovskites but also opens new avenues for circularly polarized light detection.
RESUMEN
An asymmetric structure is an important strategy for designing highly conductive molecular wires for a gap-fixed molecular circuit. As the conductance enhancement in the current strategy is still limited to about 2 times, we inserted a methylene group as a spacer in a conjugated structure to modulate the structural symmetry. We found that the conductance drastically enhanced in the asymmetric molecular wire to 1.5 orders of magnitude as high as that in the symmetric molecular wire. First-principles quantum transport studies attributed the effective enhancement to the synchronization of improved energy alignment and nearly symmetric coupling between the frontier orbitals and the electrodes.
RESUMEN
Six amides, including a new N-alkylamide (1), four known N-alkylamides (2-5) and one nicotinamide (6) were isolated from Litsea cubeba (Lour.) Pers., which is a pioneer herb traditionally utilized in medicine. Their structures were elucidated on the basis of 1D and 2D NMR experiments and by comparison of their spectroscopic and physical data with the literature values. Cubebamide (1) is a new cinnamoyltyraminealkylamide and possessed obvious anti-inflammatory activity against NO production with IC50 values of 18.45 µM. Further in-depth pharmacophore-based virtual screening and molecular docking were carried out to reveal the binding mode of the active compound inside the 5-LOX enzyme. The results indicate that L. cubeba, and the isolated amides might be useful in the development of lead compounds for the prevention of inflammatory diseases.
Asunto(s)
Litsea , Litsea/química , Simulación del Acoplamiento Molecular , Antiinflamatorios , AmidasRESUMEN
Diradicaloids are generally high-energy molecules with open-shell configuration and are quite reactive. In this work, we report a feasible synthetic approach to attaining exceptionally stable copper(I) metallacyclopentadiene diradicaloids through ligand engineering. Copper(I)-hybrid cyclopentadiene diradicaloids 1c-6c that absorb intensely in visible regions were successfully prepared in stoichiometrical yields under UV light irradiation. The diradicaloids originate from the C-C bonding coupling of two side-by-side-arranged ethynyl groups in complexes 1-6 upon photocyclization. By rational selection of substituents in triphosphine ligands, we systematically modulate the kinetic behavior of diradicaloids 1c-6c in the thermal decoloration process. With precise ligand design, we are able to obtain exceptionally stable copper(I)-hybrid cyclopentadiene diradicaloids with a half-life as long as ca. 40 h in CH2Cl2 solution at ambient temperature. As demonstrated by electron paramagnetic resonance (EPR) and variable-temperature magnetic studies, the diradicaloids manifest a singlet ground state, but they are readily populated to a triplet excited state through thermal activation in view of a small singlet-triplet energy gap of -0.39 kcal mol-1. The diradicaloids show two-step quasi-reversible reduction waves at about -0.5 and -1.0 V ascribed to successive one-electron-accepting processes, coinciding perfectly with the characteristics of diradicals.
RESUMEN
An accurate rule for predicting conductance is the cornerstone of developing molecular circuits and provides a promising solution for miniaturizing electric circuits. The successful prediction of series molecular circuits has proven the possibility of establishing a rule for molecular circuits under quantum mechanics. However, the quantitatively accurate prediction has not been validated by experiments for parallel molecular circuits. Here we used 1,3-dihydrobenzothiophene (DBT) to build the parallel molecular circuits. The theoretical simulation and single-molecule conductance measurements demonstrated that the conductance of the molecule containing one DBT is the unprecedented linear combination of the conductance of the two individual channels with respective contribution weights of 0.37 and 0.63. With these weights, the conductance of the molecule containing two DBTs is predicted as 1.81 nS, matching perfectly with the measured conductance (1.82 nS). This feature offers a potential rule for quantitatively predicting the conductance of parallel molecular circuits.
RESUMEN
Reaction of [Au(tht)2](ClO4) (tht = tetrahydrothiophene), [Cu(CH3CN)4](ClO4), 3,6-di-tert-butyl-1,8-diethynyl-9H-carbazole (H3decz), and bis(2-diphenylphosphinophenyl)ether (POP) in the presence of triethylamine (NEt3) gave the cluster complex Au4Cu2(decz)2(POP)2 as yellow crystals. As revealed by X-ray crystallography, the Au4Cu2 cluster exhibits scissor-like structure sustained by two decz and two POP ligands and stabilized by Au-Cu and Au-Au interactions. The Au4Cu2 cluster shows bright yellow to orange photoluminescence upon irradiation at >300 nm, arising from 3[π (decz)â5d (Au)] 3LMCT (ligand-to-metal charge transfer) and 3[πâπ* (decz)] 3IL (intraligand) triplet states as revealed by theoretical and computational studies. When it is mechanically ground, reversible phosphorescence conversion from yellow to red is observed owing to more compact molecular packing and thus stronger intermetallic interaction. Variable-temperature luminescence studies reveal that it displays distinct red-shifts of the emission whether the temperature is elevated or lowered from ambient temperature, suggestive of exceptional thermochromic phosphorescence characteristics.
RESUMEN
Two asymmetric PtAu2 complexes having HC≡CC6H4C≡CH (1,4-diethynylbenzene) or HC≡CCarbC≡CH (2,7-diethynyl-9-(2,3,5,6-tetrafluorophenyl)-9H-carbazole) and the corresponding bis(acetylide)-linked Pt2Au4 complexes are prepared and characterized. The structures of PtAu2 complexes 1 and 3 together with Pt2Au4 complex 2 are determined by X-ray crystallography. Relative to PtAu2 complexes, bis(acetylide)-linked Pt2Au4 complexes not only display a distinct red shift of the emission but also provide a much higher phosphorescent efficiency. Utilizing highly emissive Pt2Au4 complexes as phosphorescent dopants, high-efficiency solution-processed OLEDs are obtained with peak current efficiency of 75.9 cd A-1 and external quantum efficiency of 19.0% at luminance of 336 cd m-2 and voltage of 5.2 V. When two PtAu2 moieties are linked by a bis(acetylide) ligand, the corresponding Pt2Au4 complexes show a much improved electroluminescent performance compared with that of asymmetric PtAu2 complexes.
RESUMEN
Two heteroctanuclear Au4Ag4 cluster complexes of 4,5-diethynylacridin-9-one (H2L) were prepared through the self-assembly reactions of [Au(tht)2](CF3SO3), Ag(tht)(CF3SO3), H2L and PPh3 or PPh2Py (2-(diphenylphosphino)pyridine). The Au4Ag4 cluster consists of a [Au4L4]4- and four [Ag(PPh3)]+ or [Ag(PPh2Py)]+ units with Au4L4 framework exhibiting a twisted paper clip structure. In CH2Cl2 solutions at ambient temperature, both compounds show ligand fluorescence at ca. 463 nm as well as phosphorescence at 650 nm for 1 and 630 nm for 2 resulting from admixture of 3IL (intraligand) of L ligand, 3LMCT (from L ligand to Au4Ag4) and 3MC (metal-cluster) triplet states. Crystals or crystalline powders manifest bright yellow-green phosphorescence with vibronic-structured emission bands at 530 (568sh) nm for complex 1 and 536 (576sh) nm for complex 2. Upon mechanical grinding, yellow-green emission in the crystalline state is dramatically converted to red luminescence centered at ca. 610 nm with a drastic redshift of the emission after crystal packing is destroyed.
Asunto(s)
Luminiscencia , LigandosRESUMEN
As low-dimensional lead-free hybrids with higher stability and lower toxicity than those of three-dimensional lead perovskites, organic antimony(III) halides show great application potential in opt-electronic field owing to diverse topologies along with exceptional optical properties. We report herein an antimony(III) hybrid (MePPh3 )2 SbCl5 with a zero-dimensional (0D) structure, which exhibits brilliant orange emission peaked at 593â nm with near-unity photoluminescent quantum yield (99.4 %). The characterization of photophysical properties demonstrates that the broadband emission with a microsecond lifetime (3.24â µs) arises from self-trapped emission (STE). Electrically driven organic light-emitting diodes (OLEDs) based on neat and doped films of (MePPh3 )2 SbCl5 were fabricated. The doped devices show significant improvement in comparison to non-doped OLEDs. Owing to the much improved surface morphology and balanced carrier transport in light-emitting layers of doped devices, the peak luminance, current efficiency (CE) and external quantum efficiency (EQE) are boosted from 82â cd m-2 to 3500â cd m-2 , 1.1â cd A-1 to 6.8â cd A-1 , and 0.7 % to 3.1 % relative to non-doped devices, respectively.
RESUMEN
An in-depth study on a stimuli-responsive tetranuclear cuprous luminescent complex is reported and gives new insights into the origin and possible use of the observed stimuli-responsive luminescence. Its crystalline polymorphs with two different shapes are obtained by using different crystallization solvents and show distinct emissions, with one being blue emissive and the other being yellow emissive. Upon grinding, only the blue-emitting polymorph has a marked change in the emission color from blue to yellow, and its ground sample exhibits a yellow emission similar to that of the yellow-emitting polymorph. Interestingly, the yellow-emitting polymorph after exposure to acetone vapor can emit a blue emission and display luminescence mechanochromism similar to that of the blue-emitting polymorph. Single-crystal structural analyses of the two different polymorphs reveal the relationship between the mechanochromic luminescence and the geometrical configuration of the {Cu(µ-dppm)2Cu} unit and intramolecular "pyridyl/phenyl" π···π interactions, supported as well by their PXRD, FT-IR, TGA, and PL studies in various states and by TD-DFT analyses. The results demonstrate the different roles of switchable intramolecular π···π interactions and the geometrical configuration of the {Cu(µ-dppm)2Cu} unit in this stimuli-responsive luminescence and potential applications of such stimuli-responsive luminescence in optical sensing and anticounterfeiting encryption technologies and deepen the understanding of such stimuli-responsive luminescence originating from switchable intramolecular π···π interactions. In addition, it is clearly suggested that the rational utilization of switchable intramolecular π···π interactions is a feasible route for developing stimuli-responsive intelligent luminescent materials and devices.
RESUMEN
Unveiling the internal dynamics of rotation in molecular machine at single-molecule scale is still a challenge. In this work, three crank-shaped molecules are elaborately designed with the conformational flipping between syn and anti fulfilled by two naphthyl groups rotating freely along 1,3-butadiynyl axis. By investigating the single-molecule conductance using scanning tunnelling microscope break junction (STM-BJ) technique and theoretical simulation, the internal rotation of these crank-shaped molecules is well identified through low and high conductance corresponding to syn- and anti-conformations. As demonstrated by theoretically computational study, the orbital energy changes with the conformational flipping and influences the intraorbital quantum interference, thus eventually modulating the single-molecule conductance. This work demonstrates single-molecule conductance measurement to be a rational approach for characterizing the internal rotation of molecular machines.
Asunto(s)
Conformación Molecular , Nanotecnología , Rotación , Simulación por ComputadorRESUMEN
Nonfullerene acceptors (MQ3, MQ5, MQ6) are synthesized using asymmetric and symmetric ladder-type heteroheptacene cores with selenophene heterocycles. Although MQ3 and MQ5 are constructed with the same number of selenophene heterocycles, the heteroheptacene core of MQ5 is end-capped with selenophene rings while that of MQ3 is flanked with thiophene rings. With the enhanced noncovalent interaction of Oâ â â Se compared to that of Oâ â â S, MQ5 shows a bathochromically shifted absorption band and greatly improved carrier transport, leading to a higher power conversion efficiency (PCE) of 15.64 % compared to MQ3, which shows a PCE of 13.51 %. Based on the asymmetric heteroheptacene core, MQ6 shows an improved carrier transport induced by the reduced π-π stacking distance, related with the increased dipole moment in comparison with the nonfullerene acceptors based on symmetric cores. MQ6 exhibits a PCE of 16.39 % with a VOC of 0.88â V, a FF of 75.66 %, and a JSC of 24.62â mA cm-2 .
RESUMEN
Highly soluble d8-d10 heteronuclear phosphors afford an alternative approach to achieve high-efficiency organic light-emitting diodes (OLEDs) through a solution process. In this work, four highly phosphorescent d8-d10 heteronuclear complexes with significant Pt-Au interactions were prepared. By judicious selection of sterically hindered and π-conjugated substituents in triphosphine ligands, the phosphorescence is dramatically promoted through effectively prohibiting nonradiative thermal relaxation with an efficiency of 0.94-0.99 in doping films. Exploiting highly emissive Pt-Au complexes as phosphorescent dopants, ultrahigh-efficiency solution-processed OLEDs were attained. The peak current efficiency, power efficiency, and external quantum efficiency are 96.2 cd A-1, 65.0 lm W-1, and 26.4% for the green-emitting PtAu2 phosphor and 68.6 cd A-1, 42.5 lm W-1, and 25.1% for the orange-emitting Pt2Au phosphor, which represent the state-of-art for solution-processed OLEDs based on non-iridium phosphors.
RESUMEN
In this work, rational design of highly soluble and phosphorescent Ag-Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H3decz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of H3decz, Au+, and Ag+ generated phosphorescent Ag4Au6 cluster 1 (Φem = 0.22 in CH2Cl2) with H2decz- having a free ethynyl (-C≡CH) group. When the four free C≡CH groups in the Ag4Au6 complex 1 are further bound to four (PPh3)Au+ and four (PPh3)Ag+ moieties through M-acetylide linkages, the formation of Ag8Au10 cluster 2 not only eliminates nonradiative ethynyl C-H vibrational deactivation process but also improves dramatically the molecular rigidity so that the phosphorescent efficiency of the Ag8Au10 cluster 2 (Φem = 0.63) is nearly 3 times that of the Ag4Au6 cluster 1. The Ag8Au10 cluster structure is further rigidified using diphsophine Ph2P(CH2)4PPh2 (dppb) in place of PPh3 so that the phosphorescence of the Ag8Au10 cluster 3 (Φem = 0.77) is more efficient than that of 2. Making use of the Ag8Au10 clusters as phosphorescent dopants, high-efficiency solution-processed organic light-emitting diodes (OLEDs) were achieved with current efficiency (CE) and external quantum efficiency (EQE) of 47.2 cd A-1 and 15.7% for complex 2 and 50.5 cd A-1 and 14.9% for complex 3.
RESUMEN
The reaction of 3,6-ditert-butyl-1,8-bis(diphenylphosphino)-9-methyl-9H-carbazole (L) with CuBr resulted in the isolation of tetranuclear copper(I) complex Cu4Br4L2 as two colorless crystal morphs, i.e., green-emitting 1G and yellow-emitting 1Y. As demonstrated by X-ray crystallography, the Cu4Br4 moiety in both 1G and 1Y adopts the same chair conformations. When L is bonded perpendicularly to the Cu4 plane, 1G with green emission is obtained, while it gives a yellow emission of 1Y once the L is parallelly bonded to Cu4 plane. Theoretical computational studies suggest that the variation in ligand orientation results in a different degree of structural distortion in triplet state and thus different luminescent energy. Particularly, 1Y undergoes dramatic structural distortion from the ground (S0) to triplet excied state (T1). Interestingly, 1G can be converted into 1Y upon exposed to saturated hexane vapor, which would return to 1G upon exposure to acetonitrile vapor. As demonstrated experimentally and theoretically, the reversible luminescence transformation between 1G and 1Y is ascribed to the variation of ligand L orientations.
RESUMEN
Mechanochromic luminescence materials have attracted rapidly growing interest. Nevertheless, the designed synthesis of such materials remains a challenge, and there have been few examples based on weak intramolecular interactions. Herein, we report a new approach for preparing mechanochromic luminescence materials of Cu(I) complexes, i.e., constructing a photoluminescence system that bears a large coplanar multinuclear Cu(I) unit showing weak intramolecular π···π interactions with the planar rings of the coordinated ligands in the molecule. Using it, a series of novel mechanochromic luminescent tetranuclear Cu(I) complexes have been successfully designed and synthesized. As revealed by single-crystal X-ray crystallography, these Cu(I) complexes share an identical {Cu4[µ3-η2(N,N),η1(N),η1(N)-pyridyltetrazole]2}2+ planar fragment whose coplanar pyridyl rings exhibit weak intramolecular π···π interactions with the phenyl rings of the coordinated phosphine ligands in the molecule. All of these Cu(I) complexes exhibit reversible mechanochromic luminescence, which can be attributed to the change in the rigidity of the molecular structure resulting from the disruption and restoration of intramolecular π···π interactions between the pyridyl and phenyl rings triggered by grinding and CH2Cl2 vapor, as supported by powder X-ray diffraction and Fourier transform infrared spectrometry. In addition, the results might provide a new route for developing mechanochromic luminescence materials of Cu(I) complexes for intelligent responsive luminescent devices.
RESUMEN
BACKGROUND: Gastrointestinal (GI) dysfunction is a common and important complication of acute pancreatitis (AP), especially in patients with severe AP. Despite this, there is no consensus means of obtaining a precise assessment of GI function. AIM: To determine the association between acute gastrointestinal injury (AGI) grade and clinical outcomes in critically ill patients with AP. METHODS: Patients with AP admitted to our pancreatic intensive care unit from May 2017 to May 2019 were enrolled. GI function was assessed according to the AGI grade proposed by the European Society of Intensive Care Medicine in 2012, which is mainly based on GI symptoms, intra-abdominal pressure, and feeding intolerance in the first week of admission to the intensive care unit. Multivariate logistic regression analysis was performed to assess the association between AGI grade and clinical outcomes in critically ill patients with AP. RESULTS: Among the 286 patients included, the distribution of patients with various AGI grades was 34.62% with grade I, 22.03% with grade II, 32.52% with grade III, and 10.84% with grade IV. The distribution of mortality was 0% among those with grade I, 6.35% among those with grade II, 30.11% among those with grade III, and 61.29% among those with grade IV, and AGI grade was positively correlated with mortality (χ 2 = 31.511, P < 0.0001). Multivariate logistic regression analysis showed that age, serum calcium level, AGI grade, persistent renal failure, and persistent circulatory failure were independently associated with mortality. Compared with the Acute Physiology and Chronic Health Evaluation II score (area under the curve: 0.739 vs 0.854; P < 0.05) and Ranson score (area under the curve: 0.72 vs 0.854; P < 0.01), the AGI grade was more useful for predicting mortality. CONCLUSION: AGI grade is useful for identifying the severity of GI dysfunction and can be used as a predictor of mortality in critically ill patients with AP.
Asunto(s)
Enfermedad Crítica/mortalidad , Enfermedades Gastrointestinales/diagnóstico , Pancreatitis/mortalidad , Índice de Severidad de la Enfermedad , Adulto , Anciano , Estudios de Factibilidad , Femenino , Enfermedades Gastrointestinales/etiología , Enfermedades Gastrointestinales/mortalidad , Mortalidad Hospitalaria , Humanos , Unidades de Cuidados Intensivos/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Pancreatitis/complicaciones , Estudios Retrospectivos , Medición de Riesgo/métodosRESUMEN
Bis(diphenylphosphinomethyl)phenylphosphine (dpmp)-supported Pt2Au heterotrinuclear complexes [Pt2Au(dpmp)2(C≡CPh)4](ClO4) (1), [Pt2Au(dpmp)2(DEBf)(C≡CPh)2](ClO4) (2), and [Pt2Au(dpmp)2(DECz)(C≡CPh)2](ClO4) (3) were prepared and used in organic light-emitting diodes (OLEDs) as a new class of light emitters, where DEBf = dibenzofuran-4,6-diacetylide and DECz = 3,6-di-tert-butylcarbazole-1,8-diacetylide. Although the flexible structure of Pt2Au complex 1 (λem = 503 nm, Φem < 0.1%) results in weak photoluminescence in fluid CH2Cl2, complexes 2 (λem = 585 nm, Φem = 4.9%) and 3 (λem = 589 nm, Φem = 3.2%) with a rigid conformation give a much stronger phosphorescence. The displacement of two σ-bonded phenylacetylide ligands with a diacetylide ligand such as DEBf and DECz to fasten Pt2Au structures facilitates greatly luminescent emission so that the emissive quantum yield in doping film is as high as 89% for 2 and 93% for 3. As revealed by a theoretical study, the severe structural distortion of diacetylide-linked Pt2Au complexes 2 (λem = 585 nm) and 3 (λem = 589 nm) in a triplet excited state gives rise to significant red shifts of phosphorescent emission spectra relative to that of complex 1 (λem = 503 nm). By means of Pt2Au complexes as phosphorescent emitters, solution-processed OLEDs achieved a relatively low external quantum efficiency (EQE < 9.5%) when commercial poly(ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) was used as the hole-injection layer (HIL). In contrast, the peak EQE was increased to 18.3% with a dramatic increase of efficiency by the use of modified HILs composed of PEDOT:PSS and PSS-Na, which provide a higher work function and a better film morphology.