Search

Thermally activated delayed fluorescence (TADF) compounds are highly attractive as sensitizing and emitting materials for organic light-emitting diodes (OLEDs). The efficiency of the OLED depends on multiple parameters, most of which rely on the properties of the emitter including those that govern the internal quantum and outcoupling efficiencies. Herein, we investigate a series of aryl substituted acridine donor derivatives of the donor-acceptor TADF emitter DMAC-TRZ , with the objective of correlating their properties, such as triplet harvesting efficiency and transition dipole moment orientation, with their corresponding device efficiency. The decoration of the DMAC donor with substituted aryl groups not only modifies the molecular weight and length of the emitter but also affects the emission color and the capacity for the emitters to efficiently harvest triplet excitons. The presence of electron-withdrawing 4-cyanophenyl and 4-trifluoromethylphenyl groups in, respectively, CNPh-DMAC-TRZ and CF3Ph-DMAC-TRZ , blue-shifts the emission spectrum but slows down the reverse intersystem crossing rate constant ( k RISC ), while the opposite occurs in the presence of electron-donating groups in t BuPh-DMAC-TRZ and OMePh-DMAC-TRZ (red-shifted emission spectrum and faster k RISC ). In contrast to our expectations, the OLED performance of the five DMAC-TRZ derivatives does not scale with their degree of horizontal emitter orientation but follows the k RISC rates. This, in turn, demonstrates that triplet harvesting (and not horizontal emitter orientation) is the dominant effect for device efficiency using this family of emitters. Nonetheless, highly efficient OLEDs were fabricated with t BuPh-DMAC-TRZ and OMePh-DMAC-TRZ as emitters, with improved EQE max (∼28%) compared to the reference DMAC-TRZ devices., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The efficiency of thermally activated delayed fluorescence (TADF) in organic materials relies on rapid intersystem crossing rates and fast conversion of triplet (T) excitons into a singlet (S) state. Heavy atoms such as sulfur or selenium are now frequently incorporated into TADF molecular structures to enhance these properties by increased spin-orbit coupling [spin orbit coupling (SOC)] between the T and S states. Here a series of donor-acceptor (D-A) molecules based on 12 H -benzo[4,5]thieno[2,3- a ]carbazole and dicyanopyridine is compared with their nonsulfur control molecules designed to probe such SOC effects. We reveal that unexpected intermolecular interactions of the D-A molecules with carbazole-containing host materials instead serve as the dominant pathway for triplet decay kinetics in these materials. In-depth photophysical and computational studies combined with organic light emitting diode measurements demonstrate that the anticipated heavy-atom effect from sulfur is overshadowed by exciplex formation. Indeed, even the unsubstituted acceptor fragments exhibit pronounced TADF exciplex emission in appropriate carbazole hosts. The intermolecular charge transfer and TADF in these systems are further confirmed by detailed time-dependent density functional theory studies. This work demonstrates that anticipated heavy-atom effects in TADF emitters do not always control or even impact the photophysical and electroluminescence properties., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Optical pump-probe techniques allow for an in-depth study of dark excited states. Here, we utilize them to map and gain insights into the excited states involved in the thermally activated delayed fluorescence (TADF) mechanism of a benchmark TADF emitter DMAC-TRZ . The results identify different electronic excited states involved in the key TADF transitions and their nature by combining pump-probe and photoluminescence measurements. The photoinduced absorption signals are highly dependent on polarity, affecting the transition oscillator strength but not their relative energy positions. In methylcyclohexane, a strong and vibronically structured local triplet excited state absorption ( 3 LE → 3 LE n ) is observed, which is quenched in higher polarity solvents as 3 CT becomes the lowest triplet state. Furthermore, ultrafast transient absorption (fsTA) confirms the presence of two stable conformers of DMAC-TRZ : (1) quasi-axial (QA) interconverting within 20 ps into (2) quasi-equatorial (QE) in the excited state. Moreover, fsTA highlights how sensitive excited state couplings are to the environment and the molecular conformation.

Background: The potential benefits of the thin-walled 5F Glidesheath Slender sheath in the distal transradial access (dTRA) have not been investigated. This study aimed to compare the Glidesheath Slender versus conventional 5Fr arterial sheaths in patients undergoing diagnostic coronary angiography (CAG) through the dTRA., Methods: A total of 352 consecutive patients with an indication for CAG were randomized (1:1) to Glidesheath Slender 5Fr versus a conventional 5Fr arterial sheath for dTRA. The primary endpoint was the rate of successful hemostasis at 30 minutes after sheath removal. Follow-up ultrasound of the right radial and distal radial artery was performed 7-10 days after the procedure., Results: After exclusion of patients where a 6Fr sheath or crossover of access site was required, 108 patients in the Glidesheath Slender and 105 patients in the conventional 5Fr arterial sheath group were included in the analysis. The crossover rate to conventional radial access and the rate of successful hemostasis at 30 minutes after sheath removal were similar between the two groups (18.9% in the Glidesheath slender vs. 22% in the control group; P=0.460, and 62% vs. 51.4%; P=0.118, respectively). The level of pain associated with the procedure was significantly lower in the Glidesheath Slender group (2.69 vs. 3.29 in the control group; P=0.02). No significant difference was recorded between the two groups in the rate of access-related complications., Conclusions: Use of Glidesheath Slender for dTRA did not increase the rate of early hemostasis compared with conventional arterial sheath.

Extensive research has been devoted to the development of thermally activated delayed fluorescence emitters, especially those showing pure-blue emission for use in lighting and full-color display applications. Toward that goal, herein we report a novel weak donor, 1,4-azaborine (AZB), with complementary electronic and structural properties compared to the widely used dimethylacridan (DMAC) or carbazole (Cz) donors. Coupled with a triazine acceptor, AZB-Ph-TRZ is the direct structural analogue of the high-performance and well-studied green TADF emitter DMAC-TRZ and has Δ E ST = 0.39 eV, a photoluminescence quantum yield (Φ PL ) of 27%, and λ PL = 415 nm in 10 wt % doped mCP films. The shortened analogue AZB-TRZ possesses red-shifted emission with a reduced singlet-triplet gap (Δ E ST = 0.01 eV) and fast reverse intersystem crossing ( k RISC of 5 × 10 6 s -1 ) in mCP. Despite a moderate Φ PL of 34%, OLEDs with AZB-TRZ in mCP showed sky-blue emission with CIE 1931 ( x,y ) of (0.22,0.39) and a maximum external quantum efficiency (EQE max ) of 10.5%. Expanding the chemist's toolkit for the design of blue donor-acceptor TADF materials will enable yet further advances in the future, as AZB is paired with a wider range of acceptor groups.

We present a detailed and comprehensive picture of the photophysics of thermally activated delayed fluorescence (TADF). The approach relies on a few-state model, parametrized ab initio on a prototypical TADF dye, that explicitly accounts for the nonadiabatic coupling between electrons and vibrational and conformational motion, crucial to properly address (reverse) intersystem crossing rates. The Onsager model is exploited to account for the medium polarity and polarizability, with careful consideration of the different time scales of relevant degrees of freedom. TADF photophysics is then quantitatively addressed in a coherent and exhaustive approach that accurately reproduces the complex temporal evolution of emission spectra in liquid solvents as well as in solid organic matrices. The different rigidity of the two environments is responsible for the appearance in matrices of important inhomogeneous broadening phenomena that are ascribed to the intertwined contribution from (quasi)static conformational and dielectric disorder.

Donor-acceptor (D-A) thermally activated delayed fluorescence (TADF) molecules are exquisitely sensitive to D-A dihedral angle. Although commonly simplified to an average value, these D-A angles nonetheless exist as distributions across the individual molecules embedded in films. The presence of these angle distributions translates to distributions in the rates of reverse intersystem crossing ( k rISC ), observed as time dependent spectral shifts and multiexponential components in the emission decay, which are difficult to directly quantify. Here we apply inverse Laplace transform fitting of delayed fluorescence to directly reveal these distributions. Rather than a single average value, the crucial k rISC rate is instead extracted as a density of rates. The modes and widths of these distributions vary with temperature, host environment, and intrinsic D-A torsional rigidity of different TADF molecules. This method gives new insights and deeper understanding of TADF host-guest interactions, as well as verifies future design strategies that target D-A bond rigidity.

In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms. Based on an in silico design, the compound DiICzMes4 possesses a red-shifted emission, enhanced photoluminescence quantum yield, and smaller singlet-triplet energy gap, Δ E ST , than the parent indolocarbazole that induces MR-TADF properties. Coupled cluster calculations accurately predict the magnitude of the Δ E ST when the optimized singlet and triplet geometries are used. Slow yet optically detectable reverse intersystem crossing contributes to low efficiency in organic light-emitting diodes using DiICzMes4 as the emitter. However, when used as a terminal emitter in combination with a TADF assistant dopant within a hyperfluorescence device architecture, maximum external quantum efficiencies of up to 16.5% were achieved at CIE (0.15, 0.11). This represents one of the bluest hyperfluorescent devices reported to date. Simultaneously, recognising that MR-TADF emitters do not require acceptor atoms reveals an unexplored frontier in materials design, where yet greater performance may yet be discovered.

Wine and by-products are essential elements of a Mediterranean diet and considered as a reservoir of bioactive compounds with various health effects. Grape pomace, an easily available natural material of low cost, shares a similar wealth of health benefiting bioactive phytochemicals. The objective of this study was to explore the utilization of grape pomace from Commandaria dessert wine as main ingredient for functional infusions. Therefore, the ratio of water to grape pomace powder (40-200 mL g -1 ), infusion time (3-15 min) and temperature (55-95 °C) were optimized in terms of composition and bioactivity. Multiple response optimization indicated that brewing 200 mL water per g of material for 12.2 min at 95 °C, was the optimum method for preparing the infusion. Results also revealed a significant impact of three parameters as well as quadratic and interactive effects on composition and bioactivity of infusions. Furthermore, the infusion presents antimicrobial effects against Listeria monocytogenes serotypes and other common food pathogenic bacteria. Finally, a sensory evaluation was performed to assess the organoleptic attributes of the infusion and its improvement, with the addition of Mediterranean aromatic plants. Overall, the present work describes a promising strategy for the re-use of sun-dried grape pomace as a functional ingredient of infusions.

Commonly, thermally activated delayed fluorescence (TADF) emitters present a twisted donor-acceptor structure. Here, electronic communication is mediated through-bond via π-conjugation between donor and acceptor groups. A second class of TADF emitters are those where electronic communication between donor and acceptor moieties is mediated through-space. In these through-space charge-transfer (TSCT) architectures, the donor and acceptor groups are disposed in a pseudocofacial orientation and linked via a bridging group that is typically an arene (or heteroarene). In most of these systems, there is no direct evidence that the TSCT is the dominant contributor to the communication between the donor and acceptor. Herein we investigate the interplay between through-bond localized excited (LE) and charge-transfer (CT) states and the TSCT in a rationally designed emitter, TPA-ace-TRZ , and a family of model compounds. From our photophysical studies, TSCT TADF in TPA-ace-TRZ is unambiguously confirmed and supported by theoretical modeling.

The photophysics of multiple resonance thermally activated delayed fluorescence molecule ν-DABNA is described. We show coupling of a 285 cm -1 stretching/scissoring vibrational mode of peripheral phenyl rings to the S 1 state, which dictates the ultimate emission full-width at half maximum. However, a separate high amplitude mode, 945 cm -1 of the N -biphenyl units, mediates the reverse intersystem crossing (rISC) mechanism. Concentration-dependent studies in solution and solid state reveal a second emission band that increases nonlinearly with concentration, independent of the environment assigned to excimer emission. Even at concentrations well below those used in devices, the excimer contribution affects performance. Using different solvents and solid hosts, rISC rates between 3-6 × 10 5 s -1 are calculated, which show negligible dependence on environmental polarity or host packing. At 20 K over the first 10 ns, we observe a broad Gaussian excimer emission band with energy on-set above the S 1 exciton band. An optical singlet-triplet gap (ΔE ST ) of 70 meV is measured, agreeing with previous thermal estimates; however, the triplet energy is also found to be temperature-dependent. A monotonic increase of the exciton emission band full-width at half maximum with temperature indicates the role of hot transitions in forming vibrational excited states at room temperature (RT), and combined with an observed temperature dependency of ΔE ST , we deduce that the rISC mechanism is that of thermally activated reverse internal conversion of T 1 to T N ( n ≥ 2) followed by rapid rISC of T N to S 1 . Organic light-emitting diodes with ν-DABNA as a hyperfluorescent emitter (0.5 wt % and 1 wt %) exhibit an increase of maximum external quantum efficiency, reaching 27.5% for the lower ν-DABNA concentration. On the contrary, a Förster radius analysis indicated that the energy transfer ratio is smaller because of higher donor-acceptor separation (>2.4 nm) with weak sensitizer emission observed in the electroluminescence. This indicates excimer quenching in 1 wt % devices.

The thermally activated delayed fluorescence (TADF) donor-acceptor (D-A) molecule, DMAC-TRZ, is used as a TADF emitter "probe" to distinguish the environmental effects of a range of solid-state host materials in guest-host systems. Using the guest's photophysical behavior in solution as a benchmark, a comprehensive study using a variety of typical TADF organic light-emitting diode hosts with different characteristics provides a clearer understanding of guest-host interactions and what affects emitter performance in solid state. We investigate which are the key host characteristics that directly affect charge-transfer (CT) state energy and singlet triplet energy gaps. Using time-resolved photoluminescence measurements, we use the CT state energy distribution obtained from the full width at half-maximum (fwhm) of the emission band and correlate this with other photophysical properties such as the apparent dynamic red shift of CT emission on-set to estimate the disorder-induced heterogeneity of D-A dihedral angles and singlet triplet gaps. Further, the delayed emission stabilization energy value and time-dependent CT band fwhm are shown to be related to a combination of host's rigidity, emitter molecule packing, and the energy difference between guest and host lowest energy triplet states. Concentration dependence studies show that emitter dimerization/aggregation can improve as well as reduce emission efficiency depending on the characteristics of the host. Two similar host materials, mCPCN and mCBPCN, with optimum host characteristics show completely different behaviors, and their hosting potential is extensively explored. We demonstrate that type I and type III TADF emitters behave differently in the same host and that the materials with intrinsic small Δ E ST have the smallest disorder-induced CT energy and reverse intersystem crossing rate dispersion. We also present an optimized method to define the actual triplet energy of a guest-host system, a crucial parameter in understanding the overall mechanism of the TADF efficiency of the system., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Aims: The aim of this study was to compare the performance of the Tiger-II with Judkins 3.5L/4R catheters in coronary angiography (CAG) via the transradial approach (TRA)., Methods and Results: Consecutive patients undergoing non-urgent CAG via the right TRA were randomised to either the Tiger-II (Terumo) or Judkins (3.5L/4R; Medtronic) 5 Fr catheters; 320 patients in each group were randomised. Catheter or access site change was required in 57 (17.8%) vs. 68 (21.3%) patients allocated to the Tiger-II and Judkins group, respectively (p=0.3). The study's primary endpoint of contrast volume (ml) used until completion of CAG was lower for Tiger-II vs. Judkins group: 66.8 (54.0-82.0) vs. 73.4 (60.0-94.1), p<0.001. Angiography, fluoroscopy time (min) and severe spasm rate were also significantly lower for Tiger-II vs. Judkins group: 5.52 (4.17-7.32) vs. 6.85 (5.15-9.63), p<0.00, 2.01 (1.32-3.13) vs. 2.24 (1.50-3.50), p=0.01 and 6 (2.8%) vs. 39 (12.2%), p<0.001, respectively. The Tiger-II catheter obtained better opacification grade for the right coronary artery (RCA): 4.0 (4.0-4.0) vs. 4.0 (3.0-4.0), p=0.02, but slightly compromised opacification of the left anterior descending (LAD) and left circumflex (LCX) arteries compared with the Judkins group: 3.75 (3.0-4.0) vs. 4.0 (3.5-4.0), p<0.001, and 3.78 (3.6-4.0) vs. 4.0 (3.6-4.0), p<0.001, respectively., Conclusions: The Tiger-II was found superior to the Judkins 3.5L/4R regarding contrast volume use, procedural and fluoroscopy time, spasm rate and RCA imaging, and inferior regarding LAD and LCX imaging.

Background: The influence of diabetes mellitus (DM) on platelet reactivity (PR) in prasugrel or ticagrelor treated patients is not well studied., Methods: In an observational study involving 777 patients with acute coronary syndrome undergoing percutaneous coronary intervention treated by either prasugrel 10 mg od (n = 315) or ticagrelor 90 mg bid (n = 462), platelet function was assessed using the VerifyNow P2Y12 function assay (in PRU) at one month post intrvention., Results: In the overall population, ticagrelor and insulin-treated DM affected PR, with a decrease in log by 0.88 (corresponding to a 58 % decrease in PR) compared to prasugrel-treated patients (p < 0.001), and an increase in log by 0.26 (corresponding to a 30 % increase in PR) compared to non-diabetic patients (p = 0.01), respectively. PR in prasugrel-treated patients differed significantly by DM status: 70.0 (36.3-113.0) in non-diabetic vs 69.0 (44.5-115.3) in non insulin-treated diabetic vs 122.0 (69.0-161.0) in insulin-treated diabetic patients, p for trend = 0.01. No differences were observed in ticagrelor-treated patients. By multivariate analysis, in prasugrel-treated patients insulin-treated DM was the only factor predicting PR, with log of PR increased by 0.42 (corresponding to a 52 % increase in PR) compared to non-diabetic patients (p = 0.001). No factor was found to affect PR in ticagrelor-treated patients., Conclusions: Patients with insulin-treated DM treated with prasugrel post PCI have higher PR, than patients without DM or non insulin-treated diabetic patients treated with this drug. Ticagrelor treated patients have overall lower PR than patients on prasugrel, independent of DM status or insulin treatment., Trial Registration: Clinical Trials Gov. NCT01774955.

Background: Morphine is recommended in patients with ST-segment-elevation myocardial infarction, including those undergoing primary percutaneous coronary intervention. Suboptimal antiplatelet effect during and after primary percutaneous coronary intervention is associated with increased thrombotic complications. It was hypothesized a potential drug-drug interaction between morphine and antiplatelet agents. We sought to assess platelet inhibition after a loading dose of the currently recommended antiplatelet agents in ST-segment-elevation myocardial infarction patients according to morphine use., Methods and Results: Three hundred patients undergoing primary percutaneous coronary intervention receiving either prasugrel (n = 95) or ticagrelor (n = 205) loading dose had platelet reactivity assessed by VerifyNow 1, 2, and 4 hours after loading dose. Patients treated with morphine (n = 95; 32%) had a higher incidence of vomit (15% versus 2%; P = 0.001). P2Y12 reactivity units 2 hours after the loading dose was 187 (153-221) and 133 (102-165) in patient with and without morphine (P < 0.001); the difference persisted after excluding patients with vomit (P < 0.0001). High residual platelet reactivity (P2Y12 reactivity units ≥ 208) at 2 hours was found in 53% and 29% patients with and without morphine (P < 0.001) and without difference between prasugrel and ticagrelor patients. The independent predictors of high residual platelet reactivity at 2 hours were morphine use (odds ratio, 2.91 [1.71-4.97]; P < 0.0001) and age (odds ratio, 1.03 [1.01-1.05]; P = 0.010). Morphine remained associated with high residual platelet reactivity after propensity score adjustment (c-statistic, 0.68; 95% confidence interval, 0.66-0.70; P = 0.879 for Hosmer-Lemeshow test)., Conclusions: In patients with ST-segment-elevation myocardial infarction, morphine use is associated with a delayed onset of action of the oral antiplatelet agents. This association persisted after adjusting for the propensity to receive morphine and after excluding patients with vomit., (© 2014 American Heart Association, Inc.)