Singlet Fission in a New Series of Systematically Designed Through-space Coupled Tetracene Oligomers.

Singlet fission (SF) holds great promise for current photovoltaic technologies, where tetracenes, with their relatively high triplet energies, play a major role for application in silicon-based solar cells. However, the SF efficiencies in tetracene dimers are low due to the unfavorable energetics of their singlet and triplet energy levels. In the solid state, tetracene exhibits high yields of triplet formation through SF, raising great interest about the underlying mechanisms. To address this discrepancy, we designed and prepared a novel molecular system based on a hexaphenylbenzene core decorated with 2 to 6 tetracene chromophores. The spatial arrangement of tetracene units, induced by steric hindrance in the central part, dictates through-space coupling, making it a relevant model for solid-state chromophore organization. We then revealed a remarkable increase in SF quantum yield with the number of tetracenes, reaching quantitative (196 %) triplet pair formation in hexamer. We observed a short-lived correlated triplet pair and limited magnetic effects, indicating ineffective triplet dissociation in these through-space coupled systems. These findings emphasize the crucial role of the number of chromophores involved and the interchromophore arrangement for the SF efficiency. The insights gained from this study will aid designing more efficient and technology-compatible SF systems for applications in photovoltaics.

Entropy-driven charge-transfer complexation yields thermally activated delayed fluorescence and highly efficient OLEDs.

Exciplex-forming systems that display thermally activated delayed fluorescence are widely used for fabricating organic light-emitting diodes. However, their further development can be hindered through a lack of structural and thermodynamic characterization. Here we report the generation of inclusion complexes between a cage-like, macrocyclic, electron-accepting host (A) and various N-methyl-indolocarbazole-based electron-donating guests (D), which exhibit exciplex-like thermally activated delayed fluorescence via a through-space electron-transfer process. The D/A cocrystals are fully resolved by X-ray analyses, and UV-visible titration data show their formation to be an endothermic and entropy-driven process. Moreover, their emission can be fine-tuned through the molecular orbitals of the donor. Organic light-emitting diodes were fabricated using one of the D/A systems, and the maximum external quantum efficiency measured was 15.2%. An external quantum efficiency of 10.3% was maintained under a luminance of 1,000 cd m-2. The results show the potential of adopting inclusion complexation to better understand the relationships between the structure, formation thermodynamics and properties of exciplexes.

Engineering of Cyano Functionalized Benzo[d]imidazol-2-ylidene Ir(III) Phosphors for Blue Organic Light-Emitting Diodes.

In this study, we designed and synthesized three series of blue emitting homoleptic iridium(III) phosphors bearing 4-cyano-3-methyl-1-phenyl-6-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (mfcp), 5-cyano-1-methyl-3-phenyl-6-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (ofcp), and 1-(3-(tert-butyl)phenyl)-6-cyano-3-methyl-4-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (5-mfcp) cyclometalates, respectively. These iridium complexes exhibit intense phosphorescence in the high energy region of 435-513 nm in the solution state at RT, to which the relatively large T1 → S0 transition dipole moment is beneficial for serving as a pure emitter and an energy donor to the multiresonance thermally activated delayed fluorescence (MR-TADF) terminal emitters via Förster resonance energy transfer (FRET). The resulting OLEDs achieved true blue, narrow bandwidth EL with a max EQE of 16-19% and great suppression of efficiency roll-off with ν-DABNA and t-DABNA. We obtained the FRET efficiency up to 85% using titled Ir(III) phosphors f-Ir(mfcp)3 and f-Ir(5-mfcp)3 to achieve true blue narrow bandwidth emission. Importantly, we also provide analysis on the kinetic parameters involved in the energy transfer processes and, accordingly, propose feasible ways to improve the efficiency roll-off caused by the shortened radiative lifetime of hyperphosphorescence.

High risk of infection in 'real-world' patients receiving ibrutinib, idelalisib or venetoclax for mature B-cell leukaemia/lymphoma.

OBJECTIVE: The infection risk in patients receiving ibrutinib, idelalisib or venetoclax for chronic lymphocytic leukaemia (CLL) or B-cell lymphoma treated outside of clinical trials is incompletely defined. We sought to identify the severe infection rate and associated risk factors in a 'real-world' cohort. METHODS: We conducted a retrospective cohort study of adult patients with CLL or lymphoma treated with ibrutinib, idelalisib or venetoclax. RESULTS: Of 67 patients identified (ibrutinib n = 53, idelalisib n = 8 and venetoclax n = 6), 32 (48%) experienced severe infection. Severe infection occurred at a rate of 65 infections per 100 person-years, with a median of 17.8 months of therapy. Median time to first infection (IQR) was 5.4 months (1.4-15.9). Poor baseline Eastern Cooperative Oncology Group (ECOG) performance status and high Charlson Comorbidity Index (CCI) score associated with increased risk of severe infection [hazard ratios (95% CI) 1.57 (1.07-2.31, p = .018) and 1.3 (1.05-1.62, p = .016) respectively]. CONCLUSION: The severe infection rate for patients receiving ibrutinib, idelalisib or venetoclax for lymphoma and CLL exceeded those reported in clinical trials. Patients with poor ECOG or high CCI should be closely monitored for early signs of infection and prevention strategies actively pursued. Further prospective research is required to define optimal antimicrobial prophylaxis recommendations.

I(III)-Catalyzed Oxidative Cyclization-Migration Tandem Reactions of Unactivated Anilines.

An I(III)-catalyzed oxidative cyclization-migration tandem reaction using Selectfluor as the oxidant was developed that converts unactivated anilines into 3H-indoles is reported herein. The reaction requires as little as 1 mol % of the iodocatalyst and is mild, tolerating pyridine and thiophene functional groups, and the dependence of the diastereoselectivity of the process on the identity of the iodoarene or iodoalkane precatalyst suggests that the catalyst is present for the stereochemical determining C-N bond forming step.

Validation and improvement of a proposed scoring system to detect retained common bile duct stones in gallstone pancreatitis.

BACKGROUND: In 2009, a study from our institution used retrospective data and multivariate analysis to identify 5 quantitative variables and their cutoffs that have a positive predictive value (PPV) for common bile duct (CBD) stones in gallstone pancreatitis. They also proposed a management protocol based on the scoring system. This prospective study sought to validate that scoring system. METHODS: From October 2009 to August 2013, patients with gallstone pancreatitis were enrolled in the study. Scores of 0-5 were determined at admission, with 1 point for each criterion met: CBD ≥ 9 mm, gamma glutamyltransferase ≥ 350 U/L, alkaline phosphatase ≥ 250 U/L, total bilirubin ≥ 3 mg/dL, and direct bilirubin ≥ 2 mg/dL. All CBDs were assessed using intraoperative cholangiogram, MR cholangiopancreatography (MRCP), or endoscopic retrograde cholangiopancreatography (ERCP). RESULTS: Of 84 patients, 16 had CBD stones. A score of 0 had negative predictive value (NPV) of 100% for CBD stones (P < .001). Scores of 1 and 2 had NPV of 81% and 83%, respectively. A score of 3 had NPV of 60%. A score of 4 had PPV of 67% (P = .002). A score of 5 had PPV of 100% (P < .001). The overall accuracy of the scoring system was 88%. CONCLUSION: The scoring system is accurate in prediction of CBD stones in patients with gallstone pancreatitis. We propose that patients with 0 points undergo laparoscopic cholecystectomy, 1 and 2 points undergo laparoscopic cholecystectomy with intraoperative cholangiogram, 3 and 4 points undergo MRCP, and 5 points undergo ERCP as the first step in management for gallstone pancreatitis. The proposed protocol eliminated negative ERCPs.

Drug loading of nanoporous TiO2 films.

The loading of therapeutic amounts of drug on a nanoporous TiO(2) surface is described. This novel drug-loading scheme on a biocompatible surface, when employed on medical implants, will benefit patients who require the deployment of drug-eluting implants. Anticoagulants, analgesics and antibiotics can be considered on the associated implants for drug delivery during the time of maximal pain or risk for patients undergoing orthopedic procedures. Therefore, this scheme will maximize the chances of patient recovery.