Air-stable Perylene Diimide Trimer Material for n-type Organic Electrochemical Transistors

We report a new method to make air-stable n-type organic mixed ionic-electronic conductor (OMIEC) films for organic electrochemical transistors (OECTs) using a solution-processable small molecule helical perylene diimide trimer, hPDI[3]-C11. Alkyl side chains were attached to the conjugated core for processability and film making, which were then cleaved via thermal annealing. After the sidechains were removed, the hPDI[3] film becomes less hydrophobic, more ordered, and has a deeper lowest unoccupied molecular orbital (LUMO). These features provide improved ionic transport, greater electronic mobility, and increased stability in air and in aqueous solution. Subsequently, we use hPDI[3]-H as the active material in OECTs and demonstrate a device with a transconductance of 44 mS, volumetric capacitance of ∼250 F/cm3, µC* value of 1 F/cmVs, and excellent stability (> 5 weeks). As proof of their practical applications, we utilize a hPDI[3]-H-based OECTs as a glucose sensor and electrochemical inverter. The approach of side chain removal after film formation charts a path to a wide range of molecular semiconductors to be used as stable, mixed ionic-electronic conductors. This article is protected by copyright. All rights reserved.

Solubilizing Benzodifuranone-Based Conjugated Copolymers with Single-Oxygen-Containing Branched Side Chains

Single-oxygen-containing branched side chains are designed and used to solubilize n-type copolymers consisting of BDF (benzodifuranone), isatin, and thiophene-based units. We present a simple synthetic approach to side chains with varying linker distances between the backbone and the branching point. The synthetic pathway is straightforward and modular and starts with commercially available reagents. The side chains give rise to excellent solubilities of BDF-thiophene copolymers of up to 90 mg/mL, while still being moderate in size (26-34 atoms large). The excellent solubility furthermore allows high molar mass materials. BDF-thiophene copolymers are characterized in terms of optoelectronic and thermoelectric properties. The electrical conductivity of chemically doped polymers is found to scale with molar mass, reaching ∼1 S/cm for the highest molar mass and longest backbone-branching point distance.

Multigram-Scale Synthesis of Luminescent Cesium Lead Halide Perovskite Nanobricks for Plastic Scintillators

Cesium lead halide perovskite nanocrystals of general formula CsPbX₃ are having tremendous impact on a vast array of technologies requiring strong and tunable luminescence across the visible range and solutions processing. The development of plastic scintillators is just one of the many relevant applications. The syntheses are relatively simple but generally unsuitable to produce a large amount of material of reproducible quality required when moving from proof-of-concept scale to industrial applications. Wastes, particularly large amounts of lead-contaminated toxic and flammable organic solvents, are also an open issue. We describe a simple and reproducible procedure enabling the synthesis of luminescent CsPbX₃ nanobricks of constant quality on a scale going from 0.12 to 8 g in a single batch. We also show complete recycling of the reaction wastes, leading to dramatically improved efficiency and sustainability.

Effects of Molecular Encapsulation on the Photophysical and Charge Transport Properties of a Naphthalene Diimide Bithiophene Copolymer

Engineering the molecular structure of conjugated polymers is key to advancing the field of organic electronics. In this work, we synthesized a molecularly encapsulated version of the naphthalene diimide bithiophene copolymer PNDIT2, which is among the most popular high charge mobility organic semiconductors in n-type field-effect transistors and non-fullerene acceptors in organic photovoltaic blends. The encapsulating macrocycles shield the bithiophene units while leaving the naphthalene diimide units available for intermolecular interactions. With respect to PNDIT2, the encapsulated counterpart displays an increased backbone planarity. Molecular encapsulation prevents preaggregation of the polymer chains in common organic solvents, while it permits π-stacking in the solid state and promotes thin film crystallinity through an intermolecular-lock mechanism. Consequently, n-type semiconducting behavior is retained in field-effect transistors, although charge mobility is lower than in PNDIT2 due to the absence of the fibrillar microstructure that originates from preaggregation in solution. Hence, molecularly encapsulating conjugated polymers represent a promising chemical strategy to tune the molecular interaction in solution and the backbone conformation and to consequently control the nanomorphology of casted films without altering the electronic structure of the core polymer.

Selective photoredox direct arylations of aryl bromides in water in a microfluidic reactor

Carrying out photoredox direct arylation couplings between aryl halides and aryls in aqueous solutions of surfactants enables unprecedented selectivity with respect to the competing dehalogenation process, thanks to the partition coefficient of the selected sacrificial base. The use of a microfluidic reactor dramatically improves the reaction time, without eroding the yields and selectivity. The design of a metal free sensitizer, which also acts as the surfactant, sizeably improves the overall sustainability of arylation reactions and obviates the need for troublesome purification from traces of metal catalysts. The generality of the method is investigated over a range of halides carrying a selection of electron withdrawing and electron donating substituents.

Confidence in the Use of Direct Oral Anticoagulants in the Acute Phase of Nonvalvular Atrial Fibrillation-Related Ischemic Stroke Over the Years: A Real-World Single-Center Study

BACKGROUD AND AIM

The use of direct oral anticoagulants (DOACs) in patients with nonvalvular atrial fibrillation (NVAF)-related acute ischemic stroke (AIS) is controversial. The aims of our study were to analyze physicians' confidence in prescribing DOACs in NVAF-related AIS, the characteristics of patients receiving DOACs, and their 90-day prognosis.

MATERIAL AND METHODS

Clinical records of consecutive patients admitted to our wards for NVAF-related AIS over the years 2014-2016 were reviewed.

RESULTS

One hundred forty-seven patients, 72.7% females, mean age ± standard deviation 83.4 ± 8.8 years, were admitted to our ward for atrial fibrillation (AF)-related AIS (38 in 2014, 47 in 2015, 62 in 2016). Of these patients, 141 had NVAF-related AIS. Median length of hospital stay was 8 days (interquartile range [IQR], 6-11). In-hospital mortality was 10.8%. Ninety-eight patients (69.5%) received DOACs for secondary prevention, with increasing percentages from 2014 (62.5%) to 2016 (88%). In 88% of them, DOACs were started during hospital stay, whereas in 12% DOACs were started during ambulatory follow-up. The median time for starting DOACs was 5 days (IQR, 3-8). In patients receiving DOACs, the median National Institutes of Health Stroke Scale score was 6 (IQR, 3-12), and large ischemic lesions were present in 48%; the median modified Rankin Scale score at hospital discharge was 3 (IQR, 1-4), whereas the score at 90 days was 2 (IQR, 1-3). At the 90-day follow-up, in patients receiving DOACs, overall mortality was 3.0%, stroke recurrence was 1%, and no patients had major intracranial or extracranial bleedings.

CONCLUSION

Our study suggests that physicians are becoming increasingly confident in the use of DOACs in NVAF-related AIS. The use of DOACs seems effective and safe even when started in the acute phase of stroke.