Open-Shell and Closed-Shell Quinoid-Aromatic Conjugated Polymers: Unusual Spin Magnetic and High Charge Transport Properties.

While quinoidal moieties are considered as emerging platforms showing efficient charge transport and interesting open-shell diradical characteristics, whether these properties could be changed by extension to the conjugated polymer structure remains as a fundamental question. Here, we developed and characterized two conjugated polymers incorporating quinoids with different lengths, which have a stable close- and open-shell diradical character, respectively, namely, poly(quinoidal thiophene-thienylene vinylene) (PQuT-TV) and poly(quinoidal bithiophene-thienylene vinylene) (PQuBT-TV). A longer length of a quinoidal core led to enhanced diradical characteristics.

The Effect of Fluorine Substitution on the Molecular Interactions and Performance in Polymer Solar Cells.

Fluorine (F) substitution on conjugated polymers in polymer solar cells (PSCs) has a diverse effect on molecular properties and device performance. We present a series of three D-A type conjugated polymers (PBT, PFBT, and PDFBT) based on dithienothiophene and benzothiadiazole units with different numbers of F atoms to explain the influence of F substitution by comparing the molecular interactions of the polymers and the recombination kinetics in PSCs. The preaggregation behavior of PFBT and PDFBT in o-DCB at the UV-vis absorption spectra proves that both polymers have strong intermolecular interactions.

Phase Transformation, Exceptional Quenching Efficiency, and Discriminative Recognition of Nitroaromatic Analytes in Hydrophobic, Nonporous Zn(II) Coordination Frameworks.

Five-fold interpenetrated Zn(II) frameworks (1 and 2) have been prepared, and an irreversible phase transformation from 1 to 2 is found to occur through a dissolution-recrystallization process. Compound 1 exhibits the highest quenching efficiency (>96%) for nitrobenzene at 7 ppm among luminescent coordination polymers. Selective discrimination of nitroaromatic molecules including o-nitrophenol (o-NP), p-nitrophenol (p-NP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP) is realized in 1 and 2 as a result of the fact that the framework-analyte interaction affords characteristic emission signals.

Stable charge storing in two-dimensional MoS2 nanoflake floating gates for multilevel organic flash memory.

In this study, we investigated chemically exfoliated two-dimensional (2-D) nanoflakes of molybdenum disulfide (MoS2) as charge-storing elements for use in organic multilevel memory devices (of the printed/flexible non-volatile type) based on organic field-effect transistors (OFETs) containing poly(3-hexylthiophene) (P3HT). The metallic MoS2 nanoflakes were exfoliated in 2-methoxyethanol by the lithium intercalation method and were deposited as nano-floating gates between polystyrene and poly(methyl methacrylate), used as bilayered gate dielectrics, by a simple spin-coating and low temperature (<150 °C) process. In the developed OFET memory devices, electrons could be trapped/detrapped in the MoS2 nano-floating gates by modulating the charge carrier density in the active channel through gate bias control.

Reversible structural transformation and selective gas adsorption in a unique aqua-bridged Mn(II) metal-organic framework.

An aqua-bridged Mn metal-organic framework was prepared, and a dramatic structural transformation occurs upon solvent exchange-resolvation and desolvation-resolvation processes. The desolvated phase, formed by removing the aqua bridges, exhibits selective CO(2) uptake over N(2), H(2), and CH(4). Further, antiferromagnetic couplings are also found between Mn spins in the secondary building units.