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We report two new poly-small-molecule acceptors, PYN-BDT and PYN-BDTF, which serve, by virtue of their π-extended naphthalene rings, as broad optical cross-section macromolecular absorbers (extending to ∼900 nm; ΔE opticalgap = 1.38 eV) in all-polymer solar cells (APSCs). APSCs fabricated by blending PYN-BDT or PYN-BDTF with PM6 exhibit power conversion efficiencies (PCEs) of 7.24 and 9.08%, respectively, while blends with PBDB-T exhibits far higher PCEs of 12.06 and 13.22%, respectively; the latter cell achieves J sc = 22.28 mA cm–2, among the highest known for an APSC. The results of blend morphology, GIWAXS, charge transport, exciton and carrier dynamics, PL quenching efficiency, and impedance-based analysis indicate that the PBDB-TT:PYN-BDTF blends and their APSCs outperform the corresponding PM6:PYN-BDTF devices due to significantly suppressed bimolecular recombination. These results demonstrate that π-conjugative extension of individual polymer acceptor blocks represents an efficient strategy to broaden APSC optical cross sections, decrease bimolecular recombination, and achieve high-performance cells with enhanced J sc metrics.

Molecular motors are diverse enzymes that transduce chemical energy into mechanical work and, in doing so, perform critical cellular functions such as DNA replication and transcription, DNA supercoiling, intracellular transport, and ATP synthesis. Single-molecule techniques have been extensively used to identify structural intermediates in the reaction cycles of molecular motors and to understand how substeps in energy consumption drive transitions between the intermediates. Here, we review a broad spectrum of single-molecule tools and techniques such as optical and magnetic tweezers, atomic force microscopy (AFM), single-molecule fluorescence resonance energy transfer (smFRET), nanopore tweezers, and hybrid techniques that increase the number of observables. These methods enable the manipulation of individual biomolecules via the application of forces and torques and the observation of dynamic conformational changes in single motor complexes. We also review how these techniques have been applied to study various motors such as helicases, DNA and RNA polymerases, topoisomerases, nucleosome remodelers, and motors involved in the condensation, segregation, and digestion of DNA. In-depth analysis of mechanochemical coupling in molecular motors has made the development of artificially engineered motors possible. We review techniques such as mutagenesis, chemical modifications, and optogenetics that have been used to re-engineer existing molecular motors to have, for instance, altered speed, processivity, or functionality. We also discuss how single-molecule analysis of engineered motors allows us to challenge our fundamental understanding of how molecular motors transduce energy.

The application of fluorescent graphitic carbon nitride (g-C 3 N 4 ) nanomaterials was limited by short photoluminescence (PL) wavelength. It is great desirable to develop g-C 3 N 4 nanomaterials with long PL wavelength and high quantum yield to expand their application. Herein phenyl-modified and sulfur doped g-C 3 N 4 (PhCNS) powders with tunable PL peak from 520 to 630 nm were prepared by copolymerization of 2,4diamino-6-phenyl-1,3,5-triazine and trithiocyanuric acid. The copolymerization process of PhCNS powders was proposed after chemical structure characterization and PL mechanism of PhCNS powders were investigated by transient fluorescence. In virtue of tunable PL color, broad PL peak, and high quantum yield, PhCNS powders were utilized to fabricate green, yellow, and white light-emitting diodes with high color quality and PhCNS nanosheets were applied for multicolor bioimaging. This work provides a pathway for exploring g-C 3 N 4 nanomaterials with long PL wavelength and facilitates their application in biocompatible optoelectronic devices, fluorescent bioimaging.

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High-performance and durable perovskite solar cells (PSCs) have advanced rapidly, enabled in part by the development of superior interfacial hole-transporting layers (HTLs). Here, a new series of 2,3-diphenylthieno [3,4-b]pyrazine (DPTP)-based small molecules containing bis-and tetrakis-triphenyl amino donors (1−3) was synthesized from simple, low-cost, and readily available starting materials. The matched energy levels, ideal surface topographies, high hole mobilities of 8.57 × 10 −4 cm 2 V −1 S −1 , and stable chemical structures of DPTP-4D (3) make it an effective hole-transporting material, delivering a PCE of 20.18% with high environmental, thermal, and light-soaking stability when compared to the reference HTL materials, doped Spiro-OMeTAD and PTAA in PSC n-i-p planar devices. Overall, these DPTP-based molecules are promising HTM candidates for the fabrication of stable PSCs.

Photoexcited organic chromophores appended to stable radicals can serve as qubit and/or qudit candidates for quantum information applications. 1,6,7,12-Tetra-(4-tert-butylphenoxy)-perylene-3,4 : 9,10bis(dicarboximide) (tpPDI) linked to a partially deuterated α,γ-bisdiphenylene-β-phenylallyl radical (BDPAd 16 ) was synthesized and characterized by time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies. Photoexcitation of tpPDI-BDPA-d 16 results in ultrafast radical-enhanced intersystem crossing to produce a quartet state (Q) followed by formation of a spin-polarized doublet ground state (D 0 ). Pulse-EPR experiments confirmed the spin multiplicity of Q and yielded coherence times of T m = 2.1 � 0.1 μs and 2.8 � 0.2 μs for Q and D 0 , respectively. BDPA-d 16 eliminates the dominant 1 H hyperfine couplings, resulting in a single narrow line for both the Q and D 0 states, which enhances the spectral resolution needed for good qubit addressability.

We report the encapsulation of free-base and zinc porphyrins by a tricyclic cyclophane receptor with subnanomolar binding affinities in water. The high affinities are sustained by the hydrophobic effect and multiple •π] stacking surfaces between the substrate porphyrins and the receptor. We discovered two co-conformational isomers of the 1:1 complex, where the porphyrin is orientated differently inside the binding cavity of the receptor on account of its tricyclic nature. The photophysical properties and chemical reactivities of the encapsulated porphyrins are modulated to a considerable extent by the receptor. Improved fluorescence quantum yields, redshifted absorptions and emissions, and nearly quantitative energy transfer processes highlight the emergent photophysical enhancements. The encapsulated porphyrins enjoy unprecedented chemical stabilities, where their D/H exchange, protonation, and solvolysis under extremely acidic conditions are completely blocked. We anticipate that the ultrahigh stabilities and improved optical properties of these encapsulated porphyrins will find applications in single-molecule materials, artificial photodevices, and biomedical appliances.