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Spatial discretization of biomolecules in the complex cellular environment is crucial for biomolecular form and function. The ability to better understand the driving force of spatial discretization of biomolecules in the complex cellular matrix remains a challenging task. We report on the robust polarity sensitive solvatochromic probe,FLAM, in conjunction with spectral phasor analysis as a general method for studying environmental polarity in biological systems. We find that phase separated proteins of SFPQ have distinct polarity depending on the type of phase separation occurring, suggesting that polarity plays a role in the formation of phase separated condensates. When usingFLAMin cells, distinct subcellular environmental polarity distribution but similar trend of changes is observed for cells under similar type of stressors. Taken together, our method puts forth an exciting development in the tool set for the study of phase separation.

The optical and electrical performances of varied configurations of visually attractive mosaic cubical luminescent solar concentrator photovoltaic (LSC PV) devices have been measured. These new designs of LSC PV devices consist of four cubical lightguides containing commercially available fluorophores with edge- and bottom-mounted silicon solar cells. The 1 cm 3 cubical component LSC PVs are made of poly (methyl methacrylate) (PMMA) doped by dyes from 10 to 150 ppm. The lightguides are covered with bifacial silicon solar cells at their edges and/or bottom and connected in series or parallel, depending on the device configuration. In total, 19 different configurations of mosaic LSC PV devices have been experimentally evaluated in this study.

A series of poly(phenylene-vinylene)-based copolymers are synthesized using the Gilch method incorporating monomers with sterically bulky sidechains. The photochemical upconversion performance of these polymers as emitters are investigated using a palladium tetraphenyltetrabenzoporphyrin triplet sensitizer and MEH-PPV as reference. Increased incorporation of sterically bulky monomers leads to a reduction in the upconversion efficiency despite improved photoluminescence quantum yield. A phosphorescence quenching study indicates issues with the energy transfer process between the triplet sensitizer and the copolymers. The best performance with 0.18% upconversion quantum yield is obtained for the copolymer containing 10% monomer with bulky sidechains.

Human serum albumin (HSA) is a broadly used biomarker for the diagnosis of various diseases such as chronic kidney disease. Here, a fluorescent probe TC426 with aggregation-induced emission (AIE) characteristics is reported as a sensitive and specific probe for HSA. This probe is non-emissive in aqueous solution, meanwhile it shows bright fluorescence upon interacting with HSA, which makes it applicable in detecting HSA with a high signal to noise ratio. Besides, the fluorescence of TC426 exhibits a high linear correlation with the concentration of albumin in the range of microalbumin (20-200 mg/L), which has a significant importance for the early diagnosis of glomerulus related diseases. Compared with previously reported HSA probes TPE-4TA and BSPOTPE, TC426 shows comparable anti-interference ability towards creatinine and other major components in urine but is excited by a longer excitation wavelength at the visible light range. Finally, with the established assay, TC426 shows excellent performance in detecting HSA in real human urine, indicating its great potential in practical urinalysis.

A series of poly(phenylene-vinylene)s (PPV) was synthesized with two monomer building blocks containing methoxy and 2-ethylhexyloxy (MEH) sidechains and sterically bulky fluorenyloxy sidechains. Variations in monomer incorporation were achieved by adjusting the ratio of the monomer precursors in the synthesis of the PPVs using the Gilch polymerization method. The increased incorporation of the bulky monomer led to expected variation in photophysical properties, in particular, the enhancement of photoluminescence quantum yield. Using palladium(II) tetraphenyltetrabenzoporphyrin (PdTPTBP) as the triplet sensitizer, all polymers displayed upconverted emission in solution with the comonomer ratio for the fluorenyloxy and MEH units at 1 : 10 showing the best performance with upconversion efficiency of 0.135%. This efficiency was up to three times higher than that of two commercially available PPVs, MEH-PPV and Super yellow PPV, under the same experimental conditions. Further analysis of the efficiency of the photochemical processes involved revealed several limitations to the performance of these conjugated polymer emitters. While increasing steric bulk of the sidechains improved the photoluminescence quantum yield, it also caused variation in excited state energies of the polymers through the series. This led to poor alignment with the triplet energy of our chosen sensitizer for some of the polymers. Even when the triplet–triplet energy transfer efficiency was high, the contact triplet pair formation efficiency was found to be very low. We reasoned that the structural conformation of the polymers hindered the chromophore orbital overlap during triplet collisions required for triplet–triplet annihilation.

A series of poly(phenylene–ethynylene) copolymers with various aryl spacer units were synthesized for use as emitters in triplet–triplet annihilation upconversion. The upconversion performance of these conjugated polymers was compared to that of well-known poly(phenylene–vinylene) polymers, MEH-PPV and super yellow, in chloroform solution. The copolymer containing anthracene units outperformed both reference polymers recording a maximum upconversion quantum yield of 0.18%.

“Burn-in” degradation occurs in many polymer solar cells, which dramatically reduces the overall power output of the cells at the early hundred hours. Understanding the “burn-in” degradation mechan...

Developing photostable compounds that undergo quantitative SF is a key challenge. As singlet fission necessitates electron transfer between neighboring molecules, the SF rate is highly sensitive to...

Environmental polarity is an important factor that drives biomolecular interactions to regulate cell function. Herein, a general method of using the fluorogenic probe NTPAN-MI is reported to quantify the subcellular polarity change in response to protein unfolding. NTPAN-MI fluorescence is selectively activated upon labeling unfolded proteins with exposed thiols, thereby reporting on the extent of proteostasis. NTPAN-MI also reveals the collapse of the host proteome caused by influenza A virus infection. The emission profile of NTPAN-MI contains information of the local polarity of the unfolded proteome, which can be resolved through spectral phasor analysis. Under stress conditions that disrupt different checkpoints of protein quality control, distinct patterns of dielectric constant distribution in the cytoplasm can be observed. However, in the nucleus, the unfolded proteome was found to experience a more hydrophilic environment across all the stress conditions, indicating the central role of nucleus in the stress response process.

The photoluminescence quantum yield (ϕPL) of perylene diimide derivatives (PDIs) is often limited by aggregation caused quenching (ACQ) at high concentration or in the neat solid-state. Energy transfer in high dye concentration systems is also a key factor in determining ϕPL as a result of energy funneling to trap sites in the sample. By tuning the substituents, we present two classes of PDIs with aggregation and insulation of the PDI core. By combining these fluorophores in a polymer film, we demonstrate highly emissive samples (85% ϕPL) at high concentration (140 mM or 20% w/w). Experimental and theoretical studies provide insight into why such a combination is necessary to achieve high ϕPL. While insulated fluorophores maintain respectable ϕPL at high concentration, an improved ϕPL can be achieved in the presence of appropriately oriented fluorophore aggregates as emissive traps. The theoretical calculations show that the relative orientation of aggregated monomers can result in energetic separation of localized states from the charge-transfer and bi-excitonic states thereby enabling high ϕPL.

Molecular rotors exhibit fluorescence enhancement in a confined environment and thus have been used extensively in biological imaging. However, many molecular rotors suffer from small Stokes shift and self-aggregation caused quenching. In this work, we have synthesised a series of red emissive molecular rotors based on cationic α-cyanostilbene. Profoundly enhanced aggregation-induced emission (AIE) properties and greatly widened Stokes shifts can be achieved by molecular engineering. With specificity to stain mitochondria, we demonstrate a simple approach to achieve cell uptake and retention upon tuning the pyridinium substituent of the dyes.

Improving the efficiency of triplet fusion upconversion (TF-UC) in the solid-state is still challenging due to the aggregation and phase separation of chromophores. In this work, two 9,10-diphenylanthracene (DPA) derivatives based on the modification of the 9,10-phenyl rings with bulky isopropyl groups (bDPA-1 and bDPA-2) were used as emitters. By using platinum octaethylporphyrin (PtOEP) as the sensitizer, TF-UC performance was comprehensively investigated in 3 media: toluene solution, polyurethane thin film and nano/micro-crystals in a polyvinyl alcohol matrix. Only a small difference in upconversion efficiency between the bulky DPAs and the DPA reference was observed in toluene solution and polyurethane thin film. However, a large improvement of TF-UC quantum yield was achieved in bDPA-2/PtOEP crystals (ΦUC = (0.92 ± 0.05)%) with a low excitation intensity threshold (52 mW cm-2) compared to that of DPA/PtOEP crystals (ΦUC = (0.09 ± 0.03)%). This difference was largely attributed to improved dispersibility of the PtOEP sensitizer in the bDPA-2 emitter crystals. The bulky DPAs also show excellent stability under UV irradiation with exposure to oxygen compared to DPA. These results provide a strategy for developing efficient solid-state TF-UC systems based on nano/micro-particles of emitter-sensitizer mixtures.

For semiconductors, doping is an efficient approach to tune their energy bandgaps, charge transport, and optical properties which could enable the improvement of the corresponding performances and open up the possibility of multifunction integration. Recently, significant advances have been achieved in molecular doped organic semiconductors, especially doped organic semiconductor single crystals (OSSCs) which have features of well-defined packing structures, long-range molecular orders, and low-density defects for fundamental studies and improved properties. In this review, we will give a summary of the exciting progress of molecular doped OSSCs from the aspects of selection criteria of molecular dopants, general growth methods, and resulting optoelectronic properties as well as their applications in optoelectronic devices. Finally, a brief conclusion is given with challenges and perspectives of molecular doped OSSCs and their related promising research directions in this field.

A series of phycobilin analogues have been investigated in terms of coupled excitonic systems. These compounds consist of a monomer, a tetrapyrrole structurally similar to bilirubin (bR), and two conjugated bR analogues. Spectroscopic and computational methods have been used to investigate the degree of interchromophore coupling. We find the synthesised bR analogue shows stronger excitonic coupling than bR, owing to a different molecular geometry. The excitonic coupling in the conjugated molecules can be controlled by modifying the bridge side-group. New computed energy levels for bR using the DFT/MRCI method are also presented, which improve on published values and re-assign the character of excited singlet states.

The alternating physical properties, especially melting points, of α,ω-disubstituted n-alkanes and their parent n-alkanes had been known since Baeyer's report in 1877. There is, however, no general and comprehensive explanation for such a phenomenon. Herein, we report the synthesis and examination of a series of novel ω-phenyl n-alkyl tropylium tetrafluoroborates, which also display alternation in their physicochemical characters. Despite being organic salts, the compounds with odd numbers of carbons in the alkyl bridge exist as room temperature ionic liquids. In stark contrast to this, the analogues with even numbers of carbons in the linker are crystalline solids. These solid nonconjugated molecules exhibit curious photoluminescent properties, which can be attributed to their ability to form through-space charge-transfer complexes to cause crystallization-induced emission enhancement. Most notably, the compound with the highest photoluminescent quantum yield in this series showed an unusual arrangement of carbocationic dimer in the solid state. A combination of XRD analysis and ab initio calculations revealed interesting insights into these systems.

Here, we present a concise model that can predict the photoluminescent properties of a given compound from first principles, both within and beyond the Franck–Condon approximation. The formalism required to compute fluorescence, Internal Conversion (IC), and Inter-System Crossing (ISC) is discussed. The IC mechanism, in particular, is a difficult pathway to compute due to difficulties associated with the computation of required bosonic configurations and non-adiabatic coupling elements. Here, we offer a discussion and breakdown on how to model these pathways at the Density Functional Theory (DFT) level with respect to its computational implementation, strengths, and current limitations. The model is then used to compute the photoluminescent quantum yield (PLQY) of a number of small but important compounds: anthracene, tetracene, pentacene, diketo-pyrrolo-pyrrole (DPP), and Perylene Diimide (PDI) within a polarizable continuum model. Rate constants for fluorescence, IC, and ISC compare well for the most part with respect to experiment, despite triplet energies being overestimated to a degree. The resulting PLQYs are promising with respect to the level of theory being DFT. While we obtained a positive result for PDI within the Franck–Condon limit, the other systems require a second order correction. Recomputing quantum yields with Herzberg–Teller terms yields PLQYs of 0.19, 0.08, 0.04, 0.70, and 0.99 for anthracene, tetracene, pentacene, DPP, and PDI, respectively. Based on these results, we are confident that the presented methodology is sound with respect to the level of quantum chemistry and presents an important stepping stone in the search for a tool to predict the properties of larger coupled systems.

Bulk-heterojunction nanoparticle dispersions in water or alcohol can be employed as eco-friendly inks for the fabrication of organic solar cells by printing or coating. However, one major drawback is the need for stabilizing surfactants, which facilitate nanoparticle formation but later hamper device performance. When surfactant-free dispersions are formulated, a strong limitation is imposed by the dispersion concentration due to the tendency of nanoparticles to aggregate. In this work, pyridine end-capped poly(3-hexylthiophene) (P3HT-Py) is synthesized and included as an additive for the stabilization of P3HT:indene-C60 bis-adduct (ICBA) nanoparticle dispersions. In the presence of acetic acid (AcOH), a surface-active pyridinium acetate end-capped P3HT ion pair, P3HT-PyH+AcO-, is formed which effectively stabilizes the dispersion and hence allows the formation of dispersions with smaller nanoparticle sizes and higher concentrations of up to 30 mg/mL in methanol. The dispersions exhibit an enhanced shelf-lifetime of at least 60 days at room temperature. After the deposition of light-harvesting layers from the nanoparticle dispersions, the ion-pair formation is reversed at elevated temperatures leading to regeneration of P3HT-Py and AcOH. The AcOH evaporates from the active layer, while the performance of the corresponding solar cells is not affected by the residual P3HT-Py in the devices. Enhanced nanoparticle stability is achieved with only 0.017 wt % pyridine in the P3HT/ICBA formulation.

Photon upconversion is a process that creates high-energy photons under low photon energy excitation. The effect of molecular geometry on the triplet fusion upconversion process has been investigat...

A high-performance large-area luminescent solar concentrator (LSC) is demonstrated, fabricated via careful choice of the fluorophore system, waveguide material, and coupled photovoltaic (PV) cells....

Vertically aligning fluorophores to the surface of a waveguide is known to be an effective approach to improve the optical quantum efficiency (OQE) of luminescent solar concentrators (LSCs). While the chromophore alignment assists waveguiding of the emitted photons to the LSC edges, it also significantly reduces the light-harvesting properties of the LSC. We report here a fluorophore pair consisting of a sphere-shaped energy donor and a rod-shaped emitter that was incorporated in LSCs to provide selective fluorophore alignment to address the reduced incident-light absorption issue. A liquid-crystal polymer matrix was used to perpendicularly align the rod-shaped acceptors to a favorable orientation for light guiding, while the sphere-shaped donor was randomly oriented to maintain its light-absorbing properties. The OQE of LSC devices with this selectively aligned donor–acceptor fluorophore system is 78% without significant loss of light-harvesting capability.

Strong coupling in organic media holds the promise of efficient room temperature polariton lasing with solution-processed materials. Currently, however, only five pure-organic materials have been shown to demonstrate polariton lasing. A major challenge is to achieve high exciton–photon coupling while maintaining high photoluminescence quantum yield. Here, we utilize a series of diimide perylene materials that possess sterically hindered substituents, dispersed within a polymer matrix. The rigid structures prevent aggregation and allow high photoluminescence quantum yield (PLQY) at large dye loadings. We demonstrate that these systems can exhibit substantial Rabi splittings at dye loadings that yield film PLQYs of up to 85%, making these perylene derivatives promising materials for polariton lasers.

Several new polymers with rotatable zinc porphyrin pendants have been synthesized and their optical spectroscopic and photophysical properties, including upconversion efficiencies, determined in both fluid solution and thin films. Comparisons made with the β-substituted zinc tetraphenylporphyrin monomers and ZnTPP itself reveal that the yield of triplets resulting from either Q-band or Soret-band excitation of the polymers is surprisingly small. A detailed kinetic analysis of the fluorescence decays and transient triplet absorptions of the substituted monomers and their corresponding polymers reveals that this phenomenon is due to two parallel internal singlet quenching processes assigned to transient intrachain excimer formation. Consequently, the yields of upconverted S2 fluorescence resulting from Q-band excitation in the degassed polymers are significantly diminished in both fluid solution and thin films. Implications of these results for the design of polymer upconverting systems are discussed.

The extensive use of halomethanes (CH3X, X = F, Cl, Br, I) as refrigerants, propellants, and pesticides has drawn serious concern due to their adverse biological and atmospheric impact. However, there are currently no portable rapid and accurate monitoring systems for their detection. This work introduces an approach for the selective and sensitive detection of halomethanes using photoluminescence spectral shifts in cesium lead halide perovskite nanocrystals. Focusing on iodomethane (CH3I) as a model system, it is shown that cesium lead bromide (CsPbBr3) nanocrystals can undergo rapid (

An aromatic celebration: ChemPlusChem is pleased to publish a Special Issue on Novel Aromatics, guest-edited by Aiko Fukazawa, Shinji Toyota, Rik Tykwinski, and Wallace Wong. This project is associated with the organizers of the 18th International Symposium on Novel Aromatic Compounds (ISNA-18), to be held in Sapporo, Japan (July 21-26, 2019). The issue features fascinating, top-quality contributions covering nearly all aspects of "aromatic" chemistry, including synthesis, properties, and applications of acenes, annulenes, azulenes, fullerenes, polycyclic aromatic hydrocarbons, and thiophenes as well as porphyrins, corroles, and phthalocyanines.

The development of molecular donor/polymer acceptor blend (MD/PA)-type organic solar cells (OSCs) lags far behind other type OSCs. It is due to the large-size phase separation morphology of MD/PA blend, which results from the high crystallinity of molecular donors. In this article, to suppress the crystallinity of molecular donors, we use ternary blends to develop OSCs based on one polymer acceptor (P-BNBP-fBT) and two molecular donors (DR3TBDTT and BTR) with similar chemical structures. The ternary OSC exhibits a power conversion efficiency (PCE) of 4.85%, which is higher than those of the binary OSCs (PCE=3.60% or 3.86%). To our best knowledge, it is the first report of ternary MD/PA-type OSCs and this PCE is among the highest for MD/PA-type OSCs reported so far. Compared with the binary blends, the ternary blend exhibits decreased crystalline size and improved face-on orientation of the donors. As a result, the ternary blend exhibits improved and balanced charge mobilities, suppressed charge recombination and increased donor/acceptor interfacial areas, which leads to the higher short-circuit current density. These results suggest that using ternary blend is an effective strategy to manipulate active layer morphology and enhance photovoltaic performance of MD/PA-type OSCs.

A new conjugated polyelectrolyte containing tetraphenylethene units in the backbone is synthesized and characterized. This polyelectrolyte is water-soluble and exhibits aggregation-induced emission (AIE) behavior. It is biocompatible and can be directly used in conventional and fluorescence lifetime imaging of mouse neuroblastoma neuro-2A cells, providing useful information of cellular morphology and intracellular aggregation or motion. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 672–680.

The light-harvesting efficiency of luminescent solar concentrators (LSCs) is encumbered by reabsorption of emission and concentration quenching. Energy transfer from a high-concentration donor to a low-concentration energy trap can reduce reabsorption losses while maintaining efficient light collection. Emissive aggregates enable this approach by reducing the impact of concentration quenching, which is detrimental to the entire energy transfer process. Here we describe a LSC that utilizes emissive aggregates as energy-transfer pairs for downconversion. We characterize the photophysics of a benzothiadiazole-based emissive aggregate, PITBT-TPE, that complements a highly emissive donor, DPATPAN, and functions as a highly emissive energy-transfer acceptor even at high concentrations in excess of 180 mM in the PMMA matrix. Monte Carlo simulations of LSCs that leverage these emissive aggregates as energy-transfer pairs predicted notable optical efficiencies at large concentrator dimensions. We demonstrate for the first time a LSC that utilizes donor and acceptor AIE chromophores to reduce reabsorption.

Organic semiconductor materials have been widely used in various optoelectronic devices due to their rich optical and/or electrical properties, which are highly related to their excited states. Therefore, how to manage and utilize the excited states in organic semiconductors is essential for the realization of high-performance optoelectronic devices. Triplet-triplet annihilation (TTA) upconversion is a unique process of converting two non-emissive triplet excitons to one singlet exciton with higher energy. Efficient optical-to-electrical devices can be realized by harvesting sub-bandgap photons through TTA-based upconversion. In electrical-to-optical devices, triplets generated after the combination of electrons and holes also can be efficiently utilized via TTA, which resulted in a high internal conversion efficiency of 62.5%. Currently, many interesting explorations and significant advances have been demonstrated in these fields. In this review, a comprehensive summary of these intriguing advances on developing efficient TTA upconversion materials and their application in optoelectronic devices is systematically given along with some discussions. Finally, the key challenges and perspectives of TTA upconversion systems for further improvement for optoelectronic devices and other related research directions are provided. This review hopes to provide valuable guidelines for future related research and advancement in organic optoelectronics.

A series of four perylene diimide (PDI) chromophores were prepared with increasing steric bulk on the imide substituents with the aim of retarding the effect of concentration quenching on photoluminescence, commonly observed with these dyes. Spectroscopic investigations of the compounds in dilute solution confirmed that the photophysical properties of the PDI core chromophore were not perturbed by the bulky substituents. Solid film samples containing the PDI compounds at various concentrations dispersed in a poly(methyl methacrylate) (PMMA) matrix were examined and compared to amorphous neat films as well as crystalline samples. The PDI compounds containing di-tert-butylphenyl (bPDI-3) and trityl (bPDI-4) substituents showed near unity photoluminescence quantum yield (PLQY) up to 20 mM in PMMA compared to 10% PLQY for the reference compound (bPDI-1) without molecular insulation. Surprisingly, high concentrations (>40 mM) of a phenyl-substituted PDI compound (bPDI-2) with moderate molecular insulation form...

Synthesis of fluorene-based conjugated polyelectrolytes was achieved via Suzuki polycondensation in water and completely open to air. The polyelectrolytes were conveniently purified by dialysis and analysis of the materials showed properties expected for fluorene-based conjugated polyelectrolytes. The materials were then employed in solar cell devices as an interlayer in conjunction with ZnO. The double interlayer led to enhanced power conversion efficiency of 10.75 % and 15.1 % for polymer and perovskite solar cells, respectively.

A series of new conjugated polyelectrolytes (CPEs) containing tetraphenylethene units are synthesized and characterized. They show apparent aggregation-induced emission (AIE) characteristics and give fluorescence covering from cyan to red with high emission efficiencies in aggregates. These AIE CPEs can directly enter and stain living cells for fluorescence imaging with low cytotoxicity, and can provide information on cellular viscosity at different locations based on fluorescence lifetime imaging.

Spectroscopic, photophysical and computational studies designed to expose and explain the differences in the efficiencies of non-coherent photon upconversion (NCPU) by triplet-triplet annihilation (TTA) have been carried out for a new series of alkyl-substituted diphenyl and tetraphenyl zinc porphyrins, both in fluid solution and in solid films. Systematic variations in the alkyl-substitution of the phenyl groups in both the di- and tetraphenyl porphyrins introduces small, but well-understood changes in their spectroscopic and photophysical properties and in their TTA efficiencies. In degassed toluene solution TTA occurs for all derivatives and produces the fluorescent S2 product states in all cases. In PVA matrices, however, none of the di-phenylporphyrins exhibit measurable NCPU whereas all the tetraphenyl-substituted compounds remain upconversion-active. In PVA the NCPU efficiencies of the zinc tetraphenylporphyrins vary significantly with their steric characteristics; the most sterically crowded tetraphenyl derivative exhibits the greatest efficiency. DFT-D computations have been undertaken and help reveal the sources of these differences.

The synthesis of key 4-alkyl-substituted 5-(trimethylsilyl)thiophene-2-boronic acid pinacol esters 3 allowed a simplified alkylthiophene catenation process to access bis-, ter-, quater-, and quinquethiophene π-bridges for the synthesis of acceptor–π-bridge-donor– π-bridge-acceptor (A–π-D–π-A) electron donor molecules. Based on the known benzodithiophene-terthiophene-rhodanine (BTR) material, the BXR series of materials, BMR (X = M, monothiophene), BBR (X = B, bithiophene), known BTR (X = T, terthiophene), BQR (X = Q, quaterthiophene), and BPR (X = P(penta), quinquethiophene) were synthesised to examine the influence of chromophore extension on the device performance and stability for OPV applications. The BTxR (x = 4, butyl, and x = 8, octyl) series of materials were synthesised by varying the oligothiophene π-bridge alkyl substituent to examine structure–property relationships in OPV device performance. The devices assembled using electron donors with an extended chromophore (BQR and BPR) are shown to be more thermally stable than the BTR containing devices, with un-optimized efficiencies up to 9.0% PCE. BQR has been incorporated as a secondary donor in ternary blend devices with PTB7-Th resulting in high-performance OPV devices with up to 10.7% PCE.

Tetrabenzo[5.7]fulvalene, one of the first recognized stable members of mixed fulvalenes, has attracted widespread interest for its remarkable structure. However, little has been known about its photoactivity, most likely owning to its very weak luminescence in solution state. Here we show for the first time that this compound exhibits aggregation-induced emission (AIE) properties. Its photoluminescence and X-ray crystal structure reveal an interesting mechanism of AIE phenomenon.

A series of tetraphenylethene 9,10-diphenylanthracene (TPE-DPA) derivatives have been synthesized, and their photophysical properties studied. Photoluminescence measurements in PMMA, neat films and nanoparticle dispersions reveal that different aggregation states are formed, which leads to different photophysical behavior. The triplet excited state properties were studied using Pt(II) octaethylporphyrin (PtOEP) as triplet sensitizer. Upconverted emission from the DPA moiety is observed in nanoparticle dispersions of each derivative. A higher upconverted emission intensity is observed in aerated (compared to deaerated) solutions of the derivatives following irradiation, which is attributed to oxidation of the TPE moiety. These results provide valuable insight for the design of AIE luminogens for triplet-triplet annihilation upconversion (TTA-UC).

Collapse of the protein homeostasis (proteostasis) can lead to accumulation and aggregation of unfolded proteins, which has been found to associate with a number of disease conditions including neurodegenerative diseases, diabetes and inflammation. Here we report a maleimide-functionalized tetraphenylethene (TPE)-derivatized fluorescent dye, TPE-NMI, which shows fluorescence turn-on property upon reacting with unfolded proteins in vitro and in live cells under proteostatic stress conditions. The level of unfolded proteins can be measured by flow cytometry and visualized with confocal microscopy.

A series of amine-substituted diazocines were synthesized in three steps from methyl 2-aminobenzoate or methyl 3-aminonaphtholate. The saddle-shaped diazocine compounds showed similar interplane angle of 75° despite the different steric bulk of the amine substituents. In electrochemical experiments, these diazocines showed irreversible reduction most likely producing indolo[3,2-b]indoles rather than forming the 10-electron planar aromatic species. The carbazole-substituted naphthodiazocines showed the most interesting photophysical properties with evidence of transition from the saddle-shaped ground state to a planar excited state geometry.

Nanoscale domains of donor and acceptor materials are crucial for charge generation in organic photovoltaic devices. These domains are difficult to achieve reproducibly in blended materials, but could be engineered into single-material active layers composed of donor–acceptor block copolymers (BCPs). In this work, we report the synthesis and purification of two novel fully conjugated BCPs, P3HT-b-PFTEGTBT and P3HT-b-PFTEGT6BT. To enhance phase separation and self-assembly, these two polymers incorporate tetraethylene glycol side chains into the PFTBT acceptor block, generating an amphiphilic system. The chemical disparity of the donor and acceptor blocks allowed the development of a purification strategy capable of isolating the desired BCP from homopolymer contaminants. This is a significant improvement over previous systems in which homopolymer contaminants can dominate the reaction mixture, affecting performance and morphology. We show that preliminary morphological analysis indicates spontaneous phase separation in thin films, demonstrating the efficacy of this design strategy and the potential application of these materials in organic photovoltaic devices. Hydrophilic tetraethylene glycol moieties are incorporated into the electron-accepting block of a donor–acceptor block copolymer (BCP) to afford two novel amphiphilic materials based on the P3HT-b-PFTBT scaffold. These amphiphilic BCPs are designed to provide enhanced morphological control as organic photovoltaic active layer materials. The chemical disparity introduced by the hydrophilic side chains enabled the design of a purification system capable of isolating the BCP product, an advantage over previously reported systems.

The bulk order in donor–acceptor poly(benzodithiophene-benzotriazole) was improved by two different post-treatment procedures applied to the specimen. Two-dimensional wide-angle X-ray scattering was used to investigate the structural changes after treatment. After post-treatment the polymer turned into a highly crystalline morphology with well-resolved and intensive π-stacking reflections which were absent in the pristine sample. To understand the ordering mechanisms taking place during the two post-treatment procedures, structural parameters like coherence length and paracrystallinity were extracted from the X-ray data indicating the impact on crystallite size and cumulative lattice disorder. During temperature annealing the intralayer packing transforms from amorphous to highly ordered. On the other hand, solvent vapor annealing enhances in higher extent the interlayer organization due to interpenetration of solvent molecules between alkyl side chains. These results provide important insights for the morphology optimization of semicrystalline conjugated polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2327–2334.

Maintaining high incident light absorption while minimizing luminescence reabsorption is a key challenge for organic luminescent solar concentrators (LSCs). Energy migration and trapping using light-harvesting donors and a low-energy highly emitting acceptor is one strategy to reduce the reabsorption issue. However, concentration quenching and the potential formation of quenching aggregates is a limiting factor in realizing efficient devices. We describe the synthesis of a novel molecularly insulated perylene diimide that can resist luminescence quenching at concentrations in excess of 50 mM. Photophysical measurements show the insulated perylene diimide has an excitation energy migration diffusion length of 230 ± 10 A at 60 mM in poly(methyl methacrylate). LSC devices using a mixture of the insulated perylene diimide light absorber and perylene red (LR305) as the low-energy trap emitter exhibit reduced reabsorption and a better current output than LR305 only devices. The results demonstrate that appropri...