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A novel phase sequence for the transition from the double diamond to the double gyroid cubic phases via two non-cubic intermediate phases, an orthorhombic

Bicontinuous and multicontinuous network phases are among nature's most complex structures in soft matter systems. Here, a chiral bicontinuous tetragonal phase is reported as a new stable liquid crystalline intermediate phase at the transition between two cubic phases, the achiral double gyroid and the chiral triple network cubic phase with an

The biotic-abiotic photosynthetic system integrating inorganic light absorbers with whole-cell biocatalysts innovates the way for sustainable solar-driven chemical transformation. Fundamentally, the electron transfer at the biotic-abiotic interface, which may induce biological response to photoexcited electron stimuli, plays an essential role in solar energy conversion. Herein, we selected an electro-active bacterium

Novel bolapolyphiles, built of a p-terphenyl or bistolane core with polar glycerol end-groups and two laterally attached n-alkyl or semiperfluoroalkyl chains, form the first "single plumber's nightmare network", the simplest soft-matter cubic phase (Pm3m). Its cage-like grid comprises bundles of aromatic rods lying along the cubic unit cell edges, connected by six-way hydrogen-bonded junctions. Side-chains fill the remaining volume of this unique noninterpenetrating liquid-crystalline organic framework.

This study puts forth two new members of fully ortho-benzannulated [ n]circulenes, heptabenzo[7]circulene and octabenzo[8]circulene, which are new negatively curved nanographenes and also represent unprecedented structures of septuple [4]helicene and octuple [4]helicene, respectively. The successful synthesis of them through Scholl reaction in good to excellent yields takes advantage of the reactivity of naphthalene. Quantum chemistry calculations reveal that heptabenzo[7]circulene and octabenzo[8]circulene are both flexible π-molecules and adopt saddle-shaped geometry of C

Dyes with environment-sensitive fluorescence have proven useful to study the spatio-temporal dynamics of protein activity in living cells. When attached to proteins, their fluorescence can reflect protein conformational changes, posttranslational modifications or protein interactions. However, the utility of such dye-protein conjugates has been limited because it is difficult to load them into cells. They usually must be introduced using techniques that perturb cell physiology, limit throughput, or generate fluorescent vesicles (e.g. electroporation, microinjection, or membrane transduction peptides). Here we circumvent these problems by modifying a proven, environment-sensitive biosensor fluorophore so that it can pass through cell membranes without staining intracellular compartments, and can be attached to proteins within living cells using unnatural amino acid (UAA) mutagenesis. Reactive groups were incorporated for attachment to UAAs or small molecules (mero166, azide; mero167, alkyne; mero76, carboxylic acid). These dyes are bright and fluoresce at long wavelengths (reaching ε = 100,000 M(−1)cm(−1), φ = 0.24, with excitation 565 nm and emission 594 nm). The utility of mero166 was demonstrated by in-cell labeling of an UAA to generate a biosensor for the small GTPase Cdc42. In addition, conjugation of mero166 to a small molecule produced a membrane-permeable probe that reported the localization of the DNA methyltransferase G9a in cells. This approach provides a strategy to access biosensors for many targets, and to more practically harness the varied environmental sensitivities of synthetic dyes.

Bacterial capsular polysaccharides are important virulence factors. Capsular polysaccharides from several important Gram-negative pathogens share a conserved glycolipid terminus containing 3-deoxy-β-d- manno-oct-2-ulosonic acid (β-Kdo). The β-Kdo glycosyltransferases responsible for synthesis of this conserved glycolipid belong to a new family of glycosyltransferases that shares little homology with other such enzymes, thereby representing an attractive antivirulence target. Here, we report the development of a fluorescence polarization-based, high-throughput screening assay (FP-tag) for β-Kdo glycosyltransferases, and use it to identify a class of marine natural products as lead inhibitors. This "FP-tag" assay should be readily adaptable to high-throughput screens of other glycosyltransferases.

Nanoformulations that can respond to the specific tumor microenvironment (TME), such as a weakly acidic pH, low oxygen, and high glutathione (GSH), show promise for killing cancer cells with minima...

A thieno[3,4-b]thiophene-based electron acceptor, ATT-1, is designed and synthesized. ATT-1 exhibits a planar conjugated framework, broad absorption with a large absorption coefficient, and a slightly high LUMO energy level. Bulk-heterojunction (BHJ) solar cells based on PTB7-Th electron donor and ATT-1 electron acceptor delivered power conversion efficiencies of up to 10.07%, which is among the best performances reported for non-fullerene BHJ solar cells using PTB7-Th as the electron donor.

Nanoformulations that can respond to the specific tumor microenvironment (TME), such as a weakly acidic pH, low oxygen, and high glutathione (GSH), show promise for killing cancer cells with minimal invasiveness and high specificity. In this study, we demonstrate self-assembled copper-amino acid mercaptide nanoparticles (Cu-Cys NPs) for in situ glutathione-activated and H

Enzymatic transamination is catalyzed by pyridoxal/pyridoxamine, and it involves remarkable cooperative catalysis of a Lys residue in the transaminase. Inspired by transaminases, we developed a class of axially chiral pyridoxamines 11 bearing a lateral amine arm. The pyridoxamines exhibited high catalytic activity and excellent enantioselectivity in asymmetric transamination of α-keto acids, to give various α-amino acids in 67-99% yields with 83-94% ee's. The lateral amine arm likely participates in cooperative catalysis as the Lys residue does in biological transamination and has an important impact on the transamination in terms of activity and enantioselectivity.

Using benzo[1,2-b:4,5-b′]dithiophene and two matched 5,6-difluorobenzo[2,1,3]thiadiazole-based monomers, we demonstrate that random copolymerization of two electron deficient monomers, alternating with one electron rich monomer, forms a successful approach to synthesize state-of-the-art semiconducting copolymers for organic solar cells. Over a range of compositions, these random copolymers provide impressive power conversion efficiencies (PCEs) of about 8.0%, higher than those of their binary parent polymers, and with little batch-to-batch variation. A PCE over 8% could also be achieved when the active layer was deposited from nonhalogenated solvents at room temperature.

We herein report an efficient synthesis of dibenzo[a,m]rubicene, a new member of nonplanar cyclopenta-fused polycyclic aromatic hydrocarbon, and its derivatives. It is found that the conformation and molecular packing of dibenzo[a,m]rubicenes in the solid state can be tuned by the substituting groups, and the silylethynylated derivatives of dibenzo[a,m]rubicenes function as p-type organic semiconductors in solution-processed thin film transistors with field effect mobility of up to 1.0 cm(2) V(-1) s(-1).

Gold nanoparticles have been prepared and surface-functionalized with a 1:1 molar mixture of a hexylthiol ligand and a chiral mesogenic ligand consisting of a cholesterylbenzoate attached via an undecylthiol spacer. Grazing incidence X-ray diffraction showed that upon annealing a columnar liquid crystal (LC) structure develops with the nanoparticles forming strings on a regular oblique 2d lattice. Synchrotron radiation circular dichroism is substantially enhanced upon the isotropic-LC transition. In the proposed structural model, layers of Au columns rotate by a small angle relative to their neighbors, with the columns winding around a helical axis. The work demonstrates that it is possible to obtain chiral LC superstructures from nanoparticles coated with chiral mesogen without the addition of a separate LC or chiral dopants. The results provide direction in the development of plasmonic metamaterials interacting selectively with circularly polarized light.

Two cheliform non-fullerene acceptors, DTPC-IC and DTPC-DFIC, based on a highly electron-rich core, dithienopicenocarbazole (DTPC), are synthesized, showing ultra-narrow bandgaps (as low as 1.21 eV). The two-dimensional nitrogen-containing conjugated DTPC possesses strong electron-donating capability, which induces intense intramolecular charge transfer and intermolecular π–π stacking in derived acceptors. The solar cell based on DTPC-DFIC and a spectrally complementary polymer donor, PTB7-Th, showed a high power conversion efficiency of 10.21% and an extremely low energy loss of 0.45 eV, which is the lowest among reported efficient OSCs.

All-polymer solar cells (all-PSCs) composed of conjugated polymers as both donor and acceptor components in bulk heterojunction photoactive layers have attracted increasing attention. However, it is a big challenge to achieve optimal morphology in polymer:polymer blends. In response, we report herein a new strategy to adjust the nanoscale organization for all-PSCs. Specifically, side chain engineering of the well-known naphthalene diimide (NDI)-based polymer N2200 is modulated by introducing a fraction of linear oligoethylene oxide (OE) side chains to replace branched alkyl chains on the NDI units and by synthesizing a series of NDI-based polymer acceptors NOEx, where x is the percentage of OE chain substituted NDI units relative to total NDI units. Compared to the reference polymer NOE0, OE-chain-containing polymer NOE10 offers a much higher power conversion efficiency (PCE) of 8.1% with a record high fill factor (FF) of 0.75 in all-PSCs. Moreover, the NOE10-based all-PSC exhibits excellent long-term and thermal stabilities with >97% of the initial PCE being maintained after 300 h of aging at 65 °C. This work demonstrates an effective morphology optimization strategy to achieve highly efficient and stable all-PSCs and shows the excellent potential of NOE10 as an alternative to commercially available acceptor polymers N2200.

We report a regioregular bis-pyridal[2,1,3]-thiadiazole (BPT) acceptor strategy to construct the first ambipolar pyridal[2,1,3]thiadiazole-based semiconducting polymer (PBPTV). The use of BPT unit enables PBPTV to achieve high electron affinity, low LUMO level, and extended π-conjugation. All these factors provide PBPTV with encouraging hole and electron mobilities up to 6.87 and 8.49 cm2 V–1 s–1, respectively. Our work demonstrates that the BPT unit is a promising building block for designing high-performance electron-transporting semiconductors in organic electronics.

The absence of near-infrared (NIR) solar cells with high open circuit voltage (Voc) and external quantum efficiency (EQE) has impeded progress toward achieving organic photovoltaic (OPV) power conversion efficiency PCE > 15%. Here we report a small energy gap (1.3 eV), chlorinated nonfullerene acceptor-based solar cell with PCE = 11.2 ± 0.4%, short circuit current of 22.5 ± 0.6 mA cm–2, Voc = 0.70 ± 0.01 V and fill factor of 0.71 ± 0.02, which is the highest performance reported to date for NIR single junction OPVs. Importantly, the EQE of this NIR solar cell reaches 75%, between 650 and 850 nm while leaving a transparency window between 400 and 600 nm. The semitransparent OPV using an ultrathin (10 nm) Ag cathode shows PCE = 7.1 ± 0.1%, with an average visible transmittance of 43 ± 2%, Commission d’Eclairage chromaticity coordinates of (0.29, 0.32) and a color rendering index of 91 for simulated AM1.5 illumination transmitted through the cell.

Organic-inorganic hybrid perovskite solar cells have demonstrated unprecedented high power conversion efficiencies in the past few years. Now, the universal instability of the perovskites has become the main barrier for this kind of solar cells to realize commercialization. This situation can be even worse for those tin-based perovskites, especially for CsSnI

Despite the dominant position of aromatic fluorophores, we report herein the design and synthesis of quinoidal fluorophores based on rarely emissive quinoidal bithiophene. Quinoidal bitheno[3,4-b]thiophene, QBTT-C6, consisting of cruciform-fused (E)-1,2-bis(5-hexylthiophen-2-yl)ethene and quinoidal bithiophene, shows a fluorescence quantum yield of 8.5%, 25-fold higher than that of the parent quinoidal QBT chromophore, but its maximum emission is at similar wavelengths. QBTT-Ar's featuring intramolecular charge transfer can further shift the maximum emission into the near-infrared region. The intramolecular charge transfer is programmably enhanced by tuning the substituents on the aryl groups from the electron-withdrawing trifluoromethyl to the electron-donating methoxy groups. Unexpectedly, a positive relationship between intramolecular charge transfer and fluorescence quantum yield is observed; as a result, QBTT-FL gives an unprecedentedly high fluorescence quantum yield of up to 53.1% for quinoidal oligothiophenes. With detailed photophysical and theoretical investigations, we demonstrate that the nonradiative intersystem crossing (S1 → T2) is significantly restrained in QBTT-Ar's, which can be attributed to the faster reverse intersystem crossing (T2 → S1) characteristic of a small activation energy. This work reveals the possibility for developing red/near-infrared fluorophores from the less explored quinoidal molecules because of their intrinsically narrow bandgaps.

A series of acceptor-donor-acceptor simple oligomer-like small molecules based on oligothiophenes, namely, DRCN4T-DRCN9T, were designed and synthesized. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated. Except for DRCN4T, excellent performances were obtained for DRCN5T-DRCN9T. The devices based on DRCN5T, DRCN7T, and DRCN9T with axisymmetric chemical structures exhibit much higher short-circuit current densities than those based on DRCN6T and DRCN8T with centrosymmetric chemical structures, which is attributed to their well-developed fibrillar network with a feature size less than 20 nm. The devices based on DRCN5T/PC71BM showed a notable certified power conversion efficiency (PCE) of 10.10% under AM 1.5G irradiation (100 mW cm(-2)) using a simple solution spin-coating fabrication process. This is the highest PCE for single-junction small-molecule-based organic photovoltaics (OPVs) reported to date. DRCN5T is a rather simpler molecule compared with all of the other high-performance molecules in OPVs to date, and this might highlight its advantage in the future possible commercialization of OPVs. These results demonstrate that a fine and balanced modification/design of chemical structure can make significant performance differences and that the performance of solution-processed small-molecule-based solar cells can be comparable to or even surpass that of their polymer counterparts.

A new nonfullerene small molecule with acceptor–donor–acceptor (A–D–A) structure, namely, NFBDT, based on a heptacyclic benzodi(cyclopentadithiophene) (FBDT) unit using benzo[1,2-b:4,5-b′]dithiophene as the core unit, was designed and synthesized. Its absorption ability, energy levels, thermal stability, as well as photovoltaic performances were fully investigated. NFBDT exhibits a low optical bandgap of 1.56 eV resulting in wide and efficient absorption that covered the range from 600 to 800 nm, and suitable energy levels as an electron acceptor. With the widely used and successful wide bandgap polymer PBDB-T selected as the electron donor material, an optimized PCE of 10.42% was obtained for the PBDB-T:NFBDT-based device with an outstanding short-circuit current density of 17.85 mA cm–2 under AM 1.5G irradiation (100 mW cm–2), which is so far among the highest performance of NF-OSC devices. These results demonstrate that the BDT unit could also be applied for designing NF-acceptors, and the fused-ring b...

We investigated the structure-morphology-performance relationship of diketopyrrolopyrrole (DPP)-based low band gap polymers with different donor cores in organic field effect transistors (OFETs) and organic photovoltaics (OPVs). The change in the chemical structure led to strong physical property differences, such as crystalline behavior, blend morphology, and device performance. In addition, the choice of solvents and additives enabled one to fine tune the properties of these materials in the condensed state. For instance, when thin films were processed from solvent mixtures, both in the pure polymer and in a blend, we observed an enhanced edge-on orientation and the formation of thinner and longer polymer fibrils. In the BHJ blends, processing from a solvent mixture reduced the size scale of the phase separation and promoted the formation of a fibrillar network morphology, having a polymer-PCBM mixture filling the interfibrillar regions. The characteristic length scale of the fibrillar network dictated the specific inner surface area, which directly correlated to the performance in the OPV devices. When the BHJ mixture was processed from a single solvent, a large-scale phase separated morphology was observed that was stratified, normal to the film surface. A strong scattering anisotropy was observed in the resonant soft X-ray scattering of the blends that provided insight into the packing of the polymer chains within the fibrils. The morphology and performance trend in OPVs paralleled the performance in an OFET, suggesting that similar processing conditions should be considered in OFET fabrication.

Through-space metal/hydrogen shift is an important strategy for transition-metal-catalyzed C-H bond activation. Here we describe the synthesis and characterization of a Rh(I) 2,6-dimethoxybenzoate complex that underwent stoichiometric rearrangement via a highly unusual 1,3-rhodium migration. This aryl-to-aryl 1,3-Rh/H shift was also demonstrated in a Rh(I)-catalyzed decarboxylative conjugate addition to form a C-C bond at a meta position instead of the ipso-carboxyl position. A deuterium-labeling study under the conditions of Rh(I)-catalyzed protodecarboxylation revealed the involvement of an ortho-methoxy group in a multistep pathway of consecutive sp(3) and sp(2) C-H bond activations.

We report the synthesis of a family of multifluorine substituted oligomers and the corresponding polymer that have the same backbones but different conjugation lengths and amounts of fluorine atoms on the backbone. The physical properties and photovoltaic performances of these materials were systematically investigated using optical absorption, charge mobility, atomic force microscopy, transmission electron microscopy, grazing incidence X-ray diffraction, resonant soft X-ray scattering methods, and photovoltaic devices. The power conversion efficiencies (PCEs) based on oligomers were much higher than that in the polymer. Moreover, the devices based on BIT6F and BIT10F, which have an axisymmetric electron-deficient difluorobenzothiadiazole as the central unit, gave slightly higher PCEs than those with centrosymmetric electron-rich indacenodithiophene (IDT) as the central unit (BIT4F or BIT8F). Using proper solvent vapor annealing (SVA), particularly using thermal annealing (TA) followed by SVA, the device performance could be significantly improved. Notably, the best PCE of 9.1% with a very high FF of 0.76 was achieved using the medium-sized oligomer BIT6F with the optimized film morphology. This efficiency is the highest value reported for organic solar cells from small-molecules without rhodanine terminal group. More excitingly, devices from the shortest oligomer BIT4F showed an impressively high FF of 0.77 (the highest FF value reported for solution-processed small-molecule organic solar cells). These results indicate that photovoltaic performances of oligomers can be modulated through successive change in chain-length and fluorine atoms, alternating spatial symmetric core, and combined post-treatments.

T-shaped bolaamphiphiles composed of a biphenyl rigid core, a semiperfluorinated lateral chain, two polar 1,2-diol groups in the terminal positions and flexible alkyl spacers connecting the polar groups with the biphenyl core have been synthesized and investigated by polarizing microscopy, DSC and X-ray scattering. The influence of spacer length and position of the spacer on the self-assembly in liquid-crystalline phases was studied. A series of four different columnar phases (Col(hex)/p6mm, Col(rec)/p2gg, Col(squ)/p4gm and Col(squ)/p4mm), representing liquid-crystalline honeycomb structures composed of cylinders having hexagonal, pentagonal, and square cross section, were found on increasing the spacer length. It is also shown that introduction of aliphatic spacers in the backbone of the T-shaped bolaamphiphiles replaces the Col(rec)/c2mm phase made up of rhombic cylinders with the Col(squ)/p4mm phase composed of square cylinders. It also causes the 2d lattice of pentagonal cylinders to increase the symmetry from Col(rec)/p2gg to Col(squ)/p4gm. A temperature-dependent second-order phase transition between these two pentagonal cylinder structures was observed for the first time. Beside these effects on cylinder shape and phase symmetry the flexible spacer units also lead to reduced phase transition temperatures and allow adjustment of cylinder side length to envelop a wider range of side-chain sizes. Electron density maps suggest that this may involve sacrificing some of the hydrogen bonds.

A series of propeller-shaped π-conjugated molecules based on 2,4,6-tris(thiophene-2-yl)-1,3,5-triazines has been designed and synthesized to obtain ambipolar charge-transporting liquid-crystalline materials. The 3-fold electron-donating aromatic units are attached to the electron-accepting triazine core, which forms electro-functional octupolar π-conjugated structures. These octupolar molecules self-organize into one-dimensional columnar nanostructures and exhibit ambipolar carrier transport behavior, which has been revealed by time-of-flight measurements. In this approach, electron-donor and acceptor electro-active segments are assembled individually in each column to give one-dimensional nanostructured materials with precisely tuned electronic properties. Their desirable electronic structures responsible for both hole and electron conductions have also been examined by cyclic voltammetry and theoretical calculations. The present results provide a new guideline and versatile approach to the design of ambipolar conductive nanostructured liquid-crystalline materials.

Solar cells fabricated using alkyl ammonium metal halides as light absorbers have the right combination of high power conversion efficiency and ease of fabrication to realize inexpensive but efficient thin film solar cells. However, they degrade under prolonged exposure to sunlight. Herein, we show that this degradation is quasi-reversible, and that it can be greatly lessened by simple modifications of the solar cell operating conditions. We studied perovskite devices using electrochemical impedance spectroscopy (EIS) with methylammonium (MA)-, formamidinium (FA)-, and MA(x)FA(1-x) lead triiodide as active layers. From variable temperature EIS studies, we found that the diffusion coefficient using MA ions was greater than when using FA ions. Structural studies using powder X-ray diffraction (PXRD) show that for MAPbI3 a structural change and lattice expansion occurs at device operating temperatures. On the basis of EIS and PXRD studies, we postulate that in MAPbI3 the predominant mechanism of accelerated device degradation under sunlight involves thermally activated fast ion transport coupled with a lattice-expanding phase transition, both of which are facilitated by absorption of the infrared component of the solar spectrum. Using these findings, we show that the devices show greatly improved operation lifetimes and stability under white-light emitting diodes, or under a solar simulator with an infrared cutoff filter or with cooling.

Thiophene-based materials have occupied a crucial position in the development of organic electronics. However, the energy band gaps of oligo- and polythiophenes are difficult to modulate without resorting to push-pull electronic effects. We describe herein a new series of monodisperse oligo(thieno[3,4-b]thiophene) derivatives with well-defined regioregular structures synthesized efficiently by direct C-H arylation. These compounds show a unique palette of colors and amphoteric redox properties with widely tunable energy band gaps. The capacity to stabilize both cations and anions results in both anodic and cathodic electrochromism. Under excitation, these compounds can produce photoionized states able to interconvert into neutral triplet or form these through singlet exciton fission or intersystem crossing. These features arise from a progressive increase in quinoidization on a fully planar platform making the largest effective conjugation length among hetero-oligomers. Oligo(thieno[3,4-b]thiophene)s might represent the more distinctive family of oligothiophenes of this decade.

Due to the unique crystallinity of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), it is an excellent model polymer to study the structure-property relationship in organic devices, especially those relying on junctions of electron- and hole-transporting materials. Here, we report the synthesis and characterization of a series of monodisperse PBTTT oligothiophenes (n = 1-5) and systematically examine the evolution of crystalline behavior, morphology, and interaction with [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as the molecular conjugation length increases. We discovered that fullerene intercalation occurs when there is enough free volume between the side chains to accommodate the fullerene molecule. The intercalation of PCBM is observed beyond BTTT-2 and longer oligomers, likely similar to that of PBTTT. Interestingly, both experiments and molecular simulations show that PCBM intercalation also appears to "catalyze" a more efficient packing of the BTTT-2 dimers. Crystal structure analysis revealed that the straight BTTT-2 side chains form one-dimensional (1D) channels that could perfectly host PCBM but, in the pure material, accommodate the interdigitated side chains from adjacent layers. In the blend with PCBM, these channels are maintained and enable the cocrystallization and intercalation of PCBM. This is the first time the actual sublattice cell of PCBM has been determined from the X-ray data, and demonstration the utility of the oligomers as model systems for their polymer counterparts. Among the organic photovoltaic devices (OPVs) made from the BTTT oligomers and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) blends, the ones containing the BTTT-2 dimer exhibit the highest performance.

A novel electron acceptor was synthesized from one-step functionalization of the readily available indigo dye. The resulting bay-annulated indigo (BAI) was utilized for the preparation of a series of novel donor-acceptor small molecules and polymers. As revealed experimentally and by theoretical calculations, substituted BAIs have stronger electron accepting characteristics when compared to several premier electron deficient building blocks. As a result, the donor-acceptor materials incorporating BAI acceptor possess low-lying LUMO energy levels and small HOMO-LUMO gaps. In situ grazing incidence wide-angle X-ray scattering studies of the thin films of BAI donor-acceptor polymers indicated improved crystallinity upon thermal treatment. Field effect transistors based on these polymers show excellent ambipolar transporting behavior, with the hole and electron mobilities reaching 1.5 and 0.41 cm(2) V(-1) s(-1), respectively, affirming BAI as a potent electron accepting unit for high performance organic electronic materials.

A series of T-shaped polyphilic molecules composed of a rigid linear biphenyl core with a polar glycerol group at each end and one swallow-tail semiperfluorinated lateral chain were synthesized and their thermotropic liquid crystalline (LC) phases were investigated by X-ray diffraction, calorimetry, and microscopy. The compounds have a long alkyl spacer between the aromatic core and the fluorinated C(n)F(2n+1) ends, where n = 4, 6, 8, and 10. Upon melting, all compounds start with lamellar LC phases, followed on heating by a rectangular columnar ribbon phase with c2mm symmetry. Unusually, a ribbon is a flat bundle of molecular cores highly aligned parallel to the ribbon axis. On further heating, for n = 8 and 10, this phase is succeeded by a bicontinuous cubic phase with Ia3d symmetry. This is a new variant of the "gyroid" phase, with axially oriented rod-like molecular cores forming the skeleton of the two infinite networks and junctions separated by exactly two molecular lengths. In this tricontinuous core-shell structure (aromatic-aliphatic-perfluoroalkyl), the polar glycerol domains of appreciable size, contained within the skeleton, can be considered as micellar.

The lipid carrier specificity of the protein N-glycosylation enzyme C. jejuni PglB was tested using a logical, synthetic array of natural and unnatural C10, C20, C30, and C40 polyisoprenol sugar pyrophosphates, including those bearing repeating cis-prenyl units. Unusual, short, synthetically accessible C20 prenols (nerylnerol 1d and geranylnerol 1e) were shown to be effective lipid carriers for PglB sugar substrates. Kinetic analyses for PglB revealed clear K(M)-only modulation with lipid chain length, thereby implicating successful in vitro application at appropriate concentrations. This was confirmed by optimized, efficient in vitro synthesis allowing >90% of Asn-linked β-N-GlcNAc-ylated peptide and proteins. This reveals a simple, flexible biocatalytic method for glycoconjugate synthesis using PglB N-glycosylation machinery and varied chemically synthesized glycosylation donor precursors.

Four novel blue/green luminescent compounds, Zn(2-py-in)2(THF) (1), BPh2(2-py-in) (2), Be(2-py-in)2 (3), and BPh2(2-py-aza) (4), where 2-py-in = 2-(2-pyridyl)indole and 2-py-aza = 2-(2-pyridyl)-7-azaindole, have been synthesized and fully characterized. The 2-py-in ligand and 2-py-aza ligand in the new compounds are chelated to the central atom. Compounds 2−4 are air stable and readily sublimable, with a melting point above 250 °C. In the solid state, compounds 1−4 have an emission maximum at λ 488, 516, 490, and 476 nm, respectively. The structures of compounds 2 and 4 are similar. The blue shift of emission energy displayed by compound 4, in comparison to that of 2, is attributed to the presence of an extra nitrogen atom in the 2-py-aza ligand as confirmed by ab initio calculations on compounds 2 and 4. Electroluminescent devices of compounds 3 and 4 were fabricated by using N,N‘-di-1-naphthyl-N,N‘-diphenylbenzidine (NPB) as the hole transporting layer, Alq3 (q = 8-hydroxyquinolato) as the electron tran...

Most of the dynamic DNA devices are rationally constructed by utilizing toehold-mediated DNA strand displacement reactions. However, such approaches have been mainly limited to the operation with double-stranded hybridization and lack the versatility of DNA scaffold responses for additional levels of controlling DNA strand displacement reactions. Herein, we propose a toehold activation strategy based on the DNA tetraplex (G-quadruplex or i-motif), where the toehold domain is designed by attaching a complementary single-stranded segment (CS) to a G-rich/C-rich segment. Modulating G-quartet/C·C(+) numbers and/or the CS lengths can easily tune the strand displacement kinetics. This scheme allows fine control of DNA strand displacement rates over 2 orders of magnitude by adjusting the concentration of various environmental stimuli. This strategy expands the rule set of designing dynamic DNA devices and will be useful in building diverse environmental stimuli-fuelled molecular devices.

Monodispersed conjugated oligothiophenes are receiving attention in fundamental and applied science due to their interesting optical, optoelectronic, and charge transport properties. These "low molecular weight" polymers serve as model structures for the corresponding polymer analogues, which are inherently polydispersed. Here we report the synthesis, electronic structure, molecular packing/morphology, and charge transport properties of monodispersed oligothiophenes with up to six didodecylquaterthiophene (DDQT) building block repeat units (i.e., 24 thiophene units). At the point where the effective conjugation length is reached, the electronic structure showed convergence behavior to the corresponding polymer, poly(3,3"-didodecyl-quaterthiophene) (PQT-12). X-ray crystal structure analysis of the dimer (DDQT-2) showed that terminal thiophenes exhibit syn-conformations, similar to the terminal syn-conformations observed in the trimer (DDQT-3). The dimer also exhibits a rare bending of the terminal alkyl side chains in order to prevent steric hindrance with neighboring hydrogens attached to core thiophenes. Grazing incidence X-ray scattering measurements revealed a morphology evolution from small molecule-like packing to polymer-like packing in thin films, with a morphology transition occurring near the effective conjugation length. Charge transport measurements showed a mobility increase with decreasing chain length. We correlated the molecular packing and morphology to charge transport and determined that carrier mobilities are most sensitive to crystallinity and crystal grain misorientation. This indicates that molecular weight is not a decisive factor for improved carrier mobility in the low molecular weight region, but rather the degree in crystallinity and in-plane crystal orientation. These results represent a fundamental advancement in understanding the relationship between conjugation length and carrier mobilities in oligothiophene semiconductors.

Bent-shaped rigid-core molecules with flexible chiral dendrons grafted to the outer side of the bend were synthesized and characterized by circular dichroism, differential scanning calorimetry, X-ray scatterings, and transmission electron microscopy in solution and the solid state. The bent aromatic rods based on hepta- and nonaphenylene with nitrile groups at both ends self-assemble into well-ordered hollow tubular structures in aqueous solution, while the bent rod based on heptaphenylene without nitrile groups showed no apparent aggregations in aqueous solution. In the solid state, the rigid-flexible molecules based on heptaphenylene rod without the nitrile group self-assemble into a 2D oblique columnar structure with the columnar cross-section containing two interlocked molecules. Remarkably, the rigid flexible molecules based on hepta-, nona-, and undecaphenylene with nitrile groups self-assemble into a hexagonal columnar structure with weak 3D order. A model of vesicular channel structure is proposed based on small- and wide-angle X-ray diffraction on oriented fibers, density measurement, reconstruction and simulation of electron density maps, and molecular dynamics simulation. In contrast to the hollow tubular structure found in solution, in the solid both the outside and the interior of the columns are filled by the pendant aliphatic coils. Filling of the interior of these vesicular channels is made possible by some bent rod molecules turning their obtuse apex inward. One in 7, 2 in 8, and 4 in 10 molecules are thus inverted in a column slice in compounds with hepta-, nona-, and undecaphenylene cores, respectively. These are new examples of vesicular double-segregated columnar structures recently discovered in some dendrons.

Two series of wedge-shaped onium salts, one ammonium and the other phosphonium, having 3,4,5-tris(alkyloxy)benzyl moieties, exhibit thermotropic bicontinuous "gyroid" cubic (Cub(bi)) and hexagonal columnar liquid-crystalline (LC) phases by nanosegregation between ionophilic and ionophobic parts. The alkyl chain lengths on the cationic moieties, anion species, and alkyl chain lengths on the benzyl moieties have crucial effects on their thermotropic phase behavior. For example, triethyl-[3,4,5-tris(dodecyloxy)benzyl]ammonium hexafluorophosphate forms the thermotropic Ia3d Cub(bi) LC phase, whereas an analogous compound with trifluoromethanesulfonate anion shows no LC properties. Synchrotron small-angle diffraction intensities from the Ia3d Cub(bi) LC materials provide electron density maps in the bulk state. The resulting maps show convincingly that the Ia3d Cub(bi) structure is composed of three-dimensionally interconnected ion nanochannel networks surrounded by aliphatic domains. A novel differential mapping technique has been applied successfully. The map of triethyl-[3,4,5-tris(decyloxy)benzyl]ammonium tetrafluoroborate has been subtracted from that of the analogous ammonium salt with hexafluorophosphate anion in the Ia3d Cub(bi) phases. The differential map shows that the counteranions are located in the core of the three-dimensionally interconnected nanochannel networks. Changing from trimethyl- via triethyl- to tripropylammonium cation changes the phase from columnar to Cub(bi) to no mesophase, respectively. This sensitivity to the widened shape for the narrow end of the molecule is explained successfully by the previously proposed semiquantitative geometric model based on the radial distribution of volume in wedge-shaped molecules. The LC onium salts dissolve lithium tetrafluoroborate without losing the Ia3d Cub(bi) LC phase. The Cub(bi) LC materials exhibit efficient ion-transporting behavior as a result of their 3D interconnected ion nanochannel networks. The Ia3d Cub(bi) LC material formed by triethyl-[3,4,5-tris(decyloxy)benzyl]phosphonium tetrafluoroborate shows ionic conductivities higher than the analogous Ia3d Cub(bi) material based on ammonium salts. The present study indicates great potential of Cub(bi) LC nanostructures consisting of ionic molecules for development of transportation nanochannel materials.