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Diarylethenes were obtained from the corresponding ethenyl sulfones by photocatalyzed desulfonylation using UV or blue LEDs. When perylene and i-Pr2NEt were used as a photocatalyst and a sacrificin...

A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira-Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira-Hagihara aminoethynylation and the halogenative Friedel-Crafts benzannulation to provide the corresponding amino(halo)phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties. Further application of this approach between 2,2″- and 2',5'-dibromo-p-terphenyls with phosphinyl ynamines led to the regioselective formation of 6,13-diamino-5,12-dihalo- and 5,12-diamino-6,13-dihalo-dibenz[a,h]anthracenes via dual aminoethynylation and [4 + 2] benzannulation. The obtained analogues showed different ultraviolet-visible absorption and photoluminescence spectra with different emission quantum yields in CH2Cl2 solution and the powder state.

The thermally and photolytically induced disproportionation of 6,13-dihydropentacene derivatives into tetrahydropentacenes and pentacenes results in unique solid-state fluorescence. The fluorescence thereby depends on the molecular structure and the molecular arrangement in the solid state.

When iodide ions (I−) are electrochemically oxidized in an aqueous solution containing a high concentration of I−, an iodine (I2) film is formed on the electrode surface and inhibits further oxidation of I−. The effect of adding an organic compound as an additive on the I2 film was investigated and discussed in the light of electrochemical investigations, spectroscopic analyses, and quantum chemical calculations. Aprotonic organic compounds such as acetonitrile (AN) increased the current of I− oxidation while protonic organic compounds such as ethanol (EtOH) did not increase it. The effect did not simply correspond to the increase in solubility of I2 molecules. In the theoretical calculations, AN showed a behavior that it promoted hydration of an I2 molecule by coordinating with the I2 molecule while EtOH formed hydrogen bonds with H2O molecules and did not show the behavior. AN desorbed from the I2 molecule when the coordinated I2 molecule was hydrated. The aprotonic organic compounds were considered to act as a catalyst to promote the hydration of the I2 molecules contained in the I2 film and thereby promote dissolution of the I2 film.

On-surface chemical reaction has become a very powerful technique to conjugate small precursor molecules and several reactions have been proposed with the aim to fabricate functional nanostructures on surfaces. Here we present an unforeseen adsorption mode of 9,10-bis-((trimethylsilyl)ethynyl)anthracene on a Cu(111)surface and the resulting one-shot desilylative homocoupling of of the adsorbate by annealing at 400 K. With a combination of high-resolution atomic force microscopy and density functional theory calculations, we found that the triple bonds and silicon atoms of the monomer chemically interact with the copper surface. After the oligomerization, we discovered that the anthracene units are linked to each other via buta-1,3-diynediyl fragments while keeping the surface clean. Furthermore, the force measurement revealed the chemical nature at the center of anthracene unit.

Graphene nanoribbons are one of the most promising materials for nanoscale electronics. While various structures have successfully been synthesized by on-surface reactions, curved connections remain less investigated, yet they could prove highly useful in the development of copolymerization technology. Here, we present the synthesis of three different regioisomeric junctions on Au (111) by using 10,10'-dibromo-9,9'-bianthryl and 1,3,6,8-tetrabromopyrene. The chemical structures and the electronic properties of junctions were studied with a combination of scanning tunneling microscopy with a CO terminated tip, scanning tunneling spectroscopy, and density functional theory calculations. We found that two identical nanoribbon-junction interface electronic states appear within the band gaps of connected graphene nanoribbons.

The versatility in design of redox flow batteries makes them apt to efficiently store energy in large-scale applications at low cost. The discovery of inexpensive organic electroactive materials for use in aqueous flow battery electrolytes is highly attractive, but is thus far limited. Here we report on a flow battery using an aqueous electrolyte based on the sodium salt of flavin mononucleotide. Flavins are highly versatile electroactive molecules, which catalyse a multitude of redox reactions in biological systems. We use nicotinamide (vitamin B3) as a hydrotropic agent to enhance the water solubility of flavin mononucleotide. A redox flow battery using flavin mononucleotide negative and ferrocyanide positive electrolytes in strong base shows stable cycling performance, with over 99% capacity retention over the course of 100 cycles. We hypothesize that this is enabled due to the oxidized and reduced forms of FMN-Na being stabilized by resonance structures., Redox flow batteries using organic active materials are highly sought after because of their potential to satisfy low cost and sustainability requirements. Here, the authors report a biomimetic flow battery based on flavin mononucleotide and a hydrotrope with promising performance characteristics.

Electrochemical and UV-VIS measurements demonstrate that the pH value of a 4-hydroxy-2,2,6,6-tetramethyl-1-pipperidinyloxyl (TEMPOL) electrolyte significantly impacts its redox reversibility. The diffusion coefficient and kinetic rate constant of TEMPOL in neutral aqueous solution are determined and shown to be comparable to those of vanadium ions used for industrially utilized redox flow batteries (RFBs). RFBs that incorporate a TEMPOL catholyte and Zn-based anolyte have an average voltage of 1.46 V and an energy efficiency of 80.4% during the initial cycle, when subject to a constant current of 10 mA cm −2 . We demonstrate several factors that significantly influence the concentration and capacity retention of TEMPOL upon cycling; namely, pH and atmospheric gases dissolved in electrolyte. We expand upon the known reactions of TEMPOL in aqueous electrolyte and propose several concepts to improve its electrochemical performance in a RFB. Controlling these factors will be the key to enable the successful implementation of this relatively inexpensive and environmentally friendly battery.

Ph2P(O)-protected ethynes were successfully transformed to arylethynes in one-pot manner through t-BuOK-catalyzed deprotection followed by Sonogashira coupling with aryl halide. The arylethynes were obtained similarly by Ph2P(O)-deprotection, stannylation of the resulting terminal ethynes, and Migita-Kosugi-Stille coupling. Deprotection followed by intramolecular Eglinton coupling could be carried out in one-pot to provide cyclic butadiynes.

We demonstrate two efficient blue-green thermally activated delayed fluorescence (TADF) compounds comprising a dimeric phenylcarbazole and four cyano substituents on the phenyl rings. A comparison ...

These days, in order to stably utilize renewable energy, there are increasing demands for large-capacity power storage devices with safe and inexpensive. An aqueous redox flow battery (RFB) has low risks to ignite and can get a greater capacity easily with increasing the number of electrolyte tanks. The most famous RFB is a vanadium-type one (V-RFB). It has high efficiency and long life durability [1-3]. However, an energy density of V-RFB is relatively low and a cost is high [4, 5]. An aqueous zinc/iodine RFB (Zn/I-RFB) can overcome those limitation because zinc compounds and iodine compounds have high solubilities, and zinc and iodine are inexpensive elements [6]. Here we report a single electrolyte-type Zn/I-RFB, which can reduce its cost owing to the elimination of an expensive ion-exchange membrane. The use of an inexpensive additive enables the separation of cathode charged products through the formation of polyiodide complexes. We will introduce a specific reaction, between polyiodide and additives, and also cycling performance of a single electrolyte-type Zn/I-RFB. Electrolytes for evaluating cycle properties were prepared by dissolving 1.5 M NaI, 0.5 M ZnCl2, and some inexpensive additives in ultrapure water. Figure 1 shows a scheme of a single electrolyte-type Zn/I-RFB. A Ti mesh and a carbon felt were used as a positive electrode, and a Zn plating Fe mesh was served as a negative one. The cell was designed to insert the porous membrane, between the positive electrode and the negative one, and had a flow channel at the side of the negative. Cycle properties were measured by galvanostatic charge-discharge tests at a current density of 20 mA/cm2. Figure 2 shows pictures of charging reactions on a positive electrode; (a) without and (b) with an additive. A hydrophobic liquid was observed in Figure 2 (b) as distorted black hemispheres. The hydrophobic liquid was formed by the combination effects between cathode charged products and specific inexpensive additives. In charging, I− in electrolytes is oxidized to triiodide ions (I3 −) and partially to iodine molecules (I2) on a positive electrode [7, 8]. I2 reacts chemically with I− to form I3 − which is to diffuse from the surface of the electrode (Figure 2 (a)). However, when the rate of I2 electrochemical formation exceeds that of the chemical reaction between I2 and I−, it is considered that I2-films are formed on an electrode. These I2-films were considered to increase a resistance and to impede the charging reactions. An additive employed in this study was to accelerate the removal of the I2-films and formed hydrophobic liquid (Figure 2 (b)). The removal of the I2-films from the surface of an electrode could increase the charging currents by over 50%. The hydrophobic liquid could be also reduced because the hydrophobic liquid could contain charged products. That is, charge and discharge reactions in the hydrophobic liquid could take place. In addition, the hydrophobic liquid sank and accumulated to the bottom of an electrolytic cell. This feature is of great importance from a viewpoint of separating the charged products between a positive electrode and a negative one. When a positive electrode is allocated at the bottom side of a cell and a negative one is the top side, charged products of both the anode and the cathode can be spatially separated without an ion-exchange membrane (Figure 1). The anode charged product is zinc metal which stays on the negative electrode, and cathode charged products sunk to the bottom side don’t contact the zinc. This finding described above was verified by galvanostatic charge-discharge tests. Figure 3 indicates the result of charge-discharge tests with a prototype cell designed on the concept here. The inserted figure in Figure 3 shows the three kinds of efficiencies. The stable cyclability of the charge-discharge tests was achieved over the course of 50 cycles. Through almost all of 50 cycles, over 90 % of coulombic efficiencies were achieved without an ion-exchange membrane. This result suggests that this single electrolyte-type Zn/I-RFB is considered to be a promising candidate for large-capacity power storage devices. [1] M. Skyllas-Kazacos et al., J. Electrochem. Soc., 133, 1057 (1986). [2] M. Rychcik et al., J. Power Sources, 22, 59 (1988). [3] M. Skyllas-Kazacos et al., J. Electrochem. Soc., 158, R55 (2011). [4] V. Viswanathan et al., J. Power Sources, 247, 1040 (2014). [5] M. Zhang et al., J. Electrochem. Soc., 159, A1183 (2012). [6] B. Li et al., Nature Commun., 6, 6303 (2015). [7] T. Bejerano et al., J. Electrochem. Soc., 124, 1720 (1977). [8] L. Ma et al., J. Electrochem. Soc., 146, 4152 (1999). Figure 1

Zirconocene and titanocene bis(perfluorooctanesulfonate)s were synthesized. In contrast to the corresponding triflates and perchlorates, these compounds are air- and water-stable. They were proved to be ionic on the basis of conductivity measurements and X-ray analysis, allowing these complexes to be stored for months. The strong Lewis acidity of these cationic metallocene species, which was proved by ESR study, enabled catalytic glycosylation.

The g(zz) values of ESR spectra of superoxide (O(2)(.-) complexes of metal ion salts acting as Lewis acids with different ligands and counterions were determined in acetonitrile at 143 K. The binding energies (DeltaE) of (O(2)(.-)/Lewis acid complexes have been evaluated from deviation of the g(zz) values from the free spin value. The DeltaE value is quite sensitive to the difference in the counterions and ligands of metal ion salts acting as Lewis acids. On the other hand, the fluorescence maxima of the singlet excited states of 10-methylacridone/Lewis acid complexes are red-shifted as compared with that of 10-methylacridone, and the relative emission energies (Deltahnu(f)) vary significantly depending on the Lewis acidity of metal ion salts with different counterions and ligands. The promoting effects of Lewis acids were also examined on electron transfer from cobalt(II) tetraphenylporphyrin to oxygen in acetonitrile at 298 K, which does not occur in the absence of Lewis acids under otherwise the same experimental conditions. Both DeltaE and Deltahnu(f) values are well correlated with the promoting effects of Lewis acids on the electron transfer reduction of oxygen. Such correlations indicate that DeltaE and Deltahnu(f) values can be used as quantitative measures of Lewis acidity of metal ion salts with different ligands and counterions. The Lewis acidity thus determined can also be applied to predict the promoting effects of Lewis acids on organic synthesis.

1,3-Disubstituted tetrakis(fluoroalkyl)distannoxanes (XRf2SnOSnRf2Y)2 (Rf=C6F13C2H4, C4F9C2H4; X, Y=Cl, Br, NCS) were synthesized from readily available dibenzyltin dibromide. The dimeric formulation of these compounds that was confirmed by 119Sn-NMR spectra gave rise to a structure in which the metalloxane core is covered by the surface fluorophilic alkyl groups. Thus, these compounds exhibited high solubility in fluorocarbon solvents and large partition coefficients for FC-72 against common organic solvent.

Highly strained cyclic acetylenes 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctenes (Sondheimer–Wong diynes) having various substituents on their benzene rings were synthesized successfully by one-pot treatment of the corresponding formyl sulfones with diethyl chlorophosphate/lithium hexamethyldisilazide (LiHMDS) and then lithium diisopropylamide (LDA). When mixtures of two types of formyl sulfones bearing different substituents were subjected to this protocol, the unsymmetrically substituted Sondheimer–Wong diynes could be synthesized in a stepwise manner by isolation of the heterocoupled vinyl sulfone intermediates followed by their treatment with LDA. The UV–vis absorption spectra and cyclic voltammograms of the substituted Sondheimer–Wong diynes were recorded. The electronic effect of substituents on the diynes was investigated in their click reactions and nucleophilic and electrophilic additions.

A variety of organotin triflate clusters are obtained by treating dialkyltin oxide with triflic acid (TfOH) in different ratios. When R2SnO is exposed to 0.5 equivalents of TfOH, 3-hydroxy-1-triflato distannoxanes (1) are formed which have a novel sheet-like structure in the solid state. Treatment of R2SnO with 2/3 or one equivalent of TfOH affords a trinuclear cluster 3 or cationic dimers 2. The stoichiometry of the novel trinuclear cluster can be confirmed by various chemical reactions as well as elemental analysis. On the basis of 119Sn-NMR study, the equilibrium has been revealed between 2 and 3. The use of two equivalents of TfOH in the reaction with R2SnO offers a convenient route for R2Sn(OTf)2 (4).

The automation of multi-step chemical processes has been realized. A new concept for one-pot processes has been advanced which enables integration of various types of reactions involving carbon-carbon bond formations and functional group modifications. In the meantime, an automated synthesizer to accommodate such one-pot processes has been devised. This machine allows us to reproduce usual bench work : treatment of air-sensitive materials, control of temperature from -78°C to 100°C within ± 0.1°C accuracy, and successive addition of reagents. Several examples which were successfully conducted on the machine are described.

The reaction of α , ω -bis(organodichlorostannyl)alkanes [R(Cl 2 )SnCH 2 ] 2 Z with their corresponding organotin oxides [R(O)SnCH 2 ] 2 Z or ( t -Bu 2 SnO) 3 provides the new spacer-bridged tetraorganodistannoxanes {[R(Cl)SnCH 2 ] 2 Z]O} n ( 22 , Z=CH 2 , R=Me 3 SiCH 2 ; 23 , Z=CH 2 , R=Me 3 CCH 2 ; 24 , Z=CH 2 CH 2 , R=Me 3 SiCH 2 ; 25 , Z=CH 2 CH 2 , R=Me 3 CCH 2 ; 26 , Z=CH 2 CH 2 , R=Me 2 CHCH 2 ; 27 , Z=Me 2 Si, R=Me 3 SiCH 2 ). The acetate substituted derivative 28 {[R(AcO)SnCH 2 ] 2 CH 2 ]O} n (R=Me 3 SiCH 2 ) is obtained by reaction of 22 with silver acetate or by treatment of the organotin oxide [R(O)SnCH 2 ] 2 CH 2 (R=Me 3 SiCH 2 ) with acetic acid. The crystal structures of 23 , 24 , and 28 are described and reveal that these compounds adopt double ladder structures. Depending on the identity of Z and R in chloroform solution the compounds are either dimers ( n =2, 25 – 28 ) or tetramers ( n =4, 22 – 24 ). Also reported are preliminary studies on the catalytic activity in acylation reactions of compounds 22 , 24 – 26 , and 28 .

A variety of pentafluorophenyltin compounds were prepared and their chemical properties were examined. These compounds effectively catalyzed Mukaiyama-aldol reaction of ketene silyl acetal in sharp contrast to the inertness of normal alkyltin halides like Bu2SnCl2. The increased Lewis acidity of the pentafluorophenyltin halides was proved by 119Sn- and 13C-NMR spectra. On the other hand, the pentafluorophenyl group reduced the reactivities of tin towards both nucleophiles and electrophiles. 19F-NMR spectroscopy was invoked to elucidate this anomaly.

Ketene silyl acetals undergo facile reaction with ketones in the presence of a Lewis acid such as (C6F5)2SnBr2, TMSOTf, or Sc(OTf)3. This unique reactivity allows ketones to react in preference to aldehydes or acetals in competitive aldol-type reactions. Upon treatment with keto aldehydes or keto acetals, ketene silyl acetals provide single products derived from the exclusive reaction with the ketonic function. Particularly noteworthy is the discrimination of ketones from aldehydes in naked forms. It has been proved that such bias results from the differentiated recognition of ketone and aldehyde carbonyls. The ternary system consisting of ketene silyl acetal, carbonyl, and an appropriate Lewis acid is crucial for achieving the effective differentiation.

[reaction: see text] Syntheses of 2-aryl and 2,3-substituted indoles were realized by modified double elimination protocol. Under basic conditions, vinyl sulfones derived from the reaction of 2-aminobenzyl sulfone with benzaldehydes underwent cyclization and alkylation followed by elimination of sulfinic acid to afford 2,3-substituted indoles.

Biological redox reactions inspire us to design sustainable and environmentally safe energy storage systems. Flavins have been demonstrated as solid-state electroactive materials for Li-metal batteries. [1,2] The concentration of flavin in those composite electrodes was no more than 50 wt%, however, due to the high content of conductive carbon necessary to complement the low electronic conductivity of flavin. In nature, flavins are often found dissolved in water or fat, such as in biological systems. As they are commonly more useful in this state, so may it be in batteries as well. Interestingly, flavins have yet to be reported as an active material for any redox flow batteries (RFBs). Here we explore the use of riboflavin-5’-phosphate sodium salt (FMN-Na) for RFBs. A diffusion coefficient and a kinetic rate constant of FMN in a strongly alkaline aqueous solution are determined and shown to be comparable to those of vanadium ions used for industrially utilized RFBs. Nicotinamide (known as vitamin B3) is used as a hydrotropic agent to enhance the water-solubility of FMN-Na, and therefore, its energy density in a RFB by as much as 15 times. A RFB using strongly basic FMN-based anolyte and ferrocyanide/ferricyanide-based catholyte shows highly stable cycling performance over the course of 200 cycles. The oxidized and reduced FMN can be stabilized by a variety of resonance structures, leading to the stable cycling performance. This work shows that biological redox centers are shown to be promising materials for environmentally friendly energy storage systems and warrant future exploration in this field. References [1] Hong, J. et al. Biologically inspired pteridine redox centres for rechargeable batteries. Nat. Commun 5, 9, (2014). [2] Lee, M. et al. Redox Cofactor from Biological Energy Transduction as Molecularly Tunable Energy-Storage Compound. Angew. Chem. Int. Ed. 52, 8322-8328, (2013).

We report on novel aqueous redox flow batteries (RFBs) based on 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL) as an active material. TEMPOL is a stable and highly water-soluble nitroxyl radical compound. Electrochemical and UV-VIS measurements highlight that the pH value of electrolyte has a significant impact on the redox reversibility of TEMPOL. The half-wave potential of TEMPOL was determined to be 0.61 V vs. Ag/AgCl (0.83 V SHE.). Furthermore, its peak separation of 73 mV at a sweep rate of 10 mV s-1 is close to the theoretical value (59 mV) expected for a reversible one-electron reaction. We demonstrate that the diffusion coefficient of TEMPOL in neutral aqueous solution is comparable to the vanadium ions used in practical RFBs. TEMPOL also exhibits a quasi-reversible redox reaction, defined by a distinct kinetic rate constant, in near-neutral aqueous solutions. We show that RFBs incorporating TEMPOL catholyte and Zn-based anolyte have an average discharge voltage of 1.46 V and an energy efficiency of 80.4% during the initial cycle, when subject to a constant current of 10 mA cm-2. We also introduce a green aqueous RFB using TEMPOL catholyte and anthraquinone-2,7-disulfonic acid disodium salt (AQ27Na2) as anolyte. This green RFB contains no toxic or flammable compounds, and exhibits an open-circuit voltage of 1.22 V and an average discharge voltage of 0.74 V. The TEMPOL/Zn and TEMPOL/AQ27Na2 RFBs both show stable and long-term cycling at 10% SOC. Our approach offers a promising direction to develop inexpensive, environmentally-friendly, and safe RFBs.

The title compound, μ-penta­cyclo­[26.4.0.09,14.017,22.025,30]­dotriaconta-1,3,5,9,11,13,15,17,19,21,25,27,29,31-tetradecaene-7,24-diyne-bis­(tri­carbonyl­cobalt) di­chloro­methane solvate, [Co2(η2-C32H20)(CO)6]·CH2Cl2, has been prepared by treatment of a de­hydro­benzoannulene with octa­carbonyldi­cobalt. This cobalt complex is chiral in the solid state and exhibits alternate arrays of P- and M-conformations.

We report on the photophysical properties of 1,4-bis(2,2-diphenylethenyl)benzene (PEB) in a solution and a solid state. A poor blue photoluminescence efficiency of PEB in a solution dramatically increases in the deposited film. We explain such properties in terms of molecular dynamics and degrees of intramolecular freedom in various molecular environments. PEB as an electron-transport and emitting layer in organic light-emitting diodes (OLEDs) shows bright blue-green electroluminescence (EL) with the peak wavelength at λmax ~ 495 nm. The maximum external EL quantum efficiency of ηEL = 2.5 % and maximum luminance of 41600 cd/m2 in the optimized device were obtained, indicating that PEB possesses superior electron-transport ability.

Bi(OTf)(3)-catalyzed acylation of alcohols with acid anhydride was evaluated in comparison with other acylation methods. The Bi(OTf)(3)/acid anhydride protocol was so powerful that sterically demanding or tertiary alcohols could be acylated smoothly. Less reactive acylation reagents such as benzoic and pivalic anhydride are also activated by this catalysis. In these cases, a new technology was developed in order to overcome difficulty in separation of the acylated product from the remaining acylating reagent: methanolysis of the unreacted anhydride into easily separable methyl ester realized quite easy separation of the desired acylation product. The Bi(OTf)(3)/acid anhydride protocol was applicable to a wide spectrum of alcohols bearing various functionalities. Acid-labile THP- or TBS-protected alcohol, furfuryl alcohol, and geraniol could be acylated as well as base-labile alcohols. Even acylation of functionalized tertiary alcohols was effected at room temperature.

The crystal structure of the title compound, C48H26S2, has been determined in the monoclinic space group C2 at 123 K. The compound possesses C2 symmetry, the crystallographic twofold axis passing through the mid-point of the bond connecting the two naphthyl moieties. The dihedral angle between the two naphthyl groups is 69.3 (3)°, the dihedral angle between the phenyl and thienyl­ene groups is 83.2 (3)°, and the dihedral angle between the thienyl­ene and naphthyl groups is 8.7 (3)°.

The title compound, [(η2-C16H8)Co2(CO)6], (I), has been prepared by treatment of 5,6,11,12-tetrade­hydro­dibenzo­[a,e]cyclo­octene, (II), with dicobalt octa­carbonyl. Although one acetyl­ene in (II) remains intact upon treatment with Co2(CO)8, the other is coordinated to Co2(CO)6, exhibiting a C≡C bond lengthened to 1.356 (2) A and a C≡C—C bond angle contracted to 147.53 (16)°.

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The cationic palladium(II) aquo hydride, trans-(Cy 3 P) 2 Pd(H)(H 2 O) + BF 4 - > is an excellent catalyst for the carbonylation of alkynols to dienoic acids and esters and of alkynediols to cross-conjugated diesters