Simple non-fullerene electron acceptors with unfused core for organic solar cells

Two simple unfused-cores based electron acceptors with different side units were developed for application in non-fullerene solar cells, in which the side chains have the significant effect on their absorption spectra and photovoltaic performance.     

Synthesis, ionisation potentials and electron affinities of hexaazatrinaphthylene derivatives

Several hexaazatrinaphthylene derivatives and a tris(thieno)hexaazatriphenylene derivative have been synthesised by reaction of the appropriate diamines with hexaketocyclohexane. The crystal structure of 2,3,8,9,14,15-hexachloro-5,6,11,12,17,18-hexaazatrinaphthylene has been determined by X-ray diffraction; this reveals a molecular structure in good agreement with that predicted by density functional theory (DFT) calculations and pi-stacking with an average spacing between adjacent molecular planes of 3.18 A. Solid-state ionisation potentials have been measured by using UV photoelectron spectroscopy and fall in the range of 5.99 to 7.76 eV, whereas solid-state electron affinities, measured using inverse photoelectron spectroscopy, vary in the range -2.65 to -4.59 eV. The most easily reduced example is a tris(thieno)hexaazatriphenylene substituted with bis(trifluoromethyl)phenyl groups; DFT calculations suggest that the highly exothermic electron affinity is due both to the replacement of the outermost phenylene rings of hexaazatrinaphthylene with thieno groups and to the presence of electron-withdrawing bis(trifluoromethyl)phenyl groups. The rather exothermic electron affinities, the potential for adopting pi-stacked structures and the low intramolecular reorganisation energies obtained by DFT calculations suggest that some of these molecules may be useful electron-transport materials.     

二氧化锡纳米粒子催化四组分Hantzsch缩合合成多氢喹啉衍生物(英文)

Tin dioxide (SnO2 ) nanoparticles efficiently catalyzed unsymmetrical four-component Hantzsch condensations of various aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate to form polyhydroquinoline derivatives in excellent yields. This novel method offers several advantages over the traditional method of synthesizing these compounds, including safety, mild conditions, short reaction times, high yields, and an easy workup.     

Synthesis of diverse phenylglycine derivatives via transformation of Ugi four-component condensation primary adducts

3-(N-Substituted)amino-4-arylamino-1H-isochromenones (isocoumarins) which can be regarded as the enediamine tautomers of the Ugi four-component condensation primary adducts between 2-formylbenzoic acids, arylamines, and isocyanides undergo a facile ring cleavage with amines to give a series of phenylglycine derivatives. Thus, a synthetically useful post-condensation transformation of Ugi four-component condensation primary adducts is described for the first time.     

Synthesis of coumarin derivatives in a microfluidic flow system employing the Pechmann condensation: A case study

For the synthesis of coumarin derivatives using the Pechmann condensation scheme, an acidic ionic liquid catalyst, abbreviated as [EBsImH][HSO ₄ ] , was prepared from the ring opening of 1,4-butanesultone by 1-ethylimidazole, followed by the addition of 1 equiv. H₂SO₄(c). The [EBsImH][HSO ₄ ] -catalyzed Pechmann condensation reactions proceeded smoothly in a batch setup, with recyclable [EBsImH][HSO ₄ ] showing great catalytic activity. The acidic ionic liquid catalyst [EBsImH][HSO ₄ ] was recovered from EtOAc/H₂O extraction of the product mixture, where the H₂O layer was worked up and dried for reuse in consecutive runs of the Pechmann condensation reactions, maintaining >85% conversion for four times. The catalytic reactions were also carried out in a microfluidic flow setup. The flow parameters, the reactant molar amounts, and the additional H₂SO₄ as a modifying acid catalyst were optimized in the current case study. A minimum conversion rate of 2.8 g/hr of coumarin derivatives was demonstrated.     

Synthesis and memory characteristics of highly organo‐soluble hyperbranched polyimides with various electron acceptors

A series of hyperbranched polyimides (HBPIs) were synthesized by reacting a triamine monomer N ,N ′,N ″‐tris(4‐methoxyphenyl)‐N ,N ′,N ″‐tris(4‐phenylamino)?1,3,5‐benzenetriamine with various dianhydrides such as oxydiphthalic dianhydride (ODPA), 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic dianhydride (PMDA). The hyperbranched polyimide (6FHBPI) using 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) as dianhydride monomer was also added into the discussion. All the hyperbranched polyimides exhibited excellent organo‐solubility and high thermal stability. Memory devices with a sandwiched structure of indium tin oxide (ITO)/HBPI/Al were constructed by using these HBPIs as the active layers. All these HBPIs based memory devices exhibited favorable memory performances, with switching voltages between ?1.3 V and ?2.5 V, ON/OFF current ratios up to 10⁷ and retention times long to 10⁴ s. Tunable memory characteristics from electrical insulator to volatile memory, and then to nonvolatile memory were obtained by adjusting the electron acceptors of these HBPIs. Molecular simulation results suggested that the electron affinity and the dipole moment of these HBPIs were responsible for the conversion of the memory characteristics. With the electron affinity and dipole moment of these HBPIs increasing, the memory characteristics turned from volatile to nonvolatile. The present study suggested that tunable memory performance could be achieved through adjusting the acceptor moieties of the hyperbranched polyimides. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2281–2288     

Reactivity of 1,2-O-cyanoalkylidene sugar derivatives in trityl-cyanoalkylidene condensation

The rate-determining step of trityl-cyanoalkylidene condensation is the interaction between the cyanoalkylidene derivative (CD) and the triphenylmethyl cation. The rate of the reaction follows first-order kinetics with respect to both CD and the catalyst (Tr⁺) and is independent of the nature and concentration of the trityl ether. Glycosylation rate constants have been determined for CD's of most common monosaccharides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1485–1489, August, 1993.     

Magnesium Ethoxide as an Effective Catalyst in the Synthesis of Dicayanomethylendihydrofurans

Magnesium ethoxide was used for the first time in the synthesis of the titled compounds. In these preparations, product yields were significantly improved compared with similar synthesis catalyzed by other metal ethoxides. The effectiveness of magnesium ethoxide as catalyst was tentatively rationalized.     

How electron delocalization influences the electron-withdrawing properties of isomeric benzobischalcogenadiazoles

The fermionic potential and delocalization indices for benzo-bis-1,2,5-chalcogenadiazoles reveal inhomogeneous electron delocalization in their benzene ring, which results in compactly localized lone electron pairs on the chalcogen atoms. These features of (de)localization are rooted in a local increase in the kinetic component of the electron correlation, which expresses the Fermi hole variability and the kinetic potential response to electron density variations in the benzene ring of benzobis-1,2,5-chalcogenadiazoles. This explains their better electron-withdrawing properties compared to benzobis-1,2,3-chalcogenadiazoles     

Corannulene Molecular Rotor with Flexible Perfluorobenzyl Blades: Synthesis,Structure and Properties

Two members of a new class of organic‐acceptor perfluorobenzyl corannulenes were prepared by gas‐phase and highly‐selective solution‐phase reactions at elevated temperatures. The peculiar single‐crystal X‐ray structure of C₅‐C₂₀H₅(CF₂C₆F₅)₅ revealed two high‐energy conformers with drastically different bowl depths and orientations of perfluorobenzyl blades; the conformers are alternating in columnar packing arrangements and every pair is sandwiched by toluene molecules.     

Base-catalyzed cross coupling of secondary alcohols and aryl-aldehydes with concomitant oxidation of alcohols to ketones: An alternative route for synthesis of the Claisen-Schmidt condensation products

Base-catalyzed C–C cross coupling of secondary alcohols and aryl-aldehydes was achieved, when an alcoholic solution of an aryl-aldehyde was stirred under reflux for 45 h in the presence of a catalytic (20 mol%) amount of K₂CO₃. The consistent formation of α,α′-bis-(benzylidene) alkanones was obtained in moderate to good yields using various secondary alcohols and substituted aryl-aldehydes. Herein, α,α′-bis-(benzylidene)alkanones, which are the classical products of Claisen-Schmidt (cross aldol) condensation, have been synthesized via an alternative strategy using secondary alcohols. Bis-(benzylidene) alkanones are an integral part of various drug regimes and the production of bis-(benzylidene) alkanones without using any precious metal is a major outcome of the present reaction.     

Alkoxy substitution on simple non-fused electron acceptors for tuning the photoelectric properties of organic solar cells

In order to identify high-performance non-fused ring electron acceptors for bulk heterojunction (BHJ) solar cells, six structurally diverse molecules are designed and categorized into two series. The first series is anchored by R1 as the reference molecule, featured fixed BDT, IC-2F end groups and modified π bridges. The second series is anchored by R2 as the reference molecule, incorporated a terminal IC-2F and a central core modified with EDOT bridge. The electronic structure and photoelectric properties of all acceptor molecules were investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Charge transfer matrix (CTM), Density of states (DOS) and Reorganization energy (RE) etc. were analyzed to provide fundamental knowledge on charge transport and electronic excitation. Among the studied molecules, W2 exhibited a smaller energy gap (1.74 eV) compared to the other molecules, effectively transferring its electron from HOMO to LUMO. At the same time, the W2 molecule has excellent V_oc and FF. Furthermore, W2 displayed the largest λ_max redshift compared to R1. Although W3 had a smaller value of λ_h, the comprehensive photovoltaic parameters of W2 were more excellent. The research results not only demonstrated the feasibility of introducing different alkoxy groups to alter the structure of the π bridge and central core is a feasible method for constructing high-performance NFREAs, but also highlighted that BDT cores combined with EDOT bridges are among the most promising small molecule acceptors (SMAs) that could be considered as reasonable candidates for synthesis and incorporation into organic solar cells. The results of this study are expected to provide seminal ideas for the design of high-performance non-fullerene acceptors.     

Preparation of hole transporting polymers by condensation polymerization of triphenylamine derivatives

Hole transporting polymers were prepared by condensation polymerization of triphenylamine and N,N,N',N'‐tetraphenylbenzidine (TPD) having alkyl group with aldehydes in the presence of p‐toluenesulfonic acid. The obtained polymers had molecular weight higher than 10,000 and good film formation ability. It was found that the aromatic amine monomers were connected with aldehyde monomer at the p‐position of the phenyl group. TPD‐aldehyde polymers had almost the same UV absorption and redox potentials as those of TPD monomer indicating that the electronic structure of amine unit did not change by the polymerization. The hole transporting mobility was in the range of 10⁻³‐10⁻⁶cm²/Vs. The electroluminescent device consisting of ITO/TPD polymer/Alq/Mg‐Ag had a maximum luminance of 9000 cd/m².     

New perylene diimide electron acceptors for organic electronics: Synthesis,optoelectronic properties and performance in perovskite solar cells

Two new non-fullerene acceptors based on perylene diimide with acetylenic bridges were designed and synthesized employing Stille and Sonogashira coupling reactions as the key steps. Their optical and electronic properties were explored by UV–VIS spectroscopy and cyclic voltammetry, and energies of frontier molecular orbitals were estimated. Their preliminary studies in perovskite solar cells as electron transport materials showed the best power conversion efficiency for photocells of 14.18% value.     

An efficient synthesis of γ-amino β-ketoester by cross-Claisen condensation with α-amino acid derivatives

Cross-ester condensation between N-protected amino acid ester and the lithium enolate prepared from alkyl acetate gave the corresponding β-ketoester in high yield without the formation of the tertiary alcohol that is commonly seen as by-product. This interesting reaction is applicable to the amino acid derivatives with suitable N-protecting groups, which can help to stabilize the reaction intermediates.     

Synthesis of a new urea derivative: a dual-functional organocatalyst for Knoevenagel condensation in water

A phenylalanine–urea compound-catalyzed Knoevenagel condensation in water is reported. Various aldehydes and active methylene compounds undergo condensation at room temperature to give the desired products in high yields. The mechanism of the condensation of aldehydes with Meldrum’s acid catalyzed by the novel urea derivative is also disclosed.     

Base-catalyzed condensation of β-bromovinylaldehydes with β-ketoesters followed by water-mediated cyclization and aromatization: one-pot access to substituted benzene derivatives

A simple, convenient, one-pot synthetic approach towards substituted benzene derivatives using base-catalyzed condensation of β-bromovinylaldehydes with β-ketoesters followed by water-mediated cyclization and aromatization has been developed.     

Modified coumarins. 14. Synthesis of 7-hydroxy-[4,3′]dichromenyl-2,2′-dione derivatives

New derivatives of 3-(2-oxochromen-4-yl)chromen-2-one, modified analogs of natural dicoumarins, were prepared from substituted coumarin-4-acetic acids.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 358–365, September–October, 2004.     

Synthesis and characterization of pentachlorophenyl-metal derivatives with d0 and d10 electron configurations

By reaction of [TiCl(3)(thf)(3)] with LiC(6)Cl(5), the homoleptic organotitanium(III) derivative [Li(thf)(4)][Ti(III)(C(6)Cl(5))(4)] (1) has been prepared as a paramagnetic (d(1), S = 1/2, g(av) = 1.959(2)), extremely air-sensitive compound. Oxidation of 1 with [N(C(6)H(4)Br-4)(3)][SbCl(6)] gives the diamagnetic (d(0)) organotitanium(IV) species [Ti(IV)(C(6)Cl(5))(4)] (2). Compounds 1 and 2 are also electrochemically related (E(1/2) = 0.05 V). The homoleptic, diamagnetic (d(10)) compounds [N(PPh(3))(2)][Tl(C(6)Cl(5))(4)] (3) and [Sn(C(6)Cl(5))(4)] (4) have also been prepared. Nearly tetrahedral environments have been found for the d(0), d(10), and d(1) metal centers in the molecular structures of compounds 2-4 as well as in that of [Li(thf)(2)(OEt(2))(2)][Ti(III)(C(6)Cl(5))(4)].CH(2)Cl(2) (1') (X-ray diffraction). The reaction of the heavier Group 4 metal halides, MCl(4) (M = Zr, Hf) with LiC(6)Cl(5) in the presence of [NBu(4)]Br gives, in turn, the heteroleptic species [NBu(4)][M(C(6)Cl(5))(3)Cl(2)] (M = Zr (5), Hf (6)). Compounds 5 and 6 are isomorphous and isostructural, with the metal center in a trigonal-bipyramidal (TBPY-5) environment defined by two axial Cl ligands and three equatorial C(6)Cl(5) groups (X-ray diffraction). No redox features are observed for compounds 3-6 in CH(2)Cl(2) solution between -1.6 and +1.6 V.     

Unprecedented Nucleophilic Attack of Piperidine on the Electron Acceptor during the Synthesis of Push‐Pull Dyes by a Knoevenagel Reaction

An unprecedented nucleophilic addition of piperidine on an electron acceptor, namely, 2‐(3‐oxo‐2,3‐dihydro‐1H‐cyclopenta[b]naphthalen‐1‐ylidene)malononitrile is reported. This unexpected behavior was observed during the synthesis of push‐pull dyes using the classical Knoevenagel reaction. To overcome this drawback, use of diisopropylethylamine (DIPEA) enabled to produce the expected dyes PP1 and PP2 . The optical and electrochemical properties of the different dyes were examined. Theoretical calculations were also carried out to support the experimental results. To evidence the higher electron‐withdrawing ability of this electron acceptor, a comparison was established with two dyes ( PP3 and PP4 ) comprising its shorter analogue.