Formation of atomic hydrogen in an amine—nitrobenzene donor—acceptor pair

We have studied by EPR the oxidation—reduction processes in an amine—nitrobenzene donor— acceptor pair which, when the material is exposed to UV radiation, lead to formation of atomic hydrogen in the system. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 61–63, January–February, 2006.     

Multichromic benzimidazole‐containing polymers: Comparison of donor and acceptor unit effects

This study reports a comparative study on electrochromic properties of two donor–acceptor–donor (DAD)‐type polymers namely poly(2‐heptyl‐4,7‐di(thiophen‐2‐yl)‐1H‐benzo [d]imidazole) (BImTh) and poly(4,7‐bis(2,3‐dihydrothieno[3,4‐b] [1,4]dioxin‐5‐yl)‐2‐heptyl‐1H‐benzo[d]imidazole) (BImEd). DAD‐type monomers were polymerized electrochemically on indium tin oxide‐coated glass slides to determine the optical properties of the polymers. Electrochemical p‐doping experiments were performed to determine the band gap and absorption band values of the polymer films at different redox states. Polymerization of BImTh and BImEd yields multichromic polymers. Donor and acceptor effects are studied by comparing the PBImEd and PBImTh with corresponding benzotriazole derivatives. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Syntheses of donor acceptor biobased photocurable water‐soluble resins based on poly‐l‐lysine

We report a new kind of coating using UV waterborne technique with a biobased poly(amino acid) resin. Firstly we performed the thermal polycondensation of l ‐lysine during 15 h at 150 °C to synthesize water‐soluble oligomers of poly‐l ‐lysine (PLL) with 5–6 monomer units. These oligomers were then transformed in mild conditions to give photocurable water‐soluble resins. We grafted on the poly‐l ‐lysine backbone, allyl and maleamic acid functional groups, with a grafting rate close to 65% thanks to allyl glycidyl ether and maleic anhydride respectively. The influence of the reaction time and the reagents ratio on the grafting rate was investigated. Hence, the donor/acceptor photopolymerization of the mixture of allyl ether‐poly‐l ‐lysine (PLL‐g‐AE) with maleamic acid‐poly‐l ‐lysine (PLL‐g‐MA) in aqueous solution gave yellow transparent films. The degree of conversion and other kinetic parameters have been studied and detailed. This work contributes to the development of materials based on renewable resources and cleaner processes. It opens a new pathway to both fundamental and applied‐driven research. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 955–963     

Spatial donor/acceptor architecture for intramolecular charge-transfer emitter

Charge transfer via electron hopping from an electron donor (D) to an acceptor (A) in nanoscale, plays a crucial role in optoelectronic materials, such as organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs). Here, we propose a strategy for binding D/A units in space, where intramolecular charge-transfer can take place. The resulted material DM-Me-B is able to give bright emission in this molecular architecture because of the good control of D/A interaction and conformational rigidity. Moreover, DM-Me-B presents small singlet-triplet splitting energy, enabling thermally activated delayed fluorescence. Therefore, the DM-Me-B exhibits ～20% maximum external quantum efficiency and low efficiency roll-off at 1000 cd/m², certifying an effective strategy in controlling D/A blocks through space.     

Catalytic effects of hydrogen-bond acceptor solvent on nucleophilic aromatic substitution reactions in non-polar aprotic solvent: reactions of phenyl 2,4,6-trinitrophenyl ether with amines in benzene-acetonitrile mixtures

The effect of addition of small amounts of hydrogen-bond acceptor solvent, acetonitrile, to the benzene medium of the reactions of phenyl 2,4,6-trinitrophenyl ether with aniline and cyclohexylamine, respectively have been investigated. The addition produced similar effects in the two reactions—continuous rate increase with increasing amounts of acetonitrile. The results are interpreted in terms of the effect of amine-solvent interaction on the nucleophilicity of the amines and are in accord with our expectations based on the effects observed for hydrogen-bond donor solvent, methanol on the same reactions. It is also established from the results that the role of hydrogen-bond acceptor co-solvent could be played by an added more basic non-nucleophilic amine.     

Extraction of hydroxyaromatic compounds in river water by liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase

Liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase technique is described for the extraction of six hydroxyaromatic compounds in river water using a disposable and ready to use hollow fiber. Separation and quantitative analyses were performed using LC with UV detection at 254 nm. Analytes were extracted from the acidified sample solution (donor phase) into the organic solvent impregnated in the pores of the hollow fiber and then back extracted into the alkaline solution (acceptor phase) inside the lumen of the hollow fiber. The fiber was held by a conventional 10 microL LC syringe. The acceptor phase was sandwitched between the plunger and a small volume of the organic solvent (microcap). The acceptor solution was repeatedly moved in and out of the hollow fiber using a syringe pump. This movement provides a fresh acceptor phase to come in contact with the organic phase and thus enhancing extraction kinetics thereby leading to the improvement in enrichment of the analytes. The microcap separates the acceptor phase and the donor phase in addition to being partially responsible for mass transfer of the analytes from the donor solution to the acceptor solution. Under stirring, a fresh donor phase will enter through the open end of the fiber that will also contribute to the mass transfer. Various parameters affecting the extraction efficiency viz type of organic solvent, extraction time, stirring speed, effect of sodium chloride, and concentration of donor and acceptor phases were studied. RSD (3.9-5.6%), correlation coefficient (0.995-0.997), detection limit (2.0-51.2 ng/mL), enrichment factor (339-630), relative recovery (93.2-97.9%), and absolute recovery (33.9-63.0%) have also been investigated. The developed method was applied for the analysis of river water.     

An experimental and computational study of donor–linker–acceptor block copolymers for organic photovoltaics

Block copolymers with donor and acceptor conjugated polymer blocks provide an approach to dictating the donor–accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. We report the preparation of a series of donor‐linker‐acceptor block copolymers with poly(3‐hexylthiophene) (P3HT) donor blocks, poly((9,9‐dioctylfluorene)‐2,7‐diyl‐alt‐[4,7‐bis(thiophen‐5‐yl)‐2,1,3‐benzothiadiazole]‐2′,2″‐diyl) (PFTBT) acceptor blocks, and varying lengths of oligo‐ethylene glycol (OEG) chains as the linkers. Morphological analysis shows that the linkers increase polymer crystallinity while a combination of optical and photovoltaic measurements shows that the insertion of a flexible spacer reduces fluorescence quenching and photovoltaic efficiencies of solution processed photovoltaic devices. Density functional theory (DFT) simulations indicate that the linking groups reduce both charge separation and recombination rates, and block copolymers with flexible linkers will likely rotate to assume a nonplanar orientation, resulting in a significant loss of overlap at the donor–linker–acceptor interface. This work provides a systematic study of the role of linker length on the photovoltaic performance of donor–linker–acceptor block copolymers and indicates that linkers should be designed to control both the electronic properties and relative orientations of conjugated polymers at the interface. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1135–1143     

Synthesis,characterization, and properties of regioregular conjugated polymers containing quaterthiophene and an acceptor repeating units

Novel donor–acceptor type polymers consisting of alternating quaterthiophene and an electron withdrawing moiety, pyrazinyl or pyridinyl, have been prepared using Stille coupling approach with moderate yields. The polymers were highly soluble in common organic solvents such as tetrahydrofuran and chloroform. The structure and optical properties of the polymers were characterized by NMR, UV‐vis and fluorescence spectroscopy, and cyclic voltammetry, respectively. The polymer having pyrazine unit exhibited a red‐shift in both absorption and emission in comparison with those analogs containing pyridine because of strong electron withdrawing character of the pyrazinyl group. The polymer containing pyrazinyl as acceptor units also depicted decrease in its optical and electrochemical bandgap relative to those polymers containing 2,5‐ or 2,6‐pyridine moieties. The electrochemical behavior showed facile n‐doping and p‐doping properties of those polymers consisting of alternating quaterthiophene and the acceptor moiety. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2163–2171, 2009     

Donor–acceptor semiconducting polymers based on pyromellitic diimide

Three donor–acceptor copolymers P1 , P2 , and P3 with N,N′‐dodecylpyromellitic diimide as the electron‐acceptor unit with three diethynyl‐substituted donor monomers: 1,4‐diethynyl‐2,5‐bis(octyloxy)benzene, 2,7‐diethynyl‐9,9‐dioctyl‐9H‐fluorene, and 3,3′‐didodecyl‐5,5′‐diethynyl‐2,2′‐bithiophene have been synthesized by Sonogashira crosscoupling polymerization. The synthesized polymers showed deep highest occupied molecular orbital energy levels and larger band gaps (>2.5 eV). Polymers P1 , P2 , and P3 underwent fluorescence quenching with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), indicating the intermolecular photo‐induced charge transfer between the donor polymers and the PCBM acceptor. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1617–1622     

Control of charge transfer by conformational and electronic effects: Donor–donor and donor–acceptor phenyl pyrroles

Derivatives of N-pyrrolobenzene with a para-donor and a para-acceptor substituent on the benzene ring are compared. It is shown that by a suitable increase of the donor strength of the pyrrolo group, CT fluorescence can be achieved even for donor–donor-substituted benzenes. The ICT emission for sterically hindered compounds is more forbidden than that of unhindered phenyl pyrroles. This suggests conformational effects which induce a narrower twist angle distribution around a perpendicular minimum in the excited state.     

Effect of chain compositions on interpolymer specific interaction in solutions

An interpolymer specific interaction of polymers with complementary proton donor units and proton acceptor units was studied with viscometry. In this study, poly(styrene-co-octyl acrylate-co-acrylic acid) as proton donating polymer (PDP) and poly(styrene-co-octyl acrylate-co-4-vinylpyridine) as proton accepting polymer (PAP) with different macromolecular chain compositions were prepared by emulsion copolymerization. Complexed solutions formed by PDP and PAP were studied with a novel interaction criterion k_a based on viscosity enhance factor. The effects of macromolecular chain compositions on the ability to interpolymer interaction and complex stoichiometry were discussed. The results showed that long chain alkyl acrylate units play an important role in the interpolymer specific interaction.     

Property tuning in charge-transfer chromophores by systematic modulation of the spacer between donor and acceptor

A series of donor-acceptor chromophores was prepared in which the spacer separating 4-dimethylanilino (DMA) donor and C(CN)(2) acceptor moieties is systematically varied. All of the new push-pull systems, except 4 b, are thermally stable molecules. In series a, the DMA rings are directly attached to the central spacer, whereas in series b additional acetylene moieties are inserted. X-ray crystal structures were obtained for seven of the new, intensely colored target compounds. In series a, the DMA rings are sterically forced out of the mean plane of the residual pi system, whereas the entire conjugated pi system in series b is nearly planar. Support for strong donor-acceptor interactions was obtained through evaluation of the quinoid character of the DMA ring and by NMR and IR spectroscopy. The UV/Vis spectra feature bathochromically shifted, intense charge-transfer bands, with the lowest energy transitions and the smallest optical gap being measured for the two-dimensionally extended chromophores 6 a and 6 b. The redox behavior of the push-pull molecules was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the series 1 b, 2 b, 4 b, 5 b, in which the spacer between donor and acceptor moieties is systematically enlarged, the electrochemical gap decreases steadily from 1.94 V (1 b) to 1.53 V (5 b). This decrease is shown to be a consequence of a reduction in the D-A conjugation with increasing spacer length. Degenerate four-wave mixing experiments reveal high third-order optical nonlinearities, pointing to potentially interesting applications of some of the new chromophores in optoelectronic devices.     

Electrical conductivity of cation-and anion-exchange membranes in ampholyte solutions

Several laws governing ampholyte transport through ion-exchange membranes are established by a comparative analysis of the concentration dependence of electrical conductivity for homogeneous (CMX, AMX) and heterogeneous (MK-40, MA-41) membranes in NaCl, LysHCl, and NaH₂PO₄ solutions. The increase in the electrical conductivity of membranes in ampholyte solutions as the solutions become more dilute is explained by the increased fraction of divalent ions of the amino acid (cation-exchange membrane) or from phosphoric acid (anion-exchange membrane) in the membrane as a result of Donnan exclusion of hydrolysis products (hydroxide ions or protons, respectively).     

Influence of donor:acceptor ratio on charge transfer dynamics in non-fullerene organic bulk heterojunctions

The donor:acceptor(D:A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction(BHJ) orga nic solar cells(OSCs).The proper D:A blend ratio can provide maximized D/A interfacial area for exciton dissociation and appro p riate domain size of the exciton diffusion length,which is beneficial to obtain high-performance OSCs.Here,we comprehensively investigated the relationship between various D:A blend ratios and the charge transfer and energy transfer mechanisms in OSCs based on PBDB-T and non-fullerene acceptor IT-M.Based on various D:A blend ratios,it was found that the ratio of components is a key factor to suppress the formation of triplet states and recombination energy losses.Rational D:A blend ratios can provide appropriate donor/accepter surface for charge transfer which has been powerfully verified by various detailed experimental results from the time-resolved fluorescence measurement and transient absorption(TA) spectroscopy.Optimized coherence length and crystallinity are verified by grazing incident wide-angle X-ray scattering(GIWAXS) measurements.The results are bene ficial to comprehend the effects of various D:A blend ratios on charge transfer and energy transfer dynamics and provides constructive suggestions for rationally designing new materials and feedback for photovoltaic performance optimization in non-fullerene OSCs.     

Donor and acceptor properties of the solvents tetrahydrofuran and tetrahydrothiophene

The donor and acceptor properties of tetrahydrofuran and tetrahydro-thiophene were evaluated by means of electrochemical and spectroscopic methods. Polarographic and cyclovoltammetric data for LiClO₄, NaClO₄, KClO₄, RbClO₄, CsClO₄, Ba(ClO₄)₂, AgCF₃SO₃, TlClO₄, Zn(CF₃SO₃)₂, Cd(CF₃SO₃)₂, Cu(CF₃SO₃)₂, Pb(CF₃SO₃)₂, Mn(CF₃SO₃)₂, Co(CF₃SO₃)₂, Ni(ClO₄)₂·2H₂O, oxygen, perylene, ferrocene, and bis(biphenyl)chromium tetraphenylborate in tetrahydrofuran and of TlClO₄, CuCF₃SO₃, Pb(CF₃SO₃)₂, Cd(CF₃SO₃)₂, oxygen, ferrocene and bis(biphenyl)chromium tetraphenylborate in tetrahydrothiophene together with the potentials of the Ag/0.01 M Ag⁺-ion electrodes in these two solvents are given. Molar Gibbs (free) energies for the transfer from acetonitrile into tetrahydrofuran for Na⁺, K⁺, Rb⁺, Ag⁺, Tl⁺, Zn²⁺, Cd²⁺, and Pb²⁺, and for the transfer into tetrahydrothiophene for Ag⁺, Cu⁺, Tl⁺, Cd²⁺, and Pb²⁺ were calculated from these data. Visible spectra were obtained for the solvatochromic dyes acetylacetonato(N,N,N,N,-tetramethylethylenediamine) copper(II) perchlorate and for 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridinio)phenoxide, which served as secondary standards to obtain donor and acceptor numbers. The changes in half-wave potentials of the cations vs. bis(biphenyl)chromium(I)/(0) and the Gibbs energies of transfer are discussed on basis of hard and soft donor properties of these two solvents.     

Electrical conductivity of aqueous polymer solutions

 Theoretical equations were proposed to adequately simulate the electrical conductivity behavior of aqueous solutions of both charged and uncharged polymers. The theory, based on the mixture equation of Boned and Peyrelasse, was experimentally verified on poly(acrylic acid) (PAA) in water and poly(ethylene oxide) (PEO) in aqueous electrolyte solutions. The data analysis suggested that both the polymer coils may be depicted as oblate ellipsoids. Subsequently, the semiaxes values of the polymer coils were determined, and they were in good agreement with the results reported in the literature. Received: 25 June 1996 Accepted: 2 October 1996     

Proton donor–acceptor property of matrix during the sol–gel reaction

The UV–VIS absorption spectrum of thymol blue (TB), which was used for an in situ probe for the proton donor–acceptor property of the surrounding matrix, has been observed as a function of time during the sol–gel–xerogel reactions of tetraethyl orthosilicate under HCl catalyzed and uncatalyzed conditions. The value of relative abundance, RA _Z , of zwitter ion species was calculated. In the ethanol-containing system, RA _Z increased for 7 h, then decreased until 114 h had passed, and finally increased gradually. These dynamic changes of the RA _Z were commonly observed for all the systems. The final RA _Z values were expected larger than 0.7 irrespective of the initial chemical composition. The characteristic increase and decrease in RA _Z are ascribed to the increase and decrease in proton-donating ability from the surrounding matrix to encapsulated TB molecules. A general acidity function, H ₋, of the matrix was estimated.     

New thiophene‐phenylene‐thiophene acceptor random conjugated copolymers for optoelectronic applications

New low band gap thiophene‐phenylene‐thiophene ( TPT )‐based donor‐acceptor‐donor random copolymers were synthesized for optoelectronic device applications by a palladium‐catalyzed Stille coupling reaction under microwave heating. The acceptors included 2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐5,8‐bis[5′‐bromo‐dithien‐2‐yl‐quinoxalines] ( DTQ ) and 3,6‐bis(5‐bromothiophen‐2‐yl)‐2,5‐bis(2‐ethyl‐hexyl)‐pyrrolo[3,4‐c]‐pyrrole‐1,4‐dione ( DPP ). The prepared random copolymers were named as PTPTDTQ_0.55 , PTPTDTQ_0.34DPP_0.14 , and PTPTDTQ_0.26DPP_0.34 depending on the copolymer ratio. The optical band gaps (E) of PTPTDTQ_0.55 , PTPTDTQ_0.34DPP_0.14 , and PTPTDTQ_0.26DPP_0.34 were 1.74, 1.56, and 1.48 eV, respectively. The hole mobility obtained from the field‐effect transistor devices prepared from PTPTDTQ_0.55 , PTPTDTQ_0.34DPP_0.14 , and PTPTDTQ_0.26DPP_0.34 were 2.2 × 10^?3, 2.4 × 10^?3, and 4.7 × 10^?3 cm² V^?1 s^?1, respectively, with the on‐off ratios of 4.0 × 10⁴, 4.0 × 10⁴, and 5.3 × 10⁴. It suggested that the significant intramolecular charge transfer between the TPT and acceptor led to the band gap reduction and hole mobility enhancement. Polymer solar cells of these TPT ‐based copolymers blended with 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl‐[6,6]‐C‐71 (PC₇₁BM) under illumination of AM 1.5G (100 mW cm^?2) solar simulator exhibited a power conversion efficiency (PCE) as high as 3.71%. Besides, the near‐infrared photodetector device prepared from PTPTDTQ_0.26DPP_0.34 showed a high external quantum efficiency exceeding 32% at 700 nm (under ?3 V bias) and fast‐speed response. This study suggests that the prepared TPT ‐based donor‐acceptor random copolymers exhibited promising and versatile applications on optoelectronic devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2351–2360, 2010     

A New D–A conjugated polymer P(PTQD‐BDT) with PTQD acceptor and BDT donor units for BHJ polymer solar cells application

A novel donor–acceptor ( D–A ) copolymer comprising of weak electron donating BDT moiety and strong 9‐(2‐octyldodecyl)?8H‐pyrrolo[3,4‐b] bisthieno[2,3‐f:3',2'‐h] quinoxaline‐8,10(9H)‐dione (PTQD) unit denoted as P(PTQD‐BDT) was synthesized as donor material for polymer solar cells. P(PTQD‐BDT) shows a broad visible‐near‐infrared absorption band with an optical bandgap of 1.74 eV and possesses a relatively low‐lying HOMO level at ?5.28 eV. Bulk‐heterojunction polymer solar cell with the optimized blend of 1:2 (weight ratio) P(PTQD‐BDT):PC₇₁BM (processed with chloroform) shows an open circuit voltage of 0.92 V, a short circuit current density of 7.84 mA/cm², and a fill factor of 0.50, achieving a power conversion efficiency (PCE) of 3.61%. The PCE has been further improved to 5.55 % (J_sc = 10.34 mA/cm², V_oc = 0.88V and FF = 0.61), when 3% v ol 1,8‐diio‐dooctane (DIO) was used as solvent additive for the processing of P(PTQD‐BDT):PC₇₁BM blended film. The enhancement in J_sc is as a result of the appropriate morphology and efficient exciton dissociation into free charge carrier. The increase in PCE has been attributed to the favorable nanoscale morphology for efficient exciton dissociation and charge transport (reduction in the electron to hole mobility ratio). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2390–2398