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A mild and efficient ZrCl 4 -catalyzed synthesis of isoindigo derivatives from isatins and indolin-2-ones in refluxing ethanol is described. A variety of new functionalized isoindigo derivatives are obtained by simple filtration. Lewis acid was first used as catalyst in the synthesis of isoindigo derivatives. [ABSTRACT FROM AUTHOR]

Abstract: Donor/acceptor polymers with N-acylated isoindigo as acceptor units have been synthesized. The thermal, optical, electrochemical, and charge-transport properties of the polymers have been investigated. The new polymers show broad absorption from 450 to 900 nm. Due to the strong electron accepting characteristic of N-acylated isoindigo, the new polymers exhibit narrow optical band gaps and deep LUMO energy levels compared with the polymers based on N-alkylated isoindigo. The new polymers show n-type transport behavior and balanced ambipolar transport behavior in organic thin film transistors (OTFT) device. [Copyright &y& Elsevier]

A selected set of substituted pyridone-annelated isoindigos 3a-f has been synthesized via interaction of 5- and 6-substituted oxindoles 2a-f with 6-ethyl-1,2,9- trioxopyrrolo[3,2-f]quinoline-8-carboxylic acid (1) in acetic acid at reflux. Among these isoindigos, the 5'-chloro and 5'-bromo derivatives 3b and 3d show strong and selective antiproliferative activities against a panel of human hematological and solid tumor cell-lines, but not against noncancerous cells, suggesting their potential use as anticancer agents. In all the tested cell lines, compound 3b was a 25%-50% more potent inhibitor of cell growth than 3d, suggesting the critical role of the substitution at 5'-position of the benzo-ring E. The IC50 values after 48 hours incubation with the 5'-chloro compound 3b were 6.60 μM in K562, 8.21 μM in THP-1, 8.97 μM in HepG2, 11.94 μM in MCF-7 and 14.59 μM in Caco-2 cancer cells, while the IC50 values in noncancerous HEK-293 and L-929 were 30.65 μM and 40.40 μM, respectively. In addition, compound 3b induced higher levels apoptosis in K562 cells than 3d, as determined by annexin V/7-AAD flowcytometry analysis. Therefore, further characterization of the antitproliferative mechanisms of compounds 3b and 3d may provide a novel chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

Abstract: Two new donor/acceptor π-conjugated polymers with functional dyes, either diketopyrrolopyrrole or isoindigo as the electron accepting units and 5,10-bis(2,3-didecylthiophen-5-yl)-naphtho[1,2-b:5,6-b′]difuran as an electron donating units have been synthesized. The photo-physical, electrochemical and photovoltaic properties of the new polymers have been studied and compared. With the same donor unit, the diketopyrrolopyrrole based polymer showed low bandgap and broad absorption extended into near IR region. The isoindigo based polymer showed little absorption in near IR region. However, the isoindigo based polymer showed more efficient absorption than diketopyrrolopyrrole based polymer in the most of visible region (from 300 to 690 nm) in solution. The isoindigo based polymer showed lower HOMO and LUMO energy levels than diketopyrrolopyrrole based polymer. The isoindigo polymer based solar cell devices consistently showed higher open circuit voltages than the diketopyrrolopyrrole polymer based devices. [Copyright &y& Elsevier]

Three random conjugated polymers, RP-TiI, RP-2TiI and RP-TVTiI based on both thieno[3,4- c]pyrrole-4,6-dione and isoindigo units have been synthesized by Stille cross-coupling reaction. The optical and electrochemical properties of new polymers have been investigated. The resulted polymers showed broad absorption spectra and appropriate energy levels for polymer solar cell applications. The bulk heterojunction devices based on the blend of the polymer RP-TiI and PC61BM showed a power conversion efficiency of 1.75%. [ABSTRACT FROM AUTHOR]

The article discusses a study on the synthesis and characterization of phenothiazine-isoindigo copolymers for photovoltaic applications. Topics covered include the chemical structure of phenothiazine II (PPT-II) copolymers confirmed via its proton nuclear magnetic resonance (NMR) spectrum, the polydispersion and solubility of PPT-II, and the onsets of oxidation and reduction potential of PPT-II.

Highlights: [•] We synthesized three isoindigo based organic dyes (ID1, ID2, ID3). [•] ID1 shows higher energy conversion efficiency (3.33%). [•] Double anchor group could affect the progress of electron directional transmission. [Copyright &y& Elsevier]

• The isoindigo bearing tetraphenylethylene derivatives were synthesized successfully. • The single crystal structure and crystallographic properties were investigated. • Self-assembled soft material based on isoindigo derivatives TPE-IN1 and TPE-IN2 were studied. • X-ray crystal structure and SEM analysis revealed supramolecular self-assembly formation by means of π-π stacking interactions. In this work, we design and synthesis donor-acceptor-donor based two new chromophores containing isoindigo (IN) as an acceptor core functionalised with two donor tetraphenylethylene (TPE) on the periphery one without thiophene spacer (Coded as: TPE-IN1) another derivative with thiophene as a spacer (Coded as: TPE-IN12. For the synthesis of both the derivatives Suzuki cross-coupling reaction was employed. Fluorescence emission spectral proeprties of TPE-IN1 and TPE-IN2 was investigated in mixture of chloroform (CHCl 3):methylcyclohexane (MCH) and tetrahydrofuran (THF):water (H 2 O). The results shows an aggregation-caused quenching (ACQ) effect, which may be due to energy/electron transfer from TPE to IN core, as TPE is typically aggregation induced emission (AIE)-active chromophore. The self-assembled/aggregated structures in solution was characterized by means of fluorescence lifetime and dynamic light scattering (DLS) measurement. The crystalline morphology on the silicon wafer was investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Furthermore, our study of supramolecular self-assembly of TPE-IN1 and TPE-IN2 in THF:H 2 O (10:90%) and CHCl 3 :MCH (10:90%) solvent mixes shows various superstructures. Typically , TPE-IN1 displayed interesting hexagonal rod like morphology in THF:H 2 O mixture, where as TPE-IN2 showed self-assembled crystalline fibrous morphological micro and nanostructures via the solvophobic effect. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of synergistic structural engineering (asymmetric side chains and backbone fluorination) for polymer donors in photovoltaic applications is investigated in this study. Six isoindigo (IID)-based polymer donors with slightly different side-chain and backbone designs are composed of a bithiophene (BT) or fluorinated bithiophene moiety to form two series of polymers [PII2T (P1–P3) and PII2TF (P4–P6)] while symmetric/asymmetric side-chain combinations are composed of decyltetradecane branched alkyl side chain (DT) and siloxane-terminated side chain (SiO–C8). The results indicate the different side chain design and backbone fluorination modulate the energy levels, crystalline properties, and molecular packing behaviors of the polymers. P2 and P5 with asymmetric side chains are showed to deliver the highest power conversion efficiency (PCE) in the respective series of PII2T and PII2TF. The morphological analyses reveals that the mismatched side-chain geometry results in a face-on dominated packing to yield superior device performance. Meanwhile, the fluorinated polymers (P4–P6) show superior performance than the corresponding non-fluorinated polymers (P1–P3). Moreover, backbone fluorination largely reduces the performance difference between the polymers with symmetric side chains and asymmetric sides chains. This work demonstrates that the synergistic effect of asymmetric side chains and backbone fluorination can be a rational design towards high-performance conjugated polymers. [Display omitted] • The synergistic effect of asymmetric side chains and backbone fluorination for polymer donors in photovoltaic applications is investigated. • The polymers with the asymmetric side chains deliver the highest PCE in their respective series with other polymers with symmetric side chains. • Backbone fluorination largely reduces the performance difference between the polymers with different side-chain designs. [ABSTRACT FROM AUTHOR]

Abstract: New polymers based on two different angular-shaped naphthodifurans (NDFs) have been synthesized. The optical, electrochemical and photovoltaic properties of the new polymers were investigated. The UV–vis absorption spectra of polymer PIDNDF 1 recorded in dilute solution and as thin-film were both red-shifted compared with those of polymer PIDNDF 2. The HOMO energy levels of PIDNDF 1 and PIDNDF 2 were similar at −5.40eV. There was slight difference in the LUMO energy levels of these two polymers. The maximum power conversion efficiency (PCE) of PIDNDF 1 based solar cell devices was 1.83%, which was more than twice that of PIDNDF 2 based device. The difference on the device performance resulted from the shapes of NDF repeating units and backbone geometries of polymers. [Copyright &y& Elsevier]

An efficient green condensation reaction has been developed for synthesis of trans-isoindigo derivatives using SBA-Pr-SOH with pore size of 6 nm as a heterogeneous nanoporous acid catalyst under solvent-free conditions. Isoindigo derivatives have many industrial applications, e.g., dyes, drugs, organic solar cells, and semiconductor memories. The antimicrobial activities of these compounds have also been tested. [ABSTRACT FROM AUTHOR]

Two donor-acceptor copolymers (P1 and P2) containing isoindigo as the acceptor unit and the benzodithiophene and bisthiophene-dithieno[3,2-b:2′,3′-d]-pyrrole as the donor unit have been designed and synthesized by the Pd-catalyzed Stille coupling reaction. The copolymers show broad and flat absorption, exhibit good solubility, and thermal stability, but possess optical bandgaps of 1.62 and 1.42 eV, respectively, and different donor-acceptor distance, of which the former is shorter than the later. The power conversion efficiency of the polymer solar cells based on P2:PC61BM (1:1 wt%) reached 1.86% with open-circuit voltage of 0.54 V and a short-circuit current of 6.36 mA/cm2, under the illumination of AM 1.5, 100 mW/cm2. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highlights: [•] Isoindigo-based compound is synthesized. [•] The solar cells device shows high open-circuit voltage of 1.0V. [•] Small molecule solar cells device is solution-processing. [ABSTRACT FROM AUTHOR]

Abstract: A new easily-accessible solution-processed oligomer, with an isoindigo group as an electron acceptor and a thieno[3,2-b]thiophene flanked by thiophenes as electron donors, has been synthesized by a Stille coupling reaction. Through introducing the extended π-conjugated groups into isoindigo, the electro-optical properties of the material can be fine-tuned. The isoindigo oligomer has a broad absorption in the region from 300 to 800 nm with a narrow bandgap (1.54 eV), which is believed to be an ideal bandgap as donor materials. The oligomer possesses low HOMO energy level (−5.39 eV). The potential of optical and electronic properties encouraged us to explore the photovoltaic performance using the oligomer as the donor material in bulk heterojunction organic solar cell along with 6,6-phenyl-C61-butyric acid methyl ester as the acceptor. The solar cell based on the oligomer with an inverted device configuration provided a power conversion efficiency of 1.41% under the AM 1.5G illumination with an intensity of 100 mW cm−2 from a solar simulator. [Copyright &y& Elsevier]

A novel class of thieno[3,2-b]thiophene (TT) and isoindigo based copolymers were synthesized and evaluated as electron donor and hole transport materials in bulk-heterojunction polymer solar cells (BHJ PSCs). These π-conjugated donor-acceptor polymers were derived from fused TT and isoindigo structures bridged by thiophene units. The band-gaps and the highest occupied molecular orbital (HOMO) levels of the polymers were tuned using different conjugating lengths of thiophene units on the main chains, providing band-gaps from 1.55 to 1.91 eV and HOMO levels from −5.34 to −5.71 eV, respectively. The corresponding lowest unoccupied molecular orbital (LUMO) levels were appropriately adjusted with the isoindigo units. Conventional BHJ PSCs (ITO/PEDOT:PSS/active layer/interlayer/Al) with an active layer composed of the polymer and PC71BM were fabricated for evaluation. Power conversion efficiency from a low of 1.25% to a high of 4.69% were achieved with the best performing device provided by the D−π−A polymer with a relatively board absorption spectrum, high absorption coefficient, and more uniform blend morphology. These results demonstrate the potential of this class of thieno[3,2-b]thiophene-isoindigo-based polymers as efficient electron donor and hole transport polymers for BHJ PSCs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Addition of substituted isatins to 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone, generated in situ from 3,5-di-tert-butyl-4-hydroxybenzyl acetate, to form 1-substituted hydroxybenzyl-isatins, is reported. On the basis of these isatins novel isatin-3-thiosemicarbazones as well as isoindigo derivatives bearing a 2,6-di-tert-butylphenol moiety were obtained. The structures of all novel compounds are confirmed by IR, ¹H NMR and 13C NMR. [ABSTRACT FROM AUTHOR]

The reaction of substituted benzyl-, aroylmethyl-, or 1-phenetylisatins with hexaethyltriaminophosphine has been shown to lead to the formation of a library of 3,3′-biindolinylidene-2,2′-diones with functionalized benzyl-, aroylmethyl-, and 1-phenetyl fragments at the nitrogen atom. [ABSTRACT FROM AUTHOR]

The crystal and molecular structure of 1,1′-dimethyl-isoindigo is studied by single crystal X-ray diffraction analysis. It is shown that the molecules of 1,1′-dimethyl-isoindigo are nonplanar due to the rotation of two oxindole rings relative to the double bond. [ABSTRACT FROM AUTHOR]

The reaction of aminomethylisatins (isatin N-Mannich bases) with hexaethylphosphorous triamide leads to the formation of 1,1′-bis(dialkylaminomethyl)-3,3′-bis(indolin-3-ylidene)-2,2′-diones and 1,1′-bis(1,3-dioxo-1,3-dihydroisoindol-2-ylmethyl)-1 H,1′ H-[3,3′]bisindolylidene-2,2′-dione. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A series of arylmethylidenoxindoles was synthesized by acid or base catalysed condensation of substituted aldehydes with oxindole. The products were formed as mixtures of Z- and E-isomers that were separated using column chromatography and identified by 1H and 13C NMR. The effect of substituents on absorption maxima was investigated both experimentally and theoretically, based on time dependent density functional theory. Low temperature absorption spectroscopy in a solvent glass enabled identification of the position of the 0-0 vibronic bands. The spectral features of the parent Z-benzylidenoxindole were compared to those of trans-isoindigo and trans-stilbene. Fluorescence of arylmethylidenoxindoles in solution was not observed, as E–Z isomerization represents a dominant deactivation channel after irradiation; when this geometrical isomerization was sterically hindered at low temperature solvent glass or in solid, fluorescence of planar Z-isomers was observed. [Copyright &y& Elsevier]

Abstract: A series of functionalized isoindigos structurally related to meisoindigo (1-methylisoindigo), a therapeutic agent used for the treatment of a form of leukemia, were synthesized and evaluated for antiproliferative activities on a panel of human cancer cells. Two promising compounds (1-phenpropylisoindigo and 1-(p-methoxy-phenethyl)-isoindigo) that were more potent than meisoindigo and comparable to 6-bromoindirubin-3′-oxime on leukemic K562 and liver HuH7 cells were identified. Structure–activity relationships showed the importance of keeping one of the lactam NH in an unsubstituted state. Substitution of the other lactam NH with aryl or arylalkyl side chains retained or improved activity in most instances. An intact exocyclic double bond was also essential, possibly to maintain planarity and rigidity of the isoindigo scaffold. None of the compounds were found to inhibit CDK2 in an in vitro assay, in spite of reports linking the antiproliferative activities of meisoindigo and other isoindigos to CDK2 inhibition. Hence, these functionalized isoindigos disrupted cell growth and proliferation by other mechanistic pathways that did not involve CDK2 inhibition. [Copyright &y& Elsevier]

• A donor–acceptor copolymer from bisEDOT and isoindigo was firstly synthesized. • The polymer shows reversible and stable electrochromism with a low bandgap of 1.02 eV. • The polymer exhibits excellent EC performance with ΔT of 90% and CE up to 1025 cm2 C−1. • The fabricated ECDs reveal reversible and stable color change from green to sky-blue. High-performance electrochromic materials with high optical contrast, coloration efficiency, and excellent stability have always been critical for polymer electrochromics, and will boost diverse applications including flexible displays and wearable electronics. Herein, we develop a donor-acceptor-donor type copolymer from strong electron-withdrawing acceptor unit isoindigo and electron-donating moiety bis-EDOT by synthesizing and electropolymerizing its precursor (E)-1,1′-dihexyl-6,6′-bis(2,2′,3,3′-tetrahydro-[5,5′-bithieno[3,4-b][1,4]dioxin]-7-yl)-[3,3′-biindolinylidene]-2,2′‑dione (BisE−IDOH−BisE). Such polymer exhibits a low optical bandgap of 1.02 eV with stable and reversible electrochromism from kelly-green to sky blue. Further kinetic studies demonstrate that this polymer displays intriguing overall electrochromic performances throughout the NIR window with simultaneously high optical contrast up to 90%, high coloration efficiency of 1025 cm2 C−1, fast switching time of 1.1 s, and excellent reversible stability (< 4% loss upon 5000 cycling), which presents one of the best overall performances among the reported electrochromic polymers so far. With these amazing electrochromic properties, isoindigo-EDOT based polymers can be further developed towards device patterning and real applications like flexible indoor decoration displays and near infrared camouflage. [Display omitted] [ABSTRACT FROM AUTHOR]

Organic mixed ionic and electronic conductors are of significant interest for bioelectronic applications. Here, three different isoindigoid building blocks are used to obtain polymeric mixed conductors with vastly different structural and electronic properties which can be further fine-tuned through the choice of comonomer unit. This work shows how careful design of the isoindigoid scaffold can afford highly planar polymer structures with high degrees of electronic delocalization, while subtle structural modifications can control the dominant charge carrier (hole or electron) when probed in organic electrochemical transistors. A combination of experimental and computational techniques is employed to probe electrochemical, structural, and mixed ionic and electronic properties of the polymer series which in turn allows the derivation of important structure-property relations for this promising class of materials in the context of organic bioelectronics. Ultimately, these findings are used to outline robust molecular-design strategies for isoindigo-based mixed conductors that can support efficient p-type, n-type, and ambipolar transistor operation in an aqueous environment., (© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Photocatalytic CO 2 reduction into formate (HCOO - ) has been widely studied with semiconductor and molecule-based systems, but it is rarely investigated with covalent organic frameworks (COFs). Herein, we report a novel donor-acceptor COF named Co-PI-COF composed of isoindigo and metallated porphyrin subunits that exhibits high catalytic efficiency (∼50 μmol formate g -1 h -1 ) at low-power visible-light irradiation and in the absence of rare metal cocatalysts. Density functional theory calculations and experimental diffuse-reflectance measurements are used to explain the origin of catalytic efficiency and the particularly low band gap (0.56 eV) in this material. The mechanism of photocatalysis is also studied experimentally and is found to involve electron transfer from the sacrificial agent to the excited Co-PI-COF . The observed high-efficiency conversion could be ascribed to the enhanced CO 2 adsorption on the coordinatively unsaturated cobalt centers, the narrow band gap, and the efficient transfer of the charge originating from the postsynthetic metallation. It is anticipated that this study will pave the way toward the design of new simple and efficient catalysts for photocatalytic CO 2 reduction into useful products.

[Display omitted] • Secondary intermolecular interactions and morphology play an important role in charge carrier mobility. • Three different derivatives were synthesized with various secondary interactions/forces. • Secondary intermolecular interactions are imparted by asymmetric substitution of Isoindigo. • The highest mobility of 0.15 cm2/Vs has been observed for CSMs with van der Waals interaction. The charge carrier mobility of conjugated small molecules (CSMs) depends on the intermolecular interactions and morphology. Herein, we report the synthesis of CSMs having different side chains. Hydrogen bonding, lipophilic imbalance and van der Waals interactions are imparted through the asymmetric substitution of Isoindigo. The secondary forces impact thin film morphology, and charge carrier mobility. The CSMs having van der Waals interaction further shows higher charge carrier mobility as a function of improved morphology, and increased temperature. The highest mobility of 0.15 cm2/Vs has been achieved for CSMs with van der Waals interaction. [ABSTRACT FROM AUTHOR]

The potential of a new series of H-bonded isoindigo (ID) based small molecules as charge transporting materials was examined. The soluble precursor units contained two terminal isoindigo units bearing tert -butoxycarbonyl (Boc) solubilizing substituents. Thiophene, thienothiophene and/or diketo pyrrolopyrrole are used as π-conjugated spacers between the isoindigo units. The protected Boc-ID units are converted to the hydrogen-substituted counterparts by annealing the spin-coated precursor films up to 220 °C. The solid state molecular ordering after Boc thermal decarboxylation was investigated using thermogravimetric analysis, UV–vis spectroscopy and X-ray diffraction analysis. The thermogravimetric analysis confirmed the full removal of Boc groups. It was revealed that the formation of terminal intermolecular hydrogen bonds gave the ability to the deprotected materials to change their molecular ordering to edge-on or face-on orientation based on the spacer size and the π-conjugated length. The [-NH----O C] H-bonding dramatically improved the strength of the intermolecular interactions and induced a significant shift on the wavelength of annealed films. The hole mobilities of isoindigo based organic materials measured by the space charge-limited current (SCLC) method and showed a tenfold improvement after thermal decarboxylation. Image 1 • Synthesis of a new series of H-bonded isoindigo (ID) based small molecules. • Edge-on and/or face-on molecular orientation was studied. • The materials' charge mobilities were examined. • The hole mobility is dramatically a tenfold increased after thermal deprotection. [ABSTRACT FROM AUTHOR]

Isoindigo, an electron deficient heteroaromatic compound, was developed as a great potential building block in the construction of low bandgap conjugated polymers with enhanced optoelectronic performances. Herein, via the Donor–Acceptor approach, a novel range of conjugated copolymers were rationally designed and synthesized by employing isoindigo as acceptor, electron rich fused thiophenes (i.e. thieno[3,2- b thiophene, cyclopentadithiophene) as donors. The polymeric films can be easily obtained via spray-coating method due to their excellent solubility in common solvent. The optoelectronic properties of these copolymers were detailedly studied by electrochemical and spectroelectrochemical methods. Owing to the alternating donor–acceptor structure in the polymer backbones, as-prepared copolymers showed outstanding reversible redox activity and stability as well as tunable spectroscopic properties (e.g. bandgaps, colors) depending on the composition (i.e. D–A ratio) of the copolymers. These polymeric films demonstrated low bandgaps (E g) ranging from 1.50 to 1.53 eV. Importantly, the as-prepared films revealed distinct electrochromic switching behaviors. Highly enhanced electrochromic performance, such as high optical contrast (56.9–80.8%), fast response time (0.36–0.94 s) and high coloring efficiency (300–466.67 cm2 C−1) were found for the polymeric films in the visible or near-IR region due to the rationally designed D–A structure. Furthermore, these polymeric films showed remarkable thermal stability. All the above features make this kind of D–A typed copolymers a promising candidate for the electrochromic application. Three novel isoindigo-based D–A copolymers were synthesized, which demonstrated tunable opto-electrochemical properties and outstanding electrochromic performances, such as high optical contrast, fast switching time, and high coloration efficiency. ga1 • Three novel D–A copolymers employing isoindigo as acceptor, fused thiophenes as donors were rationally synthesized. • These copolymers exhibited low bandgaps and tunable opto-electrochemical properties. • They demonstrated excellent electrochromic performances and preferable thermo and cyclic stability. [ABSTRACT FROM AUTHOR]

In this review, the data on the application of isoindigo derivatives in the chemistry of functional materials are analyzed and summarized. These bisheterocycles can be used in the creation of organic solar cells, sensors, lithium ion batteries as well as in OFET and OLED technologies. The potentials of the use of polymer structures based on isoindigo as photoactive component in the photoelectrochemical reduction of water, as matrix for MALDI spectrometry and in photothermal cancer therapy are also shown. Data published over the past 5 years, including works published at the beginning of 2021, are given., (Copyright © 2021, Bogdanov and Mironov.)

Abstract: The biological activities of diversely substituted glycosyl-isoindigo derivatives against the causative agents of tropical diseases (malaria, Chagas disease, leishmaniasis and human African trypanosomiasis) are reported. Some of the compounds tested showed interesting activities with good selectivity indices, particularly against Trypanosoma brucei rhodesiense. These results suggested, for the first time, that glycosyl-isoindigo derivatives could be of interest for the discovery of new lead compounds to treat tropical diseases. [Copyright &y& Elsevier]

In this work, thieno[3,2- b ]thiophene based homopolymers, namely poly(5,6-bis(octyloxy)-4,7-bis(thieno[3,2- b ]thiophen-2-yl)benzo[ c ][1,2,5]selenadiazole; PBSeThTh), poly(5-(2-ethylhexyl)-1,3-bis(thieno[3,2- b ]thiophen-2-yl)-4H-thieno[3,4- c ]pyrrole-4,6(5H)-dione; PTPDThTh) and poly((E)-6,6′-bis(thieno[3,2- b ]thiophen-2-yl)-1,1′-diundecyl-[3,3′-biindolinylidene]-2,2′-dione; PIIDThTh), were obtained potentiodynamically to tailor optoelectronic properties via altering electron acceptor moieties which were 5,6-bis(octyloxy)benzo[ c ][1,2,5]selenadiazole 5-(2-ethylhexyl)-4H-thieno[3,4- c ]pyrrole-4,6(5H)-dione (TPD) and (E)-1,1′-diundecyl-[3,3′-biindolinylidene]-2,2′-dione (IID). The polymers were characterized cyclic voltammetry and spectroelectrochemistry studies. All polymers reveal ambipolar and multichromic characteristics with broad spectral absorptions, low-lying highest occupied molecular orbital (−5.69 eV, −5.59 eV, −5.60 eV), and as well as low band gap ranging from 1.58 eV to 1.86 eV. Isoindigo comprising polymer resulted in the lowest optical band gap which was 1.16 eV due to a red shift in the absorption most probably due to richer electron density and strong inter-chain interactions, structural planarity. Unlabelled Image • Low band gap polymers • Multichromic polymers • The impact of acceptor strength on the optoelectronic properties [ABSTRACT FROM AUTHOR]

In this study, a panchromatic absorptive conjugated terpolymer, BDTID-BDT3MT , is synthesized, which consists of electron-donating benzodithiophene (BDT), isoindigo (ID) as a strong electron-accepting unit, and methyl-3-thiophenecarboxylate (3 MT) as a weak electron-accepting unit. By combining these three monomers into the structure of a conjugated terpolymer, the absorption spectrum of BDTID-BDT3MT is induced to exhibit an unusually broad, strong, and uniform band in the wavelength interval from 300 to 750 nm, which helps achieving highly efficient light harvesting under solar illumination. The intriguing panchromatic absorption behavior of BDTID-BDT3MT was explained on the basis of theoretical calculations using simplified repeating units. Polymer solar cells (PSCs) based on BDTID-BDT3MT as a donating polymer and non-fullerene acceptors (e.g., ITIC-4F) exhibited a high power conversion efficiency (PCE) of 5.38%, high open circuit voltage (V oc) of 0.88 V, and short circuit current density (J sc) of 13.74 mA/cm2, while PSCs based on ternary blend systems consisting of BDTID , BDT3MT , and ITIC-4F exhibited lower PCE and J sc of 3.74% and 11.15 mA/cm2, respectively. The superior performance of PSCs based on BDTID-BDT3MT can be attributed to their high light harvesting efficiencies and relatively more favorable nano-phase film morphologies. Our results establish that BDT, ID, and 3 MT units serve as useful building blocks in the structure of conjugated terpolymers due to their remarkably broad panchromatic absorption band. Image 1 • A panchromatic absorptive conjugated terpolymer, BDTID-BDT3MT , was successfully synthesized. • Isoindigo as a strong electron-accepting unit and thiophenecarboxylate as a weak electron-accepting unit were employed. • The absorption spectrum of BDTID-BDT3MT exhibit a broad, strong, and uniform band from 300 to 750 nm. • Polymer solar cells with ITIC-4F exhibited a high power conversion efficiency of 5.38%. [ABSTRACT FROM AUTHOR]

• A facile method to synthesis π-bridge donor-acceptor small molecules. • The resulted small molecules have a narrow bandgaps around 1.43 eV. • HOMO and LUMO came from DFT calculations matched with the practical results. • The best PCE% of OPV devices were 1.3 % and 1.4 %. Alternating different donor units like ethyldioxy-thiophene (ED)/thiophenes (T) and acceptor units isoindigo (ID) /benzothiadiazle (BT) were attached together with the aid of Pd catalyzed C–H activation condition and forming [A(DA'nD')2] based two π-bridged small molecules, ID(EDBT2TH)2 and ID(EDBT3T)2. Even the new materials have a significant high molecular weight, they are obtained with high yields and are completely soluble in organic solvents which helps the solution processability of organic devices. One of the synthesized small molecules has a terminal alkyl chain and the other is longer in conjugation length by thiophene ring extension. The alternating donor/acceptor units improves the intramolecular charge transfer across the backbone structure. The absorption spectra, electrochemical properties, hole mobility, morphology of the cast films, and photovoltaic performance are investigated considering the different in the terminal group of the synthesized materials, the presence of different donor and acceptor moieties as well as (ED-ID-ED) π-bridge unit. Small molecules under study possess broad absorption with low band gaps which encouraged us to screen the power conversion efficiencies (PCE) of their photovoltaic cells. ID(EDBT2TH)2 and ID(EDBT3T)2 showed 1.4 and 1.3 %, in PCE, respectively, for their first OPV device screening. [ABSTRACT FROM AUTHOR]

• The highly ordered isoindigo based organic materials via H-bonding were obtained. • The molecular-level ordering was studied by high-voltage electron microscopy. • Molecular ordering of materials resulted in enhanced charge carrier mobilities. The synthesis of molecular-scale-ordered isoindigo and bithiophene-based small molecules has been achieved through hydrogen bonding by using ethylenediamine (EDA) as a linking material, or by the cleavage of the carbamate protecting groups bearing long alkyl chains. X-Ray diffraction and high-voltage electron microscopy (HVEM) studies show that the molecules are arranged to form body-centered cubic (BCC) or face-centered cubic (FCC) lattice structures. Formation of hydrogen-bonded networks resulted in enhanced molecular ordering that facilitated charge carrier mobility. The hole mobilities of isoindigo and bithiophene-based organic materials estimated by hole only devices enhanced from 2.42 × 10−6 cm2 V−1 s−1 to 1.23 × 10−3 cm2 V−1 s−1 for ID2T after crosslinking with ethylene diamine and from 2.79 × 10−6 cm2V−1 s−1 to 2.52 × 10−3 cm2 V−1 s−1 for NHID2TC after removing the protecting groups which are upon the formation of hydrogen bonding between molecules. [ABSTRACT FROM AUTHOR]

Two new donor–acceptor (D–A) type organic conjugated random copolymers were successfully synthesized by three-component Stille coupling polymerization of indolo[3,2-b]carbazole (ICZ), isoindigo (IID) and thiophene units, namely PITID-X (X = 1 and 2), with the controlled monomer feed ratios of 3:1:4 and 1:1:2, respectively. The strategy of incorporating different alkyl-branched donor/acceptor units and raw material feed ratios facilitated the improvement of optical properties, solubility, conjugated structure, and electrochromic performance. Cyclic voltammetry, UV-vis-NIR absorption spectra, kinetic and colorimetric measurements of the spray-coated films were recorded in the fabricated three-electrode cells. The results showed that PITID-2, whose optical/electrical properties were better than that of PITID-1, was the candidate electrochromic material due to low band gap of 1.58 eV accompanying the color changing from cyan (neutral state) to gray (oxidized state). The copolymer also illustrated fast bleaching/coloration response time of 2.04/0.33 and 1.35/1.50 s in a 4 s time interval, high coloration efficiency of 171.52 and 153.08 cm2 C−1 and stable optical contrast of 18% and 58% at the wavelength of 675 and 1600 nm, respectively. [ABSTRACT FROM AUTHOR]

Four novel materials containing isoindigo derivatives were synthesized via Stille coupling reaction. These polymers not only have excellent electrochromic properties (the highest electrochromic efficiency reaches 195 cm2 C−1), but also have low charge transfer resistance (R ct). The range of switching threshold is from −1.7 V to −4.0 V and the current ratio of the device beyond 10−5 for memory device. Moreover, the polymers can also be used as explosive detector. A sharp drop in the fluorescence intensity of the polymer appeared when trinitrotoluene (TNT) or 2, 4, 6-trinitrophenol (TNP) was added. • Multifunctional polymers for electrochromic, resistance memory, and detector devices have been synthesized and studied. • Polymers exhibit good thermal stability, excellent electrochemical properties. • Polymers have high electrochromic coloration efficiency and low charge transfer resistance. [ABSTRACT FROM AUTHOR]