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In this article, a new series of conjugated polymers based on a low-cost, easily accessible vat dye called Vat orange 1 or 2,9-dibromo-dibenzo[b,def]chrysene-7,14-dione have been prepared. This compound was made electron-donating by reducing and alkylating the ketone groups into alkoxy groups, allowing the introduction of solubilizing, branched alkyl chains at the 7 and 14 positions. Polymerization reactions using Suzuki–Miyaura coupling with 6,6′-isoindigo, 3,6-di-2-thienyl-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) and 4,7-dithieno-2,1,3-benzothiadiazole (TBT) yielded three donor–acceptor polymers with bandgap values ranging from 1.61 to 1.86 eV. Field-effect transistors (OFETs) and organic solar cells (OSCs) were fabricated and hole mobility values of up to 3.62 × 10−4 cm2 V−1 s−1 and a maximum power conversion efficiency of 1.2% were measured, respectively.

We report the successful synthesis and spectroscopic characterization of a novel, water soluble anthanthrene-based derivative, 6,12-bis(TEG)anthanthrene 3. The presence of the two long ethylene glycol side chains gives this large, six-membered polycyclic aromatic compound a high aqueous solubility. It exhibits UV–vis absorption properties similar to those of anthanthrene itself, indicating that the side chains do not have a significant effect on the electronic structure of the central chromophore. The compound exhibits strong, polarity-sensitive fluorescence in aqueous solution in the blue–green region of the spectrum, with a fluorescence quantum yield of 0.13 and a polarity sensitivity factor (PSF) of 2.0. The utility of this new fluorescent molecule as a probe of supramolecular complexation was demonstrated by its inclusion into the molecular host hydroxypropyl-β-cyclodextrin in aqueous solution. Strictly 1:1 inclusion was observed, with a moderately strong binding constant K of 650 M−1. This new fluorescence probe has significant potential applications in fluorescence-based studies of aqueous biochemical and supramolecular systems.

We report the synthesis of π-extended ullazine derivatives annulated with either electron-poor pyridine or electron-rich thiophene units through a metal-free, photochemical cyclodehydrochlorination (CDHC) reaction. The strongest electron-donor derivative, 7-tetradecylthieno[3′,2′:7,8]indolizino[6,5,4,3-ija]thieno[2,3-c]quinolone, was copolymerized with electron-deficient thienopyrroledione (TPD), isoindigo (IID), and diketopyrrolopyrrole (DPP) derivatives to provide three donor–acceptor conjugated polymers (D–A CPs). Their photophysical, electrochemical and photovoltaic (PV) properties were investigated. The polymers showed broad UV-vis-NIR absorption bands with λmax values of 612 nm, 698 nm, 788 nm in chloroform and exhibited optical bandgap (Eoptg) of 1.58 eV, 1.41 eV, 1.24 eV measured as films. Inverted bulk heterojunction polymer solar cells (BHJ-PSCs) were fabricated using these polymers as host and light-harvesting materials. The device based on P3:PC70BM blends shows the best power conversion efficiency (PCE) of 2.23% (Voc = 0.55 V, Jsc = 7.86 mA cm−2, FF = 52%). These promising results demonstrate that π-extended ullazine derivatives can be used as electron-rich building blocks for the construction of D–A CPs for efficient PSCs applications.

Four new copolymers based on anthanthrene for the dispersion of semiconducting SWNTs of various diameters have been synthesized. After optimization of the dispersion parameters, it has been observed that fluorene- and carbazole-based copolymers lead to a sc-SWNT enrichment with low amount of residual m-SWNTs for HiPCO nanotubes. For larger diameter Plasma torch SWNTs, phenyl-based and pyrene-based copolymers yield high concentration dispersions (0.08 mg ml−1), but no selectivity for either SWNT species. Our work opens up the use of large polycyclic aromatic hydrocarbon units such as anthanthrene derivatives for SWNT wrapping process.

We demonstrate the preparation of anthanthrene derivatives with fused five-membered rings. These new derivatives are prepared by a palladium catalyzed cyclopentannulation reaction from precursors derived from the low-cost dye Vat Orange 3 (4,10-dibromoanthanthrone). The new cyclopenta-anthanthrene compounds possess reduced optical and electrochemical gaps (~0.9 eV) compared to anthanthrene derivatives and are electron acceptors with lowest unoccupied molecular orbital energies of ~ -3.4 eV to -3.9 eV.

International audience; Linear and helical graphene nanoribbons (L-PyGNR and H-PyGNR) bearing electron-rich pyrrole units have been synthesized by using the photochemical cyclodehydrochlorination (CDHC) reaction. The pyrrole units in the polymer backbone make the polymer electron-rich with moderate bandgap values and relatively high HOMO energy levels. The planarization of the pyrrole unit through cyclization yields a bandgap value almost 0.5 eV lower than that measured for polypyrrole. Conductivity values in the thin film up to 0.12 S/cm were measured for the chemically oxidized L-PyGNR (four-point method). Both GNRs showed excellent fluorescence sensing properties for TNT in solution with K SV values up to 6.4 × 10 6 M −1 .

Self-assembly of organic macrocycles has been exploited as a preliminary step in the synthesis of soluble and tailorable carbon-based nanostructures. Functionalized nanotubes have been prepared using, as core building blocks, nearly planar ring structures containing several alkyne units, exploiting the geometry achieved in the spontaneous preassembling step driven by π interaction. Covalent cross-linking between these units was achieved by thermal or photochemical activation with UV light. Here, we apply a moderate pressure in a sapphire anvil cell (1.0 GPa) to facilitate the preassembling and induce the cross-linking under pressure either with visible light, absorbed by two-photon absorption, or thermally. We observe a high yield of enhanced quality cross-linked nanotubes in a sample, showing, at ambient pressure, only side-chain decomposition. These results show that moderate pressures, easily achievable in large volume cells, are able to selectively favor topochemical reactions in such complex organic ...

We studied structure, molecular orientation, morphology, and electrostatic properties of mixed self-assembled monolayers (SAMs) comprised of alkanethiolates (ATs) which are modified by a dipolar ester group embedded into the alkyl backbone at two different orientations, namely, with the dipole directed upward and downward from the substrate. The packing density and molecular orientation in these SAMs were found to be similar to those of the “parent” single-component monolayers. Applying X-ray photoelectron spectroscopy (XPS) as a morphology tool, we could estimate that the mixed SAMs represent homogeneous intermolecular mixtures of both components, down to the molecular level, excluding existence of “hot spots” for charge injection. The analysis of the C 1s XPS spectra and the work function data suggests that the composition of the mixed SAMs fully mimicked the mixing ratio of both components in the solutions from which these SAMs were prepared, which suggests a minor role of the dipole–dipole interaction...

Alkanethiolates (ATs) forming self-assembled monolayers (SAMs) on coinage metal and semiconductor substrates have been used successfully for decades for tailoring the properties of these surfaces. Here, we provide a detailed analysis of a highly promising class of AT-based systems, which are modified by one or more dipolar carboxylic acid ester groups embedded into the alkyl backbone. To obtain comprehensive insight, we study nine different embedded-dipole monolayers and five reference nonsubstituted SAMs. We systematically varied lengths of the alkyl segments, ester group orientations, and number of ester groups contained in the chain. To understand the structural and electronic properties of the SAMs, we employ a variety of complementary experimental techniques, namely, infrared reflection absorption spectroscopy (IRS), high-resolution X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), atomic force microscopy (AFM), and Kelvin probe (KP) AFM. These experiments are comp...

A new alkyne-based macrocycle that combines monoyne, diyne and tetrayne is reported. Despite its unusual trapezoid shape, the bending of the tetrayne unit allows the macrocycle to be unstrained. The macrocycle is synthesized by a combination of selective deprotection of silylated alkyne, Castro–Stephen–Sonogashira coupling and copper-mediated oxidative homocoupling. The final intramolecular cyclization proceeded in surprisingly high yield (72%) using modified Eglinton conditions in moderate dilution.

This review presents an overview of the recent developments in the area of vat dye chemistry for the preparation of π-conjugated molecules and polymers for organic electronic applications. Vat dyes are well-established molecules in the textile colouring and painting industry as they are inexpensive and highly stable. Their optical properties in the visible region are attributed to their highly conjugated sp2 carbon networks and the presence of functional groups, especially ketones that allow the formation of “leuco” species. In this review, we will show how the presence of functional groups on these highly conjugated scaffolds can be used to modify their electronic and optical properties to make them useful building blocks for semiconducting organic materials.

The solution-phase synthesis is one of the most promising strategies for the preparation of well-defined graphene nanoribbons (GNRs) in large scale. To prepare high quality, defect-free GNRs, cycloaromatization reactions need to be very efficient, proceed without side reaction and mild enough to accommodate the presence of various functional groups. In this Minireview, we present the latest synthetic approaches for the synthesis of GNRs and related structures, including alkyne benzannulation, photochemical cyclodehydrohalogenation, Mallory and Pd- and Ni-catalyzed reactions.

Polycyclic aromatic hydrocarbons (PAHs) are interesting building blocks for the preparation of conjugated polymers due to their extended π surface and planar conformation. However, their use as comonomer in conjugated polymers often leads to nonplanar main chains as a consequence of high steric hindrance at the linking point. Herein, we report the synthesis of a ladderized anthanthrene unit using an sp3 carbon bridge. Three conjugated copolymers with fluorene, isoindigo, and bithiophene derivatives have been synthesized and characterized to study the effect of such ladderization on the electronic properties. The dihedral angle between the ladderized anthanthrene and adjacent units has been significantly reduced by the formation of the sp3 carbon bridge, thus eliminating the steric hindrance with the proton at the peri position of the anthanthrene unit and red-shifting the absorption spectrum by 25 nm.

Novel nanographenes were prepared by a photochemical cyclodehydrochlorination (CDHC) reaction. Chlorinated precursors were irradiated in acetone in the presence of a base or in pure benzene and underwent multiple (up to four) regioselective cyclization reactions to provide rigid π-conjugated molecules. Pure compounds were recovered in good yields by simple filtration at the end of the reaction. The CDHC reaction showed compatibility with both electron-poor and electron-rich substrates, thus allowing the synthesis of pyridine- and thiophene-fused nanographenes. It also enabled the synthesis of sterically hindered contorted π-conjugated molecules without causing full aromatization. A kinetic study showed that the CDHC reaction under the conditions used is a very fast process, and some reactions are completed within minutes. The CDHC reaction thus shows great potential as an alternative to other reactions involving harsher conditions for the preparation of nanographenes.

Five new copolymers based on the anthanthrone moiety were synthesized using Stille coupling. The anthanthrone unit was coupled with two electron-rich units (thiophene and carbazole) and three electron-poor units (thienopyrroledione, diketopyrrolopyrrole, and benzothiadiazole). The optoelectronics properties of the polymers were investigated and suggest that the anthanthrone moiety dictates the electronic properties of the materials with little regards to the nature of the comonomers. Fluoride-promoted photoinduced electron transfer on anthanthrone derivatives yielded to radical anion species that can be reversibly oxidized to the neutral form by exposure to air.

Rhomboidal macrocyclic subunits of graphdiyne-like nanoribbon (GDNR) bearing both alkyne and diyne units, allowing for multichannel π-conjugation, were synthesized using an oxidative Glaser-type ring closing reaction. These subunits, called the "meshes" of the nanoribbon, possess phenyl groups with decyloxy solubilizing chains on each corner. The yields of the ring closing reaction highly depend on the metal (Cu or Pd) catalyst used for the macrocyclization step. Increasing the width of the meshes from one macrocycle to two fused macrocycles resulted in a decrease of the bandgap by 0.23 eV as shown by optical spectroscopy. The optimized geometries of the meshes alongside their HOMO and LUMO orbitals were calculated using DFT calculations at the B3LYP/6-31+G** level of theory. The results showed a nearly planar conformation for both meshes with HOMO and LUMO orbitals entirely delocalized over the molecules.

Six anthanthrene-based conjugated polymers with either electron-rich or electron-poor units were synthesized and characterized. All polymers exhibit optical absorption in the visible region owing to their extended conjugation. Experimental data and computational results indicate that the comonomer attached to the anthanthrene unit has only little effect on the electronic properties of the polymers.

The design of advanced new generation conjugated materials with improved properties for photovoltaic applications has been the focus of research in recent years. This work reports on novel anthanthrone/anthracene and anthanthrene/anthracene co-polymers as p-type conjugated semiconductors in organic photovoltaics. The presence of anthracene component with the grafted alkyloxy chains enhanced the solubility and process-ability of the co-polymers. The photophysical and photovoltaic parameters greatly depend on ratio of components of the co-polymers and nature of the grafted chains. Devices using the blends of SV15 and PCBM in 1:2 ratio gave $J_{\mathrm{s}\mathrm{c}}$ 3.97 mA/cm2 and higb $V_{oc}$ 0.92 V with efficiency 1.7%.

A series of ferrocene-based statistical copolymers have been prepared via radical polymerization and their nanoporous structure was characterized using inert gas adsorption–desorption isotherms and high resolution transmission electron microscopy (HRTEM). The porosity parameters of the polymers were obtained by physisorption isotherms (N 2 at −196 °C, Ar at −186 °C) and modern quenched solid density functional theory (QSDFT) methods were implemented for an advanced analysis of the polymeric materials. The materials show both microporosity and mesoporosity with relatively high surface area and pore volume, which are retained upon the incorporation of ferrocene units to the polymer backbone. The hydrogen storage capability of those polymers was also tested. The introduction of ferrocene units within the polymer structure contributed to an increase of the hydrogen adsorption ability of the porous polymers compared to their ferrocene-free equivalents.

A star-shaped molecule with three butadiyne moieties attached to a central phenyl core was self-assembled via organogel formation in different solvents and subjected to UV irradiation in its xerogels form to give a soluble conjugated 1D nanowire made of three connected polydiacetylene (PDA) chains. The resulting polymer has a slightly lower optical band gap than its linear counterpart and presents no chromism property, indicative of the rigid nature of the polymer thus obtained.

Third and fourth generation ethylene oxide-containing dendrimers containing triazole units were prepared divergently through metal-free Huisgen 1,3-dipolar cycloaddition (“click”) reaction between activated disubstituted alkyne and terminal azide groups. The growth of the dendrimers was achieved in high yield with minimal purification effort and without the participation of toxic metal or excess of reagents. Preliminary in vitro testing on different cell lines indicates that this series of dendrimers is very promising for bio-related applications.

4,10-dibromoanthanthrone, a highly robust building block, is used to synthesize a bis(triarylamine) polymer. The polymer can be oxidized twice to form a polycationic macromolecule showing magnetic properties by electron paramagnetic resonance spectroscopy. In its dicationic state, the presence of isolated radicals is possible because of the interrupted conjugation between the diphenylamine with the anthanthrone core. The high steric hindrance prevents the planarity of the adjacent groups resulting in a polyradical cationic polymer. The oxidized polymer has a strong absorption in the near-infrared region along with reversible redox stages.

The number of synthetic methods enabling the preparation of ammonium-based rotaxanes has increased very rapidly in the past ten years. The challenge in the synthesis of rotaxanes results from the rather weak interactions between the ammonium-containing rod and the crown ether macrocycle in the pseudorotaxane structure that rely mostly on O*H hydrogen bonds. Indeed, no strong base or polar solvent that could break up H-bonding can be used during the formation of rotaxanes because the two components will separate as two distinct entities. Moreover, most of the reactions have to be performed at room temperature to favor the formation of pseudorotaxane in solution. These non-trivial prerequisites have been taken into account to develop efficient reaction conditions for the preparation of rotaxanes and those are described in detail along this review.

New electroactive and photoactive conjugated copolymers consisting of alternating 2,7-carbazole and oligothiophene moieties linked by vinylene groups have been developed. Different oligothiophene units have been introduced to study the relationship between the polymer structure and the electronic properties. The resulting copolymers are characterized by UV-vis spectroscopy, size-exclusion chromatography, and thermal and electrochemical analyses. Bulk heterojunction photovoltaic cells from different copolymers and a soluble fullerene derivative, [6,6]-phenyl-C61 butyric acid methyl ester, have been fabricated, and promising preliminary results are obtained. For instance, non-optimized devices using poly(N-(4-octyloxyphenyl)-2,7-carbazolenevinylene-alt-3″,4″-dihexyl-2,2′;5′,2″;5″,2″′;5″′,2″″-quinquethiophenevinylene 1″,1″-dioxide) as an absorbing and hole-carrier semiconductor exhibit power conversion efficiency up to 0.8 % under air mass (AM) 1.5 illumination. These features make 2,7-carbazolenevinylene-based and related polymers attractive candidates for solar-cell applications.

Blue light-emitting 2,7-carbazole-based conjugated copolymers have been prepared by Yamamoto or Suzuki cross-coupling reactions. By introducing highly substituted aromatic comonomers, fully soluble high-molecular-weight copolymers have been obtained. Moreover, these amorphous polymeric materials exhibit good thermal stability and interesting redox properties. All these features make these new conjugated polymers highly promising for the development of single-polymer-layer blue-light-emitting diodes.

Light-emitting 2,7-carbazole-based homopolymers and copolymers were prepared by Yamamoto or Suzuki cross-coupling reaction. Poly(N-(2-ethylhexyl)-2,7-carbazole) (PEHC), poly(N-octadecyl-2,7-carbazole) (PODC), and poly(N-(2-ethylhexyl)-2,7-carbazole-alt-4-heptyl-2,5-pyridine) (PCPy) emit blue light while poly(N-(2-ethylhexyl)-2,7-carbazole-alt-2,3-diheptyl-5,8-quinoxaline) (PCQ) and poly(N-(2-ethylhexyl)-2,7-carbazole-alt-3,3‘,4‘ ‘‘,3‘ ‘‘ ‘-tetramethyl-3‘ ‘,4‘ ‘-dihexyl-2,2‘:5‘,2‘ ‘:5‘ ‘, 2‘ ‘‘:5‘ ‘‘,2‘ ‘‘ ‘-quinquethiophene-1‘ ‘, 1‘ ‘-dioxide) (PCPTO) emit green and red light, respectively. The fluorescence quantum yield in chloroform solution ranges from 25% for PCPTO to 83% for PCQ. All these 2,7-carbazole-based polymers do not show any evidence of excimer formation in the solid state. Most of these polymers exhibit a glass transition at ca. 60−70 °C with a degradation temperature above 385 °C. These new polymeric materials should allow the development of efficient blue-, green-, and red-light-emitting ...

The number of synthetic methods enabling the preparation of ammonium-based rotaxanes has increased very rapidly in the past ten years. The challenge in the synthesis of rotaxanes results from the rather weak interactions between the ammonium-containing rod and the crown ether macrocycle in the pseudorotaxane structure that rely mostly on O•H hydrogen bonds. Indeed, no strong base or polar solvent that could break up H-bonding can be used during the formation of rotaxanes because the two components will separate as two distinct entities. Moreover, most of the reactions have to be performed at room temperature to favor the formation of pseudorotaxane in solution. These non-trivial prerequisites have been taken into account to develop efficient reaction conditions for the preparation of rotaxanes and those are described in detail along this review.

Novel poly(3,6-hexyl-2,7-N-octylcarbazole) derivatives and poly(diindolocarbazole)s were synthesized. Optical, electrochemical, electrical and thermoelectric properties were investigated. Band structure calculations were used to predict which polymers were promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was 9,4 x10-8 Wm-1K-2 with a copolymer of carbazole and thiophene. This corresponds to a ZT at room temperature of 0.0003. Optimization of the polymer structure and doping level should lead to an increased ZT., 2005 MRS Spring Meeting: Symposium I: Organic Thin-Film Electronics, March 28-April 1, 2005, San Francisco, California, USA., Series: Materials Research Society Symposia Proceedings; no. 871

This study reports the first syntheses and characterization of 2,7-carbazolenevinylene-based oligomers and polymers. Their relatively straightforward syntheses are mainly based on Horner−Emmons or Knoevenagel coupling reaction leading to well-defined oligomers and polymers. As expected, introduction of vinylene and cyanovinylene unit into the polymer backbone decreases the band gap allowing a fine-tuning of the optical and electrical properties. These electroactive and photoactive organic materials exhibit promising performances in light-emitting devices and field-effect transistors. For instance, preliminary measurements using poly(N-(2-ethylhexyl)-2,7-carbazolenecyanovinylene-alt-2,5-dioctyloxy-1,4-phenylenevinylene) (PCCVP) have revealed orange-red emission with an intensity of 245 cd/m2 at 10 V, whereas p-type mobility of about 3.7 × 10-2 cm2/V·s and an on/off ratio as high as 106 were reached with 1,4-bis(vinylene-(N-hexyl-2-carbazole))phenylene (CPC).

The synthesis of a new class of π-conjugated based on N-alkyl-2,7-carbazole is reported. Two different synthetic pathways were used to obtain 2,7-functionalized carbazole units. The first pathway leads to N-alkyl-2,7-dichlorocarbazole which undergoes a Yamamoto coupling to obtain the homopolymer. The second synthetic method provides N-alkyl-2,7-diiodocarbazole. This monomer allows the utilization of more versatile synthetic tools such as Suzuki and Stille couplings to obtain highly regioregular copolymers. Poly(N-(2-ethylhexyl)-2,7-carbazole) (PEHC) prepared using Yamamoto coupling shows strong pure blue photoluminescence (437 nm) and electroluminescence (432 nm, 225 cd/m2) with no excimer formation.