Anthracene Polymers Research Articles

Gem-Dibromovinylenes: Highly Versatile Systems for On-Surface Synthesis

The advent of the so-called On-Surface synthesis represents a new scenario where testing new reaction conditions affording disruptive materials impossible to be obtained by conventional synthetic chemistry. In this regard, we have reported an unprecedented chemical reaction from tetrabromo-p-quinodimethanes (TBQs) which, by heating on gold surface, has allowed to obtain a variety of new 1D π-conjugated polymers,[1] some of them exhibiting a quasimetallic behavior.[2]In this presentation, new designed organic molecules endowed with gem-dibromovinylene units have been synthesized with the aim of broadening the scope of this highly reactive functional group to other on-surface chemical reactions.[3] Thus, new different polymers or molecular systems will be presented and discussed.[4] References [1] A. Sánchez-Grande, et al., "On-surface synthesis of ethynylene bridged anthracene polymers", Angew. Chem. Int. Ed., 2019, 58, 6559-6563.[2] Cirera, B., et al., “Tailoring topological order and π-conjugation to engineer quasi-metallic polymers”. Nat. Nanotechnol. 2020, 15, 437–443.[3] Sánchez-Grande, et al., "Surface-assisted Synthesis of N-substituted π-Conjugated Polymers" Adv. Sci., 2022, - advs.202200407R1[4] E. Pérez-Elvira, et al., "Generating Antiaromaticity: Thermally-selective Skeletal Rearrangements at Interfaces", Nat. Synth., 2023, NATSYNTH-22121246B.

Mechanochemical Activation of Anthracene [4+4] Cycloadducts

Controlled formation and breaking of weak chemical bonds is a versatile method for modifying the properties of materials. Anthracene [4+4] cycloadducts are a prime example that can be formed by light and opened by external forces. We address the theoretical description of mechanochemistry of these cycloadducts, where the standard constraint geometry simulates forces approach fails due to the lack of consideration of temperature. Explicit inclusion of external forces reveals the corresponding transition barriers that are clearly dominated by rupture of the [4+4] inter-anthracene bonds. Other bonds come into play at extremely large forces only, which cannot be expected to be reached under ambient conditions. The theoretical results are in line with the experimental rheology of [4+4]-linked anthracene polymers, which indicates reversible re-formation of [4+4] cycloaddition bonds with ultraviolet light after mechanochemical bond breaking due to applied shear stress.

Steric hindrance in the on-surface synthesis of diethynyl-linked anthracene polymers.

Hybrid sp-sp2 structures can be efficiently obtained on metal substrates via on-surface synthesis. The choice of both the precursor and the substrate impacts on the effectiveness of the process and the stability of the formed structures. Here we demonstrate that using anthracene-based precursor molecules on Au(111) the formation of polymers hosting sp carbon chains is affected by the steric hindrance between aromatic groups. In particular, by scanning tunneling microscopy experiments and density functional theory simulations we show that the de-metalation of organometallic structures induces a lateral separation of adjacent polymers that prevents the formation of ordered domains. This study contributes to the understanding of the mechanisms driving the on-surface synthesis processes, a fundamental step toward the realization of novel carbon-based nanostructures with perspective applications in nanocatalysis, photoconversion, and nano-electronics.

Effect of Edge Functionalization on the Bottom-Up Synthesis of Nano-Graphenes.

We demonstrate the effect of edge functionalization on the on-surface Ullmann coupling of nano-carbon materials. Unlike 10,10'-Dibromo-9,9'-bianthryl (DBBA), which is widely known to form anthracene polymers and armchair-edge graphene nanoribbons on Au(111), newly-developed precursor named 5-bromo-11(10-bromoanthracene-9-yl)anthra[2,3-b : 7,6-b']dithiophene (BABAT) with isomers, which has similar structure as DBBA with one anthracene substituted with anthradithiophene, was found to make intramolecular C-C bonding instead of long anthracene polymers after annealing at 200 °C on Au(111). The mechanism was investigated using first-principle density functional theory, which revealed that on-surface polymerization is not kinetically preferred in case of BABAT. The reaction rate of intramolecular C-C bonding of BABAT is ∼206 times faster than that of DBBA. The intramolecular C-C bonding in DBBA biradicals, on the other hand, do not take place because of faster reverse reaction. By referring to electron density of BABAT biradicals, it was concluded that thiophene functionalization modifies distribution of electron density in BABAT radicals and facilitates electrophilic addition, leading to intramolecular C-C bonding after 200 °C annealing. These results indicate that the design of radical moiety is particularly important in the on-surface Ullmann-type coupling.

On‐Surface Synthesis of Ethynylene‐Bridged Anthracene Polymers

AbstractEngineering low‐band‐gap π‐conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on‐surface synthesis protocol to overcome such difficulties and produce poly(p‐anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr2 moieties is deposited and annealed to 400 K, resulting in anthracene‐based polymers. High‐resolution nc‐AFM measurements confirm the nature of the ethynylene‐bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface‐stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design π‐conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on‐surface synthesis.

On-Surface Synthesis of Ethynylene-Bridged Anthracene Polymers.

Engineering low‐band‐gap π‐conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on‐surface synthesis protocol to overcome such difficulties and produce poly(p‐anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr2 moieties is deposited and annealed to 400 K, resulting in anthracene‐based polymers. High‐resolution nc‐AFM measurements confirm the nature of the ethynylene‐bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface‐stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design π‐conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on‐surface synthesis.

Optical and electrical characterization of thin films based on anthracene polyether polymers

Two new anthracene derivatives were characterized to improve the optoelectronic properties of π-conjugated anthracene polymers. The optical properties of the polymers were investigated by UV-visible absorption and photoluminescence (PL) spectroscopy. The energy bandgaps of anthracene-based polyether thin films were in the range 2.8–2.97eV. Green emission (504nm) was observed for anthracene/bisphenol A (An-BPA) and green-yellow emission (563nm) for anthracene/fluorinated bisphenol A. (An-BPAF) Organic diodes formed by sandwiching anthracene layers between indium–tin oxide (ITO) and aluminum contacts were characterized. The dc electrical properties of ITO/anthracene derivatives/Al diodes were studied using current–voltage measurements and showed ohmic behavior at low voltage. The conduction mechanism seems to be a space-charge-limited current with exponential trap distribution at high applied bias voltage. The ac electrical transport of the anthracene derivatives was studied as a function of frequency (100Hz–10MHz) and applied bias in impedance spectroscopy analyses. We interpreted Cole–Cole plots in terms of the equivalent circuit model as a single parallel resistance and a capacitance network in series with a relatively small resistance. The evolution of the electrical parameters deduced from fitting of the experimental data is discussed. The conduction mechanism revealed by I–V characteristics is in agreement with the impedance spectroscopy results.

Zipping Up: Cooperativity Drives the Synthesis of Graphene Nanoribbons

We investigate the cooperative effects controlling the synthesis of a graphene nanoribbon on the Au(111) surface starting from an anthracene polymer using density functional calculations including van der Waals interactions. We focus on the high-temperature cyclodehydrogenation step of the reaction and find that the reaction proceeds by simultaneously transferring two H-atoms from the anthracene units to the Au surface, leaving behind a C-C bond in the process. This step is significantly more favorable than the three other potential reaction paths. Moreover, we find that successive dehydrogenations proceed from one end of the polyanthracene and propagate step-by-step through the polymer in a domino-like fashion.

Preparation and Holographic Recording of Fluorescent Photopolymer Films Containing Anthracene Polymer for Security

Photopolymer films containing fluorescent anthracene polymer, polymethyleneanthracene (PMAn), were prepared with different concentrations of PMAn for holographic recording useful for security documents. The fluorescent photopolymer film showed enhanced fluorescent intensity due to the micro-separation which arose from grating formation and diffusion during photopolymerization. Experimental values of diffraction efficiency were well matched to the simulated values for photopolymers having different PMAn concentrations. Holography patterning was carried out using the fluorescent photopolymer under a photo-mask. A grating was confirmed using microscope techniques in the recorded area under the pattern. Importantly the recorded area showed enhanced fluorescence compared to the unrecorded part, allowing fluorescence patterns at micro scale along with the submicron grating pattern. The fluorescence pattern recorded on the photopolymer film provides additional readability of holographic reading and thus is useful for secure recording and reading of information.

Photoinduced Change in Mechanical Properties of Anthracene Polymers Containing Flexible Side Chains

Abstract Anthracene polymers containing flexible side chains were prepared and their photomechanical properties were investigated. The glass transition temperature of the polymers decreased and the photoreactivity at room temperature was enhanced with an increase of the flexible side chain content. When the polymer was formed into a fiber shape and illuminated with UV light, it bent toward the actinic light source. The deformation was investigated using a thermomechanical analyzer, which revealed that the polymers undergo fast expansion and slow contraction in response to UV light, due to the thermal expansion and photodimerization of the anthracene moiety, respectively.

Electrochemical Fluorescence Switching from Anthracene Polymer Films

Electrochemical fluorescence switching of electroactive fluorescent anthracene polymer films was studied using an electro active quencher. The fluorescence of a methylene anthracene polymer (PMAn) was intact under redox reaction in the absence of an electroactive quencher. Interestingly the fluorescence of a methylene bridged anthracene polymer (PMAn) film could be modulated by adjusting the redox state of the PMAn and redox reaction of the quencher. The electrochemical fluorescence switching from the PMAn film with a quencher was reversible and the cyclability was longer than 1,000 cycles with an ON/OFF ratio of 3.86 under the applied potential step of +2 V for 4 second. A multi state fluorescent switch was fabricated with a double layered two electrode cell that was consisting of the PMAn layer doped with a quencher and a solid polymer electrolyte layer (SPE).

Fluorescent Pattern Generation of Anthracene Polymers by Holographic Technique

Photopolymer films were prepared from the mixture of acrylate monomer, binder, a visible light sensitive photo initiator, and fluorescent polymer (polyanthracene, PMAn), to generate the fluorescent patterns by holographic method. The transparent photopolymer films were yellow colored and having maximum fluorescent emission at visible range. The diffraction efficiency of the PMAn doped film with thickness of 100 μm was maximized to 50%. Fluorescent patterns in a submicron/ micron scale were inscribed on the photopolymer film with a visible laser. As a result of the fluorescent grating patterns, the fluorescence of the film was highly enhanced compared to the unpatterned film.

2-beam Coupling 방법을 이용한 광 고분자 형광 패턴 형성

아크릴레이트계 모노머를 사용한 최적화 된 포토폴리머에 안트라센 형광폴리머를 첨가하여 형광 특성을 가지는 포토폴리머를 제조하고, 514 nm 레이저를 이용하여 2-beam coupling 방법으로 형광 포토폴리머 필름 위에 회절격자를 형성하였다. 기록 시작 후 30초 이내에 선명한 fluorescent line pattern 이 형성되었으며, 회절격자 형성 뒤, 패턴이 형성된 부분에서 형광 세기의 증가가 관찰되었다. 기록 시 간섭 빔 앞에 mask pattern 을 이용하여 <TEX>$50\;{\mu}m$</TEX> gap electrode 패턴을 형성하였다. 이 때 형성된 패턴은 micron scale gap패턴 안에 회절격자로부터 생성된 submicron scale의 grating line을 보였다. 이는 beam의 광 고분자 film 표면에 대한 각도(<TEX>$3.6^{\circ}$</TEX>, <TEX>$15^{\circ}$</TEX>), 패턴에 사용된 광 고분자의 굴절률 등으로부터 Bragg's equation 을 사용하여 계산된 이론적인 grating 간격 (<TEX>$0.6\;{\mu}m$</TEX>) 과 오차범위 안에서 일치 하였다. Fluorescent photopolymer film was prepared with composition containing acrylate monomer, binder, a visible light sensitive photo initiator, and fluorescent anthracene polymer. A fluorescent grating pattern was inscribed on the photopolymer film using a 2-beam coupling method. A 514 nm laser was coupled to generate a beam-interference pattern. A highly fluorescent diffractive line pattern was formed on the fluorescent photopolymer within 30 sec. of exposure. The fluorescence intensity was highly enhanced in the patterned area, possibly due to the change in the environment of the fluorescent polymers by the photo-polymerization of monomers. Under a photo-mask, a gap electrode pattern was formed of fluorescent gratings with a sub-micron scale, which was matched well to the calculated value (<TEX>$2.5\;{\mu}m$</TEX> and <TEX>$0.6\;{\mu}m$</TEX>) based on the refractive index of the photopolymer and beam incident angle (<TEX>$3.4^{\circ}$</TEX>, <TEX>$15^{\circ}$</TEX>) to the photopolymer surface.

Nano-layer growth of new anthracene polymer film through redox-induced polymerization

Abstract π-Conjugated new anthracene polymer film was prepared in a nanometer level from 9,10-(3,4-ethylenedioxythiophen-2-yl)anthracene [BEDOT-Ant] via direct electrochemical deposition on an ITO electrode. The growth of the polymeric nano thin film could be controlled by the potential cycle numbers. Having electro activity plus optical property, the new polymer film was electroactive and showed photoconductivity. The cyclic voltammogram (CV) for the polymer film showed new redox peaks at 0.9 and 0.5 V (vs. Ag/AgCl). The polymer film with 170 nm in thickness generated photocurrent when exposed to UV light. The polymeric thin film showed reversible photocurrent switching property.

Facile one-pot synthesis of a photo patternable anthracene polymer

A polycyclic aromatic compound, anthracene, was covalently connected through a methylene bridge via Friedel–Crafts alkylation reaction. Thus, a highly fluorescent anthracene polymer (PMAn) linked by a methylene unit was prepared in one step to produce a conjugated–nonconjugated spacer-type polymer through its reaction with chloromethyl methyl ether (CME) and FeCl 3 at 0 °C. The resultant polymer was soluble in organic solvents and showed significantly higher fluorescence (quantum yield = 0.80) compared to monomeric anthracene, 9-methylanthracene, in chloroform solution. Fluorescent thin films of PMAn as solid media were prepared with high film uniformity. The emission of the film was extinguished when the film was exposed to a UV source, due to the photodimerization of anthracene unit. A fluorescent gap electrode pattern was formed on the polymer film-forming average step depth of 8 nm and 14 nm, after 30 and 60 min irradiation with a UV light, respectively. The photo patternable fluorescent polymer afforded a convenient method of image formation and patterning.

Highly Fluorescent Anthracene Polymers for Direct Photo Patterning

Highly Fluorescent Anthracene Polymers for Direct Photo Patterning

Synthesis and characterization of poly(pyridinium salt)s with anthracene moieties exhibiting both lyotropic liquid-crystalline and UV light-emitting properties

Two poly(pyridinium salt)s with anthracene moieties in the main chain as well as tosylate and triflimide as counterions were prepared by either the ring-transmutation polymerization of phenylated bis(pyrylium tosylate) salt with 2,6-diaminoanthracene in dimethyl sulfoxide or the metathesis reaction of the corresponding tosylate polymer with lithium triflimide in acetonitrile. They were characterized for their lyotropic liquid-crystalline and UV light-emitting properties, with various experimental techniques. These ionic, conjugated anthracene polymers are the recent addition to the class of UV light-emitting polymers, since they emit UV light both in solution and in the solid state.

Application of an Anthracene Containing Polymer to a Negative Type Photoresist

Yong Woon Kim, and Taek Hyeon KimFaculty of Applied Chemistry and The Polymer Science & Technology Research Center,Chonnam National University, Gwangju 500-757, KoreaReceived February 19, 2002Key Words : Anthracene polymer, Photoresist, Photo-crosslinkingPhotoresists are very important materials for the photo-fabrication process. They are widely used for the manu-facture of microelectronics, printed circuit boards, silkscreen printing, optical disks, black matrix of color cathod-ray tubes, and so on. They can be classified into two types onthe basis of the solubility changes upon irradiation with UVlight, i.e., positive or negative types. The negative type ofphotoresist is generally more sensitive than the positive one. It is well known that anthracene or its derivatives dimerizephotochemically to give [4+4] cycloadducts across the 9,10-positions of anthracene,

Tuneable electrochemical interactions between polystyrenes with anthracenyl and tetrathiafulvalenyl sidechains.

Polymer 4 and its monomeric counterpart 3 exhibit electrochemically tuneable interactions with anthracene polymer 2 and a structurally similar monomer 1 and seen by the variation of the oxidation waves of TTF groups and the fluorescence of the anthracene.

Carbonization and Graphitization of Anthracene Polymers

Carbonization and graphitization behaviors of anthracene polymers were investigated to characterize the carbon products obtained. The polymers consisting of 3-4 anthracene units (Poly (9, 10-anthracene diylidene)) were synthesized by use of dehydration and polycondensation of polyphosphoric acids. The weight loss of the polymers occurs predominantly between 350-500°C and the yield of the products treated at 1000°C reaches 72-79%. It was found from the analyses of the evoluved gases and the FT-IR spectra that dehydrogenation at the terminal CH2 groups of the polymer and elimination of CO from quinone groups at the anthracene terminal take place at these temperature ranges. The carbonized product from anthrone polymer showed a fine mozaic texture although it melted at 290-300°C. This may be because the anthracene units are twisted with each other. Also, d002 spacing and La values obtained from X-ray diffraction profilesof the heat-treated polymer suggest that the graphitizability of the polymer is less enhanced even at high temperatures.