Imperial College London

Dr Florian Glöcklhofer

Faculty of Natural SciencesDepartment of Chemistry

Research Associate
 
 
 
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f.glocklhofer Website

 
 
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Location

 

Molecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

55 results found

Pletzer M, Plasser F, Rimmele M, Heeney M, Glöcklhofer Fet al., 2022, [2.2.2.2]Paracyclophanetetraenes (PCTs): cyclic structural analogues of poly(p‑phenylene vinylene)s (PPVs), Open Research Europe, Vol: 1, Pages: 111-111

<ns4:p><ns4:bold>Background</ns4:bold>: Poly(<ns4:italic>p</ns4:italic>-phenylene vinylene)s (<ns4:bold>PPV</ns4:bold>s) and [2.2.2.2]paracyclophanetetraene (<ns4:bold>PCT</ns4:bold>) are both composed of alternating π-conjugated <ns4:italic>para</ns4:italic>-phenylene and vinylene units. However, while the former constitute a class of π-conjugated polymers that has been used in organic electronics for decades, the latter is a macrocycle that only recently revealed its potential for applications such as organic battery electrodes. The cyclic structure endows <ns4:bold>PCT</ns4:bold> with unusual properties, and further tuning of these may be required for specific applications. <ns4:bold>Methods</ns4:bold>: In this article, we adopt an approach often used for tuning the properties of <ns4:bold>PPV</ns4:bold>s, the introduction of alkoxy (or alkylthio) substituents at the phenylene units, for tuning the optoelectronic properties of <ns4:bold>PCT</ns4:bold>. The resulting methoxy- and methylthio-substituted <ns4:bold>PCT</ns4:bold>s, obtained by Wittig cyclisation reactions, are studied by UV-vis absorption, photoluminescence, and cyclic voltammetry measurements, and investigated computationally using the visualisation of chemical shielding tensors (VIST) method. <ns4:bold>Results</ns4:bold>: The measurements show that substitution leads to slight changes in terms of absorption/emission energies and redox potentials while having a pronounced effect on the photoluminescence intensity. The computations show the effect of the substituents on the ring currents and chemical shielding and on the associated local and global (anti)aromaticity of the macrocycles, highlighting the interplay of local and global aromaticity in various electronic states. <ns4:bold>Conclusions</ns4:bold>: The study offers interesting insights int

Journal article

Pletzer M, Plasser F, Rimmele M, Heeney M, Glöcklhofer Fet al., 2021, [2.2.2.2]Paracyclophanetetraenes (PCTs): cyclic structural analogues of poly(p‑phenylene vinylene)s (PPVs), Open Research Europe, Vol: 1, Pages: 1-12, ISSN: 2732-5121

Background: Poly(p-phenylene vinylene)s (PPVs) and [2.2.2.2]paracyclophanetetraene (PCT) are both composed of alternating π-conjugated para-phenylene and vinylene units. However, while the former constitute a class of π-conjugated polymers that has been used in organic electronics for decades, the latter is a macrocycle that only recently revealed its potential for applications such as organic battery electrodes. The cyclic structure endows PCT with unusual properties, and further tuning of these may be required for specific applications. Methods: In this article, we adopt an approach often used for tuning the properties of PPVs, the introduction of alkoxy (or alkylthio) substituents at the phenylene units, for tuning the optoelectronic properties of PCT. The resulting methoxy- and methylthio-substituted PCTs, obtained by Wittig cyclisation reactions, are studied by UV-vis absorption, photoluminescence, and cyclic voltammetry measurements, and investigated computationally using the visualisation of chemical shielding tensors (VIST) method. Results: The measurements show that substitution leads to slight changes in terms of absorption/emission energies and redox potentials while having a pronounced effect on the photoluminescence intensity. The computations show the effect of the substituents on the ring currents and chemical shielding and on the associated local and global (anti)aromaticity of the macrocycles, highlighting the interplay of local and global aromaticity in various electronic states. Conclusions: The study offers interesting insights into the tuneability of the properties of this versatile class of π-conjugated macrocycles.

Journal article

Szakacs Z, Glocklhofer F, Plasser F, Vauthey Eet al., 2021, Excited-state symmetry breaking in 9,10-dicyanoanthracene-based quadrupolar molecules: the effect of donor-acceptor branch length, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 15150-15158, ISSN: 1463-9076

Journal article

Rimmele M, Nogala W, Seif-Eddine M, Roessler M, Heeney M, Plasser F, Glöcklhofer Fet al., 2021, Functional group introduction and aromatic unit variation in a set of π‑conjugated macrocycles: revealing the central role of local and global aromaticity, Organic Chemistry Frontiers, Vol: 8, Pages: 4730-4745, ISSN: 2052-4110

π-Conjugated macrocycles are molecules with unique properties that are increasingly exploited for applications and the question of whether they can sustain global aromatic or antiaromatic ring currents is particularly intriguing. However, there are only a small number of experimental studies that investigate how the properties of π‑conjugated macrocycles evolve with systematic structural changes. Here, we present such a systematic experimental study of a set of [2.2.2.2]cyclophanetetraenes, all with formally Hückel antiaromatic ground states, and combine it with an in-depth computational analysis. The study reveals the central role of local and global aromaticity for rationalizing the observed optoelectronic properties, ranging from extremely large Stokes shifts of up to 1.6 eV to reversible fourfold reduction, a highly useful feature for charge storage/accumulation applications. A recently developed method for the visualization of chemical shielding tensors (VIST) is applied to provide unique insight into local and global ring currents occurring in different planes along the macrocycle. Conformational changes as a result of the structural variations can further explain some of the observations. The study contributes to the development of structure–property relationships and molecular design guidelines and will help to understand, rationalize, and predict the properties of other π‑conjugated macrocycles.

Journal article

Plasser F, Glöcklhofer F, 2021, Visualisation of chemical shielding tensors (VIST) to elucidate aromaticity and antiaromaticity**, European Journal of Organic Chemistry, Vol: 2021, Pages: 2529-2539, ISSN: 1434-193X

Aromaticity is a central concept in chemistry, pervading areas from biochemistry to materials science. Recently, chemists also started to exploit intricate phenomena such as the interplay of local and global (anti)aromaticity or aromaticity in non‐planar systems and three dimensions. These phenomena pose new challenges in terms of our fundamental understanding and the practical visualisation of aromaticity. To overcome these challenges, a method for the visualisation of chemical shielding tensors (VIST) is developed here that allows for a 3D visualisation with quantitative information about the local variations and anisotropy of the chemical shielding. After exemplifying the method in different planar hydrocarbons, we study two non‐planar macrocycles to show the unique benefits of the VIST method for molecules with competing π‐conjugated systems and conclude with a norcorrole dimer showing clear evidence of through‐space aromaticity. We believe that the VIST method will be a highly valuable addition to the computational toolbox.

Journal article

Rimmele M, Nogala W, Seif-Eddine M, Roessler MM, Heeney M, Plasser F, Glöcklhofer Fet al., 2021, Functional Group Introduction and Aromatic Unit Variation in a Set of π-Conjugated Macrocycles: Revealing the Central Role of Local and Global Aromaticity, Publisher: American Chemical Society (ACS)

<jats:p>π-Conjugated macrocycles are molecules with unique properties that are increasingly exploited for applications and the question of whether they can sustain global aromatic or antiaromatic ring currents is particularly intriguing. However, there are only a small number of experimental studies that investigate how the properties of π-conjugated macrocycles evolve with systematic structural changes. Here, we present such a systematic experimental study of a set of [2.2.2.2]cyclophanetetraenes, all with formally Hückel antiaromatic ground states, and combine it with an in-depth computational analysis. The study reveals the central role of local and global aromaticity for rationalizing the observed optoelectronic properties, ranging from extremely large Stokes shifts of up to 1.6 eV to reversible fourfold reduction, a highly useful feature for charge storage/accumulation applications. A recently developed method for the visualization of chemical shielding tensors (VIST) is applied to provide unique insight into local and global ring currents occurring in different planes along the macrocycle. Conformational changes as a result of the structural variations can further explain some of the observations. The study contributes to the development of structure–property relationships and molecular design guidelines and will help to understand, rationalize, and predict the properties of other π-conjugated macrocycles.</jats:p>

Working paper

Yoo D-J, Heeney M, Glocklhofer F, Choi JWet al., 2021, Tetradiketone macrocycle for divalent aluminium ion batteries, Nature Communications, Vol: 12, Pages: 1-9, ISSN: 2041-1723

Contrary to early motivation, the majority of aluminium ion batteries developed to date do not utilise multivalent ion storage; rather, these batteries rely on monovalent complex ions for their main redox reaction. This limitation is somewhat frustrating because the innate advantages of metallic aluminium such as its low cost and high air stability cannot be fully taken advantage of. Here, we report a tetradiketone macrocycle as an aluminium ion battery cathode material that reversibly reacts with divalent (AlCl2+) ions and consequently achieves a high specific capacity of 350 mAh g−1 along with a lifetime of 8000 cycles. The preferred storage of divalent ions over their competing monovalent counterparts can be explained by the relatively unstable discharge state when using monovalent AlCl2+ ions, which exert a moderate resonance effect to stabilise the structure. This study opens an avenue to realise truly multivalent aluminium ion batteries based on organic active materials, by tuning the relative stability of discharged states with carrier ions of different valence states.

Journal article

Kafourou P, Park B, Luke J, Tan L, Panidi J, Glöcklhofer F, Kim J, Anthopoulos TD, Kim J, Lee K, Kwon S, Heeney Met al., 2021, One‐step sixfold cyanation of benzothiadiazole acceptor units for air‐stable high‐performance n‐type organic field‐effect transistors, Angewandte Chemie, Vol: 133, Pages: 6035-6042, ISSN: 0044-8249

Reported here is a new high electron affinity acceptor end group for organic semiconductors, 2,1,3‐benzothiadiazole‐4,5,6‐tricarbonitrile (TCNBT). An n‐type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a sixfold nucleophilic substitution with cyanide on a fluorinated precursor, itself prepared by a direct arylation approach. This one‐step chemical modification significantly impacted the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n‐type semiconductor. The electron‐deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n‐type organic field‐effect transistors (OFETs). Solution‐processed OFETs based on TCNBT IDT exhibited a charge‐carrier mobility of up to μe≈0.15 cm2 V−1 s−1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.

Journal article

Heeney M, Kafourou P, Park B, Luke J, Luxi T, Panidi J, Glöcklhofer F, Kim J, Anthopoulos TD, Kim J-S, Lee K, Kwon Set al., 2021, One-step six-fold cyanation of benzothiadiazole acceptor Units for air-stable high-performance n-type organic field-effect transistors, Angewandte Chemie International Edition, Vol: 60, Pages: 5970-5977, ISSN: 1433-7851

We report a new high electron affinity acceptor end group for organic semiconductors, 2,1,3-benzothiadiazole-4,5,6-tricarbonitrile (TCNBT). An n-type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a six-fold nucleophilic substitution with cyanides on a fluorinated precursor, itself prepared by a direct arylation approach. This one-step chemical modification was found to significantly impact the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n-type semiconductor. The highly electron-deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n-type organic field-effect transistors (OFETs). Solution-processed OFETs based on TCNBT IDT exhibited a charge carrier mobility of up to µ e ≈ 0.15 cm 2 V -1 s -1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.

Journal article

Hodsden T, Thorley KJ, Basu A, White AJP, Wang C, Mitchell W, Glocklhofer F, Anthopoulos TD, Heeney Met al., 2021, The influence of alkyl group regiochemistry and backbone fluorination on the packing and transistor performance of N-cyanoimine functionalised indacenodithiophenes, Materials Advances, Vol: 2, Pages: 1706-1714

The synthesis of two novel n-type molecular organic semiconductors based on a fluorinated indacenodithiophene core in combination with an electron withdrawing N-cyanoimine group is reported, and the influence of the regiochemistry of the solubilizing sidechain is investigated. The N-cyanoimine is confirmed to be a strongly electron accepting group, which in combination with the core fluorination resulted in high electron affinities for both materials. Single crystal analysis demonstrated that whilst both materials arrange in ordered slipped stacks with close π–π stacking distances (∼3.40 Å), significant differences in electron transfer integrals for the two regioisomers were observed, relating to differences in relative molecular displacement along the π-stacking direction. Organic thin-film transistors fabricated via blade-coating displayed electron mobility up to 0.13 cm2 V−1 s−1 for the isomer with the larger transfer integral.

Journal article

Wang S, Shaw J, Han Y, Fei Z, Glöcklhofer F, Heeney Met al., 2020, Multibranched aliphatic side chains for π-conjugated polymers with a high density of ‘unshielded’ aromatics, Chemical Communications, Vol: 56, Pages: 12138-12141, ISSN: 1359-7345

Strongly solubilising multibranched aliphatic side chains for π-conjugated polymers are reported, enabling soluble polymers with a high density of unsubstituted, ‘unshielded’ aromatics.

Journal article

Taublaender MJ, Mezzavilla S, Thiele S, Glöcklhofer F, Unterlass MMet al., 2020, Hydrothermale synthese von konjugierten polymeren am beispiel von pyrronpolymeren und polybenzimidazolen, Angewandte Chemie, Vol: 132, Pages: 15160-15171, ISSN: 0044-8249

Various polyimides and polyamides have recently been prepared by hydrothermal synthesis in nothing but H 2 O under high pressure and high temperature conditions. However, none of these polymers have a conjugated polymer backbone. We hereby report an extension of the synthetic scope of this simple and naturally environmentally friendly polymerisation technique to the production of conjugated polymers. Selected representatives of two different polymer classes, pyrron polymers and polybenzimidazoles, were synthesized hydrothermally. In addition to a mechanistic discussion of polymer formation, an electrochemical characterization of the most promising product is presented.

Journal article

Taublaender MJ, Mezzavilla S, Thiele S, Glöcklhofer F, Unterlass MMet al., 2020, Hydrothermal generation of conjugated polymers using the example of pyrrone polymers and polybenzimidazoles, Angewandte Chemie International Edition, Vol: 59, Pages: 15050-15060, ISSN: 1433-7851

Various polyimides and polyamides have recently been prepared via hydrothermal synthesis in nothing but H2 O under high-pressure and high-temperature conditions. However, none of the prepared polymers feature a truly conjugated polymer backbone. Here, we report on an expansion of the synthetic scope of this straightforward and inherently environmentally friendly polymerization technique to the generation of conjugated polymers. Selected representatives of two different polymer classes, pyrrone polymers and polybenzimidazoles, were generated hydrothermally. We present a mechanistic discussion of the polymer formation process as well as an electrochemical characterization of the most promising product.

Journal article

Taublaender MJ, Mezzavilla S, Thiele S, Glöcklhofer F, Unterlass MMet al., 2020, Back Cover: Hydrothermal Generation of Conjugated Polymers Using the Example of Pyrrone Polymers and Polybenzimidazoles (Angew. Chem. Int. Ed. 35/2020), Angewandte Chemie International Edition, Vol: 59, Pages: 15268-15268, ISSN: 1433-7851

Journal article

Taublaender MJ, Mezzavilla S, Thiele S, Glöcklhofer F, Unterlass MMet al., 2020, Hydrothermal Generation of Conjugated Polymers Using the Example of Pyrrone Polymers and Polybenzimidazoles, Angewandte Chemie, ISSN: 0044-8249

Journal article

Eder S, Yoo D-J, Nogala W, Pletzer M, Santana Bonilla A, White AJP, Jelfs KE, Heeney M, Choi JW, Glöcklhofer Fet al., 2020, Switching between local and global aromaticity in a conjugated macrocycle for high-performance organic sodium-ion battery anodes, Angewandte Chemie International Edition, Vol: 59, Pages: 12958-12964, ISSN: 1433-7851

Aromatic organic compounds can be used as electrode materials in rechargeable batteries and are expected to advance the development of both anode and cathode materials for sodium-ion batteries (SIBs). However, most aromatic organic compounds assessed as anode materials in SIBs to date exhibit significant degradation issues under fast-charge/discharge conditions and unsatisfying long-term cycling performance. Now, a molecular design concept is presented for improving the stability of organic compounds for battery electrodes. The molecular design of the investigated compound, [2.2.2.2]paracyclophane-1,9,17,25-tetraene (PCT), can stabilize the neutral state by local aromaticity and the doubly reduced state by global aromaticity, resulting in an anode material with extraordinarily stable cycling performance and outstanding performance under fast-charge/discharge conditions, demonstrating an exciting new path for the development of electrode materials for SIBs and other types of batteries.

Journal article

Meindl B, Pfennigbauer K, Stöger B, Heeney M, Glöcklhofer Fet al., 2020, Double ring-closing approach for the synthesis of 2,3,6,7-substituted anthracene derivatives., Journal of Organic Chemistry, Vol: 85, Pages: 8240-8244, ISSN: 0022-3263

A method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain, is presented. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable, protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions, followed by a deprotection and intramolecular double ring-closing condensation reaction.

Journal article

Hodsden T, Thorley KJ, Panidi J, Basu A, Marsh AV, Dai H, White AJP, Wang C, Mitchell W, Glöcklhofer F, Anthopoulos TD, Heeney Met al., 2020, Core fluorination enhances solubility and ambient stability of an IDT‐based n‐type semiconductor in transistor devices, Advanced Functional Materials, Vol: 30, Pages: 1-12, ISSN: 1616-301X

The synthesis of a novel fluorinated n‐type small molecule based on an indacenodithiophene core is reported. Fluorination is found to have a significant impact on the physical properties, including a surprisingly dramatic improvement in solubility, in addition to effectively stabilizing the lowest‐unoccupied molecular orbital energy (−4.24 eV). Single‐crystal analysis and density functional theory calculations indicate the improved solubility can be attributed to backbone torsion resulting from the positioning of the fluorine group in close proximity to the strongly electron‐withdrawing dicyanomethylene group. Organic thin‐film transistors made via blade coating display high electron mobility (up to 0.49 cm2 V−1 s−1) along with good retention of performance in ambient conditions.

Journal article

Meindl B, Pfennigbauer K, Stöger B, Heeney M, Glöcklhofer Fet al., 2020, Double ring-closing approach for the synthesis of 2,3,6,7-substituted anthracene derivatives, Publisher: ChemRxiv

<jats:p>Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.&lt;br&gt;</jats:p>

Working paper

Glöcklhofer F, Rosspeintner A, Pasitsuparoad P, Eder S, Fröhlich J, Angulo G, Vauthey E, Plasser Fet al., 2019, Effect of symmetric and asymmetric substitution on the optoelectronic properties of 9,10-dicyanoanthracene, Molecular Systems Design & Engineering, Vol: 4, Pages: 951-961, ISSN: 2058-9689

<p>Six newly synthesised 9,10-dicyanoanthracene derivatives exhibit high two-photon absorption cross sections particularly upon symmetric substitution with strong electron donors.</p>

Journal article

Reichsöllner E, Creamer A, Cong S, Casey A, Eder S, Heeney M, Glocklhofer Fet al., 2019, Fast and selective post-polymerization modification of conjugated polymers using dimethyldioxirane, Frontiers in Chemistry, Vol: 7, ISSN: 2296-2646

Modification of functional groups attached to conjugated polymer backbones can drastically alter the material properties. Oxidation of electron-donating thioalkyl substituents to electron-withdrawing sulfoxides or sulfones is a particularly effective modification. However, so far, this reaction has not been studied for the modification of conjugated polymers used in organic electronics. Crucial questions regarding selectivity and reaction time waited to be addressed. Here, we show that the reaction is highly selective and complete within just a few minutes when using dimethyldioxirane (DMDO) for the oxidation of thioalkyl substituents attached to the well-investigated conjugated polymers poly(9-(1-octylnonyl)carbazole-alt-4,7-dithienylbenzothiadiazole) (PCDTBT) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). The selectivity was confirmed by comparison with polymers obtained from pre-oxidized monomers and by control experiments using related polymers without thioalkyl substituents. Using DMDO, the oxidation yields acetone as the only side-product, which reduces the work-up to mere evaporation of solvents and excessive reagent. Our results show that this oxidation is an exciting method for the preparation of electron-deficient conjugated polymers. It may even allow the preparation of electron acceptors for solar cells directly from the electron donors.

Journal article

Rimmele M, Ableidinger K, Marsh AV, Cheetham NJ, Taublaender MJ, Buchner A, Prinz J, Fröhlich J, Unterlass MM, Heeney M, Glöcklhofer Fet al., 2019, Thioalkyl- and Sulfone-Substituted Poly(p-Phenylene Vinylene)s, Polymer Chemistry, Vol: 10, Pages: 738-750, ISSN: 1759-9954

Poly(p-phenylene vinylene)s (PPVs) have been studied for decades, but research on this interesting class of conjugated polymers is far from being completed. New applications like in bioimaging keep emerging and even simple structural variations are still waiting to be explored. Surprisingly, not even dithioalkyl-substituted PPVs (S-PPVs) have been reported in the peer-reviewed literature, although the corresponding dialkoxy-substituted PPVs (O-PPVs) like MEH-PPV or MDMO-PPV are most frequently used and although thioalkyl substituents can improve the material properties significantly. We herein report the development of a highly efficient, scalable two-step synthesis of Gilch monomers for S-PPVs starting from low-cost 1,4-diiodobenzene. A low-temperature polymerization protocol has been developed for these monomers, affording high-molecular weight S-PPVs in excellent yields. The thermal, electrochemical, and photophysical properties of S-PPVs are reported to highlight the potential of these polymers. Furthermore, treatment with dimethyldioxirane is demonstrated to result in rapid conversion into sulfone-substituted PPVs (SO2-PPVs), introducing a route to high-molecular weight SO2-PPVs with exceptional stability and solid-state photoluminescence quantum yields of up to 0.46.

Journal article

Reichsöllner E, Creamer A, Cong S, Casey A, Eder S, Heeney M, Glöcklhofer Fet al., 2019, Fast and selective post-polymerization modification of conjugated polymers using dimethyldioxirane.

Modification of functional groups attached to conjugated polymer backbones can drastically alter the material properties. Oxidation of electron-donating thioalkyl substituents to electron-withdrawing sulfoxides or sulfones is a particularly effective modification. However, so far, this reaction has not been studied for the modification of conjugated polymers used in organic electronics. Crucial questions regarding selectivity and reaction time waited to be addressed. Here, we show that the reaction is highly selective and complete within just a few minutes when using dimethyldioxirane (DMDO) for the oxidation of thioalkyl substituents attached to the well investigated conjugated polymers poly(9-(1-octylnonyl)carbazole-alt-4,7-dithienylbenzothiadiazole) (PCDTBT) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). The selectivity was confirmed by comparison with polymers obtained from pre-oxidized monomers and by control experiments using related polymers without thioalkyl substituents. Using DMDO, the oxidation yields acetone as the only side-product, which reduces the work-up to mere evaporation of solvents and excessive reagent. Our results show that this oxidation is an exciting method for the preparation of electron-deficient conjugated polymers. It may even allow the preparation of electron acceptors for solar cells directly from the electron donors.

Working paper

Rimmele M, Ableidinger K, Marsh A, Cheetham N, Taublaender J, Buchner A, Prinz J, Fröhlich J, Unterlass M, Heeney M, Glöcklhofer Fet al., 2018, Thioalkyl- and Sulfone-Substituted Poly(p-Phenylene Vinylene)s, Publisher: Royal society of chemistry

Poly(p-phenylene vinylene)s (PPVs) have been studied for decades, but research on this interesting class of conjugated polymers is far from being completed. New applications like in bioimaging keep emerging and even simple structural variations are still waiting to be explored. Surprisingly, not even dithioalkyl-substituted PPVs (S-PPVs) have been reported in the peer-reviewed literature, although the corresponding dialkoxy-substituted PPVs (O-PPVs) like MEH-PPV or MDMO-PPV are most frequently used and although thioalkyl substituents can improve the material properties significantly. We herein report the development of a highly efficient, scalable two-step synthesis of Gilch monomers for S-PPVs starting from low-cost 1,4-diiodobenzene. A low-temperature polymerization protocol has been developed for these monomers, affording high-molecular weight S-PPVs in excellent yields. The thermal, electrochemical, and photophysical properties of S-PPVs are reported to highlight the potential of these polymers. Furthermore, treatment with dimethyldioxirane is demonstrated to result in rapid conversion into sulfone-substituted PPVs (SO<sub>2</sub>-PPVs), introducing a route to high-molecular weight SO<sub>2</sub>-PPVs with exceptional stability and solid-state photoluminescence quantum yields of up to 0.46.

Working paper

Taublaender MJ, Glöcklhofer F, Marchetti-Deschmann M, Unterlass MMet al., 2018, Innentitelbild: Grüne und rasche hydrothermale Kristallisation und Synthese vollständig konjugierter aromatischer Verbindungen (Angew. Chem. 38/2018), Angewandte Chemie, Vol: 130, Pages: 12358-12358, ISSN: 0044-8249

Entgegen der chemischen Intuition genügen Wasser und hohe Temperaturen, um komplett konjugierte aromatische Verbindungen rasch zu synthetisieren und zu kristallisieren. In ihrer Zuschrift auf S. 12450 berichten M. M. Unterlass et al. über die Hydrothermal‐Kristallisation von Indigo, Pentacentetron und Perinon sowie über die direkte Synthese von Perinon aus Naphthalin‐Bisanhydrid und o‐Phenylendiamin bei hohen Temperaturen in Wasser ohne Kosolventien oder Katalysatoren. Das Bild zeigt stilisierte Kristalle und Moleküle des roten Pigments trans‐Perinon in wässriger Umgebung.

Journal article

Taublaender MJ, Glöcklhofer F, Marchetti-Deschmann M, Unterlass MMet al., 2018, Grüne und rasche hydrothermale Kristallisation und Synthese vollständig konjugierter aromatischer Verbindungen [Green and rapid hydrothermal crystallization and synthesis of fully conjugated aromatic compounds], Angewandte Chemie, Vol: 130, Pages: 12450-12454, ISSN: 0044-8249

Highly condensed, fully conjugated aromatic compounds are interesting candidates for application in organic electronics. Their electronic properties improve with increasing crystallinity. Here it is shown that the crystallization of three archetypes of such molecules - pentacentetron, indigo and perinone - can be achieved hydrothermally. This finding is extremely astonishing in view of the structure of these compounds. Furthermore, it is shown that perinone can be produced from naphthalene bisanhydride and o ‐ phenylenediamine in exclusively high-temperature water and without the addition of cosolvents or catalysts. Furthermore, the transformation can be accelerated drastically through the use of microwave radiation.

Journal article

Taublaender MJ, Glöcklhofer F, Marchetti-Deschmann M, Unterlass MMet al., 2018, Green and Rapid Hydrothermal Crystallization and Synthesis of Fully Conjugated Aromatic Compounds, Angewandte Chemie International Edition, Vol: 57, Pages: 12270-12274, ISSN: 1433-7851

Journal article

Taublaender MJ, Glöcklhofer F, Marchetti-Deschmann M, Unterlass MMet al., 2018, Inside Cover: Green and Rapid Hydrothermal Crystallization and Synthesis of Fully Conjugated Aromatic Compounds (Angew. Chem. Int. Ed. 38/2018), Angewandte Chemie International Edition, Vol: 57, Pages: 12180-12180, ISSN: 1433-7851

Journal article

Glöcklhofer F, Stöger B, Fröhlich J, 2018, Synthesis of 1,2,5,6- and 1,4,5,8-anthracenetetrone: Building blocks for π-conjugated small molecules and polymers, Synthetic Communications, Vol: 48, Pages: 2358-2365, ISSN: 0039-7911

Reliable reactions for the synthesis of two interesting anthracenetetrones have been identified and optimized. Both syntheses start from dihydroxy-9,10-anthraquinones and were selected for maximized efficiency and minimized work load. Work-up of all reactions can be achieved without column chromatography, which facilitates further scale-up. So far, both target compounds are considerably underexplored despite their promising molecular structure for use in devices and in organic synthesis, especially as building blocks for π-conjugated compounds. The crystal structure of 1,4,5,8-anthracentetrone is reported.

Journal article

Glöcklhofer F, Stöger B, Fröhlich J, 2018, Synthesis of 1,2,5,6- and 1,4,5,8-anthracenetetrone: building blocks for π-conjugated small molecules and polymers, Publisher: ChemRxiv

Reliablereactions for the synthesis of two interestinganthracenetetrones have been identified and optimized. Both synthesesstart from dihydroxy-9,10-anthraquinones and were selected formaximized efficiency and minimized work load. Work-up of allreactions can be achieved without column chromatography, whichfacilitates further scale-up. So far, both target compounds areconsiderably underexplored despite their promising molecularstructure for use in devices and in organicsynthesis, especially as building blocks for π-conjugated compounds.The crystal structure of 1,4,5,8-anthracentetrone is reported.

Working paper

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