@article{SchulzOrgzallDiezetal.2010, author = {Schulz, Burkhard and Orgzall, Ingo and Diez, Isabel and Dietzel, Birgit and Tauer, Klaus}, title = {Template mediated formation of shaped polypyrrole particles}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2009.11.034}, year = {2010}, abstract = {The formation of different micro- and nanostructures during the chemical synthesis of polypyrrole is reviewed shortly based on the conceptions of hard- and soft-templating models. Contrary to other models that emphasize the role of micelles it is found here that during the oxidative polymerization of pyrole using sulfonic acid dopants a crystalline hard template is found in the first steps of the reaction before the addition of the oxidant. This template is formed by a complex consisting of 2,5-bis(pyrrole-2-yl)pyrrolidine and the sulfonic acid anion. The acid catalyzed formation of this specific tripyrrole is discussed. (C) 2009 Elsevier B.V. All rights reserved.}, language = {en} } @article{SchulzBrehmerDietzeletal.1995, author = {Schulz, Burkhard and Brehmer, Ludwig and Dietzel, Birgit and Zetzsche, Thomas}, title = {Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s}, year = {1995}, language = {en} } @article{SarauliXuDietzeletal.2013, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {Differently substituted sulfonated polyanilines - the role of polymer compositions in electron transfer with pyrroloquinoline quinone-dependent glucose dehydrogenase}, series = {Acta biomaterialia}, volume = {9}, journal = {Acta biomaterialia}, number = {9}, publisher = {Elsevier}, address = {Oxford}, issn = {1742-7061}, doi = {10.1016/j.actbio.2013.06.008}, pages = {8290 -- 8298}, year = {2013}, abstract = {Sulfonated polyanilines have become promising building blocks in the construction of biosensors, and therefore we use here differently substituted polymer forms to investigate the role of their structural composition and properties in achieving a direct electron transfer with the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). To this end, new copolymers containing different ratios of 2-methoxyaniline-5-sulfonic acid (MAS), 3-aminobenzenesulfonic acid (ABS) and 3-aminobenzoic acid (AB) units have been chemically synthesized. All polymers have been studied with respect to their ability to react directly with PQQ-GDH. This interaction has been monitored initially in solution, and subsequently on electrode surfaces. The results show that only copolymers with MAS and aniline units can directly react with PQQ-GDH in solution; the background can be mainly ascribed to the emeraldine salt redox state of the polymer, allowing rather easy reduction. However, when polymers and the enzyme are immobilized on the surface of carbon nanotube-containing electrodes, direct bioelectrocatalysis is also feasible in the case of copolymers composed of ABS/AB and MAS/AB units, existing initially in pernigraniline base form. This verifies that a productive interaction of the enzyme with differently substituted polymers is feasible when the electrode potential can be used to drive the reaction towards the oxidation of the substrate-reduced enzyme. These results clearly demonstrate that enzyme electrodes based on sulfonated polyanilines and direct bioelectrocatalysis can be successfully constructed.}, language = {en} } @article{SchulzDietzelOrgzalletal.2009, author = {Schulz, Burkhard and Dietzel, Birgit and Orgzall, Ingo and Diez, Isabel and Xu, Chenggang}, title = {Aspects of morphology control during the oxidative synthesis of electrically conducting polymers}, issn = {0954-0083}, doi = {10.1177/0954008309339933}, year = {2009}, abstract = {The formation of micro- and nanostructures during the oxidative polymerization of polypyrrole and polyaniline is investigated using different sulfonic acid dopants. Rod- or tube-like structures are found in polypyrrole as well as in polyaniline without addition of further compounds to the initial reaction mixture of monomer, dopant and oxidant. In these cases, always a crystalline precursor complex composed of a dopand molecule and the pure monomer (aniline) or a trimeric moiety (pyrrole) serves as in-situ template. In most cases the surface of the growing polymer is covered by secondary structures with much smaller sizes so that a hierarchical order of structures at different length scales results. Corresponding model considerations for the polymerization process are outlined. Additionally, unusual structures like platelets, frames, rings, or ribbons are observed in the polypyrrole synthesis in the presence of fluorosurfactants.}, language = {en} } @article{ReicheSchulzKnochenhaueretal.1997, author = {Reiche, J{\"u}rgen and Schulz, Burkhard and Knochenhauer, Gerald and Dietzel, Birgit and Freydank, Anke-Christine and Zetzsche, Thomas and Brehmer, Ludwig}, title = {Supramolecular structures formed from heterocyclic aromatic molecules}, year = {1997}, abstract = {This paper describes the formation and structure investigation of Langmuir monolayers and Langmuir-Blodgett multilayers formed from amphiphilic derivatives of 2,5-diphenyl-1,3,4-oxadiazole. The 2,5-diphenyl-1,3,4-oxadiazole group as a functional unit with interesting physical and chemical properties is maintained, while the head group, the length of the alkyl chain and the structure of the coupling unit between aromatic and aliphatic part of these linear short-chain amphiphiles is systematically varied in order to explore the influence of this change on the film forming properties and the stability of Langmuir and Langmuir-Blodgett films. Molecular mechanics simulations are shown by these systematic variations to be suitable for the prediction of optimal chemical structures allowing for a stable stratified molecular packing. The combination of a detailed structure investigation of the multilayers based on scanning force microscopy and X-ray data with molecular mechanics simulations yields an insight into the packing of the molecules and the intermolecular interactions.}, language = {en} } @article{SarauliXuDietzeletal.2014, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {21}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00336e}, pages = {3196 -- 3203}, year = {2014}, abstract = {A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60\% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @article{HoffmannDietzelSchulzetal.2011, author = {Hoffmann, Katrin and Dietzel, Birgit and Schulz, Burkhard and Reck, Guenter and Hoffmann, Angelika and Orgzall, Ingo and Resch-Genger, Ute and Emmerling, Franziska}, title = {Combined structural and fluorescence studies of methyl-substituted 2,5-diphenyl-1,3,4-oxadiazoles - Relation between electronic properties and packing motifs}, series = {Journal of molecular structure}, volume = {988}, journal = {Journal of molecular structure}, number = {1-3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2010.11.071}, pages = {35 -- 46}, year = {2011}, abstract = {Prerequisite for the rational design of functional organic materials with tailor-made electronic properties is the knowledge of the structure-property relationship for the specific class of molecules under consideration. This encouraged us to systematically study the influence of the molecular structure and substitution pattern of aromatically substituted 1,3,4-oxadiazoles on the electronic properties and packing motifs of these molecules and on the interplay of these factors. For this purpose, seven diphenyl-oxadiazoles equipped with methyl substituents in the ortho- and meta-position(s) were synthesized and characterized. Absorption and fluorescence spectra in solution served here as tools to monitor substitution-induced changes in the electronic properties of the individual molecules whereas X-ray and optical measurements in the solid state provided information on the interplay of electronic and packing effects. In solution, the spectral position of the absorption maximum, the size of Stokes shift, and the fluorescence quantum yield are considerably affected by ortho-substitution in three or four ortho-positions. This results in blue shifted absorption bands, increased Stokes shifts, and reduced fluorescence quantum yields whereas the spectral position and vibrational structure of the emission bands remain more or less unaffected. In the crystalline state, however, the spectral position and shape of the emission bands display a strong dependence on the molecular structure and/or packing motifs that seem to control the amount of dye-dye-interactions. These observations reveal the limited value of commonly reported absorption and fluorescence measurements in solution for a straightforward comparison of spectroscopic results with single X-ray crystallography. This underlines the importance of solid state spectroscopic studies for a better understanding of the interplay of electronic effects and molecular order.}, language = {en} } @article{EmmerlingOrgzallDietzeletal.2012, author = {Emmerling, Franziska and Orgzall, Ingo and Dietzel, Birgit and Schulz, Burkhard and Larrucea, Julen}, title = {Ordering the amorphous - Structures in PBD LED materials}, series = {Journal of molecular structure}, volume = {1030}, journal = {Journal of molecular structure}, number = {23}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2012.04.040}, pages = {209 -- 215}, year = {2012}, abstract = {The class of 2,5 disubstituted-1,3,4-oxadiazoles containing a biphenyl unit on one side is intensively used as electron transport materials to enhance the performance of organic light emitting diodes (OLEDs). In contrast to the ongoing research on these materials insights in their structure-property relationships are still incomplete. To overcome the structural tentativeness and ambiguities the crystal structures of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, that of the related compound 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole and of 2-(4-biphenylyl)-5-(2,6-dimethylphenyl)-1,3,4-oxadiazole are determined. A comparison with the results of GAUSSIAN03 calculations and similar compounds in the Cambridge Structural Database leads to a profound characterization.}, language = {en} } @article{SarauliXuDietzeletal.2012, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Stiba, Konstanze and Leimk{\"u}hler, Silke and Schulz, Burkhard and Lisdat, Fred}, title = {Thin films of substituted polyanilines interactions with biomolecular systems}, series = {Soft matter}, volume = {8}, journal = {Soft matter}, number = {14}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c2sm07261k}, pages = {3848 -- 3855}, year = {2012}, abstract = {We use substituted polyanilines for the construction of new polymer electrodes for interaction studies with the redox protein cytochrome c (cyt c) and the enzyme sulfite oxidase (SO). For these purposes four different polyaniline copolymers are chemically synthesized. Three of them are copolymers, containing 2-methoxyaniline-5-sulfonic acid with variable ratios of aniline; the fourth copolymer consists of 3-amino-benzoic acid and aniline. The results show that all polymers are suitable for being immobilized as thin stable films on gold wire and indium tin oxide (ITO) electrode surfaces from DMSO solution. This can be demonstrated by cyclic voltammetry and UV-Vis spectroscopy measurements. Moreover, cyt c can be electrochemically detected not only in solution, but also immobilized on top of the polymer films. Furthermore, the appearance of a significant catalytic current has been demonstrated for the sulfonated polyanilines, when the polymer-coated protein electrode is being measured upon addition of sulfite oxidase, confirming the establishment of a bioanalytical signal chain. Best results have been obtained for the polymer with highest sulfonation grade. The redox switching of the polymer by the enzymatic reaction can also be analyzed by following the spectral properties of the polymer electrode.}, language = {en} } @article{KarageorgievStillerPrescheretal.2000, author = {Karageorgiev, Peter and Stiller, Burkhard and Prescher, Dietrich and Dietzel, Birgit and Schulz, Burkhard and Brehmer, Ludwig}, title = {Modification of the surface potential of azobenzene-containing langmuir-blodgett films in the near field of a scanning kelvin microscope tip by irradiation}, year = {2000}, language = {en} }