@article{MikatFrancoRegensteinetal.2000, author = {Mikat, J{\"u}rgen E. R. and Franco, Olga and Regenstein, Wolfgang and Reck, G{\"u}nter and Knochenhauer, Gerald and Schulz, Burkhard and Orgzall, Ingo}, title = {1,3,4-oxadiazole crystals under high pressure-phase transitions and properties}, year = {2000}, language = {en} } @article{FrancoOrgzallRegensteinetal.2006, author = {Franco, Olga and Orgzall, Ingo and Regenstein, Wolfgang and Schulz, Burkhard}, title = {Structural and spectroscopical study of a 2,5-diphenyl-1,3,4-oxadiazole polymorph under compression}, issn = {0953-8984}, doi = {10.1088/0953-8984/18/4/029}, year = {2006}, abstract = {The x-ray pattern and the Raman and luminescence spectra of crystalline 2,5-diphenyl-1,3,4-oxadiazole in one of its polymorphic forms (DPO II) have been investigated under pressure up to 5 GPa. The behaviour of the lattice parameters under compression was determined and it was found that the Murnaghan equation of state provides a good description of the volume-pressure relationship of DPO II. The values for the bulk modulus and its pressure derivative are K-0 = 8.6 GPa and K-0' = 7.2. The analysis of the Raman spectrum under compression clearly shows the pressure- induced shift of the Raman modes to higher frequencies. The mode Gruneisen parameters for the lattice modes were determined. Additionally, it was found that the emission spectrum of DPO II moves to lower energies and that the luminescence intensity decreases when pressure is applied}, language = {en} } @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} } @book{SchulzOrgzallFreydanketal.2005, author = {Schulz, Burkhard and Orgzall, Ingo and Freydank, Anke-Christine and Chenggang, X{\"u}}, title = {Self-organization of substituted 1,3,4-oxadizazoles in the solid state and at surfaces}, year = {2005}, abstract = {Different aspects of the structure formation for a class of molecules containing the diphenyl-1,3,4-oxadiazole fragment are discussed. Starting from the bulk state with the ideal crystal lattice and the derivation of some common packing motifs the formation of liquid-crystalline states are described. This leads to the consideration of structures found in Langmuir-Blodgett films and those obtained by organic molecular beam deposition. These structures may again be compared to those for the bulk crystalline state. Common features as well as characteristic differences due to peculiarities of the individual molecular structures are discussed. (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{FrancoOrgzallRecketal.2005, author = {Franco, Olga and Orgzall, Ingo and Reck, G{\"u}nter and Stockhause, Sabine and Schulz, Burkhard}, title = {Structure and high-pressure behavior of 2,5-di-(4-aminophenyl)-1,3,4-oxadiazole}, issn = {0022-3697}, year = {2005}, abstract = {The crystalline structures of two modifications of a compound containing the oxadiazole ring, 2,5-di-(4- aminophenyl)-1,3,4-oxadiazole (DAPO) were determined. One of these modifications contains water molecules in the crystal structure, which is observed for the first time for an oxadiazole crystal. Both crystals show an orthorhombic structure. The water free modification, DAPO L belongs to the space group Pbca (61) and has the lattice parameters: a = 13.461(5), b = 7.937(3) and c = 22.816(8) angstrom (CCDC 246608). The water containing pseudo-polymorph, DAPO 11, has the space group Cmcm (63) and the lattice parameters: a = 16.330(5), b = 12.307(2) and c = 6.9978(14) angstrom (CCDC 246609). To gain information on the inter molecular interactions within the crystals, X-ray experiments under compression at ambient temperature and under heating at vacuum conditions were performed. Neither DAPO I nor DAPO II undergo phase transitions in the ressure range up to 5 GPa, as could be concluded from X-ray and Raman experiments. X-ray and calorimetric studies indicate that DAPO II dehydrates into DAPO I under increasing temperature. Structural considerations suggest a two-stage process. The compression behavior of both substances is well described by the Murnaghan equation of state (MEOS) and the values of the bulk modulus and its pressure derivative are determined for these crystals. Additionally, in the case of DAPO I, also the thermal expansion coefficient an was measured. (c) 2005 Elsevier Ltd. All rights reserved}, language = {en} } @article{OrgzallFrancoRecketal.2005, author = {Orgzall, Ingo and Franco, Olga and Reck, Guenter and Schulz, Burkhard}, title = {High-pressure studies on fluorine substituted 2,5-di(phenyl)-1,3,4-oxadiazoles}, issn = {0022-2860}, year = {2005}, abstract = {Results are presented from structural and high-pressure investigations on four differently but symmetrically fluorine substituted 2,5di(phenyl)-1,3,4-oxadiazoles. The substitution pattern includes the para-, meta-, or ortho- substitution and the fully fluorinated 2,5-bis(pentafluorophenyl)-1,3,4-oxadiazole. The crystal structure depends on the molecular structure and results in a different high-pressure behavior. Parameters for the Murnaghan equation of state (EOS) are determined for every compound and the anisotropic pressure response of the crystal lattice is discussed. Although the EOS parameters, bulk modulus K. and its pressure derivative K'(o) are of the same order of magnitude for all four compounds, the anisotropy of strain is noticeably different. (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{LorenzOrgzallDorhoutetal.1996, author = {Lorenz, Bernd and Orgzall, Ingo and Dorhout, P. K. and Casey, R. and D'Adamo, R. and Hochheimer, H. D.}, title = {High pressure optical and Raman investigations of the ternary compound Cs2MoS4}, year = {1996}, language = {en} } @article{LorenzOrgzallDorhoutetal.1996, author = {Lorenz, Bernd and Orgzall, Ingo and Dorhout, P. K. and Raymond, C. C. and Hochheimer, H. D.}, title = {Pressure induced phonon softening and structural phase transitions in Cs2MoS4}, year = {1996}, language = {en} } @article{OrgzallLorenzMikatetal.1997, author = {Orgzall, Ingo and Lorenz, Bernd and Mikat, J{\"u}rgen E. R. and Dietel, Reinhard and Knochenhauer, Gerald and Schulz, Burkhard}, title = {Raman and IR spectroscopic investigation of aromatic 1,3,4-oxadiazole polymers and oligomers}, year = {1997}, abstract = {The molecular structure of poly(p-phenylene-1,3,4-oxadiazole) (POD) is investigated using i.r. and Raman spectroscopy. Both methods reveal characteristic differences for the a- and b-POD forms that are most obvious in the spectral region between 1500 and 1650 cm-1. The spectra for dimer and tetramer compounds already show the same features as found for longer chains. Based on molecular modelling calculations these differences are assigned to cis and trans conformations of the main chain segments. High pressure measurements show a linear shift of the Raman lines and support the result of the thermodynamic stability of the trans conformation.}, language = {en} } @article{LorenzOrgzallDorhoutetal.1997, author = {Lorenz, Bernd and Orgzall, Ingo and Dorhout, P. K. and Raymond, C. C. and Brister, K. and Weishaupt, K. and D'Adamo, R. and Hochheimer, H. D.}, title = {High pressure X-ray diffraction, absorption, luminescence and Raman scattering study of Cs2MoS4}, year = {1997}, language = {en} } @article{LorenzPeunOrgzall1997, author = {Lorenz, Bernd and Peun, T. and Orgzall, Ingo}, title = {Kinetic and thermodynamic investigation of cBN formation in the system BN-Mg3N2}, year = {1997}, language = {en} } @article{OrgzallLorenzMikatetal.1998, author = {Orgzall, Ingo and Lorenz, Bernd and Mikat, J{\"u}rgen E. R. and Reck, G{\"u}nter and Knochenhauer, Gerald and Schulz, Burkhard}, title = {Phase transition in 1,3,4-oxadiazole crystals under high pressure}, year = {1998}, language = {en} } @article{OrgzallLorenz1994, author = {Orgzall, Ingo and Lorenz, Bernd}, title = {Computer simulation of microstructures and geometric properties of a random system of penetrable disks : a model for compacted powders}, year = {1994}, language = {en} } @article{LorenzOrgzall1994, author = {Lorenz, Bernd and Orgzall, Ingo}, title = {Optical absorption studies of sulfur at pressure up to 20 Gpa}, year = {1994}, language = {en} } @article{OrgzallLorenzHinze1994, author = {Orgzall, Ingo and Lorenz, H. and Hinze, E.}, title = {Formation of cubic BN in the system Mg3N2-BN : some pecularities}, year = {1994}, language = {en} } @article{OrgzallLorenzHinze1994, author = {Orgzall, Ingo and Lorenz, H. and Hinze, E.}, title = {Formation of the intermediate compound Mg3BN3 in the system Mg3N2-BN}, year = {1994}, language = {en} } @article{OrgzallLorenz1994, author = {Orgzall, Ingo and Lorenz, Bernd}, title = {Kinetics of photoinduced phase transitions in sulfur below 10 Gpa}, year = {1994}, language = {en} } @article{OrgzallLorenzHinze1994, author = {Orgzall, Ingo and Lorenz, H. and Hinze, E.}, title = {Observation of cBN formation in the system Mg3N2-BN}, year = {1994}, language = {en} } @article{OrgzallLorenz1994, author = {Orgzall, Ingo and Lorenz, Bernd}, title = {Structure and fractal properties in geological crystallization processes due to nucleation and growth}, year = {1994}, 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{LorenzOrgzall1995, author = {Lorenz, Bernd and Orgzall, Ingo}, title = {Cluster shapes in the continuum description of percolating networks}, year = {1995}, language = {en} } @article{LorenzOrgzallPeun1995, author = {Lorenz, H. and Orgzall, Ingo and Peun, T.}, title = {Kinetics of fast cBN formation in the system Mg3N2-BN}, year = {1995}, language = {en} } @article{OrgzallLorenz1995, author = {Orgzall, Ingo and Lorenz, H.}, title = {Formation of cubic boron nitride in the system Mg3N2-BN : a new contribution to the phase diagram}, year = {1995}, language = {en} } @article{OrgzallLorenz1995, author = {Orgzall, Ingo and Lorenz, Bernd}, title = {On the formation of photoinduced high pressure phases in sulfur below}, year = {1995}, language = {en} } @article{OrgzallLorenzHinze1995, author = {Orgzall, Ingo and Lorenz, H. and Hinze, E.}, title = {Rapid formation of cubic boron nitride in the system Mg3N2-hBN}, year = {1995}, language = {en} } @article{OrgzallFrancoSchulz2006, author = {Orgzall, Ingo and Franco, Olga and Schulz, Burkhard}, title = {High pressure structural investigations of 2,5-di(4-pyridyl)-1,3,4-oxadiazole - importance of strain studies for the description of intermolecular interactions}, doi = {10.1088/0953-8984/18/23/001}, year = {2006}, abstract = {Results of a high pressure x-ray study of 2,5-di(4-pyridyl)-1,3,4-oxadiazole up to 2.5 GPa are presented and discussed. Parameters for the Murnaghan equation of state are derived. The bulk modulus amounts to K-0 = 4.6 +/- 0.3 GPa and its pressure derivative to K-0' = 7.4 +/- 0.6. These values are comparable to values of other diphenyl-1,3,4- oxadiazoles. The anisotropy of the compression is analysed using the strain tensor and discussed based on the anisotropy of the intermolecular interactions}, 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{EmmerlingOrgzallRecketal.2006, author = {Emmerling, Franziska and Orgzall, Ingo and Reck, G{\"u}nter and Schulz, Burkhard W. and Stockhause, Sabine and Schulz, Burkhard}, title = {Structures of substituted di-aryl-1, 3,4-oxadiazole derivatives: 2,5-bis(pyridyl)- and 2,5-bis(aminophenyl)-substitution}, series = {Journal of molecular structure}, volume = {800}, journal = {Journal of molecular structure}, number = {1-3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2006.03.076}, pages = {74 -- 84}, year = {2006}, abstract = {Crystal structures of four different di-aryl-1,3,4-oxadiazole compounds (aryl = 2-pyridyl-, 3-pyridyl-, 2-aminophenyl-, 3-aminophenyl-) are determined. Crystallization of di(2-pyridyl)-1,3,4-oxadiazole yielded monoclinic and triclinic polymorphs. The structures are characterized by the occurrence of pi-pi interactions. Additionally, in case of the aminophenyl compounds intra- as well as intermolecular hydrogen bonds are found that influence the packing motif as well. Since these molecules are often used as ligands in metal-organic complexes similarities and differences of the molecular conformation between the molecules in the pure crystals and that of the ligands in the complexes are discussed. (c) 2006 Elsevier B.V. All rights reserved.}, language = {en} } @article{MikatOrgzallSappetal.2000, author = {Mikat, J{\"u}rgen E. R. and Orgzall, Ingo and Sapp, S. and Martin, C. R. and Hochheimer, H. D.}, title = {Optical investigations of conducting polypyrrole under pressure}, year = {2000}, language = {en} } @article{MikatOrgzallLorenzetal.1999, author = {Mikat, J{\"u}rgen E. R. and Orgzall, Ingo and Lorenz, Bernd and Sapp, S. and Martin, C. R. and Burris, J. L. and Hochheimer, H. D.}, title = {High-pressure low-temperature electrical properties of template-synthesied polypyrrole at low synthesis temperature: Dimensional crossover under pressure}, year = {1999}, language = {en} } @article{OrgzallLorenzMikatetal.1999, author = {Orgzall, Ingo and Lorenz, Bernd and Mikat, J{\"u}rgen E. R. and Reck, G{\"u}nter and Knochenhauer, Gerald and Schulz, Burkhard}, title = {Phase transition in 1,3,4-oxadiazole crystals under high pressure}, year = {1999}, abstract = {Crystalline 2,5-di(4-nitrophenyl)-1,3,4-oxadiazole (DNO) has been investigated at pressures up to 5 GPa using Raman and optical spectroscopy as well as energy dispersive X-ray techniques. At ambient pressure DNO shows an orthorhombic unit cell (a = 0.5448 nm, b = 1.2758 nm, c = 1.9720 nm, density 1.513 g cm-3) with an appropriate space group Pbcn. From Raman spectroscopic investigations three phase transitions have been detected at 0.88, 1.28, and 2.2 GPa, respectively. These transitions have also been confirmed by absorption spectroscopy and X-ray measurements. Molecular modeling simulations have considerably contributed to the interpretation of the X-ray diffractograms. In general, the nearly flat structure of the oxadiazole molecule is preserved during the transitions. All subsequent structures are characterized by a stack-like arrangement of the DNO molecules. Only the mutual position of these molecular stacks changes due to the transformations so that this process may be described as a topotactical reaction. Phases II and III show a monoclinic symmetry with space group P21/c with cell parameters a = 1.990 nm, b = 0.500 nm, c = 1.240 nm, ß = 91.7°, density 1.681 g cm-3 (phase II, determined at 1. 1 GPa) and a = 1.890 nm, b = 0.510 nm, C = 1.242 nm, ß = 89.0°, density 1.733 g cm-3 (phase 111, determined at 2.0 GPa), respectively. The high-pressure phase IV stable at least up to 5 GPa shows again an orthorhombic structure with space group Pccn with corresponding cell parameters at 2.9 GPa: a = 0.465 nm, b = 1.920 nm, c = 1.230 nm and density 1.857 g cm-3 . For the first phase a blue pressure shift of the onset of absorption by about 0.032 eV GPa has been observed that may be explained by pressure influences on the electronic conjugation of the molecule. In the intermediate and high-pressure phases II-IV the onset of absorption shifts to increased wavelengths due to larger intermolecular interactions and enhanced excitation delocalization with decreasing intermolecular spacing.}, language = {en} }