@article{DolyaRojasKosmellaetal.2013, author = {Dolya, Natalya and Rojas, Oscar and Kosmella, Sabine and Tiersch, Brigitte and Koetz, Joachim and Kudaibergenov, Sarkyt}, title = {"One-Pot" in situ frmation of Gold Nanoparticles within Poly(acrylamide) Hydrogels}, series = {Macromolecular chemistry and physics}, volume = {214}, journal = {Macromolecular chemistry and physics}, number = {10}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201200727}, pages = {1114 -- 1121}, year = {2013}, abstract = {This paper focuses on two different strategies to incorporate gold nanoparticles (AuNPs) into the matrix of polyacrylamide (PAAm) hydrogels. Poly(ethyleneimine) (PEI) is used as both reducing and stabilizing agent for the formation of AuNPs. In addition, the influence of an ionic liquid (IL) (i.e., 1-ethyl-3-methylimidazolium ethylsulfate) on the stability of the nanoparticles and their immobilization in the hydrogel is investigated The results show that AuNPs surrounded by a shell containing PEI and IL, synthesized according to the one-pot approach, are much better immobilized within the PAAm hydrogel. Hereby, the IL is responsible for structural changes in the hydrogel as well as the improved stabilization and embedding of the AuNPs into the polymer gel matrix.}, language = {en} } @article{KleinpeterKoch2013, author = {Kleinpeter, Erich and Koch, Andreas}, title = {(Anti)aromaticity of dehydroannulenes of various ring size proved by the ring current effect in H-1 NMR spectra}, series = {Tetrahedron}, volume = {69}, journal = {Tetrahedron}, number = {5}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2012.12.019}, pages = {1481 -- 1488}, year = {2013}, abstract = {The spatial magnetic properties (Through-Space NMR Shieldings-TSNMRS) of already synthesized dehydro[n]annulenes of various ring size (from C-12 to C-20) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, and were examined subject to present (anti)aromaticity. For this purpose the thus quantified ring current effect of the macro cycles on proximate protons in proton NMR spectra was employed.}, language = {en} } @article{ShainyanKirpichenkoKleinpeteretal.2013, author = {Shainyan, Bagrat A. and Kirpichenko, Svetlana V. and Kleinpeter, Erich and Shlykov, Sergey A. and Osadchiy, Dmitriy Yu and Chipanina, Nina N. and Oznobikhina, Larisa P.}, title = {1,3-Dimethy1-3-silapiperidine - synthesis, molecular structure, and conformational analysis by gas-phase electron diffraction, low temperature NMR, IR and Raman Spectroscopy, and quantum chemical calculations}, series = {The journal of organic chemistry}, volume = {78}, journal = {The journal of organic chemistry}, number = {8}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/jo400289g}, pages = {3939 -- 3947}, year = {2013}, abstract = {The first Si-H-containing azasilaheterocycle, 1,3-dimethyl-3-silapiperidine 1, was synthesized, and its molecular structure and conformational properties were studied by gas-phase electron diffraction (GED), low temperature NMR, IR and Raman spectroscopy and quantum chemical calculations. The compound exists as a mixture of two conformers possessing the chair conformation with the equatorial NMe group and differing by axial or equatorial position of the SiMe group. In the gas phase, the SiMeax conformer predominates (GED: ax/eq = 65(7):35(7)\%,Delta G = 0.36(18) kcal/mol; IR: ax/eq = 62(5):38(5)\%,Delta G = 0.16(7) kcal/mol). In solution, at 143 k the SiMeeq conformer predominates' in the frozen equilibrium (NMR: ax/eq = 31.5(1.5):68.5(1.5)\%, Delta G = -0.22(2) kcal/mol). Thermodynamic parameters of the ring inversion are determined (Delta G(double dagger) = 8.9-9.0 kcal/mol, Delta H-double dagger = 9.6 kcal/mol, Delta S-double dagger = 2.1 eu). High-level quantum chemical calculations :(MP2, G2, CCSD(T)) nicely reproduce the experimental geometry and the predominance of the axial conformer in the gas phase.}, language = {en} } @article{SchmidtRiemerKarras2013, author = {Schmidt, Bernd and Riemer, Martin and Karras, Manfred}, title = {2,2 '-Biphenols via protecting group-free thermal or microwave-accelerated suzuki-miyaura coupling in water}, series = {The journal of organic chemistry}, volume = {78}, journal = {The journal of organic chemistry}, number = {17}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/jo401398n}, pages = {8680 -- 8688}, year = {2013}, abstract = {User-friendly protocols for the protecting group-free synthesis of 2,2'-biphenols via Suzuki-Miyaura coupling of o-halophenols and o-boronophenol are presented. The reactions proceed in water in the presence of simple additives such as K2CO3, KOH, KF, or TBAF and with commercially available Pd/C as precatalyst. Expensive or laboriously synthesized ligands or other additives are not required. In the case of bromophenols, efficient rate acceleration and short reaction times were accomplished by microwave irradiation.}, language = {en} } @article{DzambaskiMarkovicKleinpeteretal.2013, author = {Dzambaski, Zdravko and Markovic, Rade and Kleinpeter, Erich and Baranac-Stojanovic, Marija}, title = {2-Alkylidene-4-oxothiazolidine S-oxides - synthesis and stereochemistry}, series = {Tetrahedron}, volume = {69}, journal = {Tetrahedron}, number = {31}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2013.05.087}, pages = {6436 -- 6447}, year = {2013}, abstract = {A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.}, language = {en} } @article{MutaiHeydenreichThoithietal.2013, author = {Mutai, Peggoty and Heydenreich, Matthias and Thoithi, Grace and Mugumbate, Grace and Chibale, Kelly and Yenesew, Abiy}, title = {3-Hydroxyisoflavanones from the stem bark of dalbergia melanoxylon - isolation, antimycobacterial evaluation and molecular docking studies}, series = {Phytochemistry letters}, volume = {6}, journal = {Phytochemistry letters}, number = {4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1874-3900}, doi = {10.1016/j.phytol.2013.08.018}, pages = {671 -- 675}, year = {2013}, abstract = {Two new 3-hydroxyisoflavanones, (S)-3,4',5-trihydroxy-2',7-dimethoxy-3'-prenylisoflavanone (trivial name kenusanone F 7-methyl ether) and (S)-3,5-dihydroxy-2',7-dimethoxy-2 '',2 ''-dimethylpyrano[5 '',6 '':3',4']isoflavanone (trivial name sophoronol-7-methyl ether) along with two known compounds (dalbergin and formononetin) were isolated from the stem bark of Dalbergia melanoxylon. The structures were elucidated using spectroscopic techniques. Kenusanone F 7-methyl ether showed activity against Mycobacterium tuberculosis, whereas both of the new compounds were inactive against the malaria parasite Plasmodium falciparum at 10 mu g/ml. Docking studies showed that the new compounds kenusanone F 7-methyl ether and sophoronol-7-methyl ether have high affinity for the M. tuberculosis drug target INHA.}, language = {en} } @article{KramerKleinpeter2013, author = {Kramer, Markus and Kleinpeter, Erich}, title = {A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings}, issn = {1090-7807}, year = {2013}, language = {en} } @article{SchmidtBerger2013, author = {Schmidt, Bernd and Berger, Ren{\´e}}, title = {A deacetylation-diazotation-coupling sequence - palladium-catalyzed CC bond formation with acetanilides as formal leaving groups}, series = {Advanced synthesis \& catalysis}, volume = {355}, journal = {Advanced synthesis \& catalysis}, number = {2-3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1615-4150}, doi = {10.1002/adsc.201200929}, pages = {463 -- 476}, year = {2013}, abstract = {Acetanilides can be deacetylated and diazotized in situ, and subsequently used in Pd-catalyzed coupling reactions without isolation of the diazonium intermediate. Heck reactions, Suzuki cross-coupling reactions, and a Pd-catalyzed [2+2+1]cycloaddition have been investigated as terminating CC bond-forming steps of this one-flask sequence. The sequence does not require the exchange of solvents or removal of by-products between the individual steps, but proceeds by addition of reagents and catalysts in due course.}, language = {en} } @article{AstSchwarzeMuelleretal.2013, author = {Ast, Sandra and Schwarze, Thomas and M{\"u}ller, Holger and Sukhanov, Aleksey and Michaelis, Stefanie and Wegener, Joachim and Wolfbeis, Otto S. and K{\"o}rzd{\"o}rfer, Thomas and D{\"u}rkop, Axel and Holdt, Hans-J{\"u}rgen}, title = {A highly K+-Selective Phenylaza-[18]crown-6-Lariat-Ether-Based Fluoroionophore and its application in the sensing of K+ Ions with an optical sensor film and in cells}, series = {Chemistry - a European journal}, volume = {19}, journal = {Chemistry - a European journal}, number = {44}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201302350}, pages = {14911 -- 14917}, year = {2013}, abstract = {Herein, we report the synthesis of two phenylaza-[18]crown-6 lariat ethers with a coumarin fluorophore (1 and 2) and we reveal that compound 1 is an excellent probe for K+ ions under simulated physiological conditions. The presence of a 2-methoxyethoxy lariat group at the ortho position of the anilino moiety is crucial to the substantially increased stability of compounds 1 and 2 over their lariat-free phenylaza-[18] crown-6 ether analogues. Probe 1 shows a high K+/Na+ selectivity and a 2.5-fold fluorescence enhancement was observed in the presence of 100 mm K+ ions. A fluorescent membrane sensor, which was prepared by incorporating probe 1 into a hydrogel, showed a fully reversible response, a response time of 150 s, and a signal change of 7.8\% per 1 mm K+ within the range 1-10 mm K+. The membrane was easily fabricated (only a single sensing layer on a solid polyester support), yet no leaching was observed. Moreover, compound 1 rapidly permeated into cells, was cytocompatible, and was suitable for the fluorescent imaging of K+ ions on both the extracellular and intracellular levels.}, language = {en} } @article{ThielZehbeRoesneretal.2013, author = {Thiel, Kerstin and Zehbe, Rolf and Roesner, Jer{\^o}m{\´e} and Strauch, Peter and Enthaler, Stephan and Thomas, Arne}, title = {A polymer analogous reaction for the formation of imidazolium and NHC based porous polymer networks}, doi = {10.1039/C2PY20947K}, year = {2013}, abstract = {A polymer analogous reaction was carried out to generate a porous polymeric network with N-heterocyclic carbenes (NHC) in the polymer backbone. Using a stepwise approach, first a polyimine network is formed by polymerization of the tetrafunctional amine tetrakis(4-aminophenyl)methane. This polyimine network is converted in the second step into polyimidazolium chloride and finally to a polyNHC network. Furthermore a porous Cu(II)-coordinated polyNHC network can be generated. Supercritical drying generates polymer networks with high permanent surface areas and porosities which can be applied for different catalytic reactions. The catalytic properties were demonstrated for example in the activation of CO2 or in the deoxygenation of sulfoxides to the corresponding sulfides.}, language = {en} } @article{ThielZehbeRoeseretal.2013, author = {Thiel, Kerstin and Zehbe, Rolf and R{\"o}ser, Jerome and Strauch, Peter and Enthaler, Stephan and Thomas, Arne}, title = {A polymer analogous reaction for the formation of imidazolium and NHC based porous polymer networks}, series = {Polymer Chemistry}, volume = {4}, journal = {Polymer Chemistry}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c2py20947k}, pages = {1848 -- 1856}, year = {2013}, abstract = {A polymer analogous reaction was carried out to generate a porous polymeric network with N-heterocyclic carbenes (NHC) in the polymer backbone. Using a stepwise approach, first a polyimine network is formed by polymerization of the tetrafunctional amine tetrakis(4-aminophenyl)methane. This polyimine network is converted in the second step into polyimidazolium chloride and finally to a polyNHC network. Furthermore a porous Cu(II)-coordinated polyNHC network can be generated. Supercritical drying generates polymer networks with high permanent surface areas and porosities which can be applied for different catalytic reactions. The catalytic properties were demonstrated for example in the activation of CO2 or in the deoxygenation of sulfoxides to the corresponding sulfides.}, language = {en} } @misc{ThielZehbeRoeseretal.2013, author = {Thiel, Kerstin and Zehbe, Rolf and Roeser, Jer{\^o}m{\´e} and Strauch, Peter and Enthaler, Stephan and Thomas, Arne}, title = {A polymer analogous reaction for the formation of imidazolium and NHC based porous polymer networks}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95118}, pages = {1848 -- 1856}, year = {2013}, abstract = {A polymer analogous reaction was carried out to generate a porous polymeric network with N-heterocyclic carbenes (NHC) in the polymer backbone. Using a stepwise approach, first a polyimine network is formed by polymerization of the tetrafunctional amine tetrakis(4-aminophenyl)methane. This polyimine network is converted in the second step into polyimidazolium chloride and finally to a polyNHC network. Furthermore a porous Cu(II)-coordinated polyNHC network can be generated. Supercritical drying generates polymer networks with high permanent surface areas and porosities which can be applied for different catalytic reactions. The catalytic properties were demonstrated for example in the activation of CO2 or in the deoxygenation of sulfoxides to the corresponding sulfides.}, language = {en} } @article{InalKoelschSelrieetal.2013, author = {Inal, Sahika and K{\"o}lsch, Jonas D. and Selrie, Frank and Schenk, J{\"o}rg A. and Wischerhoff, Erik and Laschewsky, Andr{\´e} and Neher, Dieter}, title = {A water soluble fluorescent polymer as a dual colour sensor for temperature and a specific protein}, doi = {10.1039/c3tb21245a}, year = {2013}, abstract = {We present two thermoresponsive water soluble copolymers prepared via free radical statistical copolymerization of N-isopropylacrylamide (NIPAm) and of oligo(ethylene glycol) methacrylates (OEGMAs), respectively, with a solvatochromic 7-(diethylamino)-3-carboxy-coumarin (DEAC)-functionalized monomer. In aqueous solutions, the NIPAm-based copolymer exhibits characteristic changes in its fluorescence profile in response to a change in solution temperature as well as to the presence of a specific protein, namely an anti-DEAC antibody. This polymer emits only weakly at low temperatures, but exhibits a marked fluorescence enhancement accompanied by a change in its emission colour when heated above its cloud point. Such drastic changes in the fluorescence and absorbance spectra are observed also upon injection of the anti-DEAC antibody, attributed to the specific binding of the antibody to DEAC moieties. Importantly, protein binding occurs exclusively when the polymer is in the well hydrated state below the cloud point, enabling a temperature control on the molecular recognition event. On the other hand, heating of the polymer-antibody complexes releases a fraction of the bound antibody. In the presence of the DEAC-functionalized monomer in this mixture, the released antibody competitively binds to the monomer and the antibody-free chains of the polymer undergo a more effective collapse and inter-aggregation. In contrast, the emission properties of the OEGMA-based analogous copolymer are rather insensitive to the thermally induced phase transition or to antibody binding. These opposite behaviours underline the need for a carefully tailored molecular design of responsive polymers aimed at specific applications, such as biosensing.}, language = {en} } @misc{InalKoelschSellrieetal.2013, author = {Inal, Sahika and K{\"o}lsch, Jonas D. and Sellrie, Frank and Schenk, J{\"o}rg A. and Wischerhoff, Erik and Laschewsky, Andr{\´e} and Neher, Dieter}, title = {A water soluble fluorescent polymer as a dual colour sensor for temperature and a specific protein}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95336}, pages = {6373 -- 6381}, year = {2013}, abstract = {We present two thermoresponsive water soluble copolymers prepared via free radical statistical copolymerization of N-isopropylacrylamide (NIPAm) and of oligo(ethylene glycol) methacrylates (OEGMAs), respectively, with a solvatochromic 7-(diethylamino)-3-carboxy-coumarin (DEAC)- functionalized monomer. In aqueous solutions, the NIPAm-based copolymer exhibits characteristic changes in its fluorescence profile in response to a change in solution temperature as well as to the presence of a specific protein, namely an anti-DEAC antibody. This polymer emits only weakly at low temperatures, but exhibits a marked fluorescence enhancement accompanied by a change in its emission colour when heated above its cloud point. Such drastic changes in the fluorescence and absorbance spectra are observed also upon injection of the anti-DEAC antibody, attributed to the specific binding of the antibody to DEAC moieties. Importantly, protein binding occurs exclusively when the polymer is in the well hydrated state below the cloud point, enabling a temperature control on the molecular recognition event. On the other hand, heating of the polymer-antibody complexes releases a fraction of the bound antibody. In the presence of the DEAC-functionalized monomer in this mixture, the released antibody competitively binds to the monomer and the antibody-free chains of the polymer undergo a more effective collapse and inter-aggregation. In contrast, the emission properties of the OEGMA-based analogous copolymer are rather insensitive to the thermally induced phase transition or to antibody binding. These opposite behaviours underline the need for a carefully tailored molecular design of responsive polymers aimed at specific applications, such as biosensing.}, language = {en} } @phdthesis{Lemke2013, author = {Lemke, Karina}, title = {Abtrennung und Charakterisierung von Polyelektrolyt-modifizierten Nanopartikeln}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68133}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Gegenstand der Dissertation ist die gr{\"o}ßen- und eigenschaftsoptimierte Synthese und Charakterisierung von anorganischen Nanopartikeln in einer geeigneten Polyelektrolytmodifizierten Mikroemulsion. Das Hauptziel bildet dabei die Auswahl einer geeigneten Mikroemulsion, zur Synthese von kleinen, stabilen, reproduzierbaren Nanopartikeln mit besonderen Eigenschaften. Die vorliegende Arbeit wurde in zwei Haupteile gegliedert. Der erste Teil befasst sich mit der Einmischung von unterschiedlichen Polykationen (lineares Poly (diallyldimethylammoniumchlorid) (PDADMAC) und verzweigtes Poly (ethylenimin) (PEI)) in verschiedene, auf unterschiedlichen Tensiden (CTAB - kationisch, SDS - anionisch, SB - zwitterionisch) basierenden, Mikroemulsionssysteme. Dabei zeigt sich, dass das Einmischen der Polykationen in die Wassertr{\"o}pfchen der Wasser-in-{\"O}l (W/O) Mikroemulsion prinzipiell m{\"o}glich ist. Der Einfluss der verschiedenen Polykationen auf das Phasenverhalten der W/O Mikroemulsion ist jedoch sehr unterschiedlich. In Gegenwart des kationischen Tensids f{\"u}hren die repulsiven Wechselwirkungen mit den Polykationen zu einer Destabilisierung des Systems, w{\"a}hrend die ausgepr{\"a}gten Wechselwirkungen mit dem anionischen Tensid in einer deutlichen Stabilisierung des Systems resultieren. F{\"u}r das zwitterionische Tensid f{\"u}hren die moderaten Wechselwirkungen mit den Polykationen zu einer partiellen Stabilisierung. Der zweite Teil der Arbeit besch{\"a}ftigt sich mit dem Einsatz der unterschiedlichen, Polyelektrolyt- modifizierten Mikroemulsionen als Templatphase f{\"u}r die Herstellung verschiedener, anorganischer Nanopartikel. Die CTAB-basierte Mikroemulsion erweist sich dabei als ungeeignet f{\"u}r die Herstellung von CdS Nanopartikeln, da zum einen nur eine geringe Toleranz gegen{\"u}ber den Reaktanden vorhanden ist (Destabilisierungseffekt) und zum anderen das Partikelwachstum durch den Polyelektrolyt-Tensid-Film nicht ausreichend begrenzt wird. Zudem zeigt sich, dass eine Abtrennung der Partikel aus der Mikroemulsion nicht m{\"o}glich ist. Die SDS-basierten Mikroemulsionen, erweisen sich als geeignete Templatphase zur Synthese kleiner anorganischer Nanopartikel (3 - 20 nm). Sowohl CdS Quantum Dots, als auch Gold Nanopartikel konnten erfolgreich in der Mikroemulsion synthetisiert werden, wobei das verzweigte PEI einen interessanten Templat-Effekt in der Mikroemulsion hervorruft. Als deutlicher Nachteil der SDS-basierten Mikroemulsionen offenbaren sich die starken Wechselwirkungen zwischen dem Tensid und den Polyelektrolyten w{\"a}hrend der Aufarbeitung der Nanopartikel aus der Mikroemulsion. Dabei erweist sich die Polyelektrolyt-Tensid-Komplexbildung als hinderlich f{\"u}r die Redispergierung der CdS Quantum Dots in Wasser, so dass Partikelaggregation einsetzt. Die SB-basierten Mikroemulsionen erweisen sich als g{\"u}nstige Templatphase f{\"u}r die Bildung von gr{\"o}ßen- und eigenschaftenoptimierten Nanopartikeln (< 4 nm), wobei insbesondere eine Modifizierung mit PEI als ideal betrachtet werden kann. In Gegenwart des verzweigten PEI gelang es erstmals ultrakleine, fluoreszierende Gold Cluster (< 2 nm) in einer SB-basierten Mikroemulsion als Templatphase herzustellen. Als besonderer Vorteil der SB-basierten Mikroemulsion zeigen sich die moderaten Wechselwirkungen zwischen dem zwitterionischen Tensid und den Polyelektrolyten, welche eine anschließende Abtrennung der Partikel aus der Mikroemulsion unter Erhalt der Gr{\"o}ße und ihrer optischen Eigenschaften erm{\"o}glichen. In der redispergierten w{\"a}ssrigen L{\"o}sung gelang somit eine Auftrennung der PEI-modifizierten Partikel mit Hilfe der asymmetrischer Fluss Feldflussfraktionierung (aF FFF). Die gebildeten Nanopartikel zeigen interessante optische Eigenschaften und k{\"o}nnen zum Beispiel erfolgreich zur Modifizierung von Biosensoren eingesetzt werden.}, language = {de} } @misc{LiBabuTurneretal.2013, author = {Li, Hongguang and Babu, Sukumaran Santhosh and Turner, Sarah T. and Neher, Dieter and Hollamby, Martin J. and Seki, Tomohiro and Yagai, Shiki and Deguchi, Yonekazu and M{\"o}hwald, Helmuth and Nakanishi, Takashi}, title = {Alkylated-C60 based soft materials}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95358}, pages = {1943 -- 1951}, year = {2013}, abstract = {Derivatization of fullerene (C60) with branched aliphatic chains softens C60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84 °C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 ± 0.1\%) in comparison with another compound, 10 (PCE: 0.5 ± 0.1\%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices.}, language = {en} } @article{LiBabuTurneretal.2013, author = {Li, Hongguang and Babu, Sukumaran Santhosh and Turner, Sarah T. and Neher, Dieter and Hollamby, Martin J. and Tomohito, Seki and Yagai, Shiki and deguchi, Yonekazu and M{\"o}hwald, Helmuth and Nakanishi, Takashi}, title = {Alkylated-C60 based soft materials: regulation of self-assembly and optoelectronic properties by chain branching}, doi = {10.1039/C3TC00066D}, year = {2013}, abstract = {Derivatization of fullerene (C60) with branched aliphatic chains softens C60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84°C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 {\~n} 0.1\%) in comparison with another compound, 10 (PCE: 0.5 {\~n} 0.1\%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices.}, language = {en} } @article{FischerSchmidtStrauchetal.2013, author = {Fischer, Sabrina and Schmidt, Johannes and Strauch, Peter and Thomas, Arne}, title = {An anionic microporous polymer network prepared by the polymerization of weakly coordinating anions}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {52}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, number = {46}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201303045}, pages = {12174 -- 12178}, year = {2013}, language = {en} } @phdthesis{Kroener2013, author = {Kr{\"o}ner, Dominik}, title = {Analysis and control of light-induced processes in molecules: Electron and nuclear quantum dynamics for aspects of stereoisomerism and spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70477}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The habilitation thesis covers theoretical investigations on light-induced processes in molecules. The study is focussed on changes of the molecular electronic structure and geometry, caused either by photoexcitation in the event of a spectroscopic analysis, or by a selective control with shaped laser pulses. The applied and developed methods are predominantly based on quantum chemistry as well as on electron and nuclear quantum dynamics, and in parts on molecular dynamics. The studied scientific problems deal with stereoisomerism and the question of how to either switch or distinguish chiral molecules using laser pulses, and with the essentials for the simulation of the spectroscopic response of biochromophores, in order to unravel their photophysics. The accomplished findings not only explain experimental results and extend existing approaches, but also contribute significantly to the basic understanding of the investigated light-driven molecular processes. The main achievements can be divided in three parts: First, a quantum theory for an enantio- and diastereoselective or, in general, stereoselective laser pulse control was developed and successfully applied to influence the chirality of molecular switches. The proposed axially chiral molecules possess different numbers of "switchable" stable chiral conformations, with one particular switch featuring even a true achiral "off"-state which allows to enantioselectively "turn on" its chirality. Furthermore, surface mounted chiral molecular switches with several well-defined orientations were treated, where a newly devised highly flexible stochastic pulse optimization technique provides high stereoselectivity and efficiency at the same time, even for coupled chirality-changing degrees of freedom. Despite the model character of these studies, the proposed types of chiral molecular switches and, all the more, the developed basic concepts are generally applicable to design laser pulse controlled catalysts for asymmetric synthesis, or to achieve selective changes in the chirality of liquid crystals or in chiroptical nanodevices, implementable in information processing or as data storage. Second, laser-driven electron wavepacket dynamics based on ab initio calculations, namely time-dependent configuration interaction, was extended by the explicit inclusion of magnetic field-magnetic dipole interactions for the simulation of the qualitative and quantitative distinction of enantiomers in mass spectrometry by means of circularly polarized ultrashort laser pulses. The developed approach not only allows to explain the origin of the experimentally observed influence of the pulse duration on the detected circular dichroism in the ion yield, but also to predict laser pulse parameters for an optimal distinction of enantiomers by ultrashort shaped laser pulses. Moreover, these investigations in combination with the previous ones provide a fundamental understanding of the relevance of electric and magnetic interactions between linearly or non-linearly polarized laser pulses and (pro-)chiral molecules for either control by enantioselective excitation or distinction by enantiospecific excitation. Third, for selected light-sensitive biological systems of central importance, like e.g. antenna complexes of photosynthesis, simulations of processes which take place during and after photoexcitation of their chromophores were performed, in order to explain experimental (spectroscopic) findings as well as to understand the underlying photophysical and photochemical principles. In particular, aspects of normal mode mixing due to geometrical changes upon photoexcitation and their impact on (time-dependent) vibronic and resonance Raman spectra, as well as on intramolecular energy redistribution were addressed. In order to explain unresolved experimental findings, a simulation program for the calculation of vibronic and resonance Raman spectra, accounting for changes in both vibrational frequencies and normal modes, was created based on a time-dependent formalism. In addition, the influence of the biochemical environment on the electronic structure of the chromophores was studied by electrostatic interactions and mechanical embedding using hybrid quantum-classical methods. Environmental effects were found to be of importance, in particular, for the excitonic coupling of chromophores in light-harvesting complex II. Although the simulations for such highly complex systems are still restricted by various approximations, the improved approaches and obtained results have proven to be important contributions for a better understanding of light-induced processes in biosystems which also adds to efforts of their artificial reproduction.}, language = {en} } @article{KeruboMidiwoDereseetal.2013, author = {Kerubo, Leonidah Omosa and Midiwo, Jacob Ogweno and Derese, Solomon and Langat, Moses K. and Akala, Hoseah M. and Waters, Norman C. and Peter, Martin and Heydenreich, Matthias}, title = {Antiplasmodial activity of compounds from the surface exudates of senecio roseiflorus}, series = {Natural product communications : an international journal for communications and reviews}, volume = {8}, journal = {Natural product communications : an international journal for communications and reviews}, number = {2}, publisher = {NPC}, address = {Westerville}, issn = {1934-578X}, pages = {175 -- 176}, year = {2013}, abstract = {From the surface exudates of Senecio roseiflorus fourteen known methylated flavonoids and one phenol were isolated and characterized. The structures of these compounds were determined on the basis of their spectroscopic analysis. The surface exudate and the flavonoids isolated showed moderate to good antiplasmodial activity with 5,4'-dihydroxy-7-dimethoxyflavanone having the highest activity against chloroquine-sensitive (D6) and resistant (W2) strains of Plasmodium falciparum, with IC50 values of 3.2 +/- 0.8 and 4.4 +/- 0.01 mu g/mL respectively.}, language = {en} }