Helmut Ringsdorf, a luminary in polymer chemistry and the father of modern drug delivery systems, was not directly connected to the WHO Task Force on Vaccines for Fertility Regulation—but let’s imagine if he had been. Known for his groundbreaking work in designing polymers that could carry drugs to specific targets in the body, Ringsdorf would have been the perfect mad scientist to turbocharge the Task Force’s efforts.
Picture this: Ringsdorf, clad in a lab coat that somehow always had an ink stain, walks into a WHO meeting in the 1970s. He slams down a beaker of some mysterious polymer cocktail and declares, “Forget diphtheria toxoid! Let’s encapsulate anti-HCG molecules in biodegradable microspheres that release over six months. Boom! Pregnancy-proof for half a year!” The room gasps. Someone faints. A junior scientist spills coffee on their notes.
Ringsdorf’s theoretical involvement would have turned the Task Force into something out of a sci-fi movie. His expertise in molecular targeting could have led to vaccines so precise they’d make your immune system think it had a Ph.D. in reproductive biology. Need to block sperm enzymes? There’s a polymer for that. Want to neutralize placental hormones? Ringsdorf’s got you covered with a time-release nanoparticle.
Of course, Ringsdorf’s actual career was far more grounded (and ethical). He focused on advancing cancer treatments and drug delivery systems rather than dabbling in fertility regulation. But imagining him as part of this Task Force is like casting Einstein in a buddy cop movie—it doesn’t make sense, but it’s fun to think about.
Oops! According to his wikipedia page, Helmut was a Member of the World Health Organization‘s Committee on Fertility Regulation 1978–1984
Helmut Ringsdorf, the polymath of polymer chemistry, had a surprising detour in his illustrious career: serving as a member of the World Health Organization’s Committee on Fertility Regulation from 1978 to 1984. While most of his life was dedicated to designing polymers that could deliver drugs with pinpoint precision, his role on this committee suggests he briefly moonlighted as a fertility guru—because why not?
Imagine Ringsdorf walking into WHO meetings, armed with diagrams of molecular architectures and amphiphilic polymers, while the rest of the committee debated HCG vaccines and ethical quandaries. Did he propose polymer-based contraceptives? Did he sketch out liquid crystalline sperm blockers on a cocktail napkin? We’ll never know—but it’s fun to think about.
Ringsdorf’s connection to the committee was likely rooted in his expertise in biomembrane processes and molecular recognition. His research on synthetic receptors and functional polymers could have offered insights into how immunological approaches to fertility regulation might work. But let’s be honest: picturing a man who pioneered drug delivery systems sitting in meetings about sperm enzymes and placental hormones is hilariously incongruous.
Ultimately, Ringsdorf returned to his true calling—polymers—and left fertility regulation behind. His brief stint with WHO remains a quirky footnote in the career of a scientist who otherwise spent his days making molecules behave like tiny geniuses.
Other Notes
Helmut Ringsdorf (1929-2023) in Gießen, Germany is a German polymer chemist. His work has promoted cross-disciplinary discussions and collaborations in the field of polymerchemistry, biology, physics and medicine. Ringsdorf’s major research works deal with the self-assembly of polymers into functional aggregates, where ‘the whole is more than the sum of its parts’. He is known for being the first to propose covalently bonding drugs to water-soluble polymers.[1] (Wikipedia Helmut Ringsdorf page)
Memberships
1999 Russian Academy of Science, Moscow Foreign Member
1998– Conseil National de La Science, Ministere de l’Education, de la Rescherche et de la Technologie Member Advisory Board, Paris
1991 Nordrh.-Westf. Academy of Science Corresponding Member
1990–1993 German Fonds der Chemie Scientific Committee
1989–1994 Committee Scientifique, Paris Member
1985–1992 Academy of Science, Berlin/DDR Foreign Member
1979 Academy of Sciences and Literature, Mainz Member
1978–1984 Member of the World Health Organization‘s Committee on Fertility Regulation
1976–1989 DAAD (German Academic Exchange Service) Committee for Scientific Exchange
1976–1979 German Fonds der Chemie Scientific Committee
1971–1976 A. von Humboldt Foundation Member Foundation Committee
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So there is one dude in all of google who was maybe a member of something called “World Health Organization’s Committee on Fertility Regulation” and that can’t be right. There was a group or there wasn’t but a group indicates more than one person.
Research interests
Field of Expertise & Research Interests: Polymer Science as a Bridge between Material Science and Life Science.
Molecular Architecture and Functionalization of Polymeric Liquid Crystals: Synthesis, structure and property of liquid crystalline side group and main chain polymers; variation of the type of mesogens (rods, discs, boards) and variation of phases. Dye containing and photoreactive liquid crystalline polymers for reversible information storage and non linear optic materials. Phase induction and phase variation of liquid crystalline systems via Charge-Transfer-interaction and metal complexation. Photoconductive discotic systems.
Synthesis, Structure and Properties of Functional Supramolecular Systems: Polymerizable and functional amphiphiles (detergents, lipids), polymeric monolayers and multilayers via the Langmuir-Blodgett technique and via self-assembly on various surfaces. Liposomes, Black Lipid Membranes, mobile supported bilayers, H-bond induced band structures in water, organization and recognition induced functionality. Multicompartment polymer micelles.
Attempts to Mimic Biomembrane Processes: Synthetic and natural receptors in molecular assemblies; molecular recognition, 2D-crystallization and function of proteins on monolayers and liposomes, e.g. lectins, streptavidin, monoclonal antibodies, phospholipase A2 and acetylcholinesterase, tailoring of bioreactive surfaces; mixed protein multilayers. Protein–DNA-interaction at ligand lipid monolayers.
Polymers as Active Agents in the Medical Field: Polymer Therapeutics, Polymer radiation prophylactics, polymeric antitumour agents on a molecular and a cellular level.
References
- Ringsdorf, Helmut (1975). “Structure and properties of pharmacologically active polymers”. Journal of Polymer Science: Polymer Symposia. 51 (1): 135–153. doi:10.1002/polc.5070510111.
- Helmut Ringsdorf” (PDF). Humboldt University of Berlin. Retrieved 7 December 2010.
- “Laudatio for Prof. Dr. Helmut Ringsdorf on occasion of the award of the Alfred Saupe Preis 2010” (PDF) (in German and English). University of Magdeburg. Archived from the original (PDF) on 6 June 2011. Retrieved 7 December 2010.
https://en.wikipedia.org/wiki/Helmut_Ringsdorf (that page was last edited on 2 February 2022, at 17:51 (UTC))
Griffin PD. The WHO Task Force on Vaccines for Fertility Regulation. Its formation, objectives and research activities. Hum Reprod. 1991 Jan;6(1):166-72. doi: 10.1093/oxfordjournals.humrep.a137252. PMID: 1874951 which says:
Over the past 18 years, the WHO Task Force on Vaccines for Fertility Regulation has been supporting basic and clinical research on the development of birth control vaccines directed against the gametes or the preimplantation embryo. These studies have involved the use of advanced procedures in peptide chemistry, hybridoma technology and molecular genetics as well as the evaluation of a number of novel approaches in general vaccinology. As a result of this international, collaborative effort, a prototype anti-HCG vaccine is now undergoing clinical testing, raising the prospect that a totally new family planning method may be available before the end of the current decade.
PIP: The WHO Task Force on Vaccines for Fertility Regulation is one of several Task Forces, consisting of international, multidisciplinary groups of scientists and clinicians collaborating in research on specific goals, established in 1972. Its accomplishments are reviewed here. The Task Force convened a meeting in 1974 to select criteria for tissues and molecules capable of mounting antifertility responses. These molecules had to be restricted to the target tissue, sequestered in the reproductive tract, present transiently, and chemically characterized. Some of the antigens considered were sperm enzymes and membranes, as well as a data bank of sera naturally immunized against sperm. Other were anti-ovum and placenta molecules such as zona pellucida, the SP-1 placental antigen, and the placental hormones chorionic somatotrophin and human chorionic gonadotropin (hCH). Trophoblast-derived monoclonal antibodies and gene libraries are being screened. Anti-hCH is the vaccine composed of a portion of the beta subunit complexed to a carrier antigen, diphtheria toxoid, in a water- oil emulsion with an adjuvant has been tested in a phase I clinical trial in 1986-1988. A Phase II trial is being planned to see if the immune response in women is large enough to be capable of preventing pregnancy. Further improvements in the vaccine are being envisioned, such as incorporation of the peptide carrier conjugate and immune stimulant into biodegradable microspheres, hopefully to produce a longer-lasting immunity and a more stable vaccine. While the WHO Task Force on Vaccines for Fertility Regulation has been forced to cut back on some avenues of research, its success has stimulated other centers to take up several important projects, e.g. the sperm LDH and zona pellucida vaccines.
I looked up Helmut Ringsdorf articles at one of the places I frequently haunt and found five or six but ResearchGate has hundreds so…
Helmut Ringsdorf’s research while affiliated with Johannes Gutenberg-Universität Mainz and other places
Publications (349)
Structure and order of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene as revealed by diffraction and molecular simulation studies
Article
Jun 2010
TAO WANG
DONGHANG YAN
Jun Luo[…]
H. RINGSDORF
The aggregate structure of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene (HPT) was studied both for the crystalline state and the liquid crystalline state by using electron crystallography and a molecular simulation approach. In the crystalline state, HPT was found to adopt an orthorhombic P22 1 2 space group with cell parameters…
ChemInform Abstract: Thermally Irreversible Photochromic Liquid Crystal Polymers.
Article
Apr 2010
Ivan Cabrera
Achim Dittrich
Helmut Ringsdorf
Polymer therapeutics: Clinical applications and challenges for development
Article
Sep 2009
María J Vicent
Helmut Ringsdorf
Ruth Duncan
Donor-acceptor substituted polyenes
Article
Jan 2009
Christoph Bubeck
Franz Effenberger
Lukas Häußling[…]
Helmut Ringsdorf
Large molecules containing different chemical units whose interactions within the molecule result in new macroscopically observable effects, have become increasingly important.The organization of molecules of this type in ordered structures leads to functional molecular materials.Their use in molecular electronics requires that the units exhibit sp…
Preface: Polymer Science and Polymer Therapeutics: Macromolecules, Dendrimers and Nanomedicine
Article
Feb 2008
Maria Micha-Screttas
Helmut Ringsdorf
Ringsdorf, H.: Structure and properties of pharmacologically active polymers. J. Polym. Sci. Polym. Symp. 51, 135-153
Article
Mar 2007
Helmut Ringsdorf
Although the concept of using pharmacologically active macromolecular compounds as drugs is still regarded with much skepticism for both theoretical and practical reasons, interest in this field has grown in recent years because of the opportunity to take advantage of the specific properties of polymeric materials. For low molecular weight drugs, c…
Tradition and innovation in science
Article
Nov 2006
Helmut Ringsdorf
Carlo-Lorentz Mertesdorf
A Commentary on the paper ”Self‐organization of substituted azacrowns based on their discoid and amphiphilic nature„, by C. Mertesdorf and H. Ringsdorf. First published in Liquid Crystals, 5, 1757‐1772 (1989).
Polymer therapeutics: Polymers as drugs, drug and protein conjugates and gene delivery systems: Past, present and future opportunities
Article
Aug 2006
Ruth Duncan
Helmut Ringsdorf
Ronit Satchi-Fainaro
As the 21st century begins we are witnessing a paradigm shift in medical practice. Whereas the use of polymers in biomedical materials applications – for example, as prostheses, medical devices, contact lenses, dental materials and pharmaceutical excipients – is long established, polymer-based medicines have only recently entered routine clinical p…
Schwarze Lipidmembranen aus polymerisierbaren Lipiden
Article
May 2006
Roland Benz
Werner Praß
Helmut Ringsdorf
Das vollständige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1982, 869. DOI: 10.1002/ange.198208690
Rotation von polymerisierten Vesikeln im elektrischen Wechselfeld
Article
Feb 2006
Hans-Henning Hub
Helmut Ringsdorf
Ulrich Zimmermann
Polymere Modellmembranen
Article
Jan 2006
Akira Akimoto
Klaus Dorn
Leo Gros[…]
Hans Schupp
Die Stabilisierung synthetischer Membranen durch Polymerisation gelingt – je nach Monomer – unter Erhaltung der Kopfgruppeneigenschaften (a–c) oder unter Erhaltung der Kettenbeweglichkeit (d). Der Punkt symbolisiert die Kopfgruppe, das Kreuz die polymerisierbare Gruppe. Für alle vier Fälle gibt es Beispiele
Liposomen aus polymerisierbaren Glycolipiden
Article
Jan 2006
Hubert Bader
Helmut Ringsdorf
Josef Skura
Hermann Staudinger and the Future of Polymer Research Jubilees—Beloved Occasions for Cultural Piety
Article
Feb 2004
Helmut Ringsdorf
Chemistry was his life, but Hermann Staudinger’s dreams belonged to biology and to the unity of chemistry and biology. That is the central theme of this Essay,which, on the occasion of the fiftieth anniversary of the award of the Nobel Prize to Hermann Staudinger, discusses the significance of Staudinger’s discoveries for the biosciences, not only…
Hermann Staudinger und die Zukunft der Polymerforschung Jubiläumsfeiern – selbstbestimmter Anlass kultureller Frömmigkeit
Article
Feb 2004
Helmut Ringsdorf
Liquid crystalline side chain polymers and their behaviour in the electric field
Article
Mar 2003
Helmut Ringsdorf
Rudolf Zentel
The electro-optical properties of liquid crystalline polymers with polar mesogenic units in the side chain were investigated. It could be shown, that in an electric field, they show all effects known from low molecular weight liquid crystals, e.g. the Freedericksz-transition, the DAP-effect, the formation of William’s domain, and the dynamic scatte…
Nonlinear optical self diffraction in a mesogenic side chain polymer
Article
Mar 2003
Manfred Eich
Joachim H. Wendorff
Helmut Ringsdorf
Hans W. Schmidt
Nonlinear optical self diffraction effects for a light beam in a liquid crystalline polymer in its isotropic fluid state was observed. This effect is characterized by the absence of a threshold intensity, a diffraction pattern that does not depend on the polarization of the reading beam relative to that of the writing beam and which cannot be distu…
Highly oriented discotic elastomers
Article
Mar 2003
Holger Bengs
Heino Finkelmann
Juergen Kuepfer[…]
Peter Schuhmacher
X‐ray investigations of liquid‐crystalline polysiloxanes with paired mesogens
Article
Mar 2003
Siegmar Diele
Bernd Hisgen
Bernd Reck
Helmut Ringsdorf
Synthesis, structure, and phase behaviour of liquid‐crystalline rigid‐rod polyesters and polyamides with disc‐like mesogens in the main chain
Article
Mar 2003
Helmut Ringsdorf
Peter Tschirner
Otto Hermann-Schönherr
Joachim H. Wendroff
Aromatic polyesters and polyamides with disc-like mesogens in the main chain were prepared from tetra-substituted hydroquinones and derivatives of 1,4-phenylenediamine. Depending on the atomatic acids (terephthalic acid, 2,5-dialkoxyterephthalic acid) used in the condensation reaction, the repeating units of these polymers carried 4 or 6 lateral su…
Polyreactions in oriented systems, 30. Mixed monolayers and liposomes from natural and polymerizable lipids
Article
Mar 2003
Rainer Büschl
Bernd Hupfer
Helmut Ringsdorf
Photoreactive chiral liquid‐crystalline side‐group copolymers containing azobenzene mesogens
Article
Mar 2003
Helmut Ringsdorf
Claus Urban
Wolfgang Knoll
Michael Sawodny
A series of liquid-crystalline copolymers 1 with a chiral azobenzene moiety as photoreactive mesogenic unit was prepared. The polymers were fractionated and the mesophase behaviour of the high- and low-molecular weight fractions was examined. The copolymers display smectic A and cholesteric phases. For the cholesteric phases the pitch of the helix…
Synthesis and characterization of liquid‐crystalline copolymers with dichroic dyes and mesogens as side groups
Article
Mar 2003
Helmut Ringsdorf
Hans-Werner Schmidt
Heinz Eilingsfeld
Karl-Heinz Etzbach
Liquid-crystalline copolymers with covalently attached dichroic dyes were synthesized and characterized. Copolymers with high anthraquinone and trisazo-dye content were obtained by copolymerization of dye monomers with 4-cyanophenyl 4-(6-acryloyloxyhexyloxy)benzoate (1) and 6-acryloyloxyhexyl 4-(trans-4-propylcyclohexyl)benzoate (2). Particular att…
Pharmacologically active polymers, 11. Polymeric sulfonamides as potential antibacterials and carriers for antitumor agents
Article
Mar 2003
Volker Hofmann
Michael Przybylski
Helmut Ringsdorf
Helmut Ritter
A number of acryl and methacryl derivatives of different sulfanilamides (1a—I) were prepared and polymerized. The fixation of the sulfonamide to the polymerizable group was carried out directly, using the acryl- and methacrylamides, and by means of spacer groups, to favour the enzymatic or hydrolytic release of the drug moiety. Selected sulfonamide…
Liquid Crystalline Polymers with Disc-Like Mesogens
Article
Mar 2003
Willi Kreuder
Helmut Ringsdorf
Bis(2‐chloroethyl)amine bound to copolymers of N‐(2‐hydroxypropyl)methacrylamide and methacryloylated oligopeptides via biodegradable bonds
Article
Mar 2003
Helmut Ringsdorf
Brigitta Schmidt
Karel Ulbrich
Drug carriers were prepared by combining oligopeptidic sequences with synthetic polymeric chains. Soluble copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) were synthesized containing oligopeptidic side chains terminating in a drug model (p-nitroaniline). The susceptibility of these oligopeptidic sequences to degradation on incubation with lys…
Pharmacologically active polymers, 6. Sulfadiazine and boron derivatives as potential carriers for polymers into cancer tissue
Article
Mar 2003
Juan Bartulin
Michael Przybylski
Helmut Ringsdorf
Helmut Ritter
Liquid crystalline polymers with disc‐like mesogens in the main chain
Article
Mar 2003
Willi Kreuder
Helmut Ringsdorf
Peter Tschirner
Catalytic effects of cationic polymeric liposomes on the alkaline hydrolysis of aniomic phenyl esters
Article
Mar 2003
Hiromi Kitano
Makoto Katsukawa
Norio Ise[…]
Helmut Ringsdorf
Alkaline hydrolyses of anionic phenyl esters such as 4-acetoxy-3-nitrobenzoic acid and 4-butyryloxy-3-nitrobenzoic acid were examined in the presence of cationic and polymeric liposomes, liposomes of low molecular weight compounds, and micelles. All the additives accelerate the reaction due to the hydrophobic interaction between substrates and addi…
Thermal reactions of amphotropic copolymers studied by thermogravimetry and temperature‐resolved pyrolysis‐field ionization mass spectrometry
Article
Mar 2003
Bernd Plage
Hans-Rolf Schulten
Helmut Ringsdorf
Andreas Schuster
The thermal degradation mechanisms of amphiphilic acrylic copolymers containing mesogenic pyrimidine side chains and hydrophilic 2-hydroxyethyl acrylate (HEA) main-chain spacer units were investigated by thermogravimetry (TG) and pyrolysis-field ionization mass spectrometry (Py-FIMS). The degradation behaviour of these polymers depends on the amoun…
Synthesis and phase behaviour of liquid crystalline polymers from chloroacrylates and methacrylates
Article
Mar 2003
Rudolf Zentel
Helmut Ringsdorf
The monolayer polymerization of 10,12‐nonacosadiynoic acid studied by a spectroscopic technique. Polyreactions in ordered systems, 19
Article
Mar 2003
David R. Day
Helmut Ringsdorf
Conductivity and photoconductivity of undoped and doped Langmuir‐Blodgett films of a polymer with hexaalkoxytriphenylene side‐groups
Article
Mar 2003
Christian Catry
Mark Van der Auweraer
Frans C De Schryver[…]
Helmut Ringsdorf
Langmuir-Blodgett films from a polymer with triphenylene moieties in the side groups deposited on a quartz substratum with aluminium and gold electrodes show a dark conductivity in the plane of the Langmuir-Blodgett film. This dark conductivity is increased using gold electrodes as compared with aluminium electrodes. It depends in a superlinear way…
Micelle-forming block copolymers: Pinocytosis by macrophages and interaction with model membranes
Article
Mar 2003
Margaret Pratten
John B. Lloyd
Gerhard Hörpel
Helmut Ringsdorf
A block copolymer (6) with both hydrophilic and hydrophobic regions was synthesized, in order to examine its interaction with model membranes and its uptake by living cells. The copolymer comprised poly(ethylene oxide) and poly(L-lysine) with 50 mol-% substitution of the ε-amino groups with palmitoyl groups. To permit 125I-labelling, p-methoxypheny…
Microphase separation in thermotropic liquid‐crystalline polysiloxanes with paired mesogens
Article
Mar 2003
Steffi Westphal
Siegmar Diele
Annelore Mädicke[…]
Helmut Ringsdorf
Ordered and disordered glasses: A comparison of thermodynamical and dynamical properties
Article
Mar 2003
Dietmar A. Jungbauer
Joachim H. Wendorff
Willi Kreuder[…]
Helmut Ringsdorf
Characteristic dynamical properties of the glassy state were studied for side-chain polymers in which either an isotropic glassy state or a nematic glassy state could be induced at will. The dynamical properties of such ordered and disordered glasses were found to be identical. This may indicate that the decrease of the volume taking place at the i…
Reversible Digital and Holographic Optical Storage in Polymeric Liquid Crystals
Article
Mar 2003
Manfred Eich
Joachim H. Wendorff
Bernd Reck
Helmut Ringsdorf
A new reversible optical storage technique based on azo dye containing liquid crystalline polymers and copolymers is described. Monodomain films of the polymers were used as storage medium. Digital and holographic information was stored and reconstructed. The stored information can be erased and the writing process is repeatable. The storage proces…
Interaction of amphiphilic polymers with model membranes
Article
Mar 2003
Gero Decher
Ellen Kuchinka
Helmut Ringsdorf[…]
Christoph Weisgerber
The lipid bilayers of cell membranes are usually connected to two types of biopolymers: the cytoskeleton and the glycocalix. These structures are not only responsible for the stabilization of the lipid bilayer, they also alter the surface properties of the cells. Among the various attempts to mimick membrane properties using polymeric systems(1), o…
Combined liquid-crystalline polymers: Rigid rod and semiflexible main chain polyesters with lateral mesogenic groups
Article
Mar 2003
Bernd Reck
Helmut Ringsdorf
ESR investigations of γ‐irradiated sulfur‐containing vinylpolymers
Article
Mar 2003
Hans Mönig
Helmut Ringsdorf
The formation and behaviour of radiation-induced free radicals in statistical copolymers of ethoxyvinylthiomethane (1a) with N-vinylpyrrolidone (2) (1:2,5) and of ethylthiovinylthiomethane (1b) with 2 (1:3,5) has been studied using electron spin resonance spectroscopy. After a γ-irradiation of the copolymers at 77K Cα-radicals in the vinylpyrrolido…
Polymeric derivatives of activated cyclophosphamide as drug delivery systems in antitumor chemotherapy. Pharmacologically active polymers, 20
Article
Mar 2003
Takashi Hirano
Wolfgang Klesse
Helmut Ringsdorf
Synthesis of cholesteric liquid crystalline polymers. Polyreactions in ordered systems, 15
Article
Mar 2003
Heino Finkelmann
Helmut Ringsdorf
Werner Siol
Joachim H. Wendorff
High resolution electron microscopy on sanidic liquid‐crystal polymers
Article
Mar 2003
Ingrid G. Voigt-Martin
Paul Simon
Rüdiger W. Garbella[…]
Peter Tschirner
The sanidic polyamide [NM-Ph(CO 2 R) 3 (CO 2 Me)-NMCO-Ph(OR) 2 CO] n (R=C 12 H 25 ) is studied. It is shown that this polymer has a biaxial structure with quasi 2-D long range translational correlations. The correlations in one direction are limited by the length of the molecule. The oriented regions are separated by regions in which the molecules…
Electro‐optical effects of azo dye containing liquid crystalline copolymers
Article
Mar 2003
Helmut Ringsdorf
Hans‐Werner Schmidt
The synthesis and phase behaviour of azo dye containing liquid crystalline side group copolymers are described. These Copolymers show the same electro-optical effects as low molar mass guest-host systems. Their macroscopic oriented nematic structure can be frozen in below the glass transition temperature resulting in a polymer film with dichroic pr…
Polymerization of liposome‐encapsulated hydrophilic monomers
Article
Mar 2003
Vladimir P. Torchilin
Alexander L. Klibanov
Nikolay N. Ivanov[…]
Bernhard Schlarb
Polyreactions in oriented systems, 22. Topochemical polymerization of a diacetylene sulfolipid analog in monolayers and liposomes
Article
Mar 2003
Horst Koch
Helmut Ringsdorf
Pharmacologically active polymers, 7. Cyclophosphamide‐ and steroidhormone containing polymers as potential anticancer compounds
Article
Mar 2003
Hans G. Batz
Helmut Ringsdorf
Helmut Ritter
A number of acrylic and methacrylic esters and N-vinyl monomers of cyclophosphamide- and testosterone derivatives were prepared. The monomers were homopolymerized and copolymerized with hydrophilic monomers to yield watersoluble products.Es wurden Acryl-, Methacryl- und N-Vinyl-Derivate von Cyclophosphamid- und Testosteron-Derivaten synthetisiert….
Combined liquid‐crystalline polymers: Rigid‐rod type main‐chain polyester with lateral mesogenic groups
Article
Mar 2003
Bernd Reck
Helmut Ringsdorf
Kenncorwin Gardner
Howard Starkweather Jr
A series of combined main-chain side-group liquid-crystalline polymers was synthesized by melt polycondensation from trans-1,4-cyclohexanedicarboxylic acid, chloro-1,4-phenylene diacetate and 6-(4-methoxy-4′-biphenylyloxy)hexyl-1,4-phenylene diacetate. These polyesters combine the features of rigid-rod main-chain LC-polymers and of side-group LC-po…
Synthesis and phase behaviour of liquid crystalline polyacrylate
Article
Mar 2003
Michael Portugall
Helmut Ringsdorf
Rudolf Zentel
The synthesis and phase behaviour of a series of polymers having liquid crystalline sidechains and a poly(acrylic acid) backbone are described. These polymers show a dependence of the phase transition temperatures on molecular weight. In copolymers of two liquid crystalline acrylic esters, induced smectic phases occur. A comparison of the phase tra…
Pharmacologically active polymers, 17. Syntheses and characterization of polymeric derivatives of the antitumor agent methotrexate
Article
Mar 2003
Michael Przybylski
Elke Fell
Helmut Ringsdorf
Daniel S. Zaharko
Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3…
Preparation and characterization of unsymmetrical “liposomes in a net”
Article
Mar 2003
Helmut Ringsdorf
Bernhard Schlarb
Negatively charged lipid molecules were converted into polymerizable lipids by introduction of polymerizable mono- or bifunctional counterions. As an attempt to mimic the cytoskeleton of biomembranes, unsymmetrical polymeric vesicles were prepared, where the polyelectrolyte is attached either only to the inner or to the outer bilayer surfaces. Poly…
Structural Variations of Liquid-Crystalline Polymers: Cross-Shaped and Laterally linked Mesogens in Main Chain and Side Group Polymers
Article
Mar 2003
Sibylle Berg
Volker Krone
Helmut Ringsdorf
Ionic thermotropic liquid crystals formed by monomeric dipolar and polymeric multipolar amphiphiles with pyridinium head groups
Article
Mar 2003
Volker Hessel
Helmut Ringsdorf
Reinhard Festag
Joachim H. Wendorff
The synthesis and the thermotropic phase behavior of the dipolar amphiphiles C 5 H 5 N + (CH 2 ) m OCOPhPHCOO(CH 2 ) m N + C 5 H 5 and the polymeric amphiphile [(CH 2 ) 6 OPhPhO(CH 2 ) 6 OCOCH([CH 2 ] 6 N + C 5 H 5 )COO] n are described
Molecular weight of polymers from methacryloyl lipids in bilayer membranes
Article
Mar 2003
Klaus Dorn
Elizabeth V. Patton
Richard T. Klingbiel[…]
Helmut Ringsdorf
Structure and dynamics of liquid crystalline side chain polymers — A spin probe study
Article
Mar 2003
K.-H. Wassmer
Ernst Ohmes
Gerd Kothe[…]
Helmut Ringsdorf
Liquid crystalline polymers with biphenyl‐moieties as mesogenic group
Article
Mar 2003
Heino Finkelmann
Michael Happ
Michael Portugal
Helmut Ringsdorf
Evidence for a biaxial nematic phase in sanidic aromatic polyamides with 1,4,7‐trioxaoctyl side chains
Article
Mar 2003
Martina Ebert
Otto Herrmann-Schönherr
Joachim H. Wendorff[…]
Peter Tschirner
Molecular order of spacer and main chain in polymeric side‐group liquid crystals
Article
Mar 2003
Christine Boeffel
Hans Wolfgang Spiess
Bernd Hisgen[…]
Rudolf G. Kirste
Dielectric properties of a combined main‐chain/side‐chain liquid‐crystalline polymer
Article
Mar 2003
Bernhard W. Endres
Joachim H. Wendorff
Bernd Reck
Helmut Ringsdorf
The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the fl…
Observation of a nematic phase displayed by a polysiloxane with trinitrofluorenones as side groups
Article
Mar 2003
Martin Möller
Vladimir V. Tsukruk
Jürgen Wendling[…]
Helmut Ringsdorf
The synthesis and the results of the structural study of two copolysiloxanes with laterally fixed trinitrofluorenone (TNF) units is reported. The two copolysiloxanes having 2,4 (1a) and 5,3 (1b) dimethylsiloxane comonomer units per TNF side group differ significantly in their phase behaviour as evident from optical microscopy, differential scanning…
Deuteron NMR study of molecular order and motion of the mesogenic side groups in liquid‐crystalline polymers
Article
Mar 2003
Uwe Pschorn
Hans Wolfgang Spiess
Bernd Hisgen
Helmut Ringsdorf
The molecular order and mobility of two liquid-crystalline polyacrylates with phenyl benzoate moieties as mesogenic side groups and (CH2)m spacers (m = 2 and m = 6) were investigated by pulsed 2H NMR. The mesogenic side groups were isotopically labelled at the terminal phenylene ring. In the glassy state the orientational distribution function was…
On the kinetics of 4‐vinylpyridinium salt polymerization in aqueous solution
Article
Mar 2003
Volker Martin
Wolfgang Sutter
Helmut Ringsdorf
A radical mechanism is proposed for the formation of the 1,2-polymer 2 in the “spontaneous” polymerization of 4-vinylpyridinium salts 4-VP.HX (X=NO3, ClO4, HSO4, I) in aqueous solution on the basis of strong inhibition by oxygen and other radical inhibitors.Quantitative investigation of the influence of oxygen on the formation of the 1,2-polymer al…
Model considerations and examples of enantiotropic liquid crystalline polymers. Polyreactions in ordered systems, 14
Article
Mar 2003
Heino Finkelmann
Helmut Ringsdorf
Joachim H. Wendorff
Pharmacologically active polymers, 23. Linear and branched zwitterionic derivatives of polyethyleneimine as carriers for pharmacologically active components
Article
Mar 2003
Shiro Kobayashi
Leo Gros
Gojko Muacevic
Helmut Ringsdorf
To obtain a carrier polymer for pharmacologically active components, linear polyethyleneimine (LPEI) was chemically modified by reactions with acrylic acid (1a), acrylamide (1b), acrylic acid esters (1c and 1d), sodium chloroacetate, and hydrochloric acid. All product polymers 2a – 2e are soluble in water. Among these, 2a and 2e, β- and α-amino aci…
Reck, B. & Ringsdorf, H. Combined liquid crystalline polymers: mesogens in the main chain and as side groups. Macromol. Rapid Commun. 6, 291-299
Article
Mar 2003
Bernd Reck
Helmut Ringsdorf
Discotic charge transfer complexes: influence of acceptor main‐chain polymers on structure and mesophase behaviour of 2,3,6,7,10,11‐hexapentyloxytriphenylene
Article
Mar 2003
Holger Bengs
Renate Renkel
Helmut Ringsdorf[…]
Joachim H. Wendorff
It is shown that the acceptor polyesters [(CH 2 ) x OCOC(=R) COO(CH 2 ) x ] n (R=9-[2,4,7-trinitrofluorenylidene]) x=3, 6, 8) influence the chain behaviour of the discotic hexapentyloxytriphenylene without changing the phase type (D ho ). The clearing temperature of the complexes has a maximum value when x=G. Both intra- and intercolumnar distance…
Liquid Crystalline Side Chain Polymers with Low Glass Transition Temperatures
Article
Mar 2003
Helmut Ringsdorf
Arnold Schneller
X‐ray investigations of liquid crystalline homo‐ and copolysiloxanes with paired mesogens
Article
Mar 2003
Siegmar Diele
Steffi Oelsner
Frank Kuschel[…]
Rudolf Zentel
X-ray scattering experiments on oriented polysiloxanes with paired mesogens and different distances between these swallow-tailed side groups show a remarkable dependence of the smectic monolayer thickness on the degree of dilution, whereas the interplanar distance of the side groups remain nearly constant. Due to the dominating interaction of the m…
Polyreactions in oriented systems, 21. Polymeric phospholipid monolayers
Article
Mar 2003
Bernd Hupfer
Helmut Ringsdorf
Hans Schupp
Orientation of nematic liquid crystalline polymers in the electric field
Article
Mar 2003
Heino Finkelmann
Dieter Naegele
Helmut Ringsdorf
Structure of an aromatic polyamide with disc‐like mesogens in the main chain
Article
Mar 2003
Otto Herrmann-Schönherr
Joachim H. Wendorff
Helmut Ringsdorf
Peter Tschirner
Polyreactions in oriented systems, 29. Formation of oriented polypeptides and polyamides in monolayers and liposomes
Article
Mar 2003
Thomas Folda
Leo Gros
Helmut Ringsdorf
On the kinetics of the polymerization of some ammonium methacrylates with different alkyl chain lengths in aqueous solution
Article
Mar 2003
Helmut Ringsdorf
Dieter Thunig
Methacryloyloxyalkyltrimethylammonium chlorides (1a–c) with different alkyl chain lengths were synthesized and polymerized radically with 4,4′-azobis(4-cyanovalerianic acid) and K2S2O8 as initiators. With K2S2O8 as initiator, reaction orders of 0,5 and 1 with respect to initiator and monomer, were found. For the ionic monomers with longer alkyl cha…
Rufschädigend
Article
Sep 2000
Ekkehard Geyer
Horst Kunz
Herbert Meier[…]
Rolf Christian Schulz
Hurting careers
Article
Sep 2000
E Geyer
H Kunz
H Meier[…]
RC Schulz
Scanning tunneling microscopy investigation of tricycloquinazoline liquid crystals on gold
Article
Jan 2000
Renate Hiesgen
Holger Schönherr
Sandeep Kumar[…]
D. Meissner
Self-assembled monolayers (SAMs) of hexaalkylthioether derivatives of tricycloquinazoline (TCQ) on Au(111) and tungsten diselenide (WSe2) were investigated by scanning tunneling microscopy (STM). The Au(111) surfaces were found to be etched by the thioether containing solutions. Corroded surfaces which are similar to gold surfaces that were coated…
Photo-Cross-Linked Triphenylenes as Novel Insoluble Hole Transport Materials in Organic LEDs
Article
Jun 1999
Andreas Bacher
Christian H. Erdelen
Wolfgang Paulus[…]
Peter Schuhmacher
A series of new hexaalkoxytriphenylenes having 1, 2, or even 3 lateral attached acrylate moieties as polymerizable groups were synthesized and characterized. The conditions for the photopolymerization of these monomers in thin film were evaluated and tested. The bisacrylates and trisacrylates were used to build insoluble networks. When a mask is us…
Electronic coupling responsible for energy transfer in columnar liquid crystals
Article
Jun 1999
Dimitra Markovitsi
Sylvie Marguet
Lazaros K. Gallos[…]
Sandeep Kumar
Electronic coupling is the driving force for energy transfer in molecular materials and consists of several components. We determine the strength of dipolar/multipolar coupling and coupling due to orbital overlap for excitation transport in triphenylene columnar liquid crystals. We use time-resolved fluorescence spectroscopy and computer simulation…
Molecular Recognition-Induced Function and Competitive Replacement by Hydrogen-Bonding Interactions: Amphiphilic Barbituric Acid Derivatives, 2,4,6-Triaminopyrimidine, and Related Structures at the Air−Water Interface
Article
Dec 1998
Thomas M. Bohanon
Pier-Lorenzo Caruso
Steffen Denzinger[…]
Dieter Schollmeyer
The phenomenon of molecular recognition inducing further function is common in nature. However, there are few synthetic systems which achieve this cascade type mechanism, and those are generally carried out in noncompetitive solvents. Here a synthetic system is described that partakes in recognition events at an aqueous interface, which subsequentl…
Phase identification of triphenylene-based discotic monomer and its main chain polymers
Article
Sep 1998
Tao Wang
Donghang Yan
Enle Zhou[…]
Helmut Ringsdorf
A monomer, 2,3,6,7,10,11-hexakispentyloxy triphenylene (HPT) possesses a triphenylene core as a discotic mesogen. Polymers containing this discotic mesogen have been studied using wide-angle X-ray and electron diffraction. HPT is known to show a discotic liquid crystal phase, noted as Dho (h for hexagonal bidimensional lattice, o for ordered molecu…
Protein−DNA Double and Triple Layers: Interaction of Biotinylated DNA Fragments with Solid Supported Streptavidin Layers
Article
May 1998
Kuniharu Ijiro
Helmut Ringsdorf
Eckhard Birch-Hirschfeld[…]
Michael Strube
The specific interaction of streptavidin with biotinylated lipids at the air-water interface leads to a formation of optically anisotropic two-dimensional streptavidin (2-D) crystals, where two of the original four biotin-binding sites remain free. These assembled streptavidin matrixes were used as a template for docking of double-stranded oligonuc…
Protein−DNA Double and Triple Layers: Interaction of Biotinylated DNA Fragments with Solid Supported Streptavidin Layers
Article
Apr 1998
Kuniharu Ijiro
Helmut Ringsdorf
The specific interaction of streptavidin with biotinylated lipids at the air−water interface leads to a formation of optically anisotropic two-dimensional streptavidin (2-D) crystals, where two of the original four biotin-binding sites remain free. These assembled streptavidin matrixes were used as a template for docking of double-stranded oligonuc…
Induction of liquid crystalline phases in linear polyamines by complexation of transition metal ions
Article
Feb 1998
Hartmut R. Fischer
Thomas Plesnivy
Helmut Ringsdorf
Markus Seitz
In this paper, we describe the preparation and characterization of polyamine–copper complexes based onN-alkylated polyethyleneimines which were obtained by polymer analogous reduction of the corresponding N-acylated polymers. Liquid crystalline properties of the originating linear polyamides are lost in the resulting polyamines which show a higher…
Two-Dimensional Structure of Disulfides and Thiols on Gold(111)
Article
Feb 1998
Gabriele Nelles
Holger Schönherr
Manfred Jaschke[…]
Hans-Jürgen Butt
In order to find factors which determine the two-dimensional structure of self-assembled monolayers (SAMs), several classes of thiols and disulfides on gold (111) have been investigated by atomic force microscopy (AFM). SAMs were formed from a series of symmetrical and asymmetrical diethylalkanoate disulfides, ω-hydroxy- and ω-carboxyalkanethiols,…
Structure and Conformation of 2,3,6, 7,10,11 -hexakispentyloxytriphenylene by TEM and Computer Simulation
Article
Jan 1998
Gao Li
Jun Luo
Tao Wang[…]
Helmut Ringsdorf
Experimental electron diffraction patterns and high resolution images were used to determine the space group and unit cell dimensions of 2,3,6,7,10,11-hexakispentyloxytriphenylene. Subsequently the molecular conformation was calculated by energy minimized package in Cerius2. Using this method, we got the HPT crystal structure: space group: P6/mmm;…
Structure of Discotic Liquid Crystalline Compounds at the Air−Water Interface
Article
Dec 1997
David Gidalevitz
Oksana Y. Mindyuk
Paul A. Heiney[…]
Amos B. Smith
We have used grazing incidence X-ray diffraction and X-ray specular reflectivity to study the behavior of platelike hexaalkoxytriphenylene derivatives at the air-water interface. The data are consistent with a two-dimensional columnar mesophase, wherein the molecules are arranged ”edge-on” to the water surface, with intercolumnar spacings of 13-1…
Studies of Molecular Orientation and Order in Self-Assembled Semifluorinated n-Alkylthiols: Single and Dual Component Mixtures
Article
Aug 1997
M.-W. Tsao
Catherine L. Hoffmann
John Rabolt[…]
Helmut Ringsdorf
The structure, orientation and morphology of self-assembled monolayers of a semifluorinated n-alkythiol, F(CF_2)8 (CH_2)_11 SH (F8H11SH), have been investigated by polarized IR, angular dependent XPS, time-of-flight SIMS, contact angle and ellipsometric measurements. The orientation of the all trans hydrocarbon segment was found to be tilted much l…
Reduced protein adsorption on plastics via direct plasma deposition of triethylene glycol monoallyl ether
Article
Aug 1997
Dierk Beyer
Wolfgang Knoll
Helmut Ringsdorf[…]
Peter Sluka
The direct plasma-induced deposition of tri(ethylene glycol) monoallyl ether is reported. RF plasma polymerization of this monomer was carried out under both continuous wave (CW) and pulsed plasma operation. The major focus of this work was optimization of the degree of retention of the C-O-C bonds of the starting monomer during the deposition proc…
Detecting a transition-metal ammine at tailored surfaces
Article
Jul 1997
Sayeedha Iqbal
Felix J. B. Kremer
Jon A. Preece[…]
Nigel D. Tinker
The fabrication of surfaces by forming Langmuir films, which incorporate amphiphiles containing hydrophilic 18-crown-6(18C6) derivatives, at a gas/water interface is described. These Langmuir films can be transferred to a hydrophobised quartz crystal microbalance (QCM), using the Langmuir-Blodgett technique. The QCM response has been measured in aq…
Molecular Recognition via Hydrogen Bonding at the Air−Water Interface: An Isotherm and Fourier Transform Infrared Reflection Spectroscopy Study
Article
Jun 1997
Marcus Weck
Ralf Fink
Helmut Ringsdorf
Molecular recognition in Langmuir monolayers at the air−water interface as a function of headgroup orientation and substrate using isotherms and in-situ Fourier transform infrared (FT-IR) reflection spectroscopy has been investigated. Isotherm measurements show that urea and 2,4,6-triaminopyrimidine (TAP) are specifically bound to barbituric acid l…
Complex Ordering in Thin Films of Di- and Trifunctionalized Hexaalkoxytriphenylene Derivatives
Article
May 1997
Philippe Henderson
Dierk Beyer
Ulrich Jonas[…]
Jack Y. Josefowicz
We have used pressure−area isotherms, X-ray diffraction, atomic force microscopy, and infrared dichroism to study Langmuir and Langmuir−Blodgett films of 2,3,6,7,10,11-hexaalkoxytriphenylenes which were selectively di- and trifunctionalized with CnH2n−OH groups at the 2,3-, 2,6-, 3,6-, and 3,6,10-positions. The bulk phase behavior of these compound…
Catalysis of Transbilayer Lipid Migration by Hydrophobically Modified N-Isopropylacrylamide Polymers
Article
Apr 1997
Soumendu Bhattacharya
Robert A. Moss
Helmut Ringsdorf
Joachim Simon
Transverse lipid migration (flip-flop) of 2-F, a head-group-labeled dipalmitoylphosphatidylcholine (DPPC), in surface-differentiated 1:7 coliposomes with unlabeled DPPC (2-NF), is facilitated by added N-isopropylacrylamide (NIPAM) polymers at temperatures above the extended → contracted transition temperatures of the polymers (30−33 °C). The effect…
Functionalized Lipid Tubules as Tools for Helical Crystallization of Proteins
Article
Apr 1997
Philippe Ringler
Wolfgang Müller
Helmut Ringsdorf
Alain Brisson
The development of functional supramolecular devices built by self-assembly of elementary molecules and with bioactive properties arouses considerable interest in the field of nanotechnology and new materials. We report here the formation of a new class of lipid tubules exhibiting both properties of molecular recognition and crystal formation for t…
Tetraethynylethene molecular scaffolding: Nonlinear optical, redox, and amphiphilic properties of donor functionalized polytriacetylene and expanded radialenes
Article
Mar 1997
Martin Schreiber
Rik Tykwinski
Rolf Spreiter[…]
Helmut Ringsdorf
Communication: Polymers,vith polytriacetylene (PTA) backbone (see the Figure), and also expanded radialenes (a new class of macrocycles with large conjugated all-carbon cores), are of interest because of their intrinsic two-dimensional pi-electron conjugated pathways. The synthesis, electrochemical characteristics, and linear and nonlinear optical…
Supramolecular assembly using helical peptides
Article
Feb 1997
Katsuhiko Fujita
Shunsaku Kimura
Yukio Imanishi[…]
Helmut Ringsdorf
We investigated supramolecular assemblies of various hydrophobic helical peptides. The assemblies were formed at the air/water interface or in aqueous medium. The hexadecapeptide, Boc-(Ala-Aib)s-OMe (BA16M), was reported to take alpha-helical structure by X-ray analysis. Several derivatives were prepared, which have the repeating sequence of Ala-Ai…
Formation of supramolecular aggregates by hydrogen bonding based on bispyrimidine and bisbarbituric acid
Article
Feb 1997
Zhiqiang Wang
Liyan Wang
Xi Zhang[…]
Helmut Ringsdorf
Hydrogen bonds between bispyrimidine and bisbarbituric acid in equal molar ratio can lead to the formation of supramolecular aggregates. This is established by TEM, IR and DSC measurements. Additionally, WAXS pattern showed that the aggregate is of laminar structure. Both the hydrolysis of this system and termination of the aggregate’s growth were…
Photophysical Properties of Discotic Dibenzopyrenes
Article
Feb 1997
Pawel Uznanski
Sylvie Marguet
Dimitra Markovitsi[…]
Helmut Ringsdorf
The photophysical properties of three discogenic dibenzopyrenes substituted by eight pentyloxy (O5DPB), heptyloxy (O7DBPP) or decyloxy (O10DBP) side chains are studied in solution and thin films. It is shown that the absorption and fluorescence spectra of the columnar mesophases are clearly distinguishable from those of the corresponding crystallin…
Molecular Recognition by Hydrogen Bonding in Polyelectrolyte Multilayers
Article
Jan 1997
André Laschewsky
Erik Wischerhoff
Steffen Denzinger[…]
Patrick Bertrand
Functional polyanions were prepared by copolymerization of sulfopropyl acrylate and sulfopropyl methacrylate with monomers bearing triaminopyrimidine or barbituric acid functionalities, respectively. Functionalized polyelectrolyte multilayers were assembled from these copolymers by stepwise alternating adsorption with poly(choline methacrylate). Th…
Molecular dynamics in liquid crystalline N‐acylated oligoethylenimines as studied by broadband dielectric spectroscopy
Article
Nov 1996
Herbert Groothues
Friedrich Kremer
Thomas Plesnivy
Helmut Ringsdorf
The molecular dynamics and the charge transport in six liquid crystalline N-acylated oligoethylenimines were investigated by dielectric spectroscopy. The dielectric spectra in the temperature range from 125 K up to 400 K and in the frequency range between 10−2 Hz and 107 Hz could be described by a conductivity contribution and three relaxation proc…
Transient photoconductivity in a discotic hexagonal plastic crystal
Article
Oct 1996
Wolfgang Paulus
Andreas Glüsen
Peter Schuhmacher[…]
Dietrich Haarer
Charge-carrier transport in organic materials is the fundamental phys ical process behind devices such as laser printers. Charge-carrier mobility data are presented for hexabutyloxytriphenylene (H4T), which exhibits an unusually high charge-carrier mobility, which can be traced to the formation of a plastic discotic phase. The Figure shows the norm…
Formation of Hexagonal Columnar Mesophases by Linear and Branched Oligo- and Polyamides
Article
Sep 1996
Markus Seitz
Thomas Plesnivy
Klaus Schimossek[…]
Helmut Ringsdorf
The formation of columnar mesophases by N-acylated azacrown derivatives may be seen as a consequence of their discoid molecular geometry. Viewing these materials as cyclic oligomers, they are just one example of the various molecular architectures that may be realized based on the N-acylated ethylenamine fragment. By using linear oligoamides, the h…
Citations
… 46 The estimated tilt angles are within the reported values. [47][48][49][50][51][52][53][54] Overall, the tilt angles obtained for the CH 3 SS of the different concentration ratios are positioned closer to the surface normal. …
Reference: Orientational Analysis of Monolayers at Low Surface Concentrations Due to an Increased Signal-to-Noise Ratio (S/N) Using Broadband Sum Frequency Generation Vibrational Spectroscopy
Studies of Molecular Orientation and Order in Self-Assembled Semifluorinated n-Alkylthiols: Single and Dual Component Mixtures
Citing article
Aug 1997
Mei-Wei Tsao C. L. Hoffmann John F. Rabolt Harry E. Johnson Helmut Ringsdorf
… This variant showed attenuated cross-linking reactions with multiple biotinylated interaction partners 17 . There are numerous studies on interactions between SA/SAH with biotin [18][19][20][21][22][23] . However, literature on a well-designed and systematic comparison of SAHs, under standard conditions, which shows those best suited SA/SAHs for hybridization or PCR conditions is scant. …
Reference: Streptavidin Homologues for Applications on Solid Surfaces at High Temperatures
Protein−DNA Double and Triple Layers: Interaction of Biotinylated DNA Fragments with Solid Supported Streptavidin Layers
Citing article
May 1998
Kuniharu Ijiro Helmut Ringsdorf Eckhard Birch-Hirschfeld Siegfried Hoffmann Michael Strube
… 21−23 The chiral center may also dictate a particular orientation of the molecules 4 and promote transitions between different aggregate structures, such as rods, fibers and ribbons. 12 Several studies have focused on the application of tubular aggregates in drug delivery, 24,25 templating 7 and building block 26 nanochemistry, biosensors, 27 helical crystallization of proteins, 28 and rheological control of materials through gelation. 12,13,22,29 The gelation effect occurs by the entrapment of the solvent in a matrix typically built of a three-dimensional network of fibers and tubular structures stabilized by noncovalent interactions. …
Reference: Morphology, Thermal Behavior, and Stability of Self-Assembled Supramolecular Tubules from Lysine-Based Surfactants
Functionalized Lipid Tubules as Tools for Helical Crystallization of Proteins
Citing article
Apr 1997
Philippe Ringler Wolfgang Müller Helmut Ringsdorf Alain Brisson
… Earlier in 2009, participation stood at a greatly reduced 50%. Chubb Tytler highlighted the “concern with declining interest in argued that the scientific literacy of the community was science over the Years 7-10” [2], which was the catalyst becoming increasingly important and that “the community for the Victorian government to invest in the largest has got to be in a position where they are better able to school science initiative that had been undertaken in make judgments, rather than be led by the loudest and Australia for decades and it followed hundreds of National Science Communications Conference in Sydney, Victorian primary and secondary schools over a three year that hands-on approaches can produce at least period. At the international level, Jenkins [3] wrote about equivalent outcomes in terms of content knowledge and the “anxiety over the decline in interest among students, may have an advantage in terms of increasing student especially in the developed world, in the physical interest. …
Reference: Addressing the falling interest in school science in rural and remote areas using experiments and science fairs
Tradition and innovation in science
Citing article
Nov 2006
Helmut Ringsdorf C. Mertesdorf
… Luminescent LCs combining fluorescence and mesomorphism [15][16][17][18][19] have arisen intensive research interesting due to their polarized emission properties [20,21]. Such materials have wide applications as light source for liquid crystal displays (LCDs), and have great potentials in three-dimensional (3D) imaging systems and medical field [22] etc. …
Reference: Effect of the linkages on the self-assembly and photophysical properties of 4,7-diphenyl-2,1,3-benzothiadiazole-based luminescent polycatenars
Photophysical Properties of Discotic Dibenzopyrenes
Citing article
Feb 1997
Pawel Uznanski S. Marguet Dimitra Markovitsi Peter Schuhmacher Helmut Ringsdorf
… Transition to a cis isomer, which acts as an impurity, results in the destruction of ordered mesophase structures, and one observes the phase transition from a nematic to an isotropic LC [8]. Photochemical phase transitions in polymeric liquid crystals (PLCs) have also been induced using spiropyrans, spirooxazines and fulgides [9][10][11]. …
Reference: On the possibility of magnetoresistance governed by light.
ChemInform Abstract: Thermally Irreversible Photochromic Liquid Crystal Polymers.
Citing article
Apr 2010
Ivan Cabrera Achim Dittrich Helmut Ringsdorf
… Ethinyl anilines, as a group of heteroaryl acetylenes, are widely used in materials science, especially as a strong electron donor for applications in optoelectronic devices and their ability to the formation of a diazonium compound and doing the polymerization reaction [4][5][6] . Also these compounds as primary amines play a pivotal role in the synthesis of various substrates [7][8][9] . …
Reference: Electrochemical Oxidation of 4-Ethynylaniline: A Green Electrochemical Protocol for the Synthesis of Diazine Compounds
Tetraethynylethene molecular scaffolding: Nonlinear optical, redox, and amphiphilic properties of donor functionalized polytriacetylene and expanded radialenes
Citing article
Mar 1997
Martin Schreiber Rik R. Tykwinski R. Spreiter Ueli Gubler Helmut Ringsdorf
… Charge transport studies of various hexaalkoxytriphenylenes (TP-2 to TP-7) (Fig. 5.12) were studied by TOF method. From TP-2 to TP-7, all compounds exhibited Col h or ordered Col h (Col ho ) mesophase provided that TP-2 with nbutyloxy peripheral chain length displayed relatively more ordered columnar phase, i.e., columnar hexagonal plastic phase (Col hp ) ( Table 5.4) [29]. The remarkable hole mobilities of 1 x 10 À3 cm 2 V -1 s -1 were obtained for TP-3 derivative with npentyloxy peripheral alkyl chain [9]. …
Reference: Functional Discotic Liquid Crystals Through Molecular Self-Assembly: Toward Efficient Charge Transport Systems
Transient photoconductivity in a discotic hexagonal plastic crystal
Citing article
Oct 1996
Wolfgang Paulus Andreas Kettner Peter Schuhmacher Dieter Adam Dietrich Haarer
… Liquid crystals are prespective modifiers; their molecules form highly ordered structures on solid substrates, similar to the mesomorphic state. The formation of such structures is confirmed by data scanning tunneling microscopy [4,5]. Adsorbents modified with liquid crystals are able to exhibit selective properties with respect to isomers of organic substances [6,7]. …
Reference: Adsorption properties of Silochrom chemically modified with nickel acetylacetonate
Scanning tunneling microscopy investigation of tricycloquinazoline liquid crystals on gold
Citing article
Jan 2000
Renate Hiesgen Holger Schönherr Sandeep Kumar Helmut Ringsdorf Dieter Meissner
… One strategy to overcome this problem is polymerization and crosslinking of the self-organized LC molecules into LC networks with preserving the periodic nanostructures. 30,49,[181][182][183][184][185][186][187] This process certainly reduces the mobility and dynamic nature of the LC arrays, but drastically improves the mechanical properties of the samples and their thermal stability. There are some important processes for transforming nanosegregated liquid crystals into nanostructured LC networks ( Figure 9): …
Reference: Functional liquid-crystalline polymers and supramolecular liquid crystals
Photo-Cross-Linked Triphenylenes as Novel Insoluble Hole Transport Materials in Organic LEDs
Citing article
Jun 1999
Andreas Bacher Christian H. Erdelen Wolfgang Paulus Helmut Ringsdorf Peter Schuhmacher
Top co-authors (50)
Helmut Ritter
Heinrich-Heine-Universität Düsseldorf
Olaf Karthaus
Chitose Institute of Science and Technology
Joachim H. Wendorff
Thomas Plesnivy
Wolfgang Paulus
C. G. Overberger
Peter Schuhmacher
Wolfgang Knoll
Willi Kreuder
Holger Bengs
Top journals
Die Makromolekulare Chemie (66)
Angewandte Chemie (37)
Angewandte Chemie International Edition (28)
Die Makromolekulare Chemie Rapid Communications (25)
Langmuir (19)
Affiliations
Johannes Gutenberg-Universität Mainz
Department
Institute of Organic Chemistry
University of Concepción
University of Freiburg
University of Bayreuth
Massachusetts Institute of Technology
Department
Department of Chemistry
Rutgers, The State University of New Jersey
Citations
16,010
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