ABSTRACTS

NMR studies of the 216 kDa transmembrane enzyme complex Na+-NQR from V. cholerae Nedielkov R1,2, Brosig A2, Ude J1,2, Steffen W3, Fritz G4, Fritz-Steuber J3, Möller HM1,2 1Institute

of Chemistry, University of Potsdam, 14476 Potsdam, Germany

2Department

of Chemistry, University of Konstanz, 78457 Konstanz, Germany

3Institute

of Microbiology, University of Hohenheim, 70599 Stuttgart, Germany

4Institute

for Neuropathology, University of Freiburg, 79106 Freiburg, Germany

ABSTRACT The Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) plays a crucial role in V. cholerae’s energy metabolism and Na+-homeostasis. The Na+-NQR is a respiratory transmembrane enzyme complex comprising of six subunits and at least five redox-active cofactors utilizing the free energy liberated during oxidation of NADH with quinone to pump sodium ions across the cytoplasmic membrane. The sodium gradient in turn drives a number of other cellular processes like H+/Na+ antiporters and the flagellum. How redox chemistry is coupled to ion translocation as well as the molecular details of the final electron transfer steps are still unclear. STD NMR spectroscopy in combination with other methods revealed that the NqrA subunit (50 kDa) harbors the catalytic quinone binding site. Furthermore, STD-NMR, SPR experiments, and Trp fluorescence quenching titrations indicated that NqrA can bind two quinone ligands. We could show by recording interligand NOEs between ubiquinone-1 and the inhibitors DBMIB and HQNO that NqrA simultaneously interacts with two quinone-type molecules in an extended binding site providing, for the first time, direct experimental evidence for the long-standing double occupancy hypothesis. The NqrA subunit was prepared in 2H, 13C, 15N labelled form for backbone assignment of the protein and the quinone binding site was located by chemical shift perturbation mapping. This result was further corroborated by an analogous experiment monitoring chemical shift changes of ε-13Cmethionin labelled NqrA. To transfer and extend our results obtained with isolated NqrA to the holo-complex, Na+-NQR (216 kDa) will be expressed in V. cholerae in perdeuterated and specifically labelled form to allow for recording meaningful spectra (ε-13C-methionin-, ILV-labelling etc.). First promising results with uniformly 2H, 15N labelled Na+-NQR have already been obtained.

Applications of DBD Dyes P. Wessig, Potsdam/D, R. Wawrzinek, Potsdam/D, M. Mertens, Potsdam/D, D. Bader, Potsdam/D, D. Klier, Potsdam/D, F. J. Meyer-Almes, Darmstadt/D, C. Meyners, Darmstadt/D, A. Krämer, Darmstadt/D., S. Hinz, Darmstadt/D Prof. Dr. Pablo Wessig, University Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam/D Fluorescence dyes based on [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD) show remarkable large fluorescence lifetimes (10-20 ns) combined with large Stokes shifts (~100 nm).[1,2] DBD dyes of the first generation with acyl groups in 4 and 8 position (1) are sensitive to the polarity of their microenvironment. Particularly in the presence of water the fluorescence lifetime decreases drastically. So they are suited to sensing lipophilic environments.[3] Recently this behaviour could be used for the development of a biomimetic application as a biosensor based on a DBD dye of the first generation. In contrast, DBD dyes of the second generation with ethyl ester groups in 4 and 8 position called DBD ester (2) possess even in water long fluorescence lifetimes (see diagramm). The complementary interaction of both generations makes it possible to use them as ratiometric probes.[4,5]

O

O O O

O

4

O O

8

O 1

OH

O O

4

O O

O O

8

O

OH

O 2

Derivatization of the DBD dyes with a hydroxamic acid function was an aim which results in another amazing application: a fluorescence lifetime-based binding assay for acetylpolyamine amidohydrolases.[6] Literature: [1] Patent-No. EP2399913A1, P. Wessig, K. Möllnitz, R. Wawrzinek, 2011. [2] P. Wessig, R. Wawrzinek, K. Möllnitz, E. Feldbusch, U. Schilde, Tetrahedron Lett. 2011, 52 , 6192. [3] R. Wawrzinek, P. Wessig, K. Möllnitz, J. Nikolaus, R. Schwarzer, P. Müller, A. Herrmann, Bioorg. Med. Chem. Lett. 2012, 22, 5367. [4] R. Wawrzinek, J. Ziomkowska, J. Heuveling, M. Mertens, A. Herrmann, E. Schneider, P. Wessig, Chem. Eur. J. 2013, 19, 17349-17357. [5] J. Heuveling, V. Frochaux, J. Ziomkowska,R. Wawrzinek, P. Wessig, A. Herrmann, E. Schneider BBA – Biomembranes 2014, 1838,106-116. [6] C. Meyners, R. Wawrzinek, A. Krämer, S. Hinz, P. Wessig, F.-J. Meyer-Almes Anal. Bioanal. Chem. 2014, 4889-4897.

In-line particle sizing and process characterization of highly concentrated polymer dispersions by Photon Density Wave spectroscopy Marvin Münzberg, Julia Wolter, Roland Hass, Oliver Reich; University of Potsdam, Institute of Chemistry, Physical Chemistry - innoFSPEC, Potsdam, Germany

Particle sizing and optical characterization of highly concentrated polymer dispersions in technical processes is of utmost importance. However, due to the often high turbidity, inline spectroscopy is very challenging. By fiber-optical Photon Density Wave (PDW) spectroscopy it is possible to simultaneously determine the optical properties, namely the reduced scattering coefficient and the absorption coefficient, and furthermore the particle diameter. Sizing regime ranges from 50 nm to 500 µm, at high concentrations of over 40 vol%. A batch emulsion polymerization of styrene, with an expected particle size of 100 nm at 20 vol% was investigated in-line in a 1 L reactor. Additionally, a starved feed polymerization of a co-polymer in a 25 L reactor was studied. With a temporal resolution in the minute scale, a particle growth from 50 to 200 nm was observed. The volume fraction at the end of the reaction was 40 vol%. In a further industrial polymerization process porous micrometer particles (approx. 10 µm) were synthesized in a 400 L scale via suspension polymerization. Furthermore an investigation of phase inversion temperature emulsification shows the applicability of PDW spectroscopy to a system, whose droplet size changes from 30 micrometers to the nanometer regime. The influence of cooling speed and emulsifier concentration on resulting droplet size and stability of the resulting nanoemulsion due to Ostwald-ripening is investigated systematically. PDW spectroscopy has a high potential as process analytical technology for highly turbid, highly concentrated dispersions of all kinds.

Investigation of NEXAFS Resonances by Density Functional Theory Christopher Ehlert1,2 , Wolfgang E.S. Unger1 , Peter Saalfrank2 1 BAM

Bundesanstalt f¨ur Materialforschung und –pr¨ufung, Unter den Eichen 87 12203 Berlin, Germany 2 University

of Potsdam, Chemistry Department – Theoretical Chemistry, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany NEXAFS [1] is an outstanding analytical tool to investigate the electronic structure of all kinds of systems (for example complex chemistry, surfaces, nanoelectronics and self-assembled monolayers). Due to the complexity of experimental spectra, theoretical simulations have become an essential tool for their interpretation. Density functional theory has proven its power to predict NEXAFS resonances in several studies [2, 3]. Often the experimental spectra can be simulated very accurately. We present current activities in the field of NEXAFS simulations, based on our recently developed program suite.

References [1] J. St¨ohr, NEXAFS Spectroscopy (Springer Series in Surface Sciences), corrected ed. (Springer, 2003). [2] M. Leetmaa, M. Ljungberg, A. Lyubartsev, A. Nilsson, and L. Pettersson, Journal of Electron Spectroscopy and Related Phenomena 177, 135 (2010). [3] C. Ehlert, W. E. S. Unger, and P. Saalfrank, Phys. Chem. Chem. Phys. 16, 14083 (2014).

Upconversion NaSc/YF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on nanoscales

D.Klier, S. Nacak and M. Kumke. Universität Potsda, Karl-Liebknecht-Str. 24-25, D-14476 Golm, Germany.

In the present work, the upconversion luminescence of citrate acid and oleic acid capped NaSc/YF4:Gd3+:Yb3+:Er3+:Nd3+ upconversion nanoparticles (UCNP) with different crystal phases and different Y3+ to Gd3+ ratio was studied at various temperatures from 330 K > T > 4 K. Both the luminescence intensity and the ratio of luminescence bands were found to depend on temperature. Here, the crystal phase and the related phonon coupling processes play a key role for the upconversion luminescence as well as thermal population rates of the emitting energy levels. The results of this study will show that the complex interplay of different mechanism and effect causing the special temperature behavior of the UCNP can be developed in thermometry on the nanoscale, e.g. to be applied in biological systems. The performance of the probes was further improved by the use of Nd3+ as additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP.

Optische Analyse der Synthese- und Schaltprozesse von PNIPAM M. Sc. Chem. Peter Werner1, Qinlong Wang2, Dr. Oliver Reich1 1 Universität Potsdam, Institut für Chemie, Physikalische Chemie – innoFSPEC, Am Mühlenberg 3, 14476 Potsdam/Deutschland 2 National Engineering Center of Polyurethane, Xingfu South Road, No.7 Yantai, Shandong, China

Um intelligente Polymere besser nutzen zu können, ist es notwendig die Mechanismen hinter diesen Effekten aufzuklären, diese sind durch möglichst viele Informationen und Bedingungen zu charakterisieren. So können komplett aufgeklärte Mechanismen zu mehr Anwendungen der intelligenten Polymere führen, wie zum Beispiel Drug-delivery Systeme. Durch die Nutzung verschiedener faser-optischen Methoden ist die Quantifizierung unterschiedlicher Licht-MaterieWechselwirkungen möglich, die zur Aufklärung der einzelnen Effekte beitragen können.

Hier wird die Kombination von verschiedenen faser-optischen Methoden zur Charakterisierung von Poly(N-Isopropylacrylamid) (PNIPAM) in einem hoch automatisierten Reaktor dargestellt. Es wurde die radikalische Fällungspolymerisation von PNIPAM und die Schalttemperatur von PNIPAM/PNIPAM-co-MAA untersucht. PNIPAM zeigt eine starke Strukturänderung ab einer bestimmten Temperatur. Diese Temperatur wird als kritische Lösungstemperatur definiert, bei der das mit Wasser gequollene Polymer abrupt sein Wasser auslagert und einen drastische Strukturänderung aufweist.[1] Die Schalttemperatur kann durch diverse Comonomere beeinflusst werden.[2] Durch die Untersuchung des Copolymers PNIPAM-co-MAA konnte ermittelt werden, dass die kritische Lösungstemperatur verschiedenen Prozessen unterliegt. So konnte durch die Verwendung von MAA ein makroskopischer und mikroskopischer Prozess des PNIPAM-co-MAA ermittelt werden. 1% 5% 10% 0%

effekt. Streukoeffizient ms' / mm-1

1.2

1.0

0.8

0.6

0.4

0.2

0.0 26

28

30

32

34

36

38

Temperatur T / °C

Abb. 1: effektiver Streukoeffizent von verschiedenen Comonomerkonzentrationen von Poly(NIPAM-co-MAA) bei 982nm während zyklischen Temperaturänderungen [1] B. Sun, Y. Lin, P. Wu, H. W. Siesler, A FTIR and 2D-IR Spectroscopy Study on the Microdynamics Phase Seperation Mechanim of the Poly(N-isopropylacrylamide) Aqueous Solution. Macromolecules. 41, 1512-1520 [2] C. K. Chee, S. Rimmer, D. A. Shaw, I. Soutar, L. Swanson, Manipulating the Thermoresponsive Bahavior of Poly(Nisopropylacrylamide). 1. On the Conformational Behavior of a Series of N-Isopropylacrylamide-Styrene Statistical Copolymers, Macromolecules. 34 (2001) 7544-7549

Atemluftanalyse in der Veterinärmedizin durch Ionenmobilitäts- und Massenspektrometrie A. Erler1, S. Wietstock2, C. Klein2, D. Riebe1, T. Beitz1, H.-G. Löhmannsröben1 1 Universität Potsdam, Physikalische Chemie, Karl-Liebknecht-Str. 24-25, 14476 Potsdam 2 Fzmb GmbH, Forschungszentrum für Medizintechnik und Biotechnologie, Geranienweg 7, 99947 Bad Langensalza In den letzten Jahren wurde eine Reihe von Studien durchgeführt, die den Einsatz der Massen- und Ionenmobilitäts (IM)-Spektrometrie zur Analyse von Atemluft sowie zur Medikations- und Therapiekontrolle in der Humanmedizin zum Gegenstand hatten. In unserer aktuell durchgeführten Studie soll die Methode zur Medikationskontrolle in der Veterinärmedizin eingesetzt werden. Dabei erfolgt die Überwachung der Atemluft im Stall durch ein portables Multikapillarsäulen-GC-IM-Spektrometer. Parallel werden die Komponenten der Atemluftproben in Thermodesorptionsröhrchen adsorbiert und durch APCI-MS im Labor untersucht. Dazu wurde eine neuartige Ionisationskammer auf Basis einer miniaturisierten Röntgenquelle (Bruker Daltonik) entwickelt, die die Ionisationsprozesse im IMSpektrometer simuliert und den massenspektrometrischen Nachweis der Ionen erlaubt. Ein weiterer Schwerpunkt war die Anpassung des Analysensystems aus Thermodesorber, Multikapillar-GC-Säule und Ionisationskammer zur Identifizierung der in der Atemluft vorliegenden Substanzen. Die Zuordnung der im Massenspektrometer detektierten Ionen zu den Peaks im IM-Spektrum kann sowohl durch Masse-Mobilitäts-Beziehungen als auch auf dem Vergleich von experimentell bestimmten und berechneten Mobilitäten erfolgen.

Ionic liquid precursors for multicomponent inorganic nanomaterials Mr. Abouserie, Ahed1; Prof. Dr. Taubert, Andreas1 1

Institute of Chemistry, University of Potsdam

Keywords: Metal containing ionic liquid, Copper Chloride, Cobalt Chloride, Zinc Chloride Metal Containing ionic liquids combine the properties of ionic liquids with intrinsic magnetic, optical, or catalytic properties depending on the metal ion1–4, and therefore they are attractive to find applications in fields of catalysis, optical devices and electrochemical and sensing problems. The N-alkylpyridinium salts [Cn-Py]2 [MCl4] (n=4 or 12 and M=Cu(1)5,6 , Co(2)7, Zn(3)) were synthesized and structurally characterized by X-ray diffraction methods. The presence and the amount of organic materials have been studied by thermal gravimetric analysis (TGA) and elemental analysis. The melting points and clearing points were investigated by differential scanning calorimetry (DSC) and compared with results obtained by polarized optical microscopy (POM). The molecular structures of [C4-Py]2 [MCl4] were determined by single crystal X-ray diffraction. We successfully synthesized different types of metal containing ionic liquid. The Ndodecylpyridinium salts display a thermotropic liquid crystalline mesophases but the Nbutylpyridinium salts melt, with no mesomorphism, to form isotropic liquids. The phase behavior, physical properties, and miscibility of these metals were investigated by different characterization techniques.

Focal conic texture of [C12-Py]2 [MCl4] obtained under polarized optical microscopy (POM)

[1] Lee, C. K.; Hsu, K.-M.; Tsai, C.-H.; Lai, C. K.; Lin, I. J. B. Dalton Trans. 2004, 1120–1126. [2] Rampon, D. S.; Rodembusch, F. S.; Schneider, J. M. F. M.; Bechtold, I. H.; Gonçalves, P. F. B.; Merlo, A. a.; Schneider, P. H. J. Mater. Chem. 2010, 20, 715. [3] Zhuang, R.; Jian, F.; Wang, K. J. Organomet. Chem. 2009, 694, 3614–3618. [4] Jin, C.; Twamley, B.; Shreeve, J. M. Organometallics 2005, 24, 3020–3023. [5] Neve, F.; Francescangeli, O.; Crispini, A.; Charmant, J. Chem. Mater. 2001, 13, 2032–2041. [6] Thiel, K.; Klamroth, T.; Strauch, P.; Taubert, A. Phys. Chem. Chem. Phys. 2011, 13,13537– 13543. [7] Bowlas, C.; Bruce, D.; Seddon, K. Chem. Commun. 1996, 1625–1626.

Microwave-assisted Synthesis of Microporous Zn(II)- and Co(II)Imidazolate-4-amide-5-imidate Frameworks Karsten Behrens, Universität Potsdam, Potsdam, Germany; Igor. A. Baburin, Technische Universität Dresden, Dresden, Germany; Stefano Leoni, Cardiff University, Cardiff, United Kingdom; Jens Weber, Hochschule Zittau/Görlitz, Germany; Hans-Jürgen Holdt, Universität Potsdam, Potsdam, Germany

Metal-organic frameworks (MOFs) have been traditionally prepared by the solvothermal/hydrothermal methods with temperatures from room temperature up to 200 °C and reaction durations from hours to days. Also alternate techniques for MOFs synthesis were established, e.g. solvent-free synthesis and ultrasonic or microwave (MW) method.[1] In recent years we developed an isostructural series of imidazolate frameworks, named as IFP (Imidazolate Framework Potsdam). Based on a 2-substituted 4,5dicyanoimidazole precursor, the cyano groups convert under solvothermal conditions in situ into amide- imidate groups and formed with transition metals (Zn, Co) imidazolate frameworks with 1D hexagonal channels (Figure 1).[2] Herein, we represent the synthesis of IFPs under MW-assisted conditions. For assembly, the time duration of these materials can be minimized from days to under one hour when reactions are done and the resultant materials are formed also in higher yields. Co(II)-imidazolate frameworks, namely IFP-11 (R=Cl), -12 (R = Br) and -13 (R=Et) we achieved exclusively under MW conditions.[3] a)

b)

Figure 1. a) Syntheses of isostructural Zn(II)- and Co(II)-IFPs; b) sketch of the 1D hexagonal channels. References: [1] a) N. Stock, S. Biswas, Chem. Rev. 2012, 112, 933-969; b) J. Klinowski, F. A. A. Paz, P. Silva, J. Rocha, Dalton Trans. 2011, 40, 321-330; c) N. A. Khan, S. H. Jhung, Coord. Chem. Rev. 2015, 285, 11-23. [2] S. S. Mondal, A. Thomas, H.-J. Holdt, Micropor.Mesopor.Mater., doi:10.1016/j.micromeso.2015.01.049 [3] K. Behrens, I. A. Baburin, S. Leoni, F. Debatin, C. Günter, A. Zabel, R. Nöske, P. Strauch, J. Weber, H.-J. Holdt, in preparation.

Building with Colloids: Self-Assembly of (Bio)Nanoparticles at Interfaces Alexander Böker, Patrick van Rijn, Stephanie Hiltl, Patrick Wünnemann, Marco Schürings Fraunhofer-Institut für Angewandte Polymerforschung (IAP), Lehrstuhl für Polymermaterialien und Polymertechnologien, Universität Potsdam, 14476 Potsdam, Germany Email: [email protected]

Abstract This presentation deals with the use of different interfaces guiding the self-assembly of various soft colloidal particles [1]. First, we describe classical oil/water emulsion systems, the so-called Pickering emulsions. Here, the controlled assembly of protein-polymer conjugate nanoparticles (Ferritin-PNIPAAm) followed by crosslinking the polymer matrix leads to permeable, yet highly flexible and stable membranes and capsules [2,3]. The particle exhibit an unusually high interfacial activity and can even self-assemble to form hierarchical networks composed of capsules in fibres [4, 5]. Moreover, we demonstrate that nanostructured substrates produced from wrinkling instabilities with wavelengths on the order of only a few hundred nanometers, effectively guide the self-assembly of various well-defined organic nanoparticles (e.g. proteins or microgels) [6, 7]. This process allows the creation of anisotropic large scale particle arrays and supramolecular constructs like composite particulate nanoscale fibres.

References [1] P. van Rijn, M. Tutus, C. Kathrein, L. Zhu, M. Wessling, U. Schwaneberg, A. Böker Chem. Soc. Rev., 2013, 42, 6578. [2] N.C. Mougin, P. van Rijn, H. Park, A.H.E. Müller, A. Böker, Adv. Funct. Mater. 2011, 21, 2470. [3] P. van Rijn, N.C. Mougin, D. Franke, H. Park, A. Böker, Chem. Commun., 2011, 47, 8376. [4] P. van Rijn, N.C. Mougin, A. Böker, Polymer, 2012, 53, 6045. [5] P. van Rijn, H. Park, K. Özlem Nazli, N.C. Mougin, A. Böker, Langmuir, 2013, 29, 276. [6] A. Horn, S. Hiltl, A. Fery, A. Böker, Small 2010, 6, 2122. [7] S. Hiltl, M.-P. Schürings, A. Balaceanu, V. Mayorga, C. Liedel, A. Pich, A. Böker, Soft Matter, 2011, 7, 8231.

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Influence of temperature and ionic strength on the luminescence of lanthanides in complexes with small organic ligands Katja Burek, Sascha Eidner, Katlen Brennenstuhl & Michael Uwe Kumke* Institute of Chemistry (Physical Chemistry), University of Potsdam, Potsdam, Germany The comprehensive speciation analysis of actinides under environmental conditions is a fundamental basis for the assessment of the risk potential of the storage of nuclear waste. The formation of actinide complexes with naturally occurring organic ligands (such as humic substances or kerogen components leaching from clay minerals) is therefore of fundamental interest. In particular, the influence of temperature and ionic strength on the speciation has to be analysed. Both parameter will significantly depend on the type and location of a future repository to be built. Lanthanide(III)-ions (Ln(III)) are widely used as natural analogs for actinide(III)-ions (An(III)). They are non-radioactive and show simpler redox chemistry but have in general a similar chemistry in water. Small aromatic carboxylic acids can be considered as potential building blocks of humic substances or compounds leaching from kerogen. In order to use the full potential of time-resolved laser fluorescence spectroscopy (TRLFS) in the speciation analysis of Ln(III) and An(III), an exact knowledge of intra- and intermolecular photophysical processes of Ln(III) in aqueous solution with small organic ligands is indispensable. A wealth of information on the existing species in the solutions is collected by the determination of the emission intensity distribution as well as the luminescence decay kinetic varying temperature and ionic strength. The f-orbitals are only slightly involved to the binding of organic ligands because they are shielded by outer s- and p-orbitals. Nevertheless, the luminescence properties of Ln(III) are distinctly influenced by their chemical environment like the number of coordinated water molecules in the first coordination sphere as well as the number of organic ligands. Interactions between the electronic systems of the Ln(III) on the one hand side and the water molecules or the organic ligands on the other hand side can occur. Energy transfer processes to ligand-related vibration modes or triplet states as well as photo-induced electron transfer processes to form transient charge-transfer-states are possible nonradiative deactivation pathways and result in a changed photophysic of the Ln(III). In fact, the understanding of these ligand-related deactivation processes is of fundamental importance for a sound speciation analysis. In our work the luminescence of Eu(III), Tb(III), Sm(III) and Dy(III) in aqueous solutions with different ionic strength I (0 M < I < 4 M) in the presence of small organic ligands (like salicylic acid or phthalic acid) was analysed in a temperature range between 278 K and 353 K. A significant decrease of the luminescence decay time of Eu(III) or Tb(III) in complexes with salicylic acid in comparison to the pure aquo-complexes was observed. Depending on the energy difference between the triplet states of the organic ligand and the excited f-level of the Ln(III) as well as the redox chemistry of the ligand/Ln(III) couple different non-radiative deactivation processes were identified. They are responsible for the observed alterations of the Ln(III)-luminescence. For Eu(III) a photo-induced electron transfer process is postulated as the effective deactivation process while for Tb(III) the relative energy gap to a triplet state is of primary importance. For Tb(III)-complexes with salicylic acid a significant shift of the complex equilibrium with increasing ionic strength and temperature was observed. We will present results obtained for different small organic ligands in complexes with various Ln(III) to stress the complex interplay between Ln(III) and ligand properties with respect to luminescence enhancement or quenching.

Giant M14-Molecular Building Block in Hydrogen-Bonded Network Suvendu Sekhar Mondal,† Alexandra Kelling,† Uwe Schilde† and Hans-Jürgen Holdt† †Institut

für Chemie, Anorganische Chemie, Universität Potsdam, Karl-LiebknechtStraße 24-25, 14476 Potsdam, Germany

Supramolecular chemistry is of great interest in the design of new solid-state materials because it takes advantage of self-assembly to synthesized new materials by virtue of cooperative interactions such as ion−ion interactions, hydrogen bonding, dipole−dipole interactions, and aromatic π−π interaction.[1] We have developed a novel approach for the synthesis of a H-bonded assembly of molecular building blocks (MBBs), by using an imidazolate- 4,5-diamide-2-olate linker which is formed in situ under solvothermal condition.[2,3] The metal atoms (M = zinc, cobalt and cadmium for compound 1, 2 and 3, respectively) in the M(II)14-MBB formed the M6 octahedron inscribed distorted M8 cube (M6@M8). The compound 1 crystallizes in a cubic crystal system. Space group is Ia-3d (No 230), possessing the highest crystallographic symmetry. Twelve ligands, one oxide ion, two hydroxide ions and four H2O molecules assemble with fourteen zinc ions to form a tetradecanuclear Zn(II)14-MBB with peripheral amide groups, forming the H-bonded supramolecular network (Fig 1).[2] Moreover, the combination of three different types of coordination environments (octahedral, tetrahedral and distorted trigonal prismatic) around the Zn atoms in one compound is observed.[2] Compound 2 and 3 contain four DMF molecules, instead of four H2O.[3] The topology can be described as a H-bonded 8-c bcu net (body-centered cubic) with the nodes as M14-MBBs. Inspection of the reference-codes for Hbonded bcu nets in TOPOS revealed that metal-based Fig. 1 Hydrogen-bonded nodes contain only 2, 4 and 8 metal atoms. The bcu- supramolecular assembly of 1. net of this material contains the largest metal-nodes (M14) of bcu-net family. The MBBs connect by amide−amide hydrogen bonds to a 3D robust supramolecular network which can be activated for N2, CO2, CH4, and H2 gas sorption. Literature: [1] J. W. Steed and J. L. Atwood, Supramolecular Chemistry; Wiley- VCH: Weinheim, Germany, 2009. [2] S. S.Mondal, A. Bhunia, A. Kelling, U. Schilde, C. Janiak and H.-J. Holdt, J. Am. Chem. Soc., 2014, 136, 44–47. [3] S. S.Mondal, A. Bhunia, A. Kelling, U. Schilde, C. Janiak and H.-J. Holdt, Chem. Commun., 2104, 50, 5441-5443.

Exploring Routes to New Amino Acid-based Polymers Felix N. Führera, Christian Seckerb, and Helmut Schlaada,* a

University of Potsdam, Institute of Chemistry, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany

b

Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany

Amino acids and derivatives are bio-based monomers which could serve as building blocks for new sustainable polymer materials with advanced properties. Here we explore glycine- and cysteinederived monomers for polymerization by step growth (metathesis and thiol-ene polymerization) and chain growth techniques (ring-opening polymerization). (1) 1,4-Dialkenyl-2,5-diketopiperazine and O,O’-dialkenyl-N,N’-di-Boc-L-cystine undergo acyclic diene metathesis (ADMET) polymerization, using Hoveyda-Grubbs 2nd generation catalyst, to give polymers with molar masses >10 kg mol-1. These monomers can also be copolymerized with either dienes (ALTMET) or dithiols (thiol-ene polyaddition). (2) N-Propargyl glycine N-carboxyanhydride (NCA) can be polymerized by ring-opening polymerization using a primary amine initiator to give polyglycine with pendant propargyl side chains. The alkyne groups can be reacted with azides (CuAAC) or thiols (thiol-yne photoaddition) or deprotonated with tBu-P 4 base to initiate ethylene oxide polymerization.

Gold nanolenses on DNA origami substrates for surface-enhanced Raman scattering Christian Hecka,b,c, Julia Prinza, Virginia Merkc, Janina Kneippb,c, Ilko Balda,b aUniversity

of Potsdam, Department of Chemistry, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany; Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489 Berlin, Germany; cHumboldt Universität zu Berlin, SALSA & Department of Chemistry, Brook-Taylor-Str. 2, 12489 Berlin, Germany [email protected] // www.uni-potsdam.de/osci bBAM

Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures, enabling characterization of analytes at the single-molecule level. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique. In our work DNA origami is used for precise positioning of individual gold nanoparticles (AuNPs) and analyte molecules (Fig. 1). Especially high sensitivities are expected for gold nanolenses (AuNLs), employing defined rows of 3 or more differently-sized AuNPs. We assembled AuNLs consisting of different sets of AuNPs and assessed their potential for SERS measurements. Raman spectra from single AuNLs were measured and signal enhancements in comparison to isolated AuNPs will be calculated. In finite difference time domain calculations we estimate the attainable electromagnetic field enhancements in the synthesized systems. Ultimately we aim to develop a versatile platform for various SERS applications.

Funding by DFG (SALSA, part of the Excellence Initiative) and a Marie Curie FP7 Integration Grant (7th European Union Framework Programme) is gratefully acknowledged. J.K. acknowledges funding by ERC grant No. 259432 (MULTIBIOPHOT).

Figure 1: Gold nanoparticles constituting a gold nanolens are assembled by triangular DNA origami scaffold

Inverse Opal Hydrogels for Macromolecules Recognition as a Diagnostic Tool Jean-Philippe Couturier1*, A. Laschewsky1, M. Sütterlin1, E. Wischerhoff2, C. Hettrich3 1

Institut für Chemie, Universität Potsdam, 14476 Potsdam-Golm, Germany Fraunhofer Institut für Angewandte Polymerforschung IAP, 14476 Potsdam-Golm, Germany 3 Fraunhofer Institut für Zelltherapie und Immunologie IZI-BB, 14476 Potsdam-Golm, Germany 2

* e-mail: [email protected] We shall present a route to sensors based on the modulation of the visual band gap of a photonic crystal, which is induced by the selective binding of analytes. Such easy-to-use and quick responsive diagnostic tests are much needed, in particular in medicine.[1] Due to their periodical dielectric structure, photonic crystals prevent the propagation of specific wavelengths. A change of the periodicity parameters is thus indicated by a change in the reflected wavelengths.[2] In our case, the photonic crystal sensors are implemented as periodically structured responsive hydrogels in form of an inverse opal. The incorporated recognition units can specifically bind to certain low and high molar mass biomolecules, such as saccharides, catechols, glycopolymers or proteins. This induces a coil-to-globule transition of the matrix polymer (Fig.1). The specific binding event thus strongly modulates the swelling of the hydrogel matrix, and in consequence, drastically changes the periodicity parameter d. The shift of the interference bandgap (defined by 2d·sinθ = n·λ) resulting from the specific molecular recognition is easily visualized by the naked eye.[3]

Fig.1. (left) Temperature dependent transmittance of a benzoboroxol-functionalized polymer in PBS (concentration 3 g/L), in the absence and presence of its analyte (here: levodopa).

(right) UV-vis transmittance of a benzoboroxolfunctionalized inverse opal in PBS, in the absence and presence of its analyte (here: levodopa).

References: [1] [2] [3]

http://www.taschentuchlabor.de V. Alexeev, S. Das, D. Fingold, S. Asher, Clinical Chemistry 2004, 50, 2353-2360. J.-P. Couturier, M. Sütterlin, A. Laschewsky, C. Hettrich, E. Wischerhoff, Angew. Chem. Int. Ed. – Very Important Paper, 2015, in press: doi: 10.1002/anie.201500674.

A supramolecular assembly route towards stimuli-responsive poly(L-glutamate) hydrogels Charlotte Vacognea, Sarah Brosnana, Admir Masica, and Helmut Schlaadb,* a b

Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany University of Potsdam, Institute of Chemistry, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany

Polypeptides having secondary structures often undergo self-assembly, which can extend over ŵƵůƚŝƉůĞ ůĞŶŐƚŚ ƐĐĂůĞƐ͘ WŽůLJ;ɶ-benzyl-L-ŐůƵƚĂŵĂƚĞͿ ;W>'Ϳ͕ ĨŽƌ ĞdžĂŵƉůĞ͕ ĐĂŶ ĨŽůĚ ŝŶƚŽ ɲ-helices and form physical gels, whereas poly(L-glutamic acid)/poly(L-glutamate) (PLGA/PLG) exhibits limited long range order in water. In an attempt to circumvent the inability of PLGA to gel in water, we explored the photo-crosslinking gelation of statistical copolymers ƉŽůLJ;ɶ-benzyl-L-glutamate-co-allylglycine) in helicogenic organic solvents and subsequent deprotection of such gels to yield hydrogels. Unlike traditional chemical gels, our gels originated from dilute solutions (< 2% w/v) of low molar mass polymers (typically, 10 kDa). Remarkably, dioxane gels showed high mechanical stability and little shrinkage. Deprotection of dioxane gels yielded pH responsive and highly absorbent PLGA/PLG-based hydrogels, which are attractive as biomedical materials.