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  • Toward Wearable Sensors: Fluorescent Attoreactor Mats as Optically Encoded Cross-Reactive Sensor Arrays
  • Enhanced phosphorescence in dibenzophosphole chalcogenide mixed crystal
  • High Vacuum Thermal Deposition system with organic and inorganic chambers, capable of DC & RF sputtering
  • High-efficiency tris(8-hydroxyquinoline)aluminum (Alq3) complexes for organic white-light-emitting diodes and solid-state lighting
  • PheraStar for multidetection HTS microplate reading with simultaneous dual emission for measuring of fluorescence, luminescence and absorbance in UV/Vis
  • Members of the Anzenbacher Research Group
  • OLEDs with different emissive materials fabricated with a state of the art hole-injection layer
  • Supramolecular Chemistry Approach to the Design of a High-Resolution Sensor Array for Multianion Detection in Water
  • Atto-liter reactors featured in Nature Chemistry
  • Green Synthesis of Polycyclic Benzimidazole Derivatives and Organic Semiconductors
ANZENBACHER RESEARCH GROUP

The research in Anzenbacher research group is, in general, focused on the development of advanced photonic materials in two main areas: supramolecular materials for molecular sensing and materials that can be used in organic electronics, e.g. fabrication of flat displays and energy-efficient interior lights, solar cells (photovoltaics) or field-effect transistors (FETs).

Specifically, we study supramolecular aspects of heavy metal sensing anion binding and sensing, and use the generated knowledge for the preparation of materials that can be used for for fabrication of fluorescence-based optical sensors, and synthesis of artificial dyes and pigments. Recently, we have started developing sensor chips utilizing conductive polymers and other smart materials capable of signaling the presence of ions by change in color and/or luminescence. The research in the field of optical sensing led us also to synthesize materials that react to the presence of explosives such as TNT. Naturally, we have developed also sensor chip for vapors of explosives. The second important area of our research is devoted to organic electronics materials. We design and synthesis materials (chromophores and charge-transport materials) for use in OLEDs, organic photovoltaics (OPV) and thin-film solar cells. While we are pursuing synthesis and fabrication of OLEDs for application as light sources in solid-state lighting (SSL) and flat displays. These materials are mostly of the small-molecular nature such as organometallic complexes and organic chromophores. For the purpose of solid-state lighting, we are pursuing bright white-light emitting OLEDs (WOLEDs) and OLED architectures that allow fabrication of stable large devices (with 1×1 inch pixels).  we also pursue the synthesis of various semiconductor quantum dots/rods for application in solar cells, chromophores, fluorophores and dyes, mostly for organic electroluminescence and sensor applications, but also to enhance our understanding of photonic materials design. Many of these effeorts are collaborative. We have been blessed with a number of collaborations with other scientists; Together we are capable of increasing the footprint of our research and increase our knowledge.

As a departing platform for our research we utilize methods of organic and organometallic synthesis to prepare new photonic materials. We use methods of molecular spectroscopy to investigate the properties of prepared compounds and materials (NMR, MS and IR spectroscopy). We also use methods of optical spectroscopy (both steady state and time-resolved, absorption and fluorescence/luminescence) as well as optical microscopy to investigate the materials but also induce or observe chemical and photophysical changes in the investigated materials. Lately, we added a number of fabrication methods and methods of investigating organic semiconductors.

 

IN THE NEWS

Toward Wearable Sensors: Fluorescent Attoreactor Mats as Optically Encoded Cross-Reactive Sensor Arrays

Ultra-small fluorescent sensors and their application for fabrication of wavelength-addressable virtual sensor arrays capable of sensing metal cations are described. The fluorescent probes generated in situ within the fiber mats can be used as wearable sensors for identifying heavy metal ions in a qualitative and quantitative fashion. doi:10.1002/anie.201200099

Templated Synthesis of Glycoluril Hexamer and Monofunctionalized Cucurbit[6]uril Derivatives

We report that the p-xylylenediammonium ion (11) acts as a template in the cucurbit[n]uril forming reaction that biases the reaction toward the production of methylene bridged glycoluril hexamer (6C) and bis-nor-seco-CB[10]. Hexamer 6C is readily available on the gram scale by a one step synthetic procedure that avoids chromatography. Hexamer 6C undergoes macrocylization with (substituted) phthalaldehydes 12, 14, 15, and 18—in 9 M H2SO4 or concd HCl at room temperature to deliver monofunctionalized CB[6] derivatives 13, 16, 17, and 19—that are poised for further functionalization reactions. The kinetics of the macrocyclization reaction between hexamer and formaldehyde or phthalaldehyde depends on the presence and identity of ammonium ions as templates. p-Xylylenediammonium ion (11) which barely fits inside CB[6] sized cavities acts as a negative template which slows down transformation of 6C and paraformaldehyde into CB[6]. In contrast, 11 and hexanediammonium ion (20) act as a positive template that promotes the macrocyclization reaction between 6C and 12 to deliver (±)-21 as a key intermediate along the mechanistic pathway to CB[6] derivatives. Naphthalene-CB[6] derivative 19 which contains both fluorophore and ureidyl C═O metal-ion (e.g., Eu3+) binding sites forms the basis for a fluorescence turn-on assay for suitable ammonium ions (e.g., hexanediammonium ion and histamine). doi:10.1021/ja208229d

Enhanced phosphorescence in dibenzophosphole chalcogenide mixed crystal

The single crystals of 9-phenyl-9-dibenzophosphole chalcogenides {oxide (1), sulfide (2) and selenide (3)} and a mixed crystal of 2 and 3 have been prepared and characterized by X-ray diffraction analysis. Several intermolecular interactions such as π–π and Se–H were observed in the mixed crystal of 2 and 3. The mixed crystal of 2 and 3 exhibited enhanced phosphorescence compared to the pure constituent crystal (2 or 3) at low temperature. doi:10.1039/C1CE05388D

High-efficiency tris(8-hydroxyquinoline)aluminum (Alq3) complexes for organic white-light-emitting diodes and solid-state lighting.

Combinations of electron-withdrawing and -donating substituents on the 8-hydroxyquinoline ligand of the tris(8-hydroxyquinoline)aluminum (Alq(3)) complexes allow for control of the HOMO and LUMO energies and the HOMO-LUMO gap responsible for emission from the complexes. Here, we present a systematic study on tuning the emission and electroluminescence (EL) from Alq(3) complexes from the green to blue region. In this study, we explored the combination of electron-donating substituents on C4 and C6. Compounds 1-6 displayed the emission tuning between 478 and 526 nm, and fluorescence quantum yield between 0.15 and 0.57. The compounds 2-6 were used as emitters and hosts in organic light-emitting diodes (OLEDs). The highest OLED external quantum efficiency (EQE) observed was 4.6%, which is among the highest observed for Alq(3) complexes. Also, the compounds 3-5 were used as hosts for red phosphorescent dopants to obtain white light-emitting diodes (WOLED). The WOLEDs displayed high efficiency (EQE up to 19%) and high white color purity (color rendering index (CRI≈85). doi:10.1002/chem.201100707

Green Synthesis of Polycyclic Benzimidazole Derivatives and Organic Semiconductors

Polycyclic benzimidazole derivatives, an important class of compounds in organic electronics and photovoltaics, were prepared using a solvent-free "green" process based on heating carboxylic acid anhydrides and arylene diamines in the presence of zinc acetate in the solid state. Products were isolated and purified directly by train sublimation of the crude reaction mixtures. The reaction conditions were optimized using various carboxylic acid anhydrides. Optical and electrochemical properties of these materials are also described. doi:10.1021/ol201973w

RESEARCH IN THE GROUP