Home

Prof. Dr. Uwe Bunz - Research Topics

Large Heteroacenes	top
Acenes and heteroacenes are a class of structurally fascinating molecules that find applications in Organic Electronics. They are due to their packing fair to excellent charge transporting materials. Pentacene shows a high hole mobility and is a reference material in organic electronics for applications in thin film transistors. Nitrogen containing analogs are less prevalent and are therefore very attractive targets to construct electron- transporting versions of pentacen. The Bunz group has developed several synthetic schemes to prepare these attractive materials.
A simple synthesis of Diazapentacenes.
A simple synthesis of a Tetraazapentacene.
Azapentacenes and azatetracenes are deeply colored and are therefore of potential interest as absorbers in photovoltaic cells.
Selected references
Bunz, Uwe H. F.: "The larger N-heteroacenes". Pure and Applied Chemistry 2010, 82(4), 953-968.
Bunz, Uwe H. F.: "N-Heteroacenes". Chemistry - A European Journal 2009, 15(28), 6780-6789.
Appleton, Anthony Lucas; Miao, Shaobin; Brombosz, Scott M.; Berger, Nancy J.; Barlow, Stephen; Marder, Seth R.; Lawrence, Brian M.; Hardcastle, Kenneth I.; Bunz, Uwe H. F.: "Alkynylated Aceno[2,1,3]thiadiazoles". Organic Letters 2009, 11(22), 5222-5225.
Miao, Shaobin; Appleton, Anthony L.; Berger, Nancy; Barlow, Stephen; Marder, Seth R.; Hardcastle, Kenneth I.; Bunz, Uwe H. F.: "6,13-Diethynyl-5,7,12,14-tetraazapentacene". Chemistry - A European Journal 2009, 15(20), 4990-4993.
Miao, Shaobin; Brombosz, Scott M.; Schleyer, Paul v. Rague; Wu, Judy I.; Barlow, Stephen; Marder, Seth R.; Hardcastle, Kenneth I.; Bunz, Uwe H. F.: "Are N,N-Dihydrodiazatetracene Derivatives Antiaromatic?" Journal of the American Chemical Society 2008, 130(23), 7339-7344.
Wu, Judy I.; Wannere, Chaitanya S.; Mo, Yirong; Schleyer, Paul von Rague; Bunz, Uwe H. F.: "4n pi Electrons but Stable: N,N-Dihydrodiazapentacenes". Journal of Organic Chemistry 2009, 74(11), 4343-4349.

Cruciform Fluorophores	top
Cruciforms change their emission color depending upon their substituent pattern. The effects are dramatic.
The orbital structure of cruciforms (XF) is highly variable. In the case of hydrocarbon-based XFs (Top) HOMO and LUMO are congruent, i.e. spatially overlapping, while in the case of the donor-acceptor substituted XFs the HOMO and the LUMO only overlap in the central benzene ring. As a consequence, HOMO and LUMO are independently addressable by different analytes.
Exposure of the dibutylamino-pyridine XF (see circled structure) to increasing amounts of zinc triflate reveals a rare two stage sensory response that originates from the successive stabilization of the HOMO and the LUMO.
Exposure of 9 XFs to 20 metal cations in DCM; alkali metals do not show chromic responses; metal triflates give the best results. In this array MnCl2 and CaCl2 were used and these do not show binding. CaOTf2 and MnOTf2 do give color reactions. The colors are obtained by subtraction of the refe­rence from the test samples using ImageJ.
Selected references
Zucchero, Anthony J.; McGrier, Psaras L.; Bunz, Uwe H. F.: "Cross-Conjugated Cruciform Fluorophores". Accounts of Chemical Research 2010, 43(3), 397-408.
Wilson, James N.; Bunz, Uwe H. F.: "Switching of Intramolecular Charge Transfer in Cruciforms: Metal Ion Sensing". Journal of the American Chemical Society 2005, 127(12), 4124-4125.
Zucchero, Anthony J.; Wilson, James N.; Bunz, Uwe H. F.: "Cruciforms as functional fluorophores: Response to protons and selected metal ions". Journal of the American Chemical Society 2006, 128(36), 11872-11881.
Tolosa, Juan; Zucchero, Anthony J.; Bunz, Uwe H. F.: "Water-soluble cruciforms: response to protons and selected metal ions". Journal of the American Chemical Society 2008, 130(20), 6498-6506.
Wilson, James N.; Smith, Mark D.; Enkelmann, Volker; Bunz, Uwe H. F.: "Cruciform pi-systems: effect of aggregation on emission". Chemical Communications 2004, (15), 1700-1701.
Hauck, Martina; Schoenhaber, Jan; Zucchero, Anthony J.; Hardcastle, Kenneth I.; Mueller, Thomas J. J.; Bunz, Uwe H. F.: "Phenothiazine Cruciforms: Synthesis and Metallochromic Properties". Journal of Organic Chemistry 2007, 72(18), 6714-6725.
McGrier, Psaras L.; Solntsev, Kyril M.; Schoenhaber, Jan; Brombosz, Scott M.; Tolbert, Laren M.; Bunz, Uwe H. F.: "Hydroxy-cruciforms". Chemical Communications 2007, (21), 2127-2129.
McGrier, Psaras L.; Solntsev, Kyril M.; Miao, Shaobin; Tolbert, Laren M.; Miranda, Oscar R.; Rotello, Vincent M.; Bunz, Uwe H. F.: "Hydroxycruciforms: amine-responsive fluorophores". Chemistry - A European Journal 2008, 14(15), 4503-4510.

Hyperbranched Conjugated Polymers	top
Selected references
Kim, Ik-Bum; Phillips, Ronnie; Bunz, Uwe H. F.: "Carboxylate Group Side-Chain Density Modulates the pH-Dependent Optical Properties of PPEs". Macromolecules 2007, 40(15), 5290-5293.
Kim, Ik-Bum; Erdogan, Belma; Wilson, James N.; Bunz, Uwe H. F.: "Sugar-poly(para-phenylene ethynylene) conjugates as sensory materials: Efficient quenching by Hg2+ and Pb2+ ions". Chemistry - A European Journal 2004, 10(24), 6247-6254.
Kim, Ik-Bum; Bunz, Uwe H. F.: "Modulating the Sensory Response of a Conjugated Polymer by Proteins: An Agglutination Assay for Mercury Ions in Water". Journal of the American Chemical Society 2006, 128(9), 2818-2819.
Kim, Ik-Bum; Dunkhorst, Anna; Gilbert, James; Bunz, Uwe H. F.: "Sensing of Lead Ions by a Carboxylate-Substituted PPE: Multivalency Effects". Macromolecules 2005, 38(11), 4560-4562.
Bunz, Uwe H. F.: "Poly(aryleneethynylene)s". Macromolecular Rapid Communications 2009, 30(9-10), 772-805.

Water Soluble Conjugated Polymers

Selected references

Kim, Ik-Bum; Phillips, Ronnie; Bunz, Uwe H. F.: "Carboxylate Group Side-Chain Density Modulates the pH-Dependent Optical Properties of PPEs". Macromolecules 2007, 40(15), 5290-5293.

Kim, Ik-Bum; Erdogan, Belma; Wilson, James N.; Bunz, Uwe H. F.: "Sugar-poly(para-phenylene ethynylene) conjugates as sensory materials: Efficient quenching by Hg2+ and Pb2+ ions". Chemistry - A European Journal 2004, 10(24), 6247-6254.

Kim, Ik-Bum; Bunz, Uwe H. F.: "Modulating the Sensory Response of a Conjugated Polymer by Proteins: An Agglutination Assay for Mercury Ions in Water". Journal of the American Chemical Society 2006, 128(9), 2818-2819.

Kim, Ik-Bum; Dunkhorst, Anna; Gilbert, James; Bunz, Uwe H. F.: "Sensing of Lead Ions by a Carboxylate-Substituted PPE: Multivalency Effects". Macromolecules 2005, 38(11), 4560-4562.

Bunz, Uwe H. F.: "Poly(aryleneethynylene)s". Macromolecular Rapid Communications 2009, 30(9-10), 772-805.

Novel Conjugated Polymer Architectures

Electrospun Preparations Change Color

Selected references

Jiang, Yunfei; Perahia, Dvora; Wang, Yiqing; Bunz, Uwe H. F.: "Side Chain vs. Main Chain. Who Dominates? A Polyester-Grafted Poly(p-phenyleneethynylene) with Two Different Morphologies". Macromolecules 2006, 39(15), 4941-4944.

Wang, Yiqing; Park, Jong Seung; Leech, Jake Peter; Miao, Shaobin; Bunz, Uwe H. F.: "Poly(aryleneethynylene)s with Orange, Yellow, Green, and Blue Solid-State Fluorescence". Macromolecules 2007, 40(6), 1843-1850.

Conjugated Polymer Gold Nanoparticle Constructs: Nanosensors	top
Array-based sensing of protein analytes at 5 mM using the PPE-gold nanoparticle constructs.
a, Fluorescence response (DI ) patterns of the NP–PPE sensor array (NP1–NP6) against various proteins (CC, cytochrome c; b-Gal, b-galactosidase; PhosA, acid phosphatase; PhosB, alkaline phosphatase; SubA, subtilisin A). Each value is an average of six parallel measurements. b, Canonical score plot for the first two factors of simplified fluorescence response patterns obtained with NP–PPE assembly arrays against 5 mM proteins. The canonical scores were calculated by LDA for the identification of seven proteins. The 95% confidence ellipses for the individual proteins are also shown.
Selected references
Bunz, Uwe H. F.; Rotello, Vincent M.: "Gold Nanoparticle-Fluorophore Complexes: Sensitive and Discerning "Noses" for Biosystems Sensing". Angewandte Chemie, International Edition 2010, 49(19), 3268-3279.
Phillips, Ronnie L.; Miranda, Oscar R.; Mortenson, David E.; Subramani, Chandramouleeswaran; Rotello, Vincent M.; Bunz, Uwe H. F.: "Gold nanoparticle-PPE constructs as biomolecular material mimics: understanding the electrostatic and hydrophobic interactions". Soft Matter 2009, 5(3), 607-612.
Phillips, Ronnie L.; Miranda, Oscar R.; You, Chang-Cheng; Rotello, Vincent M.; Bunz, Uwe H. F.: "Rapid and efficient identification of bacteria using gold-nanoparticle-poly(para-phenyleneethynylene) constructs". Angewandte Chemie, International Edition 2008, 47(14), 2590-2594.
You, Chang-Gheng; Miranda, Oscar R.; Gider, Basar; Ghosh, Partha S.; Kim, Ik-Bum; Erdogan, Belma; Krovi, Sai Archana; Bunz, Uwe H. F.; Rotello, Vincent M.: "Detection and identification of proteins using nanoparticle-fluorescent polymer 'chemical nose' sensors". Nature Nanotechnology 2007, 2(5), 318-323.

Click Chemistry

Click Chemistry: Changing the Fluorescence

Click Chemistry: Nanostructuring with Heated Tips

Selected references

Brombosz, Scott M.; Appleton, Anthony Lucas; Zappas, Andrew J., II; Bunz, Uwe H. F.: "Water-soluble benzo- and naphtho-thiadiazole-based bistriazoles and their metal-binding properties". Chemical Communications 2010, 46(9), 1419-1421.

Schweinfurth, David; Hardcastle, Kenneth I.; Bunz, Uwe H. F.: "1,3-Dipolar cycloaddition of alkynes to azides. Construction of operationally functional metal responsive fluorophores". Chemical Communications 2008, (19), 2203-2205.

Bakbak, Selma; Leech, Peter J.; Carson, Bradley E.; Saxena, Shubham; King, William P.; Bunz, Uwe H.: "1,3-Dipolar cycloaddition for the generation of nanostructured semiconductors by heated probe tips". Macromolecules 2006, 39(20), 6793-6795.

Englert, Brian C.; Bakbak, Selma; Bunz, Uwe H. F.: "Click Chemistry as a Powerful Tool for the Construction of Functional Poly(p-phenyleneethynylene)s: Comparison of Pre- and Postfunctionalization Schemes". Macromolecules 2005, 38(14), 5868-5877.

zuletzt bearbeitet am:	04. August 2010
durch: