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Putting Fluorous Tails to Work. From Catalysis to Optoelectronics

Putting Fluorous Tails to Work. From Catalysis to Optoelectronics. Gianluca Pozzi CNR - Istituto di Scienze e Tecnologie Molecolari via Golgi 19, 20133 Milano. gianluca.pozzi@istm.cnr.it.

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Putting Fluorous Tails to Work. From Catalysis to Optoelectronics

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  1. Putting Fluorous Tails to Work.From Catalysis to Optoelectronics Gianluca Pozzi CNR - Istituto di Scienze e Tecnologie Molecolari via Golgi 19, 20133 Milano gianluca.pozzi@istm.cnr.it

  2. Fluorous= of, relating to, or having the characteristic of highly fluorinated saturated organic materials, molecules or molecular fragments (J.A. Gladysz, D.P. Curran Tetrahedron2002, 58, 3823)

  3. Organocatalysis Asymmetric Biphasic ….. Catalysis Organic (opto)electronics A Cinderella in the Fluorous World ? PG Nanoparticles Reagents Surface coating Crystal engineering High-throughput techniques Synthesis Materials ….. ….. Fluorous Imaging Proteomics Metabolomics Drug delivery Life Science Biomedical technologies Microaarray Blood substituents ….. …..

  4. Bordeaux (France) 2005 Fluorous catalysis and synthesis with a pinch of other topics. Organic electronics never cited. Yokohama (Japan) 2007 Catalysis and synthesis still well represented. Increased attention to other fluorous applications, but organic electronics. Jackson Hole (USA) 2009 Fluorous materials take the lead (self-assembly, nanostructures). Fluorous molecules for organic electronics are mentioned at last (S. Gorun).

  5. …but also compounds with fluorous tails, including monomeric species n-type semiconductors (OFETs) Fluorinated Organic Materials for Electronic and Optoelectronic applications: the role of the fluorine atom F. Babudri, G. M. Farinola, F. Naso, R. Ragni Chem. Commun. 2007, 1003-1022 Mainly conjugated oligomers and polymers with aromatic and vinylic C-F bonds Emissive layer in OLEDs p-type semiconductor (OFETs)

  6. Fluorinated Organic Materials for Electronic and Optoelectronic applications: the role of the fluorine atom F. Babudri, G. M. Farinola, F. Naso, R. Ragni Chem. Commun. 2007, 1003-1022 • Increased thermal and oxidative stability • Enhanced hydrophobicity and lipophobicity • Lower LUMO and HOMO energy levels • Charge mobility along preferred directions (self-assembledmolecular architectures) • Improved processability

  7. Fluorinated Organic Materials for Electronic and Optoelectronic applications: the role of the fluorine atom F. Babudri, G. M. Farinola, F. Naso, R. Ragni Chem. Commun. 2007, 1003-1022 Mainly conjugated oligomers and polymers with aromatic and vinylic C-F bonds Emissive layer in OLEDs p-type semiconductor (OFETs) …but also compounds with fluorous tails, including monomeric species n-type semiconductors (OFETs)

  8. High-Performance n-Type Organic Thin-Film Transistors Based on Solution Processable Perfluoroalkyl-Substituted C60 Derivatives M. Chikamatsu, A. Itakura, Y. Yoshida, R. Azumi, K. Yase Chem. Mater. 2008, 20, 7365-7367 • Excellent field-effect electron mobility me = 0.25 cm2 V-1s -1 • TFTs still operating when exposed to air

  9. Functionalized Perylenes: Origin of the Enhanced Electrical Performances C. Piliego, F. Cordella, D. Jarzab, S. Lu, Z. Chen, A. Facchetti, M. A. Loi Appl. Phys. A2009, 95, 303-308. • Solution processable (spin coating) • Electron mobility me = 0.15 cm2 V-1s -1 • High degree of co-facial arrangement and smooth morphology

  10. ITO PEDOT:PSS + - P3HT Acceptor PCBM Donor F-PCBM Al Self-organized Buffer Layers in Organic Solar Cells Q. Wei, T. Nishizawa, K. Tajima, K. HashimotoAdv. Mater. 2008, 20, 1-6 PCBM F-PCBM

  11. ITO PEDOT:PSS + - P3HT Acceptor PCBM Donor F-PCBM Al Self-organized Buffer Layers in Organic Solar Cells Q. Wei, T. Nishizawa, K. Tajima, K. HashimotoAdv. Mater. 2008, 20, 1-6 • Decreased hole-electron recombination loss at the P3HT / Al interface • Reduced energy barrier for electron injection and collection • decreased metal work function ? • increased HOMO and LUMO energy levels of the organic layer ?

  12. Phase Separation and Affinity between a Fluorinated Perylene Diimide Dye and an Alkyl-Substituted Hexa-peri-Hexabenzocoronene G. De Luca, A. Liscio, M. Melucci, T. Schnitzler, W. Pisula, C. G. Clark, L. Monsù Scolaro, V. Palermo, K. Müllen, P. SamorìJ. Mater. Chem.2010, 20, 71–82 n-type semiconductor (acceptor) p-type semiconductor (donor) • Strong intermolecular interaction in the blends • (C–H….F–C interactions + p-stacking) • Control of the phase separation at different scales

  13. Semiperfluoroalkyl Polyfluorenes for Orthogonal Processing in Fluorous Solvents J.-K. Lee, H. H. Fong, A. A. Zakhidov, G. E. McCluskey, P. G. Taylor, M. Santiago-Berrios, H. D. Abruna, A. B. Holmes, G. G. Malliaras, C. K. Ober Macromolecules2010, 43, 1195-1198 HFE-7500 • Light emitting polymers • Increased band gap (blue emission) • Photolitographic conditions compatible with fluorous solvents

  14. Phthalocyanine derivatives (Pcs) Catalysis Dyes Photodynamic therapy Photo-litography Liquid Crystals (Opto)electronics

  15. Phthalocyanine derivatives (Pcs) Catalysis • (Aerobic) Oxidation of hydrocarbons, alcohols, organic sulfides • Photooxidations (photodegradation of pollutants) • Degradation of lignin • ….

  16. Phthalocyanine derivatives (Pcs) Catalysis • Separation from products • Site isolation • Bleaching • …. A fluorous approach can help

  17. Fluorous Pcs Functionalization of preformed Pcs Harsh reaction conditions Number and location of RF = ? I. Rábai in Handbook of Fluorous Chemistry, Wiley-VCH2004, Ch. 14

  18. Fluorous Pcs Cyclization of fluorous building-blocks Milder reaction conditions Better control on substitution pattern Eur. J. Org. Chem. 2001, 181

  19. Reaction Organic phase Substrate Product O2 Catalyst Catalyst Fluorous phase Recycling

  20. Fluorous Pcs M. Özer et al. Appl. Organometal. Chem. 2009, 23, 55 Spacers matter time = 9h PO2 = 2 atm Conv. = 6.5% time = 24h PO2 = 6 atm Conv. = 6.5% FB oxidation of benzylic alcohol

  21. Phthalocyanine derivatives (Pcs) (Opto)electronics • Nonlinear optical materials • Electrochromic devices • TFT • Dye Sensitized Solar Cells (DSC) • ….

  22. - - - - Sensitizer Semiconductor Working electrode (Photoanode) TCO = Trasparent conducting oxide FTO = Fluorine-doped SnO2 Mesoporous semiconductor film Nanostructured metal oxide (TiO2, 100-300 nm) Thickness = 2 – 10 mm TCO TCO FTO FTO Pt Sensitizer Ru polypyridyl complexes Organic dyes, other metal complexes (extended) conjugated p-systems Red Ox Charge carrier Electrolyte with a redox shuttle (I-/I3-) Organic hole transporter Counterelectrode (Cathode) Pt = catalyst for the electrochemical reduction of the charge carrier

  23. Photocurrent generation - - (2) S* (3) Dye regeneration 2 S+ + 3 I- 2 S + I3- ECB LUMO EF (2) Electron injection S* S+ + e-TiO2 (5) (6) (4) Carrier regeneration I3- + 2 e-Pt 3 I- 0 Maximum voltage (1) Light absorption and photoexcitation S + hu S* (1) I3- (3) (4) 0.5 Side Processes I- S/S+ 1.0 HOMO (5) Recombination S+ + e-TiO2 S e- e- e- e- e- (6) Dark current I3- + 2 e-TiO2 3 I- V vs NHE -0.5

  24. Dye functions Light harvesting Elevated e over visible and NIR regions Electron injection Proper energy levels / location of MO; good electronic contact with TiO2 Further requirements • Stability (in the ground, excited and oxidized states) • Reduced e- recombination (and dark current) incidence • Non-aggregating properties • Hydrophobicity p A TiO2 D e-

  25. Further requirements • Stability (in the ground, excited and oxidized states) • Reduced e- recombination (and dark current) incidence • Non-aggregating properties • Hydrophobicity Dye functions Light harvesting Intense absorptionin the red / NIR, transparency over a large portion of the Vis Electron injection Energy levels / location of MO ? Electronic contact with TiO2?

  26. Further requirements p D A e- • Stability (in the ground, excited and oxidized states) • Reduced e- recombination (and dark current) incidence • Non-aggregating properties • Hydrophobicity Dye functions Light harvesting Electron injection E. Palomares et al. Chem. Commun.2004, 2112

  27. Further requirements p D A e- • Stability (in the ground, excited and oxidized states) • Reduced e- recombination (and dark current) incidence • Non-aggregating properties • Hydrophobicity Dye functions Light harvesting Electron injection P. Y. Reddy et al. Angew. Chem.Int. Ed.2007, 46, 373. H.Imahori et al. Acc. Chem. Res. 2009, 42, 1809

  28. p D A e- Unsymmetrical Fluorous Pcs Light harvesting Electron injection …at least we hope so! • Stability (in the ground, excited and oxidized states) • Reduced e- recombination (and dark current) incidence • Non-aggregating properties • Hydrophobicity

  29. = = Bulky fluorous electron-donating moiety ???? (COOH)n M = Zn Unsymmetrical Fluorous Pcs

  30. B. A. Bench et al. Angew. Chem.Int. Ed.2002, 41, 748 S. P. Keizer et al. J. Am. Chem.Soc.2003, 125, 7067 C. Keil et al. Thin Solid Films2009, 517, 4379 R. Gerded et al. Dalton Trans.2009, 209, 1098 Gorun’s ZnPc • Does not aggregate • Stable • Active (photo) oxygenation catalyst • … EW –CF(CF3)2 groups

  31. A lesson learned from catalysis Spacers matter

  32. Dipole Vector 3.04 Debye

  33. LUMO DE HOMO-LUMO = 2 eV (labs 620 nm)

  34. LUMO PcCOO-Ti(IV) .

  35. H.Weitman et al. Photochem. Photobiol.2001, 73, 473 M. R. Reddy et al. Angew. Chem.Int. Ed.2006, 45, 8163 • Does not aggregate • Acceptable photosensitivity • CF3CH2O- = positive mesomeric effect • Does not aggregate • Stable enough to be used as a photosensitizer • CF3CH2O- = EW character

  36. D. Sukeguchi et al. J. Fluorine.Chem.2009, 130,361 • No intramolecular electron and/or charge transfer • Pc = donor; fullerene = acceptor in standard Pc-fullerene dyads • CF3CH2O- EW effect prevails

  37. = = (COOH)n M = Zn Unsymmetrical Fluorous Pcs

  38. Unsymmetrical Fluorous Pcs B A A3B • Statistical condensation affords mixtures of Pcs (mainly A4 and A3B products) • Chromatographic separation of A4, A3B, A2B2,…. is possible • X = H products A3B are obtained as mixtures of regioisomers • Chromatographic separation of regioisomers is not feasible

  39. Unsymmetrical Fluorous Pcs F81-ZnPc(COOH)n UV-Vis, IR, MALDI-TOF

  40. Fluorous Phthalonitriles

  41. Fluorous Phthalonitriles

  42. Fluorous Phthalonitriles Template tetracyclization fails to afford the corresponding Pc

  43. Fluorous Phthalonitriles Template tetracyclization affords the corresponding Pc

  44. F68-ZnPcCOOH Faintly soluble in PFCs F54-ZnPc(COOH)2 Soluble in OS + freon F27-ZnPc(COOH)2 Aggregation in organic solvents Unsymmetrical Fluorous Pcs

  45. Soluble in OS, addition of amphiphilic solvents (BTF, freon…) helps Processable for DSC Unsymmetrical Fluorous Pcs F81-ZnPcCOOH F81-ZnPc(COOH)2

  46. Unsymmetrical Fluorous Pcs Light harvesting Intense absorptionin the red / NIR, transparency over a large portion of the Vis F81-ZnPcCOOH (Et2O) 664 nm 675 nm 1.7 x 10-5 M 3.4 x 10-6 M 344 nm A 603 nm l (nm)

  47. Unsymmetrical Fluorous Pcs Light harvesting Intense absorptionin the red / NIR, transparency over a large portion of the Vis F81-ZnPc(COOH)2 (Et2O/CCl2FCF2Cl 3/1) 1.6 x 10-5 M 3.2 x 10-6 M 344 nm 664 nm 681 nm 633 nm A l (nm)

  48. 400 500 600 700 800 Unsymmetrical Fluorous Pcs Light harvesting Intense absorptionin the red / NIR, transparency over a large portion of the Vis F81-ZnPc(COOH)2 (Et2O/CCl2FCF2Cl 3/1) F81-ZnPc(COOH)2 on TiO2 681 nm 695 nm A (a.u.) A (a.u.) l (nm) l (nm)

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