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EP Thesis Defence 2016

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EP Thesis Defence 2016

  1. 1. Study of the Size-Reduction Effect on the Photophysical Properties of [Ru(bpy)3][NaCr(ox)3] Nano-Crystals and Functionalization of their Surface Elia Previtera November 24, 2016 Département de Chimie Physique, Université de Genève Hauser Group
  2. 2. Nano-Size Materials Applications: Medicine, Bio-imaging, IT, Solar-Energy Harvesting and Conversion, Lasers, Catalysis, Displays ….. Quantum Dots: tunable emission wavelength…... Gold Nanoparticles: tunable absorption wavelength….. Size 1 SIZE DEPENDENT PROPERTIES 5 nm 10 nm 15 nm 20 nm 80 nm 90 nm 100 nm Nano Today 2011.
  3. 3. Nano-Size Materials 2The New York Times article of February 22, 2005.
  4. 4. Nano-Size Materials At least one dimensions between 1 and 100 nm X At least one physical or chemical size- dependent property M.L. Grieneisen, M. Zhang, Small 2011, 7, No. 20, 2836-2839. What is What in the Nanoworld: A Handbook on Nanoscience and Nanotechnology 2012. 3
  5. 5. Energy Transfer and Migration .. ... . .. Homo-Energy Transfer or Energy Migration Hetero-Energy Transfer .. .. . . . . .. . . . . . . .. ... . .. 4
  6. 6. Radiative Energy Transfer and Migration Acceptor or DonorDonor* S0 S1 S0 S1 hν hν’ 5
  7. 7. Non-radiative Energy Transfer and Migration HOMO LUMO Förster AcceptorDonor* Dexter AcceptorDonor* kEET F ∝ 1 RDA ⎛ ⎝ ⎜⎜ ⎞ ⎠ ⎟⎟ 6 kEET Ex ∝exp − 2RDA RDA 0 ⎛ ⎝ ⎜⎜ ⎞ ⎠ ⎟⎟ HOMO LUMO 10 Å < Rc F < 80 Å 1 Å < Rc Ex < 10 Å 6
  8. 8. Non-radiative Energy Transfer and Migration ΩDA = gD (E)gA (E)dE∫ Spectral overlap integral ΩDA λ Emi(A)Emi(D)Abs(D) Abs(A) I gD gA 7
  9. 9. Energy Transfer and Migration in Natural Antennae 6 CO2 + 6 H2O C6H12O6 + 6 O2 Respiration Photosynthesis Sunlight Energy stored Energy storedEnergy released Nature, 1995, 374, 517. 8
  10. 10. Energy Transfer and Migration in Natural Antennae Photosynthetic unit of Rhodopseudomonas acidophila Nature, 1995, 374, 517. 9
  11. 11. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3] Anionic Chiral 3D Polymeric Oxalate Networks [NaCr(ox)3][Ru(bpy)3] Na++ D3 [Cr(ox)3]3- Crystal system Cubic Z = 4 Chiral Spacegroup P213 Site symmetry of
 all metal ions C3 S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 10
  12. 12. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3] Anionic Chiral 3D Polymeric Oxalate Networks [NaCr(ox)3][Ru(bpy)3] Na++ D3 [Cr(ox)3]3- Crystal system Cubic Z = 4 Chiral Spacegroup P213 Site symmetry of
 all metal ions C3 S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 11
  13. 13. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3] Anionic Chiral 3D Polymeric Oxalate Networks [NaCr(ox)3][Ru(bpy)3] Na++ D3 [Cr(ox)3]3- Crystal system Cubic Z = 4 Chiral Spacegroup P213 Site symmetry of
 all metal ions C3 S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 12
  14. 14. 3D oxalate network: [Ru(bpy)3][NaCr(ox)3] [Ru(bpy)3]2+: antenna Oxalate Networks to Study Photo-Induced Energy Transfer Bulk: efficient energy migration in the 2E state of Cr(III) [NaCr(ox)3]2- network: energy migration Is there any influence of the crystal size on the energy migration within the 2E state of the [Cr(ox)3]3- chromophores? hν Energy Transfer Milos. M. et al., Coor. Chem. Rev., 252, 2000, 2540 13
  15. 15. Reference System: Microcrystals of [Ru(bpy)3][NaCr(ox)3] Tetrahedral microcrystalline particles with side length 4 µm S. Decurtins et al., J. Amer. Chem. Soc. 116 (1994) 9521. 5 µm 14
  16. 16. How to Synthesize Nanocrystals? Ø  Synthesis by the Reverse Micelles technique Aqueous phase: Solubilization of [Ru(bpy)3]Cl2 .6H2O and K3[Cr(ox)3].3H2O Surfactant: Sodium bis(2-ethylhexyl) Sulfosuccinate (AOT) Solvent: n-Heptane TEM à Tetrahedral Shape of Nanocrystals Centrifugation and washing in EtOH 15
  17. 17. Size Controlled Micro- and Nanocrystals Tetrahedral Shape of Nanoparticles ImageJ Large Size Distribution 16 1000 nm
  18. 18. Size & Volume Weighted Distribution Iluminescence ≈ a3 a 17Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 < Size > = Σa Number of NPs < Size Signal > = Σ(a x a3) Total a3
  19. 19. Size Controlled Micro- and Nano-crystals Ø  Modification of the water-to-surfactant ratio (Wo) Wo = [H2O] [Surfactant] Size Control of final product! Wo= 2 Wo= 5 Wo= 8 2.5 µm MPs changing Wo and lowering the concentration of reactants inside micelles (Wo= 8 and 0.025 M) Previtera E. et al., Adv. Mater. 2015, 27, 1832. 18
  20. 20. Size Controlled Micro- and Nanocrystals 2θ = 5.8° 140 nm 220 nm 360 nm 450 nm 670 nm 2.5 µm 4 µm Previtera E. et al., Adv. Mater. 2015, 27, 1832. 19
  21. 21. Chromium (III): d3 in C3 Symmetry Ligand field states 4A2(t2g 3) 4T2(t2g 2eg 1) 4A2 2E Oh C3 + Hso R1 R2 D (2E) = 13.7 cm-1 D (4A2) = 1.3 cm-1 hν hν Spin-flip
 Δr ≈ 0 t2g → eg
 Δr ≈ 0.1 Å2E(t2g 3) ISC t2g eg t2g eg t2g eg E RCr-O Ms = ± 3/2 Ms = ± 1/2 20
  22. 22. Solid State Spectroscopy Background Homogeneous line width and inhomogeneous band broadening Lorentzian with the homogeneous linewidth Γhom 2E 4A2 R1 D A perfect crystal Electronic origin of Chromium (III) Andreas Hauser, Lecture Notes. 21
  23. 23. Solid State Spectroscopy Background Homogeneous line width and inhomogeneous band broadening Lorentzian with the homogeneous linewidth Γhom 2E 4A2 R1 D A perfect crystalA real crystal Electronic origin of Chromium (III) Gaussian profile with the i n h o m o g e n e o u s b a n d broadening Γinh Andreas Hauser, Lecture Notes. 22
  24. 24. Excitation Spectra of Cr3+ R-Lines Previtera E. et al., Adv. Mater. 2015, 27, 1832. 23
  25. 25. Excitation Spectra of Cr3+ R-Lines Previtera E. et al., Adv. Mater. 2015, 27, 1832. 24
  26. 26. Luminescence Spectra Previtera E. et al., Adv. Mater. 2015, 27, 1832. 25
  27. 27. Solid State Spectroscopy Background Laser selective excitation non-resonant 
 fluorescence 2E 4A2 R1 D resonant fluorescence In the absence of any other processes only the excited subset emits. The principle of Fluorescence Line Narrowing Spectroscopy (FLN) Andreas Hauser, Lecture Notes. 26
  28. 28. Solid State Spectroscopy Background Fluorescence Line Narrowing Spectroscopy Setup 27
  29. 29. FLN Spectra Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 Ø  Energy Transfer Core à Surface 28
  30. 30. FLN Spectra across the R1 Absorption Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 Size: 140 nm Ø  Smaller numbers of members in the FLN multiline pattern at lower energy 29
  31. 31. FLN Spectra across the R1 Absorption Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 Size: 670 nm Size: 2.5 µm Ø  Smaller numbers of members in the FLN multiline pattern at lower energy 30
  32. 32. ZFS as Function of FLN Excitation Wavelength Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 Ø  Crystalline environment of the [Cr(ox)3]3- chromophores at the surface is slightly different to that of the complexes in the bulk 31
  33. 33. Time Resolved FLN Spectra Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 hν’ Energy migration inside 2E of Cr(III) Cr3+ 2E 4A2 hν 4A2 2E Cr3+ Cr3+ Cr3+ 4T2 Core Surface 32
  34. 34. Luminescence Decay Kinetics Ø  Directional Energy Transfer from the Core to the Surface Previtera E. et al., Adv. Mater. 2015, 27, 1832. Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 Multi line pattern decay (at 14394 cm-1) τ4 µm = 1.3 ms τ2.5 µm = 155 µs τ670 nm = 132 µs τ140 nm = 57 µs Broad band rise to maximum intensity (at 14371 cm-1) 220 µs for 2.5 mm 180 µs for 670 nm 60 µs for 140 nm Broad band rise to maximum intensity (at 14351 cm-1) 400 µs for 2.5 mm 360 µs for 670 nm 180 µs for 140 nm 33 l
  35. 35. How far does the energy travel? Ø  Average distance travelled by the energy is of the order of a few hundreds nm RC resonant process à up to 30 Å Ø  l = 140 nm à d = 30 nm 10 steps for energy migration Core à Surface Ø  l = 670 nm à d = 138 nm 46 steps for energy migration Core à Surface Ø  l = 2.5 µm à d = 510 nm 170 steps for energy migration Core à Surface Previtera E. et al., Adv. Mater. 2015, 27, 1832. Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 34
  36. 36. Energy Transfer Mechanism Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 1A1 [Ru(bpy)3]2+ 35 << 1 µs < 1 ns
  37. 37. Conclusions •  Size-controlled micro- and nano-crystals of [Ru(bpy)3][NaCr(ox)3] •  Directional Energy Transfer from the Core to the Surface •  Average distance travelled by the energy is of the order of few hundreds nm Previtera E. et al., Adv. Mater. 2015, 27, 1832. Previtera E. et al., Eur. J. Inorg. Chem. 2016, 1972-1979 36 l
  38. 38. Control of the surface state $  Growth of oxalate network shell with cavities filled with energy acceptor [Cr(bpy)3]3+ $  Direct chemical grafting of Ln3+ complexes (Ln3+ = Er3+, Eu3+, Yb3+) 37
  39. 39. Growing an Oxalate network shell •  Core: 670 nm NPs [Ru(bpy)3][NaCr(ox)3] and [Ru(bpy)3][NaAl(ox)3] = RuCr, RuAl •  Core-Shell: [Ru(bpy)3][NaAl(ox)3]@[Ru(bpy)3][NaCr(ox)3] = RuAl@RuCr [Ru(bpy)3][NaCr(ox)3]@[NaCr(ox)3][Cr(bpy)3]ClO4 = RuCr@CrCr [Ru(bpy)3][NaAl(ox)3]@[NaCr(ox)3][Cr(bpy)3]ClO4 = RuAl@CrCr 38
  40. 40. Growing an Oxalate network shell PUMP Reactants Size nm [Ru(bpy)3][NaMIII(ox)3] MIII = Cr3+, Al3+ 670 (NH4)3[Cr(ox)3] - [Ru(bpy)3]Cl2 .6H2O - [Cr(bpy)3]ClO4 - NaCl - 39
  41. 41. Growing an Oxalate network shell Surface change •  Roughness •  Round corners Bigger average size RuAl RuAl@RuCr RuCr RuCr@CrCr RuAl RuAl@CrCr 40
  42. 42. Growing an Oxalate network shell 41
  43. 43. Growing an Oxalate network shell Ø  Energy Transfer Core à Shell? 42
  44. 44. Growing an Oxalate network shell 43
  45. 45. Growing an Oxalate network shell 44
  46. 46. Conclusions •  It is possible to grow an Oxalate network shell of good crystalline quality containing in its cavities the energy acceptor [Cr(bpy)3]3+. •  No evidence of energy transfer towards the shell in RuCr@CrCr was found. 45
  47. 47. Direct chemical grafting of Ln3+ complexes
 Up-Conversion Nanoparticles Nature Materials 2011. 46
  48. 48. Direct chemical grafting of Ln3+ complexes
 365 nm a) b) [Rh(bpy)3][NaAl(ox)3]ClO4 + [Eu(hfac)3dig] [Rh(bpy)3][NaAl(ox)3]ClO4@[Eu(hfac)3] + dig Preliminary Test 47 hfac = hexafluoroacetylacetonate dig = diglyme or bis(2-methoxyethyl)ether
  49. 49. Direct chemical grafting of Ln3+ complexes
 [Rh(bpy)3][NaAl(ox)3]ClO4 + [Eu(hfac)3dig] [Rh(bpy)3][NaAl(ox)3]ClO4@[Eu(hfac)3] + dig 48
  50. 50. Direct chemical grafting of Ln3+ complexes Reactants Size nm [Ru(bpy)3][NaCr(ox)3] RuCr 220 [Eu(hfac)3dig] Eu - [Er(hfac)3dig] Er - [Yb(hfac)3dig] Yb - RuCr + [Ln(hfac)3dig] RuCr@[Ln(hfac)3] + dig 49 hfac = hexafluoroacetylacetonate dig = diglyme or bis(2-methoxyethyl)ether
  51. 51. Excitation Spectra of Cr3+ R-Lines
 50
  52. 52. ZFS as Function of FLN Excitation Wavelength 51
  53. 53. Direct chemical grafting of Ln3+ complexes
 Ø  Energy Transfer Core à [Ln(hfac)3] 52
  54. 54. Down-Converted Luminescence 53
  55. 55. Down-Converted Luminescence
 54
  56. 56. Down-Converted Luminescence 55
  57. 57. Down-Converted Luminescence 56
  58. 58. •  Improving of the NPs’ surface. •  Quenching of the broad band luminescence. •  Efficient excitation energy transfer from the 2E excited states of the [Cr(ox)3]3- ions located at the surface towards the lanthanides complexes grafted at the NPs’ surface. •  Good indication of down conversion luminescence related to the lanthanides transitions 4I9/2à4I15/2 and 2F5/2à2F7/2 for Erbium and Ytterbium. •  No up-conversion luminescence. Conclusions 57
  59. 59. Outlook •  Direct chemical grafting of [Gd(hfac)3dig] 6P3/2 5/2 7/2 8S7/2 32200cm-1 •  Enhancing of the lifetime of the surface [Cr(ox)3]3- chromophores? •  Would direct excitation of [Gd(hfac)3] complexes grafted at the surface give directional energy transfer towards the chromophores located at the surface or further into the core? 58
  60. 60. •  This work contributes to the expansion of the basic knowledge about nano-size materials. •  The energy can travel few hundreds of nanometers in NCs. This important basic knowledge can be useful for future applications in solar energy harvesting and conversion. •  This work demonstrates that also particles with sizes bigger than 100 nm can show size-dependent properties. General Conclusions 59
  61. 61. Acknowledgements Prof. Hauser Dr. Lawson Daku Dr. Chakraborty Dr. Suffren Dr. Sun Teresa Delgado Perez Andrea Missana Catherine Ludy Nahid Jeddi Patrick Barman Dominique Lovy Laurent Devenoge Hauser’ Group: Prof. Decurtins Prof. Hagemann Dr. Tissot Jury members: Dr. Moury Dr. Olchowka Dr. Bierwagen Manish Sharma Daniel Sethio Angelina Gigante Hagemann’ Group: Prof. Piguet Dr. Nozary Piguet’ Group: Dr. Varnholt Dr. Lawson Daku Dr. Chakraborty Dr. Moury Andrea Missana Manish Sharma Corrections: 60
  62. 62. Thank you for your attention! 61

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