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Origin of Simultaneous Donor- Acceptor Emission in Single Molecule of Peryleneimide- Terrylenediimide Labeled Polyphenylene Dendrimers Sergey M.Melnikov.

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Presentation on theme: "Origin of Simultaneous Donor- Acceptor Emission in Single Molecule of Peryleneimide- Terrylenediimide Labeled Polyphenylene Dendrimers Sergey M.Melnikov."— Presentation transcript:

1 Origin of Simultaneous Donor- Acceptor Emission in Single Molecule of Peryleneimide- Terrylenediimide Labeled Polyphenylene Dendrimers Sergey M.Melnikov Edwin K.L.Yeow,Hiroshi Uji-I,Mircea Cotlet Klaus Mullen, Frans C De Schryver Jorg Enderlein, and Johan Hofkens J.Phys.Chem.C. 2007, 111, Kou ITOH MIYASAKA Lab. 1

2 Contents ● Background about dendrimers and its application ● Introduction Energy transfer process ● Experimental Confocal Single Molecule Spectroscopy Wide-field Spectroscopy (defocused imaging) ● Conclusion 2

3 Background T1P 4 T2P 8 :Perylenemonoimide unit :Terylenediimide unit Potential application to new photonic device core interior surface 3

4 single photon sourceartificial light-harvesting system light pulse Single photon light energy J.P.C.B.2004,108, J.A.C.S.2007,129, R Example of photonic devices 4 R R R

5 Evaluation and understanding of the dendrimers Ensemble measurementsSingle molecule measurements Energy transfer Electron transfer Emission lifetime etc. Dynamics, Efficiency of Ultra-high temporal resolution Reliable average values Emission dynamics of individual molecular systems Photon antibunching Enables us to evaluate single nanoscale dendrimers Complementary use of both measuring methods can give us comprehensive understanding of the dendrimers. Introduction 5

6 Introduction - Energy transfer processes transition probability ω is Förster theory D* + A → D + A* ω =( 1/τ 0 )・( R 0 / R ) 6 R : distance between molecules R 0 : critical transfer distance τ 0 : lifetime of donor S 1 -S 1 annihilation Hopping S 1 * + S 1 * → S o + S 1 * S 1 * + S 0 → S 0 + S 1 * S0S0 S1S1 S0S0 S1S1 AcceptorDonor S0S0 S1S1 S0S0 S1S1 SnSn AcceptorDonor Orientation of dipole moment Fluorescence of donor Absorption of acceptor Spectral overlap 6 Important factors in R 0 6 ( R 0 6 ∝    D J 

7 The purpose of this research hν0hν0 TDI unit PI unit Exciton blockade 7 hν2hν2 T1P 4 hν2hν2 hν1hν1 hν0hν0

8 Energy transfer processes Directional FRET Hopping S 1 (PI)-S 1 (TDI) annihilationS 1 (PI)-S 1 (PI) annihilation 8

9 Sample preparation Spin-coat method Well cleaned cover glass Zeonex film (thickness = 100~200nm) single molecule ② Spin-coat on cover glass ① T1P 4 and T2P 8 in chloroform ( + Zeonex(Polynorbornene) ) 2000 rpm Cover glass Concentration is M 9

10 Experimental Setup Fluorescence from PDI unit Fluorescence from PI unit 10

11 Typical fluorescence transients of single molecules. (Parts A and B display T1P 4 molecules, and parts C and D,T2P 8. Parts A and C correspond to pulse excitation, and parts B and D, to CW excitation. T1P 4 A:pulse B:CW T2P 8 C:pulse D:CW Fluorescence from TDI Fluorescence from PI 11

12 Two-colar fluorescence transients of single molecules. (Parts A and B display T1P 4 molecules, and parts C and D,T2P 8. Parts A and C correspond to pulse excitation, and parts B and D, to CW excitation. T1P 4 A:pulse B:CW T2P 8 C:pulse D:CW 12

13 Pulse T1P 4 12(11 % )27(25 % )71(64 % ) T2P 8 51(15 % )81(24 % )207(61 % ) CW T1P 4 7(11 % )16(24 % )43(65 % ) T2P 8 11(11%) 14(25 % )70(74 % ) Occurrence of three different modes of behavior for single molecules Discussion Excitation type compound Dual-color emission Only red emission Red followed by green emission 13

14 Discussion Probability of excitation T2P 8 P82P82 P81P81 =0.421 T1P 4 P42P42 P41P41 =0.177 Number of chromophores(PI) Number of chromophore(s) excited 14 PijPij chromophorecompoundr [nm] PI - PDIT1P T2P PI - PIT1P T2P Intramolecular distances

15 Fluorescence decay time and time constant of annihilation Dual-color fluorescence cannot be solely explained by exciton blockade. PI emission PI-TDI annihilation (T1P 4 ) PI-TDI annihilation (T2P 8 ) 4 ns220 ps1 ns Directional FRET 5.9 nm Energy hopping 4.8 nm S1-S1 annihilation (between PI and PI) 5.3 nm S1-S1 annihilation (between PI and PDI) 3.7 nm Forster Radii (critical transfer distance) 15

16 Dipole moment The pattern of radiation defocus ①② ① ② Orientation of dipole moment Ref. J. Enderlein et al J.Opt.Soc.Am.B,2003,20, Polymer,2006,47, Wide-field Imaging (defocused imaging) 16

17 Optical Setup ( Wide-field Spectroscopy ) Defocus Fluorescence detection from PI unit Fluorescence detection from TDI unit 17

18 Typical example of emission of T1P 4 and T2P 8 Defocused images of single molecule embedded in a polymer film. Parts A and B correspond to T1P 4 molecules, and parts C and D, to T2P 8 18 T1P 4 T2P 8 Fluorescence from TDI Fluorescence from PI

19 Orientation of dipole 19

20 Possible explanation of these results Annihilation and hopping 20

21 Conclusion The authors have investigated a fundamentally photochemical process (energy transfer) in dendrimers, T1P 4 and T2P 8. Single molecule detection by confocal microscopy and wide-field imaging revealed that the two-color emission from the dendrimers cannot be explained only by the exciton blockade. 21


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