1

Ben Zhong Tang ( 唐 本忠 )

The Hong Kong University of Science & Technology

Aggregation-Induced Emission (AIE)

NANO601A: Advanced Topics in Nano Science & Technology

5:00–5:50 pm, 18 Oct. 2006 (Wednesday), Room 4505

2

OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

3

Light-Emitting Materials and Devices

4

Flexible or bendable Wide viewing angle

Simple device structure

5

Many chromophoric molecules are fluorescent in solutions but become less or even nonemissive

when fabricated into thin solid films

Aggregation Quenches Light Emission!

A thorny problem in the development of

efficient light-emitting diodes (LEDs)

It would be nice, if a molecule can emit efficiently in the solid (aggregative) state

6

OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

7

Siloles: a group of wonder molecules

• Faintly luminescent when dissolved

• Highly emissive when aggregated!

8

October 8, 2001

C&EN, 2001, 79 (41), 29.

Aggregation-Aggregation- Induced Induced

Emission (AIE)Emission (AIE)

9

Photoluminescence peak intensity of 3 vs. composition of glycerol/methanol mixtures; concentration of HPS: 10 M; excitation wavelength: 407 nm.

PhPh

PhPhSi

Ph Ph

Viscochromism

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(A) Photoluminescence spectra of 3 in 1,4-dioxane at different temperatures. (B) Effect of temperature on the peak intensity of the photoluminescence of 18 in dioxane and THF.

Concentration of 18: 10 M; excitation wavelength: 407 nm.

Thermochromism

PhPh

PhPhSi

Ph Ph

11

Restricted Intramolecular Rotation

ER,Ph’/ER,Ph

1x,y (kcal/mol) (HPS / 5.8) 12,4 70.1/ 5.6 12,5 50.0/ 6.4 13,4 100.3/10.6

12

inacetone

13

Optical Properties of Siloles

max (nm) PLa PL decaya

1x,y solna solid (%) A1/A2b 1/2

b

(HPSc 500 462 0.10 100/ 0 0.02/) 12,4 500 461 0.59 79/ 21 0.03/0.32 12,5 480 478 4.4 55/ 45 0.09/0.87 13,4 495 487 69 0/100 /6.18

a Measured in THF. b Fraction (A, %) and lifetime (, ns) of shorter- (1) or

longer-lived species (2). c Shown for comparison, with its solution data

measured in acetone.

thin solid film

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Sensitive and Regioselective Chemosensor

Stern-Volmer plots for the PL quenching of a THF solution of 13,4 by o-, m- and p-NAs. Concentration of 13,4: 3.96 M; excited wavelength: 389 nm.

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Vapochromism (on TLC plates)

acetone chloroformcontrol

16PL spectra of the water/methanol (6:4) solutions of a water-soluble silole (5.7 × 10-5 M) in the presence of KOH (8.4 × 10-4 M) and

BSA (concentration given in the figure). The spectrum of a “pure” BSA solution (0.50 wt %) is shown for comparison. ex = 378 nm.

Biosensor

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Y Y Y

Biolabel

Schematic illustration of the preparation of biofunctional silole nanocrystals. HPS was ball-milled into nanocrystals in an aqueous surfactant followed by encapsulation with polyelectrolyte multilayers of nanometer thickness and the attachment of a specific immunoreagent. The analyte is first immobilized by the capture antibody pre-adsorbed on the solid phase and then exposed to

the antibody-labeled nanocrystal detectors.

silolesilolenano-nano-

particleparticle

analyte

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y = 1268.7x + 84.062

R2 = 0.9888

0

1000

2000

3000

0.0 0.5 1.0 1.5 2.0

Log (M IgG, g/L)

Flu

ores

cenc

e In

tens

ity (

FIU

)

Sandwich fluorescence immunoassay of M IgG using Gt α M IgG–HPS nanocrystals () and Gt α M IgG–FITC (■) as labels. Abbreviations: M IgG = mouse immunoglobulin G, Gt = goat, and FITC

= fluorescein isothiocyanate.

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Blue Electroluminescence of Silole Crystal

Current efficiency of an LED of 12,4 and (inset) EL and PL spectra of its amorphous (a) and crystalline (k) films

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Silole Von (V) CE (cd/A) PE (lm/W) L (cd/m2) EL

(%)

——————————————————————————

2 3.4 20 14 9 234 8

3 4.0 15 10 55 880 7

Alq3

Silole

ITO (anode)

Al (cathode)

LiF

V

TPDCuPc

Green Electroluminescence of Amorphous Films

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Silole-Based Photovoltaic Cell

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OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

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(A) PL spectra of 3,4-bis(diphenylmethylene)-1,2-diphenyl-1-cyclobutene in absolute acetone and water/acetone mixtures; concentration: 10 μM; excitation wavelength: 367 nm, (B) Quantum yield vs. solvent composition of water/acetone mixture.

Aggregation-Induced Emission (AIE)

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Photos of 3,4-bis(diphenylmethylene)-1,2-diphenyl-1-cyclobutene in water/acetone mixtures (10 μM) under illumination of a UV lamp (365 nm); water contents (vol %) are given in the photos

0 10 20 30 40 50 60 70 80 90

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OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

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27

28

90

99

watercontent(vol %)

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NH

H

NH

O

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OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

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AIE (yellow)

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AIE (red)

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• Green emission (polarized light)

• Polarization: ~0.44

• Helical Aggregates

AIE (green)AIE (green)

AIE (yellow)AIE (yellow)

AIE (Red)AIE (Red)

O

NC CN

R =

R R

O

H

H

H

WaterContent

Increases

Color-Tunable AIE (Pyran)

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OUTLINE

• Introduction

• Silole

• Cyclcobutene

• Fulvene

• 4H-Pyran

• Tetraphenylethene

• Conclusion

• Acknowledgment

35(A) FL spectra of 1 in water/AN mixtures and (B) dependence of FL quantum yield (F) of 1 on solvent composition of the water/AN mixture. Concentration of 1: 10 μM; excitation wavelength: 350 nm.

36(A) Change of fluorescence spectrum of 2·Na2 (5 μM) with addition of BSA in an aqueous phosphate buffer (pH = 7.0). (B)

Plot of fluorescence intensity at 476 nm versus BSA concentration. (C) Linear region of the binding isotherm of 2 to BSA.

37(A) Change of FL spectrum of 3 with addition of BSA in an aqueous phosphate buffer. (B) Plot of FL intensity at 472 nm versus BSA concentration. (C) Linear region of the (I/I0 – 1)–[BSA] plot in panel B

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Photophysical Properties of TPEs 1–3 in Solution (soln),a

Aggregate (aggr),b and Binding (bindg)c States

ab, nmd em, nm (F, %)e

TPE soln aggr soln aggr bindg

1 311 330 394 (0.11) 477 (15.30)

2 312 316 393 (0.57) 439 ( 8.90) 467 (35.7)

3 312 320 398 (0.37) 442 (17.47) 472 (58.2)

a In acetonitrile for 1 and 2 (10 μM); in water for 3 (5 μM). b In 99% water/AN mixture

for 1 and 2; in 99% AN/water mixture for 3. c In BSA solution of 2·Na2 or 3 in an aqueous

phosphate buffer with pH = 7.0. d Absorption maximum. e Emission maximum (quantum

yield given in the parentheses); excitation wavelength: 350 nm.

39(A) Effect of dye concentration on the FL intensity of buffer solution of 2·Na2 at 467 nm or 3 at 472 nm in the absence or presence of

BSA (10 μg/mL). (b) Effect of BSA (100 g/mL) and/or SDS (1 mg/mL) on the FL spectrum of a buffer solution of 3 (5 M).

40(A) Emission spectra of 4 (2.5 μM) in an aqueous phosphate buffer (pH = 7) and in the buffers containing 300 μg/mL ct DNA and 500 μg/mL BSA. (B) Plots of fluorescence intensities of buffer solutions of 4 at 463 nm versus concentrations of ct DNA and BSA.

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SUMMARY

• Silole/TPE: blue and green light emissions• Cyclobutene/fulvene: blue light emission• Pyran: yellow, green and red light emissions• Visco-, thermo-, vapo- and crystallochromism• Chemosensor and biolabel (DNA and protein)• Strong photoluminescence• Efficient electroluminescence• Good photovoltaic performance

Aggregation-Induced Emission (AIE)An unusual but general phenomena observable in the molecules

whose intramolecular rotations are restricted in the aggregative (solid) states

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1 Chem. Commun. 2005, 3583–3585. 2 J. Phys. Chem. B 2005, 109, 10061–10066.3 J. Inorg. Organomet. Polym. Mater. 2005, 15, 287–291.4 Chem. Res. Chinese Univ. 2005, 21, 13–14.5 Chem. Commun. 2006, 1133–1135.6 Chinese J. Lumin. 2006, 27, 281–284.7 J. Chinese Chem. Soc. 2006, 53, 243–246.8 J. Polym. Sci., Part A: Polym. Chem. 2006, 44, 2487–

2498.9 Mol. Cryst. Liq. Cryst. 2006, 446, 183–191.10 Chem. Commun. 2006, in press.11 Chem. Phys. Lett. 2006, in press.12 Nonlinear Opt. Quant. Opt. 2006, in press.

Joined Publications 13. J. Phys. Chem. B 2005, 109, 1135–1140.14. Chem. Phys. Lett. 2005, 402, 468–473.15. J. Am. Chem. Soc. 2005, 127, 6335–6346.16. J. Phys. Chem. B 2005, 109, 17086–17093.17. Chem. Phys. Lett. 2006, 419, 444–449.

Scientific Publications on AIE Systems (2005–2006)

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1. The 7th International Symposium on Biotechnology Metal Complexes and Catalysis, Beijing, 17–20 August 2005. (Plenary Lecture)

2. The 88th Canadian Chemistry Conference and Exhibition, Saskatoon, Canada, 27 May–1 June 2005.

3. The 8th International Conference on Frontiers of Polymers and Advanced Materials, Cancun, Mexico, 22–28 April 2005.

4. APC-2005: The Fourth Asian Photochemistry Conference, Taipei, 5–12 Jan. 2005.

5. The 3rd International Conference on Photoresponsive Organics and Polymers, Val Thorens, France, 15–20 Jan. 2006.

6. Advanced Biotechnology Symposium, Multidisciplinary Research Center, Shantou University, 1 July 2006.

7. Supramolecular Systems Serial Symposium: Supramolecular Organic Luminescent Crystals and Solids, Changchun, 26–27 Dec. 2005.

8. Symposium on Organic and Polymeric Light-Emitting and Lasing Materials and Devices, Guangzhou, 7–11 Nov. 2005.

9. International Symposium on Organic Optoelectronic Materials and Thin Film Device, Changchun, 10–13 August 2005.

Invited Talks on AIE Systems (2005–2006)

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(1) J. Am. Chem. Soc. 2002, 124, 14410.(2) Angew. Chem., Int. Ed. 2004, 43,

6346.(3) J. Am. Chem. Soc. 2004, 126, 10232.(4) Chem. Eur. J. 2004, 10, 791.(5) J. Am. Chem. Soc. 2005, 127, 9071.(6) J. Am. Chem. Soc. 2005, 127, 10350.(7) J. Am. Chem. Soc. 2005, 127, 9071.(8) J. Am. Chem. Soc. 2005, 127, 11661.(9) J. Am. Chem. Soc. 2005, 127, 10951. (10) J. Am. Chem. Soc. 2005, 127, 9021. (11) J. Phys. Chem. B 2005, 109, 19627.(12) J. Phys. Chem. B 2005, 109, 13472.(13) J. Phys. Chem. B 2005, 109, 19627. (14) J. Phys. Chem. B 2005, 109, 13472.(15) J. Org. Chem. 2005, 70, 2778.(16) Inorg. Chem. 2005, 44, 2003. (17) Chem. Commun. 2005, 5465.(18) Chem. Commun. 2005, 5465.(19) Angew. Chem. Int. Ed. 2006, 45, 1404. (20) Chem. Eur. J. 2006, 12, 3966. (21) Chem. Eur. J. 2006, 12, 3287. (22) Adv. Funct. Mater. 2006, 16, 681.

Examples of Other AIE Systems (published by other research groups)

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Acknowledgements

• Ministry of Science and Technology• Hong Kong Research Grants Council• National Science Foundation of China