Aggregation-Induced Emission (AIE) NANO601A: Advanced Topics in Nano Science & Technology 5:00–5:50 pm, 18 Oct. 2006 (Wednesday), Room 4505 Aggregation-Induced Emission (AIE) Ben Zhong Tang (唐 本忠) The Hong Kong University of Science & Technology

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

Light-Emitting Materials and Devices

Simple device structure Flexible or bendable Wide viewing angle

Aggregation Quenches Light Emission! 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

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

Siloles: a group of wonder molecules Faintly luminescent when dissolved Highly emissive when aggregated!

Aggregation- Induced Emission (AIE) October 8, 2001 Aggregation- Induced Emission (AIE) C&EN, 2001, 79 (41), 29.

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

Thermochromism (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.

Restricted Intramolecular Rotation

in acetone

thin solid film

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 mM; excited wavelength: 389 nm.

Vapochromism (on TLC plates) acetone control chloroform

Biosensor PL 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. lex = 378 nm.

Biolabel Y silole nano-particle analyte 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.

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.

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

Green Electroluminescence of Amorphous Films 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 Siloles: Excellent LED Materials

Silole-Based Photovoltaic Cell

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

Aggregation-Induced Emission (AIE) (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.

0 10 20 30 40 50 60 70 80 90 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

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

water content (vol %) 90 99

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

AIE (yellow)

AIE (red)

Color-Tunable AIE (Pyran) AIE (green) AIE (yellow) AIE (Red) Water Content Increases Green emission (polarized light) Polarization: ~0.44 Helical Aggregates

OUTLINE Introduction Silole Cyclcobutene Fulvene 4H-Pyran Tetraphenylethene Conclusion Acknowledgment

(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.

(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.

(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

(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).

(A) Emission spectra of 4 (2 (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.

SUMMARY Aggregation-Induced Emission (AIE) An unusual but general phenomena observable in the molecules whose intramolecular rotations are restricted in the aggregative (solid) states 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

Scientific Publications on AIE Systems (2005–2006) Chem. Commun. 2005, 3583–3585. J. Phys. Chem. B 2005, 109, 10061–10066. J. Inorg. Organomet. Polym. Mater. 2005, 15, 287–291. Chem. Res. Chinese Univ. 2005, 21, 13–14. Chem. Commun. 2006, 1133–1135. Chinese J. Lumin. 2006, 27, 281–284. J. Chinese Chem. Soc. 2006, 53, 243–246. J. Polym. Sci., Part A: Polym. Chem. 2006, 44, 2487–2498. Mol. Cryst. Liq. Cryst. 2006, 446, 183–191. Chem. Commun. 2006, in press. Chem. Phys. Lett. 2006, in press. Nonlinear Opt. Quant. Opt. 2006, in press. Joined Publications J. Phys. Chem. B 2005, 109, 1135–1140. Chem. Phys. Lett. 2005, 402, 468–473. J. Am. Chem. Soc. 2005, 127, 6335–6346. J. Phys. Chem. B 2005, 109, 17086–17093. Chem. Phys. Lett. 2006, 419, 444–449.

Invited Talks on AIE Systems (2005–2006) The 7th International Symposium on Biotechnology Metal Complexes and Catalysis, Beijing, 17–20 August 2005. (Plenary Lecture) The 88th Canadian Chemistry Conference and Exhibition, Saskatoon, Canada, 27 May–1 June 2005. The 8th International Conference on Frontiers of Polymers and Advanced Materials, Cancun, Mexico, 22–28 April 2005. APC-2005: The Fourth Asian Photochemistry Conference, Taipei, 5–12 Jan. 2005. The 3rd International Conference on Photoresponsive Organics and Polymers, Val Thorens, France, 15–20 Jan. 2006. Advanced Biotechnology Symposium, Multidisciplinary Research Center, Shantou University, 1 July 2006. Supramolecular Systems Serial Symposium: Supramolecular Organic Luminescent Crystals and Solids, Changchun, 26–27 Dec. 2005. Symposium on Organic and Polymeric Light-Emitting and Lasing Materials and Devices, Guangzhou, 7–11 Nov. 2005. International Symposium on Organic Optoelectronic Materials and Thin Film Device, Changchun, 10–13 August 2005.

Examples of Other AIE Systems (published by other research groups) J. Am. Chem. Soc. 2002, 124, 14410. Angew. Chem., Int. Ed. 2004, 43, 6346. J. Am. Chem. Soc. 2004, 126, 10232. Chem. Eur. J. 2004, 10, 791. J. Am. Chem. Soc. 2005, 127, 9071. J. Am. Chem. Soc. 2005, 127, 10350. J. Am. Chem. Soc. 2005, 127, 11661. J. Am. Chem. Soc. 2005, 127, 10951. J. Am. Chem. Soc. 2005, 127, 9021. J. Phys. Chem. B 2005, 109, 19627. J. Phys. Chem. B 2005, 109, 13472. J. Org. Chem. 2005, 70, 2778. Inorg. Chem. 2005, 44, 2003. Chem. Commun. 2005, 5465. Angew. Chem. Int. Ed. 2006, 45, 1404. Chem. Eur. J. 2006, 12, 3966. Chem. Eur. J. 2006, 12, 3287. Adv. Funct. Mater. 2006, 16, 681.

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