4:00pm - 4:15pmOral
From ACQ to AIE: The Suppression of the Strong p–p Interaction of Naphthalene Diimide Derivatives through the Adjustment of their Flexible Chains
Wuhan University, China
In 2001, Tang`s group proposed a novel phenomenon of aggregation-induced emission (AIE), which is opposite to ACQ (aggregation caused quenching). For AIE molecules, the mechanism was considered to be the restriction of intramolecular motions (RIM), including rotations and vibrations. Based on this, a series of molecules with AIE activity were achieved for many practical applications such as bio-imaging, fluorescent probes, OLED and so on.
In our work, unlike normal ACQ-to-AIE conversion through the introduction of aromatic rings to big p-conjugation system, by adjusting the flexible chains, the optical property of naphthalene diimide derivatives (NDIs) could change from ACQ to AIE while the original p-system core and related properties of NDIs remained nearly unchanged, as the result of the tunable packing modes. To the best of our knowledge, it is the first case of realizing the ACQ-to-AIE transformation just through the modification of the flexible chains without disturbing the original p system, which provides an alternative approach for the inhibition of unwanted p-p stacking.
4:15pm - 4:30pmOral
Dramatic Difference in Aggregation-induced Emission and Supramolecular Polymerization of Tetraphenylethene Stereoisomers
Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Canter for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong S.A.R. (China)
We report herein the supramolecular polymers constructed by quadruple hydrogen bonding in pure stereoisomers of ureidopyrimidinone-functionalized tetraphenylethenes ((Z)-TPE-UPy and (E)-TPE-UPy). The ureidopyrimidinone groups with hydrogen-bonding sites resulted in macroscopic separation of the isomers by column chromatography in high yields. The structures of (Z)-TPE-UPy and (E)-TPE-UPy were confirmed by 2D COSY and NOESY NMR spectroscopy. Interestingly, the two isomers show distinct fluorescence: (Z)-TPE-UPy exhibited green emission while (E)- gave blue emission. Such difference has inspired us to study their photophysical properties and ability for constructing polymers by supramolecular assembly. The probable relationship between the two sides was also exploited. The cavity offered by two ureidopyrimidinone groups make (Z)-TPE-UPy suitable for Hg2+ detection. In contrast, the high molecular weight of the polymers prepared from (E)-TPE-UPy promoted us to obtain highly fluorescent fibers and 2D/3D photopattern from its chloroform solution.
4:30pm - 4:45pmOral
α,β-Unsatured Acrylonitriles Compounds as Emitting Materials and Computational Investigations of Optoelectronic Devices
1Benemérita Universidad Autónoma de Puebla, Mexico; 2Conacyt- Benemérita Universidad Autónoma de Puebla, Mexico; 3Shanmugha Arts, Science, Technology & Research Academy (SASTRA) University, India; 4Centro de Investigaciones en Óptica A.C. (CIO), Mexico
α,β-Unsatured acrylonitriles compounds with pyridine-substituted core are a class of important fluorescent materials and their electroluminescence properties are studied for OLEDs. In this work, 4-(diphenylamino)phenyl was used as donor (D) and pyridine-substituted and phenyl as acceptor attached to α,b-unsatured nitrile. The compounds are highly emissive in solid films, with dominant green to yellow emissions. Efficient organic light-emitting diodes were fabricated with the mentioned compounds as emissive layer luminance, current-voltage behavior, and power efficiency are reported here. For the preparation of the device the fluorescent low molecular weight compounds were deposited by thermal evaporation while an alternative cathode known as Field´s metal was deposited by drop casting; Field´s metal is an eutectic alloy of Bi, In and Sn. Performance of devices using Field´s metal was compared with some others using aluminum as cathode. Electrical properties such threshold voltage, about 3-8 volts, and current density were affected by the chemical structure of emitting material, but not by the metal used as cathode. Results showed that the eutectic alloy is a good alternative as cathode in organic light emitting diodes. Also in this work is present results of theoretical calculations using the density functional theory (DFT) to evaluate the structural parameters, electronic properties, HOMO-LUMO gaps, Molecular orbital densities, Ionization Potential (IPs), Electronic Affinities (EAs) as well as the intermolecular interactions are analyzed and quantified by using Hirshfeld surface analysis, PIXEL energy.
4:45pm - 5:00pmOral
A Red-emitting AIEgen for Luminescent Solar Concentrators
1Department of Chemistry and Industrial Chemistry, University of Pisa, Italy; 2NEST – Scuola Normale Superiore, Istituto Nanoscienze – CNR (CNR-NANO), Italy; 3CNR IPCF Bari c/o Department of Chemistry, Italy ; 4Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong S.A.R. (China)
Fluorescent collectors are a promising path to cost-effective photovoltaic (PV) technologies thanks to several advantages: low weight, ability to work well with diffuse light and no needs of sun tracking or cooling apparatuses. Conventional fluorescent collectors are made of poly(methyl methacrylate) (PMMA) or polycarbonate (PC) slabs doped with red-emitting fluorophores that are generally preferred since their fluorescence well matches the Si-based PV cells band gap. However, their fluorescence is strongly quenched in condensed phase, thus strongly limiting the generation of electric current.
This study reports for the first time the use of a red-emitting AIEgen, i.e. TPE-AC, for the realization of efficient luminescent solar concentrators (LSCs) based on poly(methyl methacrylate) (PMMA) and polycarbonate (PC) thin films (25±5 μm). TPE-AC is an AIEgen with D-A features that absorbs visible light in the range between 400-550 nm and emits fluorescence peaked at 600-620 nm with a maximum quantum yield (QY) of 50% when dispersed (0.1-1.5 wt.%) in PMMA and PC matrices. QY and lifetime investigations demonstrated that fluorescence quenching occurred with TPE-AC concentration, even if the optical features still maintained significant also at the highest fluorophore content. Study of the LSCs performances yields worthy optical efficiencies of 6.7% for TPE-AC/PC systems thanks to the superior light harvesting features and compatibility of the AIEgen within the PC matrix.
5:00pm - 5:30pmInvited
Indolone and Quinoxaline Based AIE Chromophores by Multicomponent Syntheses
University of Duesseldorf, Germany
Multi-component reactions are efficient and effective methods for sustainable and diversity-oriented synthesis of functional chromophores. In particular, transition metal catalyzed multicomponent sequences have recently gained a considerable interest for heterocycle and fluorophore syntheses, and also for AIE chromophore syntheses. In particular, indolone and quinoxaline based luminophores display AIE characteristics, and quinoxaline systems show pronounced emission solvochromicity. In the series of indolones dually emissive AIE bichromophores are now accessible by sequentially Pd-catalyzed four-component sequences, and sequentially Cu-catalyzed multicomponent processes have been disclosed for the syntheses of angular donor-quinoxaline- triazole conjugates.
 a) Levi, L.; Müller, T. J. J. Chem. Soc. Rev. 2016, 45, 2825. b) Müller, T. J. J.; D’Souza,D. M. Pure Appl. Chem. 2008, 80, 609
 D’Souza, D. M.; Müller, T. J. J. Chem. Soc. Rev. 2007, 36, 1095
 Levi, L.; Müller, T. J. J. Eur. J. Org. Chem.2016, 2907
 Müller, T. J. J. In Aggregation Induced Emission: Materials and Applications, Fujiki, M.; Tang, B. Z.; Liu, B. Eds., ACS Symposium Series e-book,2016, Chapter 6, pp 85-112
 a) D'Souza, D. M.; Muschelknautz, C.; Rominger, F.; Müller, T. J. J. Org. Lett. 2010, 12, 3364. b) Muschelknautz, C.; Frank, W.; Müller, T. J. J. Org. Lett. 2011, 13, 2556. c) Muschelknautz, C.; Visse, R.; Nordmann, J.; Müller, T. J. J. Beilstein J. Org. Chem. 2014,10, 599
 a) Gers, C. F.; Nordmann, J.; Kumru, C.; Frank, W.; Müller, T. J. J. J. Org. Chem. 2014, 79, 3296. b) Gers-Panther, C. F.; Fischer, H.; Nordmann, J.; Seiler, T.; Behnke, T.; Würth, C.; Frank, W.; Resch-Genger, U.; Müller, T. J. J. J. Org. Chem. 2017, 82, 567
 Denissen, M.; Itskalov, D.; Frank, W.; Müller, T. J. J. manuscript in preparation
 Merkt, F. K.; Pieper, K.; Müller, T. J. J. manuscript in preparation
5:30pm - 5:45pmOral
Pure Organic Molecules with Improved Persistent Room-Temperature Phosphorescence and Their Applications
Department of Chemistry, Sun Yat-sen University, China
Purely organic luminescent materials with room-temperature phosphorescence (RTP) have recently gained increasing attention because of their long-lived triplet excitons. Compared with their inorganic or organometallic counterparts, they are considerably cheaper, environmentally safer and biologically friendly, which make them promising candidates for advanced applications in displays, data storage, molecular sensing and time-resolved bioimaging. However, there is no consistent mechanism and no universal design strategy for efficient organic persistent RTP (pRTP) materials.
A new mechanism for pRTP is presented here, based on intermolecular electronic coupling (IEC) of hybrid organic units (with different excited state configuration, i.e., nπ* and ππ*), which may be applicable to a wide range of organic molecules. Following this mechanism, successful design strategy to obtain efficient pRTP have been developed: (1) utilizing a heavy halogen atom to further increase the intersystem crossing rate of the coupled units, RTP with a long lifetime of 0.28 s and a very high quantum efficiency (QE) of 5% was thus achieved; (2) modulating the IEC and the heavy atom effect independently by molecular structure design, the phosphorescence QE was further increased to 11%, which is among the highest ones of long-wavelength persistent materials. In addition, their applications in different fields have also been exploited: (1) applying as new multi-stimuli responsive luminescent materials with multi-channel expressive, including linearly tunable emission colors, time-resolved emission and color tunable persistent luminescence; (2) forming nano-crystals for bioimaging.
These results represent an important step in the understanding and application of organic pRTP luminescence, which will hopefully promote new work focused on the development of new persistent luminescent materials.
1. Nat. Mater., 2015, 14, 685.
2. Chem 2016, 1, 592.
3. Angew. Chem. Int. Ed., 2016, 55, 2181.
4. Angew. Chem. Int. Ed. 2015, 54, 6270.
5:45pm - 6:15pmInvited
Engineering Ultrasmall Metal Nanoclusters for Biomedical Applications
National University of Singapore, Singapore
Ultrasmall metal nanoclusters (NCs) have attracted increasing attention from the scientific community due to their fascinating physicochemical properties. Today, functional metal NCs are finding growing acceptance in biomedical applications. To achieve a better performance in biomedical applications, metal NCs can be interfaced with biomolecules, such as proteins, peptides, and DNA, to form a new class of biomolecule-NC composites (or bio-NCs in short), which typically show synergistic or novel physicochemical and physiological properties. In this talk, I will discuss some of our recent studies at the interface of metal NCs and biomolecules, highlighting some unique physicochemical properties and the biological functions of bio-NCs.