ORCID Profile
0000-0002-9779-0517
Current Organisation
Hong Kong University of Science and Technology
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Publisher: American Chemical Society (ACS)
Date: 03-08-2018
Abstract: Far-red and near-infrared (NIR) fluorescent materials possessing the characteristics of strong two-photon absorption and aggregation-induced emission (AIE) as well as specific targeting capability are much-sought-after for bioimaging and therapeutic applications due to their deep penetration depth and high resolution. Herein, a series of dipolar far-red and NIR AIE luminogens with a strong push-pull effect are designed and synthesized. The obtained fluorophores display bright far-red and NIR solid-state fluorescence with a high quantum yield of up to 30%, large Stokes shifts of up to 244 nm, and large two-photon absorption cross-sections of up to 887 GM. A total of three neutral AIEgens show specific lipid droplet (LD)-targeting capability, while the one with cationic and lipophilic characteristics tends to target the mitochondria specifically. All of the molecules demonstrate good biocompatibility, high brightness, and superior photostability. They also serve as efficient two-photon fluorescence-imaging agents for the clear visualization of LDs or mitochondria in living cells and tissues with deep tissue penetration (up to 150 μm) and high contrast. These AIEgens can efficiently generate singlet oxygen upon light irradiation for the photodynamic ablation of cancer cells. All of these intriguing results prove that these far-red and NIR AIEgens are excellent candidates for the two-photon fluorescence imaging of LDs or mitochondria and organelle-targeting photodynamic cancer therapy.
Publisher: American Chemical Society (ACS)
Date: 22-04-2005
DOI: 10.1021/JP0503462
Abstract: We synthesized a group of silole regioisomers 1(x,y), whose photoluminescence varied dramatically with its regiostructure. By internally hindering the intramolecular rotation, we succeeded in creating a novel silole (1(3,4)) that is strongly luminescent in solutions and whose fluorescence quantum yield in acetone is as high as 83%. We revealed that 1(3,4) was a sensitive chemosensor capable of optically discriminating nitroaromatic regioisomers of p-, o-, and m-nitroanilines. Against general belief, crystal formation of 1(2,4) blue-shifted its emission color and boosted its emission efficiency. The light-emitting diode based on the crystal of 1(2,4) emitted a strong blue light (464 nm) in a high current efficiency (5.86 cd/A).
Publisher: American Chemical Society (ACS)
Date: 11-09-2018
Abstract: In this work, we report the application of the aggregation-induced emission luminogens (AIEgens) as color converters for visible light communication (VLC). In the form of pure solid powder, the AIEgens studied herein have demonstrated blue-to-red full-color emissions, large -6 dB electrical modulation bandwidths up to 279 MHz (∼56× that of commercial phosphor), and most of them can achieve high data rates of 428-493 Mbps (up to ∼49× that of commercial phosphor) at a maximum bit error rate of 3.8 × 10
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SC01108E
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC33780K
Abstract: Melding a benzothiazolium unit with tetraphenylethene generates a new hemicyanine luminogen with aggregation-induced emission characteristics the luminogen exhibits crystochromism and its solid-state emission can be repeatedly tuned from yellow or orange to red by grinding-fuming or grinding-heating processes due to the transformation from the crystalline to the amorphous state and vice versa.
Publisher: American Chemical Society (ACS)
Date: 03-11-2017
DOI: 10.1021/JACS.7B08592
Abstract: π-Bonds connected with aromatic rings were generally believed as the standard structures for constructing highly efficient fluorophores. Materials without these typical structures, however, exhibited only low fluorescence quantum yields and emitted in the ultraviolet spectral region. In this work, three molecules, namely bis(2,4,5-trimethylphenyl)methane, 1,1,2,2-tetrakis(2,4,5-trimethylphenyl)ethane, and 1,1,2,2-tetraphenylethane, with nonconjugated structures and isolated phenyl rings were synthesized and their photophysical properties were systematically investigated. Interestingly, the emission spectra of these three molecules could be well extended to 600 nm with high solid-state quantum yields of up to 70%. Experimental and theoretical analyses proved that intramolecular through-space conjugation between the "isolated" phenyl rings played an important role for this abnormal phenomenon.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9QM00156E
Abstract: Excited-state “double-bond” torsion plays an important role in the nonluminescent behaviour of a stilbene-based twisted isomer.
Publisher: Wiley
Date: 09-11-2017
Publisher: American Chemical Society (ACS)
Date: 15-08-2017
Abstract: In this study, the concentration gradient inside evaporating binary sessile droplets of 30, 50, and 60 vol % tetrahydrofuran (THF)/water mixtures was investigated. The 5 μL THF/water droplets were evaporated on a transparent hydrophobic substrate. This is the first demonstration of local concentration mapping within an evaporating binary droplet utilizing the aggregation-induced emission material. During the first two evaporation stages of the binary droplet, the local concentration can be directly visualized by the change of fluorescence emission intensity. Time-resolved average and local concentrations can be estimated by using the pre-established function of fluorescence intensity versus water volume fraction.
Publisher: American Chemical Society (ACS)
Date: 02-07-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5SC01226K
Abstract: Racemic low-conjugated non-emissive THPs 1–3 can form highly emissive RS - and RR / SS -packing polymorphs with mixed through-bond and through-space conjugation.
Publisher: American Chemical Society (ACS)
Date: 22-08-2019
DOI: 10.1021/JACS.9B06196
Abstract: Acrylonitriles with aggregation-induced emission (AIE) characteristics have been found to show promising applications in two-photon biomedical imaging. Generally, elaborate synthetic efforts are required to achieve different acrylonitriles with distinct functionalities. In this work, we first reported the synthesis of two different group-functionalized AIE-active acrylonitriles (TPAT-AN-XF and 2TPAT-AN) obtained simply by mixing the same reactants at different temperatures using a facile and transition metal-free synthetic method. These two AIE luminogens (AIEgens) exhibit unique properties such as bright red emission in the solid state, large Stokes shift, and large two-photon absorption cross section. Water-soluble nanoparticles (NPs) of 2TPAT-AN were prepared by a nanoprecipitation method. In vitro imaging data show that 2TPAT-AN NPs can selectively stain lysosome in live cells. Besides one-photon imaging, remarkable two-photon imaging of live tumor tissues can be achieved with high resolution and deep tissue penetration. 2TPAT-AN NPs show high biocompatibility and are successfully utilized in in vivo long-term imaging of mouse tumors with a high signal-to-noise ratio. Thus, the present work is anticipated to shed light on the preparation of a library of AIE-active functionalized acrylonitriles with intriguing properties for biomedical applications.
Publisher: Wiley
Date: 18-01-2022
Abstract: From the past years, the most commonly reported state‐of‐the‐art binary bulk heterojunction organic solar cells (OSCs) are mostly based on mixtures of polymer donors and fullerene‐free acceptors (polymer:NFA). However, along with it are a number of contradictory propositions, including (but not limited to) strategies to reduce energy loss and improve photocurrent generation through energy level alignments. Due to the resulting high similarity of molecular fragments from polymer:NFA heterojunctions, the effects of vertical molecular stratification are not yet well studied. Herein, the time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) molecular depth profiling reveals a vertical stratification in PM6:IT‐4Cl and illustrates how it can significantly influence the photovoltaic properties. The said inhomogeneity is also bound to introduce microstructure variations within device active layers. Consequently, it is systematically demonstrated how thin‐film microstructures can influence optoelectronic properties, wherein important metrics (e.g., energy losses and molecular energy offsets) are highly dependent. Thus, the understanding from this work provides foundations for more precise development of strategies to further advance OSC technology in future studies.
No related grants have been discovered for Wong Kam Sing.