Conference Programme

The overview and detailed programme is posted below.

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Overview
Session
N-04: Symp N
Time:
Tuesday, 20/Jun/2017:
1:30pm - 3:30pm

Session Chair: Guozhu Chen, University of Jinan
Session Chair: Jiating HE, Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR)
Location: Rm 304

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Presentations
1:30pm - 2:00pm
Invited

The General Pathway of Precursor Conversion to Monomers at Low Temperature of Colloidal Semiconductor Metal Chalcogenide Nanocrystals

Kui YU

Sichuan University, China

A worldwide interest in the last thirty years has been witnessed in the development of colloidal semiconductor nanocrystals (NCs), which targets various applications including bio-imaging, light emitting diodes (LEDs), and solar cells. There have been significant efforts focusing on photoluminescent colloidal quantum dots (QDs) which are spherical in shape. However, NC synthesis has been performed as an empirical art, and the current state-of-the-art in the NC synthesis is essentially empirical with a large number of recipes developed, lacking of mechanism-enabled design. There has been very little insight into the molecular mechanism by which monomers are generated. Since 1993, tri-n-octylphosphine (P(C8H17)3 or TOP) has been used to synthesize colloidal metal chalcogenide (ME) NCs and the synthesis requires high reaction temperature. Only recently, dioctylphosphine (HP(C8H17)2 or DOP) has been identified to be an active impurity existing in commercial TOP (90% or 97%) and to be one of the reasons for low particle yield and low synthetic reproducibility for the NC synthesis. With the use of commercial available secondary phosphines, such as diphenylphosphine (HPPh2 or DPP) to mimic the presence of DOP, we have been focusing on the mechanism of precursor conversions to monomers at low temperature in the reaction of MXn + E=TOP + DPP in 1-octadecene, together with the presence of five HY additives including acids, amines, alcohols, thiols, and phosphines. Based on our extensive 31P NMR, we propose a general mechanism; based on our DFT efforts, we provided the detailed skeleton of our proposed intermediates. The insight gained on the molecular pathway of precursor evolution to monomers should advance the design and synthesis of colloidal semiconductor NCs at low temperature with high quality, yield and reproducibility.

References:

[1] K. Yu, et al Effect of tertiary and secondary phosphines on low-temperature formation of quantum dots. Angew. Chem. Int. Ed. 2013, 52, 4823–4828.

[2] K. Yu, et al The formation mechanism of binary semiconductor nanomaterials shared by single-source and dual-source precursor approaches at ambient temperature. Angew. Chem. Int. Ed. 2013, 52, 11034–11039.

[3] K. Yu, et al Mechanistic Study of the Role of Primary Amines in Precursor Conversions to Semiconductor Nanocrystals at Low Temperature. Angew. Chem. Int. Ed. 2014, 53, 6898–6904.

[4] K. Yu, et al General low temperature reaction pathway from precursors to monomers before nucleation of compound semiconductor nanocrystals. Nat. Commun. 2016, 12223. DOI:10.1038.


2:00pm - 2:30pm
Invited

Designing and Building New 2D Materials from the Bottom Up

Maryam ABYAZISANI1, Mario Isaac Ormaza VERA2, Tanveer HUSSAIN2, Nunzio MOTTA1, Josh LIPTON-DUFFIN1, Marlies HANKEL2, Jennifer MACLEOD1

1School of Chemistry, Physics and Mechanical Engineering and Institute for Future Environments, Queensland University of Technology, Australia; 2The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Australia

2D polymers are an emerging class of materials which stand to revolutionize technologies from energy storage to sensing to electronics. To date, many of the studied 2D materials have been naturally-occurring and chemically simple: graphene, MoS2, BN, etc., have small crystal unit cells and occupy thermodynamic minima that prevent much variation in the structure or composition of the material. The synthesis of engineered 2D polymeric materials with more complex structures and tailored physical and chemical properties can, at least theoretically, be achieved by through a bottom-up approach, starting from purpose-designed organic building blocks. The flexibility of this approach provides new opportunities for the a priori design of materials optimized for specific applications. In this talk, I will discuss our progress in using surface-confined polymerization of simple building blocks to create new materials for applications in sensing and electrochemical charge storage.


2:30pm - 3:00pm
Invited

Plasmonic and Magnetic NPs for Biomedical Applications

Thanh Thi Kim NGUYEN

University College London, United Kingdom

In this presentation I will the most recent results of our group on synthesis and functionalisation of nanoparticles (Au nanorods, Au nanoworms, high magnetic moment iron oxide nanoparticles, as well as novel structure of magnetic core@shell) for biomedical applications such as sensing, photo- and magnetic induced hyperthermia cancer treatment. We are currently studying the nucleation and growth of nanoparticles, and the kinetic studies in batch to translate to microfluidic flow synthesis for manufacturing of reproducibile and scale up the syntheses for industrial use in collaboration with various industrial partners as well as clinicians in the hospitals.

References:

[1] Pallares, R. M., Bosman, M., Thanh, N.T.K. *, and Su, X. (2016) Plasmonic multi-logic gate platform based on sequence-specific binding of estrogen receptors and gold nanorods. Nanoscale. 8: 19919–20126. Front cover.

[2] Pallares, R. M., Lim, S. H., Thanh, N.T.K.*, and Su, X. (2016) Growth of Anisotropic Gold Nanoparticles in Photoresponsive Fluid and Application to UV Exposure Sensing and Erythema Prediction. Nanomedicine. 11: 2845-2860

[3] Hervault, A., Lim, M., Boyer, C., Dunn, A., Mott, D., Maenosono, S. and Thanh, N. T. K.* (2016) Doxorubicin loaded dual pH- and thermo-responsive magnetic nanocarrier for combined magnetic hyperthermia and targeted controlled drug delivery applications. Nanoscale. 8: 12152-12161

[4] Hachani, R., Lowdell, M., Birchall, M., Hervault, A., Merts, D., Begin-Colin, S., Thanh, N.T.K.*Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles for potential MRI contrast agents. (2016) Nanoscale. 8, 3278-3287.

[5] Pallares, R. M., Su, X., Lim, S. H., Thanh, N. T. K* (2016) Fine-Tuning Gold Nanorods Dimensions and Plasmonic Properties Using the Hofmeister Salt Effects. Journal of Material Chemistry C. 4: 53-61

[6] Blanco-Andujar, C., Southern, P., Ortega, D., Nesbitt, S.A., Pankhurst, Q.A., and Thanh, N.T.K.(2016)Real-time tracking of delayed-onset cellular apoptosis induced by intracellular magnetic hyperthermia. Nanomedicine. 11: 121-136.


3:00pm - 3:15pm
Oral

Compact and Monovalent Quantum Dot-DNA Conjugates for Quantitative Nucleic Acid Imaging

Liang MA, Andrew M. SMITH

University of Illinois at Urbana Champaign, United States

Quantum dots (QDs) are a class of light-emitting nanocrystals that have been diversely applied for molecular labeling and imaging. Compared with conventional organic fluorophores and chromophores, QDs provide a greater number of distinguishable colors with much higher brightness and photostability. A highly promising translational application is the use of QD conjugates of DNA for visualization and quantification of nucleic acid sequences in pathological tissue specimens through fluorescence in situ hybridization (FISH). However, FISH with QD-DNA probes has been limited due to the relative large size, multivalency, and nonspecific binding of commercially available QDs. Here we present novel technologies to overcome these limitations to yield compact, homogeneous, and monovalent QD-DNA conjugates for cellular nucleic acid detection. We optimized multidentate polymeric ligands to generate small (7-12 nm), stable (over months in storage) and monodisperse QDs. We optimized these surface coatings to minimize nonspecific binding to cells and tissues, and engineered click-chemistry functionalities for rapid and efficient binding to DNA. We further optimized covalent reaction chemistries to maximize the yield of monovalent QD-DNA over polyvalent conjugates by tuning the reaction rate, functional group numbers on the QD surface, and QD size. Oligonucleotides in the final products remained functional toward sequence-specific hybridization with target genes, validated by gel electrophoresis and single-molecule imaging. Compared with FISH using organic dyes, these QDs allow accurate quantification of mRNA in cells with much higher photostability and enhanced spectral multiplexing. We anticipate that this work will provide a broadly applicable tool for nucleic acid quantification and imaging in a wide range of biomedical contexts, especially for cancer diagnosis.


3:15pm - 3:30pm
Oral

Can We Design Auxetic Polymers at the Molecular Level ?

Armand SOLDERA1, Francois PORZIO1, Etienne CUIERRIER1, Clement WESPISER1, Royale UNDERHILL2

1University of Sherbrooke, Canada; 2Defence R&D Canada, Atlantic Research Centre, Canada

Most of natural and conventional materials display a positive Poisson’s ratio. Nevertheless, the route toward materials with negative Poisson’s ratio, known as auxetic materials, open the door for an improvement of mechanical properties. Auxetic structures based on macroscopic units, such as processed foams, have been reported. Unfortunately, these materials present low density, which hinder their usefulness. More recently, the effort is turned toward the design of auxetic materials with smaller and smaller structural units. Actually, the Holy Grail is definitively a molecular auxetic unit. In this field, simulation is a significant asset, since it gives the possibility to test fresh strategies without having resort to synthesis.

Our objective is to develop a simulation protocol that will enable linking molecular structure to physical properties, in order to design a predictive tool for the development of synthesis-friendly auxetic polymers. The lack of simple existing auxetic systems at the molecular level means that the simulation crucial step of validation cannot be carried out. A specific procedure must therefore be established. The actual transition from the structure of a molecule to the final functionality of a material is far from straightforward. To describe real systems, a series of models is required. Models must first be chosen to efficiently describe the system of interest. We thus propose to calibrate our strategy first on isotropic compounds such as polymers, or organic glasses. The procedure is then applied to anisotropic materials, such as liquid crystals. The agreement with experimental behavior allowed us to extrapolate the procedure to potentially auxetic compounds, thus offering great opportunities to reveal auxetic properties prior to the synthesis of the molecules.


3:30pm - 3:45pm
Oral

Robust Microporous Organic Copolymers Containing Triphenylamine for High Pressure CO2 Capture Application

Yanqin YANG1, Tae-Hyun BAE1,2

1Singapore Membrane Technology Centre, Nanyang Technological University, Singapore; 2School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore

Implementation of carbon capture and sequestration (CCS) technology in the coal-fired power plants, which accounts for ~ 67% of reported CO2 emission, is depicted to be an effective way to reduce CO2 emission and then alleviate global warming and associated environmental issues. Integrated gasification and combined cycle (IGCC) systems equipped with pre-combustion CO2 capture are promising in this regard, wherein high pressure shifted synthesis gas (CO2/H2/H2O mixture with trace of H2S) can be separated via pressure swing adsorption (PSA) with solid adsorbent, which is more energy-efficient than liquid amine based absorption process.

Overall system efficiency and economic feasibility of PSA process for CO2/H2 separation are largely dependent on the performance of solid adsorbent employed. Various adsorbents including zeolites, activated carbon and metal-organic frameworks have demonstrated a potential capability for this application owing to their large surface areas and affinity for CO2. However, most adsorbents showing promising performances in dry condition are not stable or lose their capability for capturing CO2 in the presence of H2O and acidic gases such as H2S.

To address this issue, a series of triphenylamine-containing microporous organic copolymers (PP-N-x) possessing high surface areas (1010 to 1251 m2 g-1) as well as excellent hydrolytic and acid stability were synthesized and evaluated for potential application in high pressure CO2 capture above-mentioned. Among the adsorbents tested, PP-N-25 exhibited the highest CO2/H2 selectivity over the entire pressure range along with the good CO2 uptake capability which is comparable to HKUST-1, a commercial metal-organic framework possessing coordinately open metal sites. Subsequent breakthrough experiment revealed that PP-N-25 maintains decent CO2 adsorption capability even in the presence of H2O while HKUST-1 lost CO2 capturing capability in humid condition.



 
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