Hong Yan

Agency for Science, Technology and Research (A*STAR) | A*Star · Institute of Materials Research and Engineering (IMRE)

Mono-TPE modified POSS molecules, in which the flexible spacers between TPE and POSS moieties control their self-assembly and aggregation, exhibit a unique unadulterated monomer emission in organic solvents as well as an AIE emission in THF/water.

A type of nanostructured material comprising reduced graphene oxide (RGO) modified polydimethylsiloxane (PDMS) for fabric coating is described. RGO modified PDMS was prepared through an aryl radical assisted addition reaction, followed by hydrosilylation with Si-H terminated PDMS or poly(dimethylsiloxane-co-methylhydrosiloxane) (PDMS-co-PHMS) in th...

While nanoparticle plasmonic coupling is known to be responsible for the enhancement of the local electrical field that determines optical or spectroscopic properties, understanding of the structural details of the interparticle interactions remains elusive. This report describes findings of an investigation of plasmonic coupling of gold nanopartic...

Aggregation induced emission (AIE) active copolymers P1-6 with high molecular weights (14,000-17,000) and low polydispersity indices (1.3-1.4) were prepared through copolymerization of N-isopropyl acrylamide (NIPAM) and tetra(phenyl)ethene (TPE)-based acrylate monomers. Copolymers P1-6 show comparable thermal stability to poly(N-isopropylacrylamide...

A novel pyrrolophthalazine dione (PPD) acceptor was sophisticatedly designed and synthesized via inverse electron demand Diels-Alder reaction, followed by aromatization with N-bromosuccinimide. The PPD moiety was incorporated into donor-acceptor type conjugated polymers through Stille coupling polymerization to yield a series of polymers P1-P3 with...

A new electron acceptor 6-alkylpyrrolo[3,4-d]pyridazine-5,7-dione (PPD) with a very low LUMO level has been synthesized via a challenging inverse electron demand Diels-Alder reaction between thiophene and furan-decorated tetrazine substrates and an electron-deficient 1-alkyl-1H-pyrrole-2,5-dione unit. The PPD monomer has been incorporated into a se...

This paper reports on a type of new AIE active copolymers which derived from polyhedral oligomeric silsesquioxanes (POSS) and tetraphenylethene (TPE)-containing acrylate monomers. The porous films were conveniently fabricated by electrospinning with a concentration of 2% in acetone/chloroform. The presence of POSS units in the copolymers facilitate...

An NIR-triggered drug delivery system was developed by capping photo-switchable azobenzene-based rotaxane onto Au nanorod-mesoporous silica core-shell hybrids. Drug release from the nanocarrier in zebrafish embryo models could be controlled remotely under NIR irradiation, showing significant drug spreading to the adjacent tissues.

Acrylate monomers with aggregation-induced emission (AIE) attributes were prepared by reacting 4-(1,2,2-triphenylvinyl)phenol with 1-bromoalkan-1-ol, followed by the treatment with acryloyl chloride in the presence of a base. The resulting acrylate monomers were polymerized by free radical polymerization to give very high molecular-weight AIE-activ...

A novel series of well-defined alternating poly[2,7-(9,9-di(2-ethylhexyl)fluorenyl)-alt-pyridinyl] (PDEHFP) copolymers were synthesized using palladium(0)-catalyzed Suzuki coupling reaction in high yields. These polymers were characterized using 1H NMR, UV-visible and fluorescence spectroscopies, gel permeation chromatography, thermal analysis and...

This paper describes a facile and reproducible protocol for the preparation of a supramolecular photodynamic therapeutic agent mediated by host-guest encapsulation in the absence of inorganic matrix. Two distinct approaches were explored to modulate the size and morphology of supramolecular nanoparticles (SNPs). One approach is through changing the...

In order to selectively target malignant cells and eliminate severe side effects of conventional chemotherapy, biocompatible and redox-responsive hollow nanocontainers with tumor specificity were fabricated. The mechanized nanocontainers were achieved by anchoring mechanically interlocked molecules, i.e., [2]rotaxanes, onto the orifices of hollow m...

A novel and efficient method for preparation of methylthio arylbutadiynes (Ar-C�C-C�C-SCH3 ) was described, and a series of compounds have been expediently obtained by the one-pot protocol starting from methylthiomethyl phenyl sulfone (MP-S) and arylpropargyl aldehydes. The mechanism was discussed on the basis of trapping and characterization of key...

The ability to harness the nanoscale structural properties is essential for the exploration of functional properties of nanomaterials. This report demonstrates a novel strategy exploring bifunctional nanoparticles for spectroscopic detection and magnetic intervention of DNA assembly, disassembly, and enzyme cutting processes in a solution phase. In...

The ability to monitor biomolecular recognition such as DNA hybridization and enzymatic reactivity in solutions with high sensitivity is important for developing effective bioassay strategies. Surface enhanced Raman scattering (SERS) based on use of solid substrates to produce the SERS effect for the detection often requires substrate preparation w...

Imposing chirality into nanoscale superstructures is one of major steps forward towards systematic understanding and utilization of nanomaterials. In an attempt to achieve tunable chirality during in-situ preparation of hybrid nanomaterials, we here report a novel unimolecular strategy of employing a coordinatable organogelator for the realization...

Three photothermal-responsive a-cyclodextrin-based [2]rotaxanes were prepared via the copper(I)-catalyzed azide–alkyne cycloaddition, in which the a-cyclodextrin ring was threaded onto the azobenzene dumbbell component. The difference between the three [2]rotaxanes are the length of the ethylene glycol repeating chains connected between the azobenz...

Host-guest complexation between pillararene trimer 1 and biviologen 2 was used to fabricate the dynamic supramolecular self-assembly, which exhibits a reversible multidimensional transformation from 0D to 3D upon concentration changes. As a comparison, assemblies built by the complexation between 1,4-dimethoxypillar[5]arene and 2 only show spherica...

Transformation of mechanically interlocked molecules (e.g., rotaxanes and catenanes) into nanoscale materials or devices is an important step towards their real applications. In our current work, an azobenzene-modified β-cyclodextrin (β-CD) derivative that can form a self-inclusion complex in aqueous solution was prepared. The self-included β-CD de...

Graphene and its derivatives have been widely used on account of their remarkable electronic, mechanical, and thermal properties. For example, graphene was recently used as a platform for developing novel molecular devices. Strategies for integrating numerous functional molecules and materials, for example, DNA, polymers, proteins, nanoparticles, a...

Detecting or intervening in biomolecular processes for medical diagnostics, drug delivery, and bacterial inactivation requires a functional probe which interfaces not only the targeted biomolecules but also provides an external stimulus. Metal nanoparticles serve as such functional probes. A key challenge is the ability to tailor the size, composit...

Fluorescent vesicles were successfully prepared through the self-assembly of a fluorescein-functionalized pillar[5]arene. The vesicular superstructure exhibits thermo-responsive emission under variable temperatures.

The design and construction of novel artificial molecular machines can be categorized as one of currently important fields of modern chemistry. In the present work, a novel photo-responsive [3]rotaxane containing two cucurbit[7]uril (CB[7]) rings and a dumbbell component consisting of one trans-azobenzene unit along with two viologen units was deve...

On and off: Ester hydrolysis catalyzed by a Zn(II) -coordinated β-cyclodextrin dimer can be switched on and off using light in the presence of gold nanoparticles with azobenzene units attatched to their surfaces. Under visible light, the azobenzene units are trans and bind tightly to the dimer, thus leading to reduced catalysis. Under UV light, the...

Release me! A new class of photothermal-responsive [2]rotaxane-appended mesoporous silica nanoparticles (MSNPs) was developed. Remote-controlled movement of the α-cyclodextrin ring (green) upon trans-cis isomerization of the azobenzene axle (red) enables the loading and release of drugs on demand. Curcumin-loaded MSNPs were shown to release curcumi...

An effective self-assembly route for construction of Pt(II)-bridged [3]rotaxane functionalized gold nanoparticles was developed through a stepwise introduction of Pt(II) coordination and gold-thiol binding in turn. The sequential self-assembly process can be quantitatively controlled and directly monitored by the naked eye.

The ability to control and tailor the interparticle structures and properties of molecularly-mediated assembly of nanoparticles in terms of molecular size, shape, and structure is essential for exploring the nanostructured multifunctional properties. This report describes the results of an investigation on how such molecular size, shape, and struct...

A nanoparticle-based strategy has been demonstrated using structurally-tailored tert-butylcalixarenes immobilized on gold nanoparticles to tune the guest access to the calixarene cone cavity for cationic recognition. This strategy exploits the interparticle charge-induced aggregation upon selective capture of metal cations into the nanoparticle-imm...

The report describes a strategy for the synthesis of gold nanoparticles for which size and surface reactivity of the particles are controlled by the molecular sizes of dendritic arenethiols (DAT) as capping agents. This strategy exploits two important attributes of the DAT molecules: one involving the utilization of the umbrella-like structure with...

The rigidity, conjugation, and shape-persistent architectures of aryl ethynyls of V, Y, and X shapes serve as an ideal model system for defining interparticle structures, which have been demonstrated for the mediated assembly of gold nanoparticles.

Tandem inter- and intramolecular Eglington couplings take place with good selectivity to afford an enantiopure three-dimensional cyclophyne with a large cavity.

Stereochemical study of cyclophynes, which is otherwise rather difficult to perform, can be achieved by vibrational CD spectroscopy.

New types of enantiopure compounds were synthesized to gain better insight into the structural features of phenylene ethynylene cyclophynes. Besides the previously obtained meta-substituted arylene ethynylenes, 1, ortho-connected phenylene ethynylene units were incorporated to give cyclophynes with ortho/meta and ortho/ortho connection modes, 2 and...