Jong Hwa Jung

Functionalized magnetic nanoparticles as chemosensors and adsorbents for toxic metal ions in environmental and biological fields

Functionalized magnetic nanoparticles, composed of both inorganic and organic components, have recently been examined as promising platforms for detection and separation applications. This unique class of nanomaterials can retain not only beneficial features of both the inorganic and organic components, but can also provide the ability to systematically tune the properties of the hybrid materials through the combination of appropriate functional components. This tutorial review focuses on the recent development of functionalized magnetic nanoparticles for use in biological and environmental applications, in which these chromogenic and fluorogenic chemosensors can selectively detect and separate specific toxic metal ions.

A Selective Fluoroionophore Based on BODIPY‐functionalized Magnetic Silica Nanoparticles: Removal of Pb2+ from Human Blood

Get the lead out: The title fluorescence receptor exhibits a high affinity and selectivity for Pb(2+) over competing metal ions in water (see picture) with an overall emission change of approximately 8-fold at the emission maximum for Pb(2+). The fluorescence receptor can remove 96 % of 100 ppb Pb(2+) from human blood, and can be useful and effective for the selective and rapid removal of Pb(2+) in vivo.

Spectral Characterization of Self‐Assemblies of Aldopyranoside Amphiphilic Gelators: What is the Essential Structural Difference Between Simple Amphiphiles and Bolaamphiphiles?

An aldopyranoside-based gelators (dodecanoyl-p-aminophenyl-beta-D-aldopyranoside)s and [1,12-dodecanedicarboxylic-bis(p-aminophenyl-beta-D-aldopyranoside)]s 1-4 were synthesized, and their gelation ability was evaluated in organic solvents and water. Simple aldopyranoside amphiphiles 1 and 2 were found to gelate organic solvents as well as water in the presence of a small amount of alcoholic solvents. More interestingly, not only extremely dilute aqueous solutions (0.05 wt%) of the bolaamphiphiles 3 and 4, but solutions of 3 and 4 in several organic solvents could be gelatinized. These results indicate that 1-4 can act as versatile amphiphilic gelators. We characterized the superstructures of the aqueous gels and organogels prepared from 1-4 using SEM, TEM, NMR and IR spectroscopy, and XRD. The aqueous gels 1 and 2 formed a three-dimensional network of puckered fibrils diameters in the range 20-200 nm, whereas the aqueous gels 3 and 4 produced filmlike lamellar structures with 50-100 nm thickness at extremely low concentrations (0.05 wt%). Powder XRD experiments indicate that the aqueous gels 1 and 2 maintain an interdigitated bilayer structure with a 2.90 nm period with the alkyl chain tilted, while the organogels 1 and 2 take a loosely interdigitated bilayer structure with a 3.48 nm period. On the other hand, the aqueous- and the organogels 3 and 4 have 3.58 nm spacing, which corresponds to a monolayered structure. The XRD, 1H NMR and FT-IR results suggest that 1-4 are stabilized by a combination of the hydrogen-bonding, pi-pi interactions and hydrophobic forces.

Fabrication of silica nanotubes by using self-assembled gels and their applications in environmental and biological fields

This critical review focuses on the preparation methods of a variety of the silica nanotubes by self-assembled organogels and the recent development of silica-based organic-inorganic hybrid nanomaterials for use as chemosensors in environmental studies as well as adsorbents for inorganic guest molecules and in biological applications for delivery of organic guest molecules (127 references).

Sol-gel polycondensation in a cyclohexane-based organogel system in helical silica: creation of both right- and left-handed silica structures by helical organogel fibers.

Chiral amide- and urea-type organic gelators (1-6), based on cyclohexanediamine, have been prepared, and the superstructures of the organogels were evaluated by circular dichroism (CD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The CD spectrum of the amide-based organogel system 1+2 exhibited a negative sign for the first Cotton effect, indicating that the dipole moments in the gelator aggregate orient into an anticlockwise direction. In contrast, the system 3+4 has a positive sign for the first Cotton effect, indicating that they orient into a clockwise direction. In the mixture of urea- and amide-based organogels, CD spectra of 5+2 and 6+4 revealed negative and positive signs, respectively. The helical structure of the amide-based organogels 1+2 and 3+4 clearly showed left- and right-handed structures, respectively, by SEM. To transcribe the chiral, helical structures of the organogels into silica gel, the sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out in acetonitrile or ethanol. Very surprisingly, the left- and right-handed structures of the silica can be created by transcription of left- and right-handed structures of the organogels 1+2 (R enantiomer) and 3+4 (S enantiomer), respectively. In addition, in the mixture systems of urea- and amide-based organogels, the right- and left-handed structures of the organogels 5+2 (R enantiomer) and 6+4 (S enantiomer) were precisely transcribed into the silica structure. The findings suggest that the sol-gel polycondensation proceeds along the surface of the helical structure of the organogels. We therefore believe that the sol-gel polycondensation by means of molecular assembly templates abundantly built in the organogel phase is a new strategy to create superstructured silica materials.

Ligand- and Anion-Directed Assembly of Exo-Coordinated Mercury(II) Halide Complexes with O2S2-Donor Macrocycles

Assembly reactions of mercury(II) halides (Cl, Br, and I) with two O2S2 macrocycles (L(1) and L(2)) having different interdonor (S...S) distances were investigated, and four types of supramolecular complexes (1-4b) were obtained depending on the S...S distances as well as the size of the halide anions. Photoluminescence of these compounds was also studied.

Highly enantioselective synthesis of organic compound using right- and left-handed helical silica

Abstract Highly enantiomerically enriched (up to 96–97% ee) 5-pyrimidyl alkanol was obtained by the addition of diisopropylzinc to pyrimidine-5-carbaldehyde in the presence of the artificially designed chiral inorganic material, right- and left-handed helical silica.

A Chromo‐Fluorogenic Tetrazole‐Based CoBr2 Coordination Polymer Gel as a Highly Sensitive and Selective Chemosensor for Volatile Gases Containing Chloride

Crystalline coordination polymers are a newer class of organic–inorganic hybrid nanomaterials created by infinitely extending metal–ligand coordination interactions. These polymers show promise in a broad range of applications, including gas storage, molecular sieves, ion exchange, sensing, magnetism, and catalysis. [1, 2] Recently, a rational-design strategy for supramolecular gels based on the concept of coordination polymers is attracting interest. [3–6] In particular, recent studies have demonstrated that simple bridging organic units can facilitate the formation of coordination polymer gels in the absence of auxiliary moieties (e.g., urea, sugar, cholesterol, long alkyl chains), offering new possibilities to produce functional soft materials from structurally

Morphological control of helical solid bilayers in high-axial-ratio nanostructures through binary self-assembly

Mixed molecular species of cardanyl glucoside derived from renewable resources provide nanotubes upon self-assembly in water, while the saturated homologue generated a twisted fibrous morphology. The cardanyl glucoside mixture was fractionated into four individual components in order to study their contribution to the nanotube formation. The rational control of self-assembled helical morphologies was achieved by binary self-assembling of the saturated and monoene derivatives. This method can generate a diversity of self-assembled high-axial-ratio nanostructures (HARNs), ranging from twisted ribbons and helical ribbons to nanotubes.

Chiral Arrangement of Achiral Au Nanoparticles by Supramolecular Assembly of Helical Nanofiber Templates

Chiral materials composed of organized nanoparticle superstructures have promising applications to photonics and sensing. Reliable customization of the chiroptical properties of these materials remains an important goal; hence, we report a customizable scheme making use of modular gelator components for controlling the helicity and formation of nanofibers over long length scales resulting in hydrogel templates. Controlled growth of gold nanoparticles at spatially arranged locations along the nanofiber is achieved by UV reduction of Au(I) ions on the supramolecular templates. The resulting materials were found to have significant interparticle interactions and well-defined helicity to provide high quality, chiroptically active materials. With this novel approach, the tailored assembly of nanoparticle superstructures with predictable chiroptical properties can be realized in high yield, which we expect to allow rapid advancement of chiral nanomaterials research.