Changsik Song

In a previous publication, we described the use of biradicals, in that case two TEMPO molecules tethered by an ethylene glycol chain of variable length, as polarizing agents for microwave driven dynamic nuclear polarization (DNP) experiments. The use of biradicals in place of monomeric paramagnetic centers such as TEMPO yields enhancements that are a factor of approximately 4 larger (epsilon approximately 175 at 5 T and 90 K) and concurrently the concentration of the polarizing agent is a factor

Abstract Over the past decade, lithium‐ion batteries (LIBs) have been widely applied in consumer electronics and electric vehicles. Polymer electrolytes (PEs) play an essential role in LIBs and have attracted great interest for the development of next‐generation rechargeable batteries with high energy density. Due to the several practical applications of LIBs and high demands for LIBs performance, many state‐of‐the‐art PEs with different structures and functionalities have been developed to regu

Stable pi-dimers are formed upon oxidation of the model units of proposed calix[4]arene-based molecular actuators in a solvent of low dielectric constant (CH 2Cl 2) at room temperature. Evidence from UV-vis, EPR, and DPV are all in agreement with the pi-dimer formation. In addition, pi-dimer formation is dependent upon the conformational flexibility of the calix[4]arene hinge.

Because of the environmental issues associated with thermoset or network polymers, recyclable polymers are highly in demand, and the use of sustainable biomass-derived ingredients is also becoming increasingly important. In this work, we utilized 2,5-bis(hydroxymethyl)furan as a starting material to produce network polyurethanes (NPUs) under facile, solvent-free (solid-state) ball milling conditions. Urethane bonds may undergo thermally controlled transcarbamoylation, a reversible dynamic covale

Electroconductive hydrogels are composed of 3-dimensionally structured hydrogels and conducting molecules with electrical, optical, and reversible redox properties.

Picket-fence-type substituents effectively suppress the π–π stacking interaction of flat aromatic molecules and enhance solid-state emission for application in organic light-emitting diodes.

We report the design and synthesis of annulated thiepins designed to undergo bent-to-planar transformation driven by aromatization under electrochemical control. Thiepins are conjugated seven-membered ring systems with a thioether in the macrocycle. We synthesized thermally stable thiepins that are electropolymerizable to give rise to thiepin-containing electroactive polymers. Extended thiepin systems undergo sulfur extrusion with oxidation, and this feature has utility in peroxide sensing.

We developed a terpyridine-functionalized microgel (<bold>tpy-mG</bold>) for its supramolecular assembly.

Two isomeric polymers, which contain meta- or para-phenylene linkages between conducting segments, have been synthesized and compared by electrochemical methods. The nonconjugated poly(1,5-diacetoxy-m-phenylene tetrathienylene) (PMPT-OAc) showed similar electroactivity to the para-isomer, poly(2,5-diacetoxy-p-phenylene tetrathienylene) (PPPT-OAc), in the cyclic voltammetry and in-situ conductivity measurements. Spectroelectrochemistry showed a similar buildup of sub-band-gap electronic transitio

Single-walled carbon nanotubes (SWCNTs) were fabricated using AC dielectrophoresis into chemocapacitive sensors, and molecular receptors were applied for the selective detection of several chemical warfare agents (CWAs). The selective responses toward nerve simulants (G and V), choking and blister agents as well as a pesticide were investigated with specific receptor molecules that were either covalently functionalized or noncovalently coated onto the surfaces of the SWCNTs. The SWCNT-based chem

ABSTRACT Bis(hydroxymethyl)furan (BHMF) is a promising biomass‐derived polymer platform, but it is incompatible with traditional methods used for synthesizing polycarbonates (PCs) owing to its thermal instability. In this study, BHMF‐based furanic (FR) PCs were prepared successfully at a relatively low temperature through the mediation of carbonyldiimidazole. The low T g of aliphatic FR‐PCs was controlled elaborately, exploiting the reactivity of furan in the Diels–Alder reactions and the molecu

Stimuli-responsive polymeric systems are of considerable interest due to their potential applications in environment-adaptive technologies such as smart surfaces. Traditionally, such systems can be constructed either by dynamic noncovalent (supramolecular) or dynamic covalent chemistry, but the use of both chemistries in one system may offer unique opportunities for structural diversity and various controllability. Herein, we report that hydrazone–pyridinum conjugates, which can be dynamically e

We report an electrochemical transformation of binaphthols to give peri-xanthenoxanthene (PXX) groups in small molecules and within polymer backbones. The monomer 7,7′-bis(2,2′-bithiophen-5-yl)-1,1′-bi-2,2′-naphthol (2) was subjected to electropolymerization, resulting in the segmented conducting polymer that is stable at low potentials. However, high-potential electrochemical oxidation promoted cyclization of binaphthol units gives PXX, which transforms the moderately conducting segmented polym

Anion-coordination chemistry is important in biological and industrial processes and to alleviate environmental issues. Although thiourea has been studied for customized anion receptor applications via hydrogen-bonding interactions, it is seldom applied to anion-responsive actuators. In this study, we prepared thiourea-based soft gels using a facile one-step synthesis and tested them for anion-specific or anion-selective responses in actuation (i.e., volume transition). The thiourea-based soft g