• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1679-1684
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• 2011

Interfacial reactions kinetics often differ from kinetics of bulk reactions. Here, we describe how the density change of an immobilized reactant influences the kinetics of interfacial reactions. Self-assembled monolayers (SAMs) of alkanethiolates on gold were used as a model interface and the Diels-Alder reaction between immobilized quinones and soluble cyclopentadiene was used as a model reaction. The kinetic behavior was studied using varying concentrations of quinones. An unusual threshold density of quinones (${\Gamma}_c$ = 5.2-7.2%), at which the pseudo-first order rate constant started to vary as the reaction progressed, was observed. This unexpected kinetic behavior was attributed to the phase-separation phenomena of multi-component SAMs. Additional experiments using more phase-separated two-component SAMs supported this explanation by revealing a significant decrease in ${\Gamma}_c$ values. When the background hydroxyl group was replaced with carboxylic or phosphoric acid groups, ${\Gamma}_c$ was observed at below 1%. Also, more phase-separated thermodynamically controlled SAMs produced a lower critical density (3% < ${\Gamma}_c$ < 4.9%) than that of the less phaseseparated kinetically controlled SAMs (6.5% < ${\Gamma}_c$ < 8.9%).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.13-17
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• 2006

Pentacene channel for organic thin film transistor was deposited on the SiOC film by thermal evaporation. The growth of pentacene is related with the Diels-Alder reaction and the nucleophilic reaction by the thermal induction. The surface is an important factor to control the recursive Diels-Alder reaction for growing of pentacene on SiOC far The terminal C=C double bond of pentacene molecule was broken easily as a result of attack of the nucleophilic reagents on the surface of SiOC film. The nucleophilic reaction can be accelerated by increasing temperature on surface, and it maks pentacene to grow hardly on the SiOC film with a flow rate ratio of $O_2/(BTMSM+O_2)=0.5$ due to its inorganic property. The nucleophlic reaction mechanism is $SN_2(bimolecular nucleophilic substitution)$ type.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.83-88
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• 2019

In order to understand the in vivo biodistribution of repebody protein (RB), an efficient and simple radiolabeling method for the protein is needed. We demonstrate a detailed protocol for the radiosynthesis of an ¹¹¹In radiolabeled tetrazine prosthetic group and its application to the efficient radiolabeling of trans-cyclooctene-group conjugated repebody protein using inverse-electron-demand Diels-Alder reaction. First, 1,2,4,5-tetrazine (Tz) conjugated with a DOTA chelator, was used for preparing the radiolabeled DOTA complex with ¹¹¹In. Second, the trans-cyclooctene (TCO) functionalized repebody protein was synthesized which allows for the preparation of radiolabeled proteins by copper-free click chemistry. Following incubation with the ¹¹¹In-radiolabeled DOTA complex (¹¹¹In-Tz), the TCO-functionalized RB (TCO-RB) was radiolabeled successfully with ¹¹¹In, with a high radiochemical yield (69.5%) and radiochemical purity (>99%). The radiolabeling of repebody protein by copper-free click chemistry was accomplished within 20 min, with great efficiency in aqueous conditions. These results clearly indicate that the present radiolabeling method will be useful for the efficient and convenient radiolabeling of trans-cyclooctene-group containing biomolecules.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.395-398
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• 1992

In order to study the influence of a 6'-methyl group in ring C of griseofulvin ${\underline{(1)}}$ on the fungicidal activity, 6'-methyl group was replaced with a larger phenyl group as $({\pm})-6'-phenylgriseofulvin$ ${\underline{(3)}}$, $({\pm})-6'-epiphenylgriseofulvin$ ${\underline{(4)}}$, synthesized by a Diels-Alder cycloaddition. Their biological activities were examined against Botrytis allii (IFO 9430) and B. cinerea (AHU 9573). $({\pm})-6'-Phenylgriseofulvin $ ${\underline{(3)}}$ showed high activity in $25\;{\mu}g/disc$.

• Natural Product Sciences
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• v.25 no.3
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• pp.233-237
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• 2019

Three Diels-Alder type adducts, guangsangon E (1), chalcomoracin (2) and sorocein I (3) were isolated from hairy root cultures of Morus macroura. The structures of the isolated compounds (1-3) were determined by spectroscopic method (NMR and MS), and spectral comparison to literature. Cytotoxic activities of the isolated compounds (1 - 3) were investigated against P-388 murine leukemia cell line. Guangsangon E (1) showed the most potent cytotoxicity against P-388 murine leukemia cell line with $IC_{50}$ value of $2.75{\pm}0.32{\mu}g/mL$. To the best of our knowledge, guangsangon E (1) and sorocein I (3) were reported for the first time from the tissue cultures of M. macroura.

• Journal of the Korean Chemical Society
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• v.40 no.7
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• pp.483-491
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• 1996

Dieis-Alder reaction between cyclopentadiene and 5-membered ring compounds which have exo-cyclic double bond has been studied using the PM3 method. Transition states do not show large geometrical change with the variation of dienophiles. Two isomers are possible due to the rotation of the exo-cyclic double bond of a dienophile. The reactivity for the formation of different products are explained using the FMO energy gap. The exo and endo selectivity of the reaction has been also studied from the correlation between the deformation energy and the activation barrier. Minimum energy reaction path is discussed using the Curtin-Hammett principle.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.288-288
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• 2008

• Bulletin of the Korean Chemical Society
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• v.16 no.8
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• pp.694-696
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• 1995

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.792-793
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• 1995

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.389-391
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• 1999