• Journal of Photoscience
• /
• 제6권3호
• /
• pp.117-121
• /
• 1999

Photoinduced electron transfer of C60 has been studied by the laser photolysis measuring the transient absorption bands in near-IR region. The electron transfer aromatic amines via the triplet state of C60 is confirmed by the decay of the transient absorption bands of the triplet state of C60 and the rise of the anion radical of C60 and the cation radicals of amines. The rate and efficiency of electron transfer are strongly affected by the donor ability of amines and polarity of solvents. Back electron-transfer kinetics is also strongly affected by the solvent polarity.

• Bulletin of the Korean Chemical Society
• /
• 제12권4호
• /
• pp.429-433
• /
• 1991

The photoinduced electron transfer reactions of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in various polar solvents were studied by measuring time-resolved fluorescence. The temperature dependence on the fluorescence decay rate in acetonitrile, methanol, ethanol and buthanol was carried out to obtain the activation energy and Arrehnius factor for the photoinduced electron transfer reaction. It was found that as the dielectric constant of the solvent increases, the activation energy and the reaction rate increase. This implys that the Arrehnius factor is important in controlling the photoinduced electron transfer reaction rate. In water, TMPD exists in three forms (cationic, protonated and neutral forms) due to the high dielectric constant and strong proton donating power of water. The photoinduced electron transfer reaction was found to be very fast (< 50 ps) and also the long liverd component in the fluorescence decay profile attributable to the photoexcited protonated form of TMPD was observed. Probably, the reaction pathway and the reaction coordinate seem to be different depending on the solvents studied here.

• Bulletin of the Korean Chemical Society
• /
• 제31권10호
• /
• pp.2801-2805
• /
• 2010

A nucleophilic substitution reaction of 4-chloro-7-nitrobenzofurazan (NBF-Cl) with anilines in MeOH-MeCN mixtures was conducted at 25, 35, and $45^{\circ}C$. Based on the higher $\beta_{nuc}$ values (1.0 - 1.6) of the reaction and a good correlation of the rate constants with the reduction potentials of the aniline nucleophiles, the present reaction was initiated by a single electron transfer (SET). After this step, the reaction proceeds through a transition state similar to the normal $S_NAr$-Ad.E pathway.

• Journal of Photoscience
• /
• 제5권3호
• /
• pp.125-129
• /
• 1998

Occurrence of an electron (or H atom equivalent to one electron plus H+) transfer from $\alpha$- tocopherol $\alpha$(TOH) to a number of photosensitizers in theri triplet states were investigated by monitoring the ESR signal of $\alpha$-chromaoxyl radical ($\alpha$(TO.) in ethanolic solutions of $\alpha$TOH and the sensitizers under continuous illumination. Every sensitizer molecule examined, such as protocholorophyllide (Pchl), hematoporphyrin and rose bengal which are generally regarded as efficient type II photosensitizers and thus have long-lived triplet states, was found to actively participate in an electro transfer reaction with $\alpha$TOH even under air-saturation conditions, generating $\alpha$TOH complex as an intermediate in a fashion of Michaelis-Menten type of reaction. For the reaction of $\alpha$TOH with triplet Pchl, the rate law was derived by applying the steady approximation for the binary complex, triplet Pchl-$\alpha$TOH , which turned out to be well consistent with the kinetic data.

• Bulletin of the Korean Chemical Society
• /
• 제10권3호
• /
• pp.258-261
• /
• 1989

The electrochemical behaviors of 4-(2)-thiazolylazo)-resorcinol (TAR) in acetonitrile solution was studied by DC polarography, cyclic voltammetry, controlled-potential coulometry and UV-Vis spectroscopy. The electrochemical reduction of TAR occurs in four-one electron reduction steps in acetonitrile solution. The products of the first and the third electron transfer are speculated to be a relatively stable anion radical. The second electron transfer to the dianion is followed by a chemical reaction producing a protonated species. The product of the fourth electron transfer also produces the corresponding amine compounds with a following reaction. Also every reduction wave was diffusion controlled. The first reduction wave is considerably reversible and the other waves are less reversible.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.375.1-375.1
• /
• 2016

Polymerase chain reaction (PCR) has revolutionized genetics and become one of the most popular techniques in modern biological and medical sciences. It can be used not only as an in vitro DNA amplification method but also used in many bioassay applications. The PCR can be used to exponentially produce a large number of DNA copies from a small quantity of DNA molecules in a few hours. However, as unwanted DNA fragments are also often manufactured, the amplification efficiency of PCR is decreased. To overcome this limitation, several nanomaterials have been employed to increase the specificity of the PCR reaction. Recently, graphene has attracted a great interest for its excellent electron transfer, thermal and biocompatibility. Especially, gold nanoparticle-coated graphene oxide (GO/AuNPs) led to enhance electron and thermal transfer rate and low-charge transfer resistance. Therefore, we report the development of a demonstration for the PCR efficiency using a large-scale production of the GO and combination of gold nanoparticles. Because a thermal conductivity is an important factor for improving the PCR efficiency in different DNA polymerases and different size samples. When PCR use GO/AuNPs, the result of transmission electron microscopy and real-time quantitative PCR (qPCR) showed an enhanced PCR efficiency. We have demonstrated that GO/AuNPs would be simply outperformed for enhancing the specificity and efficiency of DNA amplification procedure.

• Bulletin of the Korean Chemical Society
• /
• 제31권6호
• /
• pp.1711-1714
• /
• 2010

• Bulletin of the Korean Chemical Society
• /
• 제6권5호
• /
• pp.291-295
• /
• 1985

The efficiency of photosensitization of methyl linoleate (ML) oxidation by N-acetyl-L-trypophan(NAT) and 3-methyl indole(scatole) was markedly enhanced by increased concentration of ML in ethanol solution. The fluorescence intensities of sensitizers were observed to be quenched by ML, indicating that ML interacts with the indole excited singlet state. The inhibition of photosensitization by azide demonstrated a possible role of singlet oxygen in the photosensitization. The steady state kinetic treatment of azide inhibition of photosensitization was expected to show linear increase of reciprocal yield of ML oxidation product vs. reciprocal ML concentration at constant azide concentration, but the actual slope was nonlinear. This indicates another competing reaction involved in the photosensitization, As a possible competing reaction, electron transfer from ML to the excited sensitizer was proposed, since the measured fluorescence quenching rate constant closely resembled electron transfer rate constant determined from ML concentration dependence of oxidation product formation.

• Journal of Microbiology
• /
• 제39권3호
• /
• pp.149-153
• /
• 2001

The electron transfer reaction is one of the most essential processes of life. Not only does it provide the means of transforming solar and chemical energy into a utilizable form for all living organisms, it also extends into a range of metabolic processes that support the life of a cell. Thus, it is of great interest to understand the physical basis of the rates and reduction potentials of these reactions. To identify the major determinants of reduction potentials in redox proteins, we have chosen the simplest electron transfer protein, rubredoxin, a small (52-54 residue) iron-sulfur protein family, widely distributed in bacteria and archaea. Rubredoxins can be grouped into two classes based on the correlation of their reduction potentials with the identity of residue 44; those with Ala44 (ex: Pyrococcus furiosus) have reduction potentials that are ∼50 mV higher than those with Va144 (ex: Clostridium pasteurianum). Based on the crystal structures of rubredoxins from C. pasteurianum and P. furiosus, we propose the identity of residue 44 alone determines the reduction potential by the orientation of the electric dipole moment of the peptide bond between 43 and 44. Based on 1.5 $\AA$ resolution crystal structures and molecular dynamics simulations of oxidized and reduced rubredoxins from C. pasteurianum, the structural rearrangements upon reduction suggest specific mechanisms by which electron transfer reactions of rubredoxin should be facilitated.

• 농업과학연구
• /
• 제11권2호
• /
• pp.315-321
• /
• 1984

0.1M tetraethylammoniumperchlorate (TEAP)를 지지전해질로 한 acetonitrile속에서 direct current (DC), differential pulse (DP) polarography 및 cyclo voltammetry (CV) 방법에 의한 Sumithion의 전기화학적 환원반응은 -1.0~-2.50volt vs. Ag-AgCl 범위에서, 제1단계로 P-Oph 결합의 분열에 의하여 dimethylthiophosphonyl radical과 p-nitro-m-cresol이 생성되는 1전자 유사가역반응이 일어나고, 제2단계는 전형적인 1전자 비가역 반응으로 dimethylthiophosphonyl radical이 dimethylthiophosphonate가 되며, 제3단계 반응은 2.7volt vs. Ag-AgCl의 높은 음전위에서 p-nitro-m-cresol은 4전자 비가역반응에 의한 nitro group의 환원으로 p-hydroxy-amino-m-cresol이 생성되는 총 3단계의 비가역적인 electron-transfer chemical reaction (EC) 메카니즘으로 전극반응이 진행됨을 알았다.