• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.80-84
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• 1989

Two properties of sodium naphthalenide (2), i.e. a strong base and a good electron donor were utilized for one pot synthesis: 2-alkylthiobenzimidazoles were synthesized in excellent yields from the reactions of benzimidazoline-2-thione (1) with an equimolar amount of alkyl halides in the presence of 2. Continuous addition of a different alkyl halide without the isolation of 2-alkylthiobenzimidazoles afforded 1-alkyl-2-alkylthiobenzimidazoles having different alkyl groups at N and S atoms in excellent yields. Further addition of 2 to 1-alkyl-2-alkylthiobenzimidazoles gave excellent yields of 1-alkylbenzimidazoline-2-thiones. When 2 in THF was added to a suspension of 1-alkyl-2-alkylthiobenzimidazoles in THF, a bond cleavage between N and C of alkyl group as well as S and C of alkyl group occurred. This is in contrast to the observation in which only cleavage between S and C of alkyl group takes place in the homogeneous solution.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.65-69
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• 1990

The nucleophilic substitution reactions of naphthalene-1,5-disulfonyl chloride and 4-fluorosulfonylbenzenesulfonyl chloride with p-substituted anilines and methyl substituted pyridines in methanol-acetonitrile mixtures and hydrolyses of those disulfonyl halides have been studied by means of conductometric and polarographic methods. A large difference in the selective parameter, ${\rho}_N$ between mono-sulfonyl chloride and disulfonyl halide can be taken as an evidence that the second $SO_2Cl$ grolup of naphthalene-1,5-disulfonyl chloride also takes part in the reaction in contrast to sulfonyl fluoride in 4-fluorosulfonylbenzenesulfonyl chloride, which only acts as a substituent in the nucleophilic substitution reaction.

• Electronic Materials Letters
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• v.14 no.6
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• pp.657-668
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• 2018

Organic-inorganic hybrid lead halide perovskites have been extensively investigated for various optoelectronic applications. Particularly, owing to their ability to form highly crystalline and homogeneous films utilizing low-temperature solution processes (< $150^{\circ}C$), perovskites have become promising photoactive materials for realizing high-performance flexible solar cells. However, the current use of mesoporous $TiO_2$ scaff olds, which require high-temperature sintering processes (> $400^{\circ}C$), has limited the fabrication of perovskite solar cells on flexible substrates. Therefore, the development of a low-temperature processable charge-transporting layer has emerged as an urgent task for achieving flexible perovskite solar cells. This review summarizes the recent progress in low-temperature processable electron- and hole-transporting layer materials, which contribute to improved device performance in flexible perovskite solar cells.

• Bulletin of the Korean Chemical Society
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• v.19 no.7
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• pp.770-776
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• 1998

Several ABCH type chiral calix[4]arenes were prepared from monoalkyl calix[4]arenes by treating with various acyl halide, followed by reacting with benzoyl chloride in pyridine. These asymmetrically substituted ABCH type calix[4]arenes are obtained as racemates mixture which are confirmed by the chiral shift reagent in 1H NMR spectra. The molecular and crystal structure of 5-nitro-26-allyloxy-25-benzoyloxy-28-isobutyryloxy-27-hydroxycalix[4]arene 8a has been determined by the X-ray diffraction method. Two independent enantiomeric molecules are crystallized in a 1: 1 racemate mixture. They are in the partial cone conformation in which the benzoyloxy phenyl group is down. There is a bifurcated intramolecular hydrogen bonding involving three functional groups in each molecule.

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.870-873
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• 1995

A new ternary transition-metal selenide, Ta2Ni3Se8 has been synthesized from a eutectic halide flux. The structure of this phase has been characterized by single crystal X-ray diffraction techniques. The compound crystallizes in the orthorhombic system (D2h9-Pbam, a= 14.788(4) Å, b= 10.467(3) Å, c=3.4563(8) Å) with two formula units in the unit cell. This compound adopts the Nb2Pd3Se8 structure type. Hence, there are two chains of edge-sharing selenium trigonal prisms centered by tantalum atoms and these chains are interconnected through two kinds of nickel atoms. Nickel occupies both square planar and square pyramidal sites as does palladium in Nb2Pd3Se8. Electrical conductivity measurements indicate that this material is semiconducting.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.379-381
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• 1988

Racemic nuciferal(1) and nuciferol(2), the terpenic natural perfumeries, have been synthesized by a simple procedure. The benzylic halide 6; 1-(1-chloroethyl)-4-methylbenzene, was prepared by converting p-tolualdehyde(4) into 1-(p-tolyl)-1-ethanol(5), followed by convertion of 5 into corresponding chloride. The Grignard reagent of 6 was reacted with the bromoacetal 7, 2-(2-bromoethyl)-1,3-dioxolane, to give a crosscoupling product 8, which was hydrolysed to 4-(p-tolyl)-pentanal (9). The Wittig reaction of isopropylide 10 with 9 yielded arcurcumen(11). The stereospecific allylic oxidation of the gem-dimethyl olefin 11 with selenium dioxide afforded a trans-aldehyde, (${\pm}$)-1, which was reduced to corresponding alcohol, (${\pm}$)-2.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1060-1064
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• 1995

The reactivity of superoxide ion (O2-.) with halogenated substrates is investigated by cyclic voltammetry and rotated ring-disk electrode method in aprotic solvents. The more positive the reduction potential of the substituted nitrile, the more facile is nucleophilic displacement by O2-.. The reaction rates of halogenonitriles with O2-. vary according to the leaving-group propensity of halide (Br > Cl > F). The relative reaction rates of other substituted nitriles are in the order of electron-withdrawing propensity of the substituent group (CN > C(O)NH2 > Ph ≒ CH2CN). The reaction of O2-. with dihalocarbons indicates that five-membered rings can be rapidly formed by the cyclization of substrate and O2-., and the relative rates of cyclization depend on the number of methylenic carbons {Br(CH2)nBr, [n=1 < 2 < 3 > 4 > 5]}. Mechanisms are proposed for the reaction of O2-. with halogenated substrates.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.148-154
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• 1992

With nonhardening fixer, dichromated bleacher and alcohol drying, the diffraction efficiency of over 71o/c has been achie'{ed for holographic phase gratings in silver halide emulsion. The swollen emulsion of Agfa 8E75 HD film is identified by scanning electron microscope (SEM) after chemical processing. Dichromated bleacher and rapid dehydration using alcohol drying make a strong modulation so that diffraction efficiency is. increased over 20%. The principal characteristic parameters in coupled wave theory are investigated and new modified parameter values are presented by computer simulation. Controlling the emulsion thickness has an important role as a potential source for high diffraction efficiency.ciency.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.516-519
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• 1994

The derivatives of methyl 5-hydroxy-dinaphtho[1,2-2',3']furan-7,12-dione-6-carboxylate (MHDDC) were synthesized by condensing alkyl sulfate or alkyl halide with MHDDC in organic solvent, and their structures were identified by NMR, MS, UV, IR etc. We also investigated the physico-chemical properties, physiological activities, and set up the micro-analytical method of the compounds.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.238-242
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• 1989

The relations between the repulsive interactions and the electron density overlaps are investigated for various closed shell-closed shell pairs, including the systems containing alkali and halide ions. It is found that the repulsive interaction($V_{rep}$) depends on the overlap of the electron density($S_{\rho}$) according to a simple exponential relation, $V_{rep}$ = $As_{\rho}\;^{\alpha}$. Furthermore, for most of the closed shell systems the $\alpha$ values are near unity and the A values do not vary much. The same tests are also performed for the open shell-closed shell, and the open shell-open shell pairs. Although the results for these systems also show exponential dependences of the repulsive interactions on the density overlaps, the details of the dependence differ greatly from those for the closed shell systems and also vary widely from one individual system to another.