• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.940-951
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• 2011

Reaction of 1-methylpyrimidine-(1H,3H,5H)-2,4,6-trione (1-MBA 1) as an unsymmetrical barbituric acid with cyanogen bromide and various aldehydes in the presence of triethylamine and/or pyridine afforded diastereomeric mixtures of new class of heterocyclic stable 5-aryl-1,1'-dimethyl- and 5-aryl-3,1'-dimethyl-1H,1'H-spiro[furo[2,3-d]pyrimidine-6,5'-pyrimidine]2,2',4,4',6'(3H,3'H,5H)-pentaones which are dimeric forms of 1-methyl barbiturate at the range of $0^{\circ}C$ to room temperature. In the reaction of some aldehydes with 1-MBA and BrCN were afforded a mixture of diastereomers. Another two aldehydes such as 4-cyano- and 2-hydroxybenzaldehydes gave exclusively two diastereomers in which binded to the salt of triethylammonium hydrobromide by intermolecular H-bond in ratio of 1:1. 4-Hydroxybenzaldehyde and 2-pyridinecarbaldehyde gave exclusively one diastereomer under the same condition. Aldehydes possessing strong electron-donor were produced exclusively two geometric isomers of Knoevenagel adduct (E- and Z-isomers). The structures of compounds were deduced by $^1H$ NMR, $^{13}C$ NMR and FT-IR spectroscopy. Mechanism of the formation is discussed.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2291-2296
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• 2013

An efficient carbon monoxide (CO) sensor was developed based on poly(3,4-ethylenedioxy)thiophenepoly(styrenesulfonate) (PEDOT:PSS) modified with a new pyrimidine-fused heterocyclic compound, bis(2-hydroxyphenyl)dihydropyrido[2,3-d:6,5-d]dipyrimidine-tetraone (B2HDDT). B2HDDT remains stable in the polymer matrix through interactions with functional groups of the polymer. It created prominent sites that captured CO gas, and the experimental parameters, including the amount of doped B2HDDT in the PEDOT:PSS film, were optimized. The sensor probe was also examined to verify its reliability for detecting CO in the presence of atmospheric gases in a discriminating manner. NMR, AFM, and FT-IR spectra were obtained to evaluate the structure and morphology of the B2HDDT-doped PEDOT:PSS (PEDOT:PSS/B2HDDT) film. The content of 35 vol % B2HDDT (7.0 mM) in PEDOT:PSS provided the largest response factor (${\Delta}R/R_o$) for the CO gas. The sensor response was reproducible, with a relative standard deviation < 5% (n = 5). The detection limit was determined to be $0.44{\pm}0.05$ vol %.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.455-456
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• 2006

최근 많은 학자들에 의해서 차세대 디스플레이로 각광 받고 있는 유기EL에 대한 연구가 활발하게 진행되고 있다. 그 중에서 본 연구에서 수행하고자 하는 분야는 유기EL의 발광재료의 개발에 대한 연구이다. 그 분야중 하나가 세계적으로 많은 학자들에 의해서 연구되고 있는 전이금속을 이용한 발광재료의 개발이다. 그 중 본 연구에서는 양 말단 금속을 가교체로 연결한 이 핵 금 착체에 관한 연구를 수행하였다. 이러한 가교체들은 유기물의 결합 상태에서 나타나는 전자전이외에 금속과 유기물사이의 결합에 의해 나타날 수 있는 전자전이 또 한 가지고 있다. 이러한 전자전이로 인해 발광재료로서의 특징을 가질 수 있다. 이러한 착체를 합성하기위해 가교체 $H-C{\equiv}C-C{\equiv}C-C-H$와 $(Cis)H-C{\equiv}C-CH=CH-C{\equiv}C-H$를 이용하여 금과 N-Heterocyclic-Carbene가 배위결합된 양말단의 금속 그룹을 연결하여 합성하였다. 합성된 착체는 FT-IR, $^1H$-NMR, $^{13}C$-NMR, UV/VIS/NIRspectrophotometer, Emission spectrometer를 사용하여 분석하였다.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.594-602
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• 2011

The effect of ${\alpha}$-, ${\beta}$- and ${\gamma}$-picolines on the stereochemistry of the coordination compounds of lanthanide(III) nitrates derived from 4[N-(furfural)amino]antipyrine semicarbazone (FFAAPS) has been studied. The general composition of the present coordination compounds is [Ln(FFAAPS)$(NO_3)_3$Pic] (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy or Ho and Pic=${\alpha}$-, ${\beta}$- or ${\gamma}$-picolines). All these coordination compounds have been characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibility, infrared and electronic spectra. The infrared studies suggest that the FFAAPS behaves as a neutral tridentate ligand with N, N, O donor while ${\alpha}$-, ${\beta}$- or ${\gamma}$-picoline is coordinated to the lanthanide(III) ions via heterocyclic N-atom. Nitrates are bicovalently bonded in these compounds. From the electronic spectral data, nephelauxetic effect (${\beta}$), covalence factor ($b^{1/2}$), Sinha parameter (${\delta}%$) and the covalence angular overlap parameter (${\eta}$) have been calculated. Thermal stabilities of these complexes have been studied by thermogravimetric analysis. The coordination number of lanthanide(III) ions in the present compound is found to be ten. The antibacterial studies screening of the primary ligand FFAAPS and the complexes showed that the present complexes have moderate antibacterial activities.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.306-315
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• 2001

Our study is aimed at proposal of systematic verification method of molecular structure using measuring method of selective ionic determination and spectrometry on 34 kinds of surfactants such as sodium dodecyl sulfate(SDS) which are most widely used today. In the IR spectrum, unsaturated fatty acids reveal themselves by HC= at $3000{\sim}3020cm^{-1}$, and intensity of $720cm^{-1}$ depends on carbon length of alkyl group. Also ethylene oxide(EO) adducts exhibit weak characteristic bands by $-CH_{2}-CH_{2}-O$ at 1350, 1100 and $950cm^{-1}$. Isethionate can be distinguished from diester succinate by intensity ratio of 1740 and $1200cm^{-1}$ spectrums, the ratio of latter is close to 1 due to 2 carboxylate radical in diester succinate. Quaternary ammonium salts exhibit characteristic band of $C_{4}N^{+}$ at $1000-900㎝^{-1}$. In the case of dialkyl dimethyl ammonium salts in quaternary ammonium surfactants, the spectrum of $3000cm^{-1}$ by $N-CH_{3}$ collapses to a very weak band at $3020cm^{-1}$. In ammonium heterocyclic derivatives, pyridinium salts show characteristic bands at 1640 and $1460cm^{-1}$, while imidazolinium salts exhibit characteristic band at $1620-1610cm^{-1}$. In the characteristic spectrum at $1080-1050cm^{-1}$ on OH radicals of the alkyl esters, primary alcohol appears as weak band and the 2 bands show in almost same intensity when primary and secondary alcohols exist together in one molecule. Also, alkyl ester of polyhydric alcohols appears as various broad band.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.167-173
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• 2013

A series of highly efficient red phosphorescent heteroleptic iridium(III) complexes 1-6 containing two cyclometalating 2-(2,4-substitued phenyl)quinoxaline ligands and one chromophoric ancillary ligand were synthesized: (pqx)$_2Ir$(mprz) (1), (dmpqx)$_2Ir$(mprz) (2), (dfpqx)$_2Ir$(mprz) (3), (pqx)$_2Ir$(prz) (4), (dmpqx)$_2Ir$(prz) (5), (dfpqx)$_2Ir$(prz) (6), where pqx = 2-phenylquinoxaline, dfpqx = 2-(2,4-diflourophenyl)quinoxaline, dmpqx = 2-(2,4-dimethoxyphenyl)quinoxaline, prz = 2-pyrazinecarboxylate and mprz = 5-methyl-2-pyrazinecarboxylate. The absorption, emission, electrochemical and thermal properties of the complexes were evaluated for potential applications to organic light-emitting diodes (OLEDs). The structure of complex 2 was also determined by single-crystal X-ray diffraction analysis. Complex 2 exhibited distorted octahedral geometry around the iridium metal ion, for which 2-(2,4-dimethoxyphenyl)quinoxaline N atoms and C atoms of orthometalated phenyl groups are located at the mutual trans and cis-positions, respectively. The emission spectra of the complexes are governed largely by the nature of the cyclometalating ligand, and the phosphorescent peak wavelengths can be tuned from 588 to 630 nm with high quantum efficiencies of 0.64 to 0.86. Cyclic voltammetry revealed irreversible metal-centered oxidation with potentials in the range of 1.16 to 1.89 V as well as two quasi-reversible reduction waves with potentials ranging from -0.94 to -1.54 V due to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated C^N ligands.

• Biomolecules & Therapeutics
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• v.32 no.4
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• pp.442-450
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• 2024

The type-1 cannabinoid receptor (CB₁R) is a potential therapeutic target in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Owing to their structural diversity, it is not easy to derive general structure-activity relationships (SARs) for CB₁R ligands. In this study, CB₁R ligands were classified into six structural families, and the corresponding SAR was determined for their affinities for CB₁R. In addition, we determined their functional activities for the activation of extracellular signal-regulated kinases (ERKs). Among derivatives of indol-3-yl-methanone, the highest ligand affinity was observed when a pentyl and a naphthalenyl group were attached to the N1 position of the indole ring and the carbon site of the methanone moiety, respectively. In the case of adamantane indazole-3-carboxamide derivatives, the presence of fluorine in the pentyl group, the substituent at the N1 position of the indazole ring, strongly increased the affinity for CB₁R. For (naphthalen-1-yl) methanone derivatives, the presence of 4-alkoxynaphthalene in the methanone moiety was more beneficial for the affinity to CB₁R than that of a heterocyclic ring. The functional activities of the tested compounds, evaluated through ERK assay, were correlated with their affinity for CB₁R, suggesting their agonistic nature. In conclusion, this study provides valuable insight for designing novel ligands for CB₁R, which can be used to control psychiatric disorders and drug abuse.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.506-512
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• 2007

Various long chain aliphatic acid hydrazides react with aromatic and heterocyclic aldehydes in alcoholic medium in refluxing conditions to give corresponding 2-hydroxy benzylidene and 1H-indol-3-ylmethylene hydrazides, a newer class of mosquito para-pheromones. We describe here synthesis of various novel long chain aliphatic acid (2- hydroxy benzylidene and 1H-indol-3-ylmethylene) hydrazides by conventional as well as microwave irradiation techniques. The structures of these compounds have been confirmed by spectroscopic techniques (FTIR, NMR & MS). Some of the interesting features of the electron impact mass spectral fragmentation pattern of these compounds have also been discussed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.117-126
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• 1984

Aflatoxins are toxic and carcinogenic secondary metabolites which are produced by trains of A. flavus and A. parasiticus during their growth on foods and feedstuffs. Aflatoxins are a group of closely related heterocyclic compounds of which $B_1$, $B_2$, and $G_2$ are the major members. Aflatoxins are synthesized via a polyketide pathway in which the general steps are acetate, an-thraquinones, xanthone and aflatoxins. Aflatoxin formation is favored by high moisture or high $a_w$(0.95${\sim}$0.99). The limiting $a_w$ for aflatoxin production on agricultural commodities is 0.83. Optimum temperature for aflatoxin production by the molds is $25{\sim}30^{\circ}C$ and the incubation time for the maximum production of the toxin is 7${\sim}$15 days. The limiting temperatures for aflatoxin production are ${\leq}7.5^{\circ}C\;and\;\geq40^{\circ}C$. Cycling temperatures may or may not stimulate aflatoxin production depending on the amplitude of cycling, substrate and strains of molds. Aflatoxin pro-ducing molds are aerobic organisms and thus have a requirement for oxygen. A decreasing $O_2$ concentration and/or increasing concentrations of $CO_2$ or $N_2$ depress the mold growth and aflatoxin formation. A. flavus grows competitively or associatively in the presence of other microorganisms and occasionally loses the competition with other microorganisms. Some lactic acid bacteria have been shown to reduce growth and aflatoxin production by A. parasiticus. Carbon source is the most important nutritional factors affecting aflatoxin formation by the molds. Sucrose, fructose and glucose are the most favorable carbon sources. Food substrates of plant derived products which have high carbohydrate content such as agricultural commodities and their products are most vulnerable to contamination by aflatoxins.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.14-21
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• 1993

N-Heterocyclic aromatics (NHA) are widely occurring environmental pollutants formed during the pyrolysis of nitrogen-containing organic chemicals. NAH are found in significant amounts in tobacco condensates, synthetic fuels, polluted river sediment, and effluents from the heating of coal. Following topical application 7H-dibenzo[c, g]carbazole (DBC) induces cancer in liver as well as skin, indicating that dermal exposure can lead to systemic effect. DBC and dibenz[a,j]acridine (DBA) are examples of NHA. The potency of many carcinogenic compounds is related, at least in part, to the efficiency of their biological activation. We undertook studies to determine which initial metabolites lead to the formation of high levels of carcinogen-DNA adducts in vivo. DBC and DBA's, DBA, trans-DBA-1,2-dihydrodiol (DBA-1,2-DHD), trans-DBA-3,4-dihydrodiol (DBA-3,4-DHD), and trans-DBA-5,6-dihydrodiol (DBA-5,6-DHD), were applied to the skin of mice. There were six adducts that were related to DBC application. These addusts were seen in the target organ, liver at high levels, but at very low levels in non-target organs, skin, lung and kidney. In skin, DBA produced two distinct adducts. The same two adducts were seen when DBA-3,4-DHD was applied. In addition the total adduct level elicited by DBA-3,4-DHD higher than that of parent compound. Two adducts were seen when DBA-5,6-DHD was applied, but these were very different from adducts seen with DBA. These results suggested that activation of DBA to DNA-binding compounds in skin includes initial formation of DBA-3,4-DHD.