• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.1033-1036
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• 2001

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.633-634
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• 2001

• Journal of the Korean Chemical Society
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• v.64 no.6
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• pp.438-442
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• 2020

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.229.2-229.2
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• 2001

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3173-3179
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• 2010

New complex $[Mn(II)H_{1.5}L]_2[Mn(II)H_3L]_2(ClO_4)_5{\cdot}3H_2O$ (1), where $H_3L$ is tris {2-(4-imidazolyl)methyliminoethyl} amine (imtren), has been prepared by reacting manganese(II) perchlorate hexahydrate with the imtren ligand in methanol. X-ray crystallographic study revealed that the imtren ligand hexadentately binds to Mn(II) ion through the three Schiff-base imine N atoms and three imidazole N atoms with a distorted octahedral geometry, and the apical tertiary amine N atom of the ligand pseudo-coordinates to Mn(II), forming overall a pseudo-seven coordination environment. The hydrogen-bonds between imidazole and imidazolate of $[Mn(II)H_{1.5}L]^{0.5+}$ complex ions are extended to build a 2D puckered network with trigonal voids. $[Mn(II)H_3L]^{2+}$ complex ions constitutes another extended 2D puckered layer without hydrogen bonds. Two layers are wedged each other to constitute overall stack of the crystal. Peroxidase activity of complex 1 was examined by observing the oxidation of 2,2'-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) with hydrogen peroxide in the presence of complex 1. Generation of $ABTS^{+{\cdot}}$ was observed by UV-vis and EPR spectroscopies, indicating that the complex 1, a fully-coordinated mononuclear Mn(II) complex with nitrogen-only ligand, has a heme-independent peroxidase activity.

• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.2
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• pp.127-135
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• 2007

Precocious metamorphosis was induced in two popular bivoltine breeds i.e. YB and $NB_4D_2$ by an imidazole compound having anti-juvenile hormone activity. The chemical was administered by feeding treatment with mulberry leaf to freshly moulted (0-6 hrs) IV instar larvae. The dose of the chemical was found to be breed specific being 650 ppm for YB and 500 ppm for $NB_4D_2$. The chemical caused complete skipping up of the fifth instar larvae which is most susceptible to diseases. But IV instar was somewhat prolonged. As a result the total larval period was reduced by 4-5 days. However, some of the rearing and reeling parameters like cocoon yield, cocoon weight, shell weight, shell %, filament length and fecundity were reduced for that particular generation only. The effective rate of rearing (ERR %) was significantly increased in trimoulters during the most unfavourable August - September seed crop season. Number of cocoons / kg and number of male moth were significantly higher in trimoulters. These may be useful for preparation of $multi{\times}bi$ hybrid seed. Fine denier was also found in trimoulter cocoon which is the cause of getting fine silk filament from trimoulter cocoons. Normal mating behaviour and emergence pattern was recorded in trimoulters. Bivoltine trimoulter males also showed competence for mating with multivoltine females. These results suggest the possibility of getting trimoulter males during hot and humid seasons when rearing of bivoltine is almost impossible particularly in Eastern and North Eastern India.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.98-106
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• 2022

Metal-organic frameworks (MOFs) are widely used in various fields because they make it easy to control porous structures according to combinations of metal ions and organic linkers. In addition, ZIF (zeolitic imidazolate framework), a type of MOF, is made up of transition metal ions such as Co²⁺ or Zn²⁺ and linkers such as imidazole or imidazole derivatives. ZIF-67, composed of Co²⁺ and 2-methyl imidazole, exhibits both chemical stability and catalytic activity. Recently, due to increasing need for energy technology and carbon-neutral policies, catalysis applications have attracted tremendous research attention. Moreover, demand is increasing for material development in the electrocatalytic water splitting and metal-air battery fields; there is also a need for bifunctional catalysts capable of both oxidation/reduction reactions. This review summarizes recent progress of bifunctional catalysts for electrocatalytic water splitting and metal-air batteries using ZIF-67. In particular, the field is classified into areas of thermal decomposition, introduction of heterogeneous elements, and complex formation with carbon-based materials or polyacrylonitrile. This review also focuses on synthetic methods and performance evaluation.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.512-519
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• 1991

The axial ligations of nitrogenous bases (pyridine, imidazole, 1-methylimidazole and 2,6-lutidine) to Zn(II)-, Cu(II)-, and Ni(II)-tetrakis(o-chlorophenyl)porphyrin(o-ClTPP), and -tetraphenylporphyrin (TPP) were investigated in organic solvents $(CH_2Cl_2,\;C_6H_6,\;CH_3NO_2,\;(CH_3)_2CO,\;CHCl_3,\;DMF\;and\;DMSO)$ and at 0.01M of ionic strength. The equilibrium constants for the ligation reactions of methalloporphyrins were determined using spectrophotometric method at 15∼35${\circ}C$. In case of M(II)-TPP the equilibrium constants K were considerably larger than those of M(II)-(o-Cl)TPP, depending on steric effect of the porphyrin. The linear relationships between logK of the axial ligation and $pK_a$ of nitrogenous base were shown in M(II)-TPP, but not in M(II)-(o-Cl)TPP. The stabilities of MTPP(L) were controlled by the reation enthalpy and entropy, while those of M(o-Cl)TPP almost by the reaction entropy. The coordinating power of solvent to the methalloporphyrin were also studied in $CHCl_3,\;(CH_3)_2CO$, DMF and DMSO. From those results the solvent effects on the equilibrium constants were discussed.

• Journal of the Korean Chemical Society
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• v.5 no.1
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• pp.33-37
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• 1961

We have shown that carboxy-peptidase destroys the biological activity of angiotensin octa-and deca-peptides. Since Proline occurs as the seventh amino acid from the amino end of the chain and since carboxypeptidase does not cleave proline from a peptid chain, it is evident that the heptapeptid H.asp-arg-val-tyr-ileu-his-pro.OH is formed by this hydrolysis. This peptide must then be biologically inactive. In order to determine whether the phenyl group of the C-terminal amino acid was the necessary requirement for biological activity of the octapeptide, $ala^8$ angiotensin octapeptide(amino acids of peptides numbered from amino end) was synthesized. For this synthesis the four dipeptides were prepared: carbobenzoxy-L-prolyl-L-alanine-P-nitrobenzyl-ester, m.p. $134-135^{\circ}C,$ carbobenzoxy-L-isoleucyl-imidazole benzyl-L-histidine methyl ester, m.p. $114-116^{\circ}C,$ carbobenzoxy-L-valyl-L-tyrosine hydrazide and carbobenzoxy B-benzyl-L-aspartyl-nitro-L-arginine. The first three dipeptides were obtained as crystalline compounds. Imidazole-benzyl-L-histidine was used in the hope that it would block the histidine imidazole against side reactions in steps subsequent to the formation of the C-terminal tetrapeptide. Also, it was through that the imidazole benzylated peptides would be easier to crystallize. This, however, was not the case. The tetrapeptide, carbobenzoxy-L-isoleucyl-L-im, benzyl-histidyl, L-prolyl-L-alanine-nitrobenzyl ester was not obtained in a crystalline form. Neither could the mono-or dihydrobromide of the tetrapeptide free base be induced to crystallize. Carbobenzoxy-L-valyl-L-tyrosine azide was condensed with the tetrapeptide free base to yield the protected hexapeptide; carbobenzoxy-L-valyl-L-tyrosyl-L-isoleucyl-L-im, benzyl, histidyl-L-Prolyl-L-alanine-nitrobenzyl ester. Upon removal of the carbobenzoxy group with hydrogen bromide in acetic acid an amorphous free base hexapeptide ester was obtained. This compound gave the correct C, H, N analysis and contained the six amino acids in the correct ratio. The octapeptide was obtained by condensing this hexapeptide with carbobenzoxy-B-benzyl-L-aspartyl-nitro, L-arginine using the mixed anhydride method of condensation. This amorphous product was proven to be homogenous by chromatography in two solvent systems and upon hydrolysis yielded the eight amino acids in correct ratio. The five protecting groups were removed from the octapeptide by hydrogenolysis over palladium black catalyst. Biological assay of the free peptide indicated that it possessed less than 0.1 per cent of both pressor and oxytocic activity of the phenylalanine8 angiotensin. This suggests that the phenyl group is a point of attachment between angiotensin and its biological receptor site.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2800-2802
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• 2013