• Rapid Communication in Photoscience
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• 제3권3호
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• pp.42-47
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• 2014

Development of molecular and supramolecular systems showing efficient photoinduced energy or electron transfer are of current research interest due to their applications in various chemical and biological processes. Various polypyridine metal complexes including Ru(II), Ru(III), Os(II), Pt(II), Fe(II), Re(I), Ir(III) and so on as a metal center introduce for expanding some more understanding of molecular-scale photoelectronics. Their complexes are concisely classified by the types of relay ligands as follows; (a) metal-direct ligand-metal system; dinuclear or trinuclear systems, (b) metal-nonconjugated ligand-metal system and metal-nonconjugated ligand system having flexible/rigid ligand, (c) metal-conjugated ligand-metal system, and (d) conjugated ligand-metal-conjugated ligand system and metal-self assembly ligand-metal system. It is pointed out that the role played by the relay ligands is important in constructing the metal complexes.

• Mycobiology
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• 제35권3호
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• pp.150-153
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• 2007

New $N_2O_2$ donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and $^1H$ NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of $10{\sim}31{\mu}g/ml$.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.925-929
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• 2005

Some new metal(II) complexes, $M^{II}L_2$ [M = Mn (1), Co (2), Ni (3), Cu (4), and Zn (5)] of 2-acetylpyridine benzoylhydrazone ligand (HL) containing trifunctional NNO-donor system have been synthesized and crystallographically characterized for the complex 1 and 5. The complexes consist of two ligands to give sixcoordinate, which are bonded to the metal atom on a meridional plane through acetylpyridine ring nitrogen, azomethine nitrogen, and benzoyl oxygen atoms, respectively. The coordination geometry for other complexes was identified on the basis of the physicochemical data by elemental analyses, FAB -MS, IR, $^1H$ NMR, and electronic spectral measurements. The resulting data indicated that the complexes are accordance with the above formulation.

• 대한화학회지
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• 제43권5호
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• pp.511-516
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• 1999

2-hydroxy-1-naphthaldehyde와 2-aminopyridine으로부터 $N_2O$형의 세자리 Schiff Base 리간드인 (2-hydroxy-1-naphthyllidine)-o-iminopyridine [NOIPH]리간드와 Cobalt(II), Nickel(II) 및 Copper(II) Acetate들과 반응시켜 Schiff Base 전이금속(II) 착물들을 합성하였다. 이 리간드와 전이금속(II)착물들의 구조를 원소분석, IR, UV-vis, NMR 분광법 및 TGA 방법으로 확인하였다. 중심 금속인 전이금속(II) 이온은 $N_2O$형의 주개원자를 갖는 세자리 리간드의 페놀기에 있는 산소와는 이온결합을, 아로매틱 아민의 질소와는 배위결합을 형성하여 비이온성의 착물을 형성하였다. 착물에서 리간드들은 전이금속(II) 이온과 2:I의 몰비로 결합하며 4배위 구조임을 알았다.

• 대한화학회지
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• 제56권6호
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• pp.679-691
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• 2012

New series of metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Pt(II) with 4-(p-chlorophenyl)-1-(pyridin-2-yl)thiosemicarbazide (HCPTS) have been synthesized and characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, $^1H$ NMR, mass and ESR) and thermal studies. The IR data suggest different coordination modes for HCPTS which behaves as a monobasic bidentate with all metal ions except Cu(II) and Zn(II) which acts as a monobasic tridentate. Based on the electronic and magnetic studies, Co(II), Cu(II), Pd(II) and Pt(II) complexes have square - planner, Ni(II) has mixed stereochemistry (tetrahedral + square planar), while Zn(II) is tetrahedral. Molar conductance in DMF solution indicates the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complex show $g_{\parallel}$ (2.2221) > $g_{\perp}$ (2.0899) > 2.0023 indicating square-planar structure and the presence of the unpaired electron in the $d_x2_{-y}2$ orbital with significant covalent bond character. The thermal stability and degradation kinetics of the ligand and its metal complexes were studied by TGA and DTA and the kinetic parameters were calculated using Coats-Redfern and Horowitz-Metzger methods. The complexes have more antibacterial activity against some bacteria than the free ligand. However, the ligand has high anticancer activities against HCT116 (human colon carcinoma cell line) and HEPG2 (human liver hepatocellular carcinoma cell line) compared with its complexes.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.4021-4026
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• 2011

Functions of the luteinizing hormone releasing hormone (LHRH) and its induced release by divalent metal ions have received great attention because this neurotransmitter subsequently regulates the secretion of luteinizing hormone (LH). Metal-LHRH complexes were synthesized by addition of various Cu(II),Ni(II),Zn(II) ions into LHRH in order to understand how the induced release of LHRH is possible. The degree of complexation was monitored by $^1H$, $^{13}C$-NMR chemical shifts, and final products were identified by Mass spectrometry. Solutionstate structure determination of Zn(II)-LHRH out of metal-complexes was accomplished by using NMR and NMR-based distance geometry (DG). Interproton distance information from nuclear Overhauser effect spectroscopy was utilized for structure determination. Structure obtained in this study has a cyclic conformation exhibiting a specific ${\alpha}$-helical turn with residue numbers His[2]-Leu[7] out of 10 amino acids. Comparison of chemical shifts and EPR studies of Ni(II),Cu(II)-LHRH complexes exhibit that these metal complexes have 4-coordination geometry.

• 대한화학회지
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• 제57권6호
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• pp.712-720
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• 2013

Microwave assisted syntheses of Zn(II), Cd(II) and Hg(II) complexes with 3-aminopyridine (3AP) and nitrite ($NO_2{^-}$) ions have been reported. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ($^1H$, $^{13}C$), thermal and electron impact mass spectral studies. The spectroscopic studies reveal the composition, the nature of nitrite ligand in the complexes, electronic transitions, chemical environments of C and H atoms thermal degradation of the complexes. On the basis of characterization data, distorted tetrahedral geometry is suggested for Zn(II), Cd(II) and Hg(II) complexes. The organic ligand (3AP) and their metal complexes were screened against gram negative pathogenic bacteria and fungi in vitro. The results are compared with our previous report J. Korean Chem. Soc. 2013, 57, 341 on 4-aminopyridine and nitrite ion complexes of the same metal ions.

• 대한화학회지
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• 제57권3호
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• pp.341-351
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• 2013

Zn(II), Cd(II) and Hg(II) complexes with a general composition[$M(L)_2(X)_2$], where L=4-aminopyridine (4AP) and $X=NO_2{^-}$ were prepared under microwave irradiation. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR ($^1H$, $^{13}C$), XPS spectral and thermal studies. The spectroscopic studies reveal the composition, different modes of bonding, electronic transition, different chemical environment of C and H atoms and the electronic state of the metal atoms. On the basis of the characterization data, tetrahedral geometry is suggested for all the complexes. The free ligand (4-aminopyridine) and their metal complexes were screened against phytopathogenic fungi and bacteria in vitro and the activities were compared.

• 대한화학회지
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• 제55권6호
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• pp.912-918
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• 2011

Tetraaza Schiff base macrocyclic ligands, $L^1$,$L^2$ and their transition metal chelates have been synthesized and characterized by elemental analyses, IR, electronic, EPR and $^1H$ NMR spectra, TGA and magnetic measurements. The molar conductance of one milli-molar solution of the complexes measured in DMF indicates that the divalent metal complexes are nonelectrolyte while those of trivalent metal ion, are 1:1 electrolytic in the same solvent. The reduction of Racah parameter from the free ion value confirms the presence of considerable covalence of metal ligand sigma bond in the Co(II) and Mn(II) complexes. The EPR spectra of Cu(II) complexes at room temperature shows axial symmetry indicating a $d_x{^2}_{-y}{^2}$ ground state with significant covalent character. The thermal analysis suggests that the complexes do not contain water molecules because only the metal is left as residue.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.473-482
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• 2012

A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, $^1H$ NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.