• Mass Spectrometry Letters
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• v.14 no.3
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• pp.110-115
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• 2023

The reaction of (COD)PdCl₂ with new C₃-symmetric tridentate L (COD = 1,5-cyclooctadien; L = 1,3,5-tris(picolinoyloxyethyl)cyanurate) in a mixture of acetone and dichloromethane produces single crystals consisting of unprecedented monometallacyclic [PdCl₂(L)]. This cyclic compound arises from trans-chelation of two of three donating pyridyl groups of L, while the third pyridyl group remains uncoordinated. Electrospray ionization mass spectrometry (ESI-MS) data on L exhibited the major peak corresponding to [C₂₇H₂₄N₆O₉ + H⁺]⁺. Fast atom bombardment mass spectrometry (FABMS) data on [PdCl₂(L)], however, showed the mass peak corresponding to the L instead of the present palladium(II) compound species, due to the insolubility and dissociation in solution. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, single-crystal X-ray diffraction (SC-XRD) measurement.

• Analytical Science and Technology
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• v.11 no.5
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• pp.366-373
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• 1998

Polydentate Schiff base ligands, BSDT(1,9-bis(2-hydroxyphenyl)-2,5,8-triaza-1,8-nonadiene) having $N_3O_2$ atoms, BSTT(1,12-bis(2-hydroxyphenyl)-2,5,8,11-tetraaza-1,11-dodecadiene) having $N_4O_2$ atoms, BSTP(1,15-bis(2-hydroxyphenyl)-2,5,8,11,14-pentaaza-1,14-pentadodecadiene) having $N_5O_2$ atoms were synthesized. Protonation constants of these polydentate ligands were measured by potentiometry. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1:1 complexes with Schiff base ligands. Stability constants for the complex formation were in the order of Cu(II)>Ni(II)>Zn(II), and for the ligands were in the order of BSTP>BSTT>BSDT. There are due to the increase in the number of donor atoms. Both enthalpy and entropy changes were obtained in negative values. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2043-2048
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• 2014

Two isomers of a new tetraaza macrotricycle 2,2,4,9,9,11-hexaazamethyl-1,5,8,12-tetraazatricyclo[$10.2.2^{5.8}$]-octadecane ($L^2$) containing additional N-$CH_2CH_2$-N linkages, C-meso-$L^2$ and C-racemic-$L^2$, have been prepared by the reaction of 1-bromo-2-chloroethane with C-meso-$L^1$ or C-racemic-$L^1$ ($L^1$ = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Both C-meso-$L^2$ and C-racemic-$L^2$ react with copper(II) ion to form $[Cu(C-meso-L^2)]^{2+}$ or $[Cu(C-racemic-L^2)]^{2+}$ in dehydrated ethanol, but do not with nickel(II) ion under similar conditions. Crystal structure of [Cu(C-racemic-$L^2$)($H_2O$)]$(ClO_4)_2$ shows that the complex has distorted square-pyramidal coordination geometry with an apically coordinated water molecule. Unexpectedly, the Cu-N distances [2.016(3)-2.030(3) ${\AA}$] of [Cu(C-racemic-$L^2$)($H_2O$)]$(ClO_4)_2$ are longer than those [1.992(3)-2.000(3) ${\AA}$] of [Cu(C-racemic-$L^1$)($H_2O$)]$(ClO_4)_2$. As a result, $[Cu(C-racemic-L^2)(H_2O)]^{2+}$ exhibits weaker ligand field strength than $[Cu(C-racemic-L^1)(H_2O)]^{2+}$. The copper(II) complexes readily react with CN- ion to yield the cyano-bridged dinuclear complex $[Cu_2(C-meso-L^2)_2CN]^{3+}$ or $[Cu_2(C-racemic-L^2)_2CN]^{3+}$. Spectra and chemical properties of $[Cu(C-meso-L^2)]^{2+}$ and $[Cu_2(C-meso-L^2)_2CN]^{3+}$ are not quite different from those of $[Cu(C-racemic-L^2)]^{2+}$ and $[Cu_2(C-racemic-L^2)_2CN]^{3+}$, respectively.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1747-1751
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• 2006

The dinuclear tetraazadiphenol macrocyclic nickel(II) complexes [$Ni_2$([20]-DCHDC)]$Cl_2$ (I), [$Ni_2$([20]-DCHDC)]$(ClO_4)_2{\cdot}2CH_3CN $ (II(b)) and [$Ni_2$([20]-DCHDC)$(NCS)_2$] (III) {$H_2$[20]-DCHDC = 14,29-dimethyl-3,10,18,25-tetraazapentacyclo-[25,3,1,$0^{4,9}$,$1^{12,16}$,$0^{19,24}$]ditriacontane-2,10,12,14,16(32),17,27(31), 28,30-decane-31,32-diol} have been synthesized by self-assembly and characterized by elemental analyses, conductances, FT-IR and FAB-MS spectra, and single crystal X-ray diffraction. The crystal structure of II(b) is determined. It crystallizes in the monoclinic space group P2(1)/c. The coordination geometries around Ni(II) ions in I and II(b) are identical and square planes. In complex III each Ni(II) ion is coordinated to $N_2O_2$ plane from the macrocycle and N atoms of NCS- ions occupying the axial positions, forming a square pyramidal geometry. The nonbonded Ni…Ni intermetallic separation in the complex II(b) is 2.8078(10) $\AA$. The FAB mass spectra of I, II and III display major fragments at m/z 635.1, 699.4 and 662.4 corresponding to [$Ni_2$([20]-DCHDC)(Cl + 2H)]$^+$, [$Ni_2$([20]-DCHDC)$(ClO_4\;+\;2H)]^+$ and [$Ni_2$([20]-DCHDC)(NCS) + 6H]$^+$, respectively.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.722-726
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• 1993

Organotin(IV) complexes of ylidenemalonates $(R_xSn)_{x-1}(O_2C)_2C=C(SR')_2\;(R=n-C_4H_9,\;C_6H_5,\;cyclo-C_6H_{11},\;CH_3OOCCH_2CH_2;\;x=2,3;\;R'=CH_3,\;R_2'=-CHCH-,\;-CH_2CH_{2^-})$ have been synthesized and characterized by means of various spectroscopic methods. The X-ray crystal structure of $(Ph_3Sn)_2(O_2C)_2C=C(SCH_3)_2$ has been determined (Pi; a= 9.704(2) ${\AA}$, b= 14.412(1) ${\AA}$, c= 14.760(3) ${\AA}$, ${alpha}$=74.26(1)$^{\circ}$, ${beta}$=99.38(l)$^{\circ}$, ${\gamma}$=79.09(1)$^{\circ}$, $V= 1950.7(7){\AA}^3$) and refined to R= 0.045. The crystal structure discloses a discrete molecule with bidentate-like carboxylate ligand. For diorganotin analogues, the structures are discussed in terms of IR, $^1H-NMR,\;^{13}C-NMR$, and FAB mass spectrometry. The mass spectrum indicates that the diorganotin complexes of ylidenemalonates are dimeric.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.444-453
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• 2011

VO(II), ZrO(II), Hf(IV), $UO_2$(II), Sn(II), V(V)$O_3$, Ru(III), Cd(II), Ho(III) and Yb(III) complexes of N'-(2-hydroxybenzyl)-2-(phenylamino)acetohydrazide ($H_2L^1$, 1) and N'-((3-hydroxy-naphthalen-2-yl)methylene)-2-(phenylamino)-acetohydrazide ($H_2L^2$, 13) have been synthesized and characterized by elemental analyses, $^1H$ NMR, IR, UV-Vis, conductance, thermal analyses (DTA and TG). The spectral data showed that the ligands behave as neutral bidentate, monobasic bidentate, monobasic tridentate or bibasic tridentate ligand bonded to the metal ions through the azomethine nitrogen atoms, phenolic hydroxyl group in protonated or deprotonated form and enolic or ketonic carbonyl group. The ligands and their metal complexes exhibit higher antifungal and antibacterial inhibitory effects than parent ligands and the solution of metal ions. Most of metal complexes exhibit higher antifungal activity than standard antifungal drug (amphotricene B). It is also clear that the ligands and their metal complexes have higher antifungal activity than antibacterial activity.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.355-362
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• 2009

The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized oxovanadium(IV) Schiff-base; N,N'-bis(4-hydroxysalicylidene)-ethylene-1, 2-diamineoxovanadium(IV), [VO($(OH)_2$-salen)]; has been covalently anchored on modified MWNTs. The new modified MWNTs ([VO($(OH)_2$-salen)]-MWNTs]) have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), UV-Vis, Diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The analytical data indicated a composition corresponding to the mononuclear complex of tetradentate Schiff-base ligand. The characterization of the data showed the absence of extraneous complex, retention of MWNTs and covalently anchored on modified MWNTs. Liquid-phase oxidation of cyclohexane with $H_2O_2$ to a mixture of cyclohexanone, cyclohexanol and cyclohexane-1,2-diol in $CH_3$CN have been reported using oxovanadium(IV) Schiff-base complex covalently anchored on modified MWNTs as catalysts. This catalyst is more selective toward cyclohexanol formation.

• Mycobiology
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• v.35 no.3
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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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• v.18 no.6
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• pp.653-656
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• 1997

The new unsymmetric $N_6$ ligand 1-amino-13-(2-pyridyl)-3,6,9,12-tetraazatridecane (aptatd) containing one pyridyl group has been synthesized and characterized by EA, IR, and NMR. Its proton association constants $(log K_H^n)$ and stability constants $(log K_{ML})$ for Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), and Zn(Ⅱ) ions were determined at 298.1 K and ionic strength 0.100 mol $dm^{-3}$ (KNO₃) in aqueous solution by potentiometry: log $K_H^1$=8.80, log $K_H^2$=8.49, log $K_H^3$=6.84, log $K_H^4$=4.17, log $K_H^5$=3.47; log $K_{ML}(Co^{2+})$=18.00, log $K_{ML}(Ni^{2+})$=21.31, log $K_{ML}(Cu^{2+})$=23.62, log $K_{ML}(Zn^{2+})$=15.60. The X-ray structure of its nickel(Ⅱ) complex [Ni(aptatd)]$(ClO_4)_2$ are reported: orthorhombic space group Pbca, a=15.715(1) Å, b=14.280(2) Å, c=19.443(2) Å, V=4363.4 (9) ų with Z=8. The geometry around nickel is a distorted octahedron with the pyridine nitrogen atom being cis to the nitrogen atom of the terminal primary amine.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.368-373
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• 1991

Palladium(II) complexes of the type Pd(IEAA-NR)$_2$ (R = H, CH$_3$, C$_2$H$_5$, n-C$_3$H$_7$, n-C$_4$H$_9$, or CH$_2$C$_6$H$_5$), where IEAA-NR represents N-alkyl derivative of isonitrosoethylacetoacetate (H-IEAA) imine, have been prepared. And the structure of the complexes have been studied by elemental analyses, electronic, infrared, $^1$H and $^{13}$C-NMR spectra. It is proposed that both of IEAA-NR ligands coordinate to metal through nitrogens of imine and isonitroso groups to form 5-membered chelate rings in the complexes.