Ritu Bala

Cationic cobaltammines as anion receptors. Part V. Synthesis, characterization and X-ray structure of [CO(NH3)6]ClMoO4·3H2O

Orange, single crystals of the bimetallic salt hexaamminecobalt(III) chloride molybdate trihydrate, [Co (NH3)6]ClMoO4·3H2O, have been prepared by reacting hot aqueous solutions of hexaamminecobalt(III) chloride and sodium molybdate dihydrate in a 1:1 molar ratio. The salt was characterized by elemental analyses and spectroscopic studies (IR and electronic). The title complex salt crystallizes in orthorhombic, space group Pnma, with au2009=u200918.408(2), bu2009=u20098.672(1), cu2009=u20098.661(1)u2009Å, Vu2009=u2009 1382.6(3) Å3, Zu2009=u20094 and Ru2009=u20090.0255. A single-crystal X-ray structure determination revealed the presence of discrete ions [Co(NH3)6]3+, Cl− and and three lattice water molecule in the solid state. The formation of this salt suggests that [Co(NH3)6]3+ may be used as an anion receptor for the molybdate ion.

Synthesis, spectroscopic characterization and X-ray crystal structure determination of trialkylbenzylammonium trans-diamminetetranitrocobaltate(III) salts where alkyl = methyl and ethyl

The two cobalt(III) complex salts [(CH3)3NCH2C6H5][trans-Co(NH3)2(NO2)4] and [(C2H5)3 NCH2C6H5][trans-Co(NH3)2(NO2)4] have been synthesized by reacting [(CH3)3NCH2C6H5]Cl and [(C2H5)3NCH2C6H5]Cl, respectively, with K[trans-Co(NH3)2(NO2)4], in aqueous medium at room temperature. The salt [(C2H5)3NCH2C6H5][trans-Co(NH3)2(NO2)4] crystallized from an acetone–water mixture; monoclinic, space group P21/n, cell dimensions au2009=u200910.620(1), bu2009=u200914.954(1), cu2009=u200914.100(1) Å, βu2009=u2009109.88°, Vu2009=u20092105.8(3)u2009Å3, Zu2009=u20094. An X-ray structure determination revealed the presence of discrete ions [(C2H5)3NCH2C6H5]+ and [trans-Co(NH3)2(NO2)4]− in the structure. In the anion cobalt(III) is coordinated octahedrally with the expected trans geometry.

Synthesis and spectroscopic characterization of trans-[Co(en)2(NO2)2]X (X = dodecyl sulfate, picrate, diclofenac or saccharinate) and the single-crystal X-ray structure of the saccharinate salt, trans-[Co(en)2(NO2)2](C7H4NSO3)·H2O

trans-[Co(en)2(NO2)2]X complexes, where Xu2009=u2009C12H25SO4 (1), C6H2N3O7 (2), C14H10Cl2NO2 (3) and C7H4NSO3 (4), have been synthesized by slowly mixing aqueous solutions of trans-dinitrobis(ethylenediamine)cobalt(III) nitrate and sodium dodecyl sulfate, picrate, diclofenac and saccharinate, respectively, at a 1u2009:u20091 mol ratio. Good crystals of trans-dinitrobis (ethylenediamine)cobalt(III) saccharinate monohydrate, [Co(en)2(NO2)2](C7H4NSO3)·H2O, were obtained. The salt is orthorhombic, space group P21212, with au2009=u200921.553(2), bu2009=u20098.503(1), cu2009=u200910.238(1)u2009Å, Zu2009=u20094, Vu2009=u20091876.3(3)u2009Å3, R 1u2009=u20090.0286 and wR 2u2009=u20090.0727. A structure determination revealed an ionic structure consisting of discrete [Co(en)2(NO2)2]+ cations and [C7H4SO3N]– anions.

Sonochemical synthesis, characterization, antimicrobial activity and textile dyeing behavior of nano-sized cobalt(III) complexes.

Using ultrasonic irradiations, nano-sized cobalt(III) coordination complexes, [Co(NH3)6]Cl3·2H2O (A), [Co(en)3]Cl3·3H2O (B) (en-ethylenediamine) and [Co(dien)2]Cl3·3.5H2O (C) (dien-diethylenetriamine) were synthesized. These complexes were characterized by spectroscopic studies like IR, UV/Visible and NMR. Morphology of these complexes was determined by SEM and particle size with the help of TEM & Zeta-sizer. The comparative thermal stability along with phase difference between nano structures and their respective bulk complexes has been studied by thermal gravimetric analysis (TGA) and X-ray powder diffraction (XRD) study respectively. The dyeing behavior of nano-sized Co(III) complexes and their respective bulks has also been studied (using both exhaust and pad dyeing methods) on cotton and wool fabrics and results shown rationalized dyeing behavior. All these complexes were further tested for antimicrobial activity (against B. subtilis, E. coli, K. pneumoniae, F. oxysporum and A. alternate) and it was observed that nano sized complexes enhanced the activity further.

Binding of p-aminobenzoate anion to bis(diethylenetriamine)cobalt(III) cation in solution and solid phases: synthesis, characterization, and X-ray structure determination of s-fac-[Co(dien)2]Cl(p-aminobenzoate)2·3H2O

The reaction of an isomeric mixture of [Co(dien)2]Cl3 with sodium salt of p-aminobenzoic acid in aqueous medium leads to the formation of dark orange coloured crystals of composition s-fac-[Co(dien)2]Cl(p-aminobenzoate)2·3H2O. The configuration of the cationic isomer was initially determined with the help of spectroscopic data (NMR, UV–Vis, and IR). The binding properties of s-fac-bis(diethylenetriamine)cobalt(III) cationxa0with p-aminobenzoate anionxa0has been determined (in solution phase) with the help of UV–Vis spectroscopic titrations. Single crystal X-ray structure determination of title complex reveals the presence of one cation, three anions (one Cl and two p-aminobenzoates) along with three lattice water molecules. The crystal lattice is stabilized by electrostatic forces of attraction and H-bond interactions (N–H···O, N–H···Cl, O–H···O, and O–H···Cl). The water molecules of crystallization play a major role in stabilizing the complex by forming intermolecular H-bonds with Cl− and O atoms of p-aminobenzoate and water.Graphical Abstract

Second-sphere coordination in anion binding: trans-bis­(ethyl­enediamine-κ2N,N′)dinitro­cobalt(III) periodate

In the title complex, [Co(NH2CH2CH2NH2)2(NO2)2](IO4), the cations are situated on two sets of inversion centres and are linked by pairs of complementary N—H⋯O hydrogen bonds into columns arranged in an approximately hexaxadgonal manner. The periodate anions can be envisaged as occupying triangular hollows above and below approximate hexaxadgonal close-packed layers of trans-bisxad(ethylxadenediamine-κ2N,N′)dinitroxadcobalt(III) cations.

Sonochemical synthesis, characterization, thermal and semiconducting behavior of nano-sized azidopentaamminecobalt(III) complexes containing anion, CrO42− or Cr2O72−

New nano-sized cobalt(III) coordination complexes, [Co(NH3)5N3]CrO4 (1N) and [Co(NH3)5N3]Cr2O7 (2N) were synthesized using an innovative sonochemical methodology based on reaction between [Co(NH3)5N3]Cl2 and potassium salt of CrO42- or Cr2O72- in aqueous medium. These complexes were also compared with their respective bulks which were synthesized under identical conditions in the absence of sonicaion. All the complexes were characterized by elemental analysis and spectroscopic techniques (UV-visible and IR). Morphology and particle size of nano-sized complexes was determined by SEM and Zeta-sizer respectively. TGA was used for comparative thermal stability and XRD to identify the phase difference between nano structures and bulk complexes. Furthermore, the electrical property was investigated and all complexes were found to be electrical semiconducting materials and 2N shows better result than others. The single crystals X-ray structure study of new [Co(NH3)5N3]Cr2O7 revealed the presence of discrete ions, [Co(NH3)5N3]2+ and Cr2O72-, crystallizes in monoclinic, space group Pc, with R=0.0636 in the solid state.

Synthesis, structures, antimicrobial activity and biosafety evaluation of pyridine-2-formaldehyde-N-susbtituted-thiosemicarbazonates of copper(II)

Pyridine-2-formaldehyde-N1-substituted-thiosemicarbazones {(C5H4N4)HC2N3–N2(H)–C1(S)N1HR} (abbrev. HL1-R: R = Me, Et, Ph) with copper(I) halides in an acetonitrile–dichloromethane mixture (1u2006:u20061, v/v) have yielded a novel series of CuII complexes with a central coordination core: [CuIIX(N,N,S-L1-R)] (R = Me, Et, Ph: X = I, 1–3; Br, 4–6, Cl, 7–9), which have been characterized with the help of analytical data, IR, UV-visible and ESR spectroscopy, ESI-mass spectrometry and single crystal X-ray crystallography. The thio-ligands coordinate to CuII as anions (L1-R)− through pyridyl nitrogen-N4, azomethine nitrogen-N3 and thiolato sulfur and CuII is further bonded to iodide, bromide or chloride. In order to explore their bio-activity, complexes (1–9) as well as the previously reported CuII complexes of 2-benzoylpyridine-N-substituted thiosemicarbazones {(C5H4N4)(C6H5)–C2N3–N2(H)–C1(S)–N1HR; HL2-R}, namely, [CuIIX(N,N,S-L2-R)] (R = Me, Et, Ph: X = I, 10–12; Br, 13–15; Cl, 16–18), have been evaluated for their antimicrobial potential against different microbial strains. The microbial strains investigated are Staphylococcus aureus (MTCC740), Klebsiella pneumoniae (MTCC530), Shigella flexneri (MTCC1457), Salmonella typhimurium 1 (MTCC98), Salmonella typhimurium 2 (MTCC1251), Escherichia coli (MTCC119), Staphylococcus epidermidis (MTCC435), methicillin resistant Staphylococcus aureus (MRSA) and a yeast culture Candida albicans (MTCC227). Several complexes tested have shown high antimicrobial activity; specifically, against methicillin resistant Staphylococcus aureus, Staphylococcus epidermidis and Salmonella typhimurium 2; the activity is found to be high at low minimum inhibitory concentration (MIC) values as compared to that of the standard Gentamicin. Using MTT cytotoxicity assay {MTT = 3-[(4,5-dimethylthiazol-2-yl)-2,5-diphenyl]tetrazolium bromide}, complexes tested were found to be biosafe with high cell viability (90–98%).

One-pot synthetic approach to isolate a single isomer of bis(diethylenetriamine)cobalt(III) cation in bulk using benzoates and the isomeric effects of the cation on ion association with anions

Abstract Using a one-pot synthetic approach, a single isomer of bis(diethylenetriamine)cobalt(III) cation, [Co(dien)2]3+ is obtained in bulk from the isomeric mixture (s-fac : u-fac : mer is 7 : 28 : 65) using sodium salts of benzoates (BBz-bromobenzoate, DNBz-dinitrobenzoate, MBz-methylbenzoate) in aqueous medium. Herein, we report the syntheses and characterization of three complexes of composition mer-[Co(dien)2]Cl(p-BBz)2·H2O (1), s-fac-[Co(dien)2](o,p-DNBz)3·H2O (2) and mer-[Co(dien)2]Cl(p-MBz)2·4H2O (3) in the continuation of our earlier work, where benzoate (Bz), p-chlorobenzoate (CBz), p-nitrobenzoate (NBz) and p-aminobenzoate (ABz) were used. The isomeric identification of complex cation was initially made on the basis of spectroscopic characterization (UV–visible, IR and NMR). The binding properties of [Co(dien)2]3+ with benzoates (p-BBz, o,p-DNBz, p-MBz, Bz, CBz, NBz or ABz) have been studied using standard UV–visible spectroscopic titrations in aqueous medium and comparison indicate ion association constants of s-fac > mer. The single-crystal X-ray diffraction structure analysis of 3 reveals the presence of discrete ions ([Co(dien)2]3+, chloride, p-MBz) along with four lattice water molecules. The structure of 3, with formula [Co(dien)2](p-MBz)2Cl·4H2O, consists of alternating layers made of benzoate ions and layers made of [Co(dien)2]3+, chloride and water molecules. These layers result in the formation of their respective columns and intermolecular cohesion of p-MBz within the columns of [Co(dien)2]3+ is achieved via electrostatic and H-bonding interactions.