Three novel mononuclear Mn( iii )-based magnetic materials with square pyramidal versus octahedral geometries

International audienc

Water-Stable Manganese(Iv) Complex Of A N2O4-Donor Non-Schiff-Base Ligand: Synthesis, Structure, And Multifrequency High-Field Electron Paramagnetic Resonance Studies

A novel water-stable (t1/2 ∼ 6.8 days) mononuclear manganese(IV) complex of a hexacoordinating non-Schiff-base ligand (H 4L) with N2O4-donor atoms has been synthesized and characterized crystallographically. High-frequency electron paramagnetic resonance experiments performed on a single crystal reveal a manganese(IV) ion with an S = 3/2 ground spin state that displays a large single-ion anisotropy, setting the record of mononuclear manganese(IV) complexes reported so far. In addition, spin-echo experiments reveal a spin-spin relaxation time T2 ∼ 500 ns. © 2014 American Chemical Society

Mn^II- and Co^II-Catalyzed Transformation of 2‑Cyanopyrimidine to Methylimidate by Sodium Azide: Isolation, Structural Characterization, and Magnetic Studies on 2D Mn^II- and Cu^II-Complexes

The Mn^II-mediated transformation of 2-cyanopyrimidine to methylimidate in the presence of inorganic azide is proven through isolation and structural characterization of a metal complex. Though the reaction conditions are favorable for a “click” reaction leading to the formation of tetrazole, as evidenced from recent studies, we are astonished to see the formation of methylimidate in MeOH instead of tetrazole, which is supposed to form only in the presence of catalytic amount of corresponding alkoxide ion as base. The catalytic nature of this transformation reaction was confirmed by performing these experiments under catalytic conditions and analyzing the products using liquid chromatography–mass spectrometry techniques, which clearly showed ∼96% and ∼60% selectivity of methylimidate along with almost 100% conversion in the presence of Mn^II and Co^II as catalysts, respectively. In absence or presence of other metal ions like Cu^II, Ni^II, Fe^II, Zn^II, etc. only tetrazole formation takes place. So the present findings extended the formation of methylimidate catalyzed by metal ions in the presence of azide ion in alcoholic medium. Importantly, a probable mechanism for this unexpected transformation was framed based on the structural analysis and high-resolution mass spectrometry (electrospray ionization MS⁺) studies. The magnetic studies were also performed on complexes [Mn­(L)­(N₃)₂]_<i>n</i> (<b>1</b>) and [Cu (L²)₂]_<i>n</i> (<b>2a</b>), showing anti-ferromagnetic character for compound <b>1</b> and negligible coupling for the copper complex <b>2a</b>

Novel CuII–MII–CuII (M = Cu or Ni) trinuclear and [NaI 2CuII 6] hexanuclear complexes assembled by bi-compartmental ligands: syntheses, structures, magnetic and catalytic studies

International audienceIn the present work, two compartmental ligands H2L1 and H2L2 were in situ generated during the synthesesof new trinuclear complexes, [Cu2Ni(L1)(2,2’-bpy)2(NO3)2][ClO4]2 (5), [Cu3(L2)(NO3)2][ClO4]2 (6), and[Cu3(L2)(NCS)2(NO3)]+ that co-crystallize in 7 with a [Cu6(L2)2Na2(NO3)6(NCS)4] unit to give the final molecularformula [Cu6(L2)2Na2(NO3)6(NCS)4][Cu3(L2)(NCS)2(NO3)]2(NO3)2·5H2O (7). The magnetic propertystudies of 5–7 revealed weak CuII–CuII ferromagnetic interactions in compound 6 (JCu–Cu/kB = +1.4(1) K)and 7 (JCu–Cu/kB = +1.6) while in intranuclear CuII–NiII–CuII compound 5, the magnetic couplingbetween two CuII ions is switched off by the diamagnetic square planar NiII bridge.....

Rhodamine-azobenzene based single molecular probe for multiple ions sensing: Cu 2+ , Al 3+ , Cr 3+ and its imaging in human lymphocyte cells

A photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) regulated rhodamineazobenzene chemosensor (L) was synthesized for chemoselective detection of Al3+, Cr3+, and Cu2+ by UV-Visible absorption study whereas Al3+ and Cr3+ by Iluorimetric study in EtOH-H2O solvent. L showed a clear fluorescence emission enhancement of 21 and 16 fold upon addition of Al3+ and Cr3+ due to the 1:1 host-guest complexation, respectively. This is first report on rhodamine-azobenzene based Cr3+ chemosensor. The complex formation, restricted imine isomerization, inhibition of PET (photo-induced electron transfer) process with the concomitant opening of the spirolactam ring induced a turn-on fluorescence response. The higher binding constants 6.7 x 10(3) M-1 and 3.8 x 10(3) M-1 for Al(3+ )and Cr3+, respectively and lower detection limits 1 x 10(-6)M and 2 x 10(-6) M for Al3+ and Cr3+, respectively in a buffered solution with high reversible nature describes the potential of L as an effective tool for detecting Al3+ and Cr3+ in a biological system with higher intracellular resolution. Finally, L was used to map the intracellular concentration of Al3+ and Cr3+ in human lymphocyte cells (HLCs) at physiological pH very effectively. Altogether, our findings will pave the way for designing new chemosensors for multiple analytes and those chemosensors will be effective for cell imaging study

Water-Stable Manganese(IV) Complex of a N₂O₄‑Donor Non-Schiff-Base Ligand: Synthesis, Structure, and Multifrequency High-Field Electron Paramagnetic Resonance Studies

A novel water-stable (<i>t</i>_1/2 ∼ 6.8 days) mononuclear manganese­(IV) complex of a hexacoordinating non-Schiff-base ligand (H₄L) with N₂O₄-donor atoms has been synthesized and characterized crystallographically. High-frequency electron paramagnetic resonance experiments performed on a single crystal reveal a manganese­(IV) ion with an <i>S</i> = ³/₂ ground spin state that displays a large single-ion anisotropy, setting the record of mononuclear manganese­(IV) complexes reported so far. In addition, spin–echo experiments reveal a spin–spin relaxation time <i>T</i>₂ ∼ 500 ns

Water-Stable Manganese(IV) Complex of a N₂O₄‑Donor Non-Schiff-Base Ligand: Synthesis, Structure, and Multifrequency High-Field Electron Paramagnetic Resonance Studies

A novel water-stable (<i>t</i>_1/2 ∼ 6.8 days) mononuclear manganese­(IV) complex of a hexacoordinating non-Schiff-base ligand (H₄L) with N₂O₄-donor atoms has been synthesized and characterized crystallographically. High-frequency electron paramagnetic resonance experiments performed on a single crystal reveal a manganese­(IV) ion with an <i>S</i> = ³/₂ ground spin state that displays a large single-ion anisotropy, setting the record of mononuclear manganese­(IV) complexes reported so far. In addition, spin–echo experiments reveal a spin–spin relaxation time <i>T</i>₂ ∼ 500 ns

A multi-spectroscopic and molecular docking approach for DNA/protein binding study and cell viability assay of first-time reported pendent azide bearing Cu(II)-quercetin and dicyanamide bearing Zn(II)-quercetin complexes

In the current study, one new quercetin-based Zn(II) complex [Zn(Qr)(CNNCN)(H2O)2] (Complex 1) which is developed by condensation of quercetin with ZnCl2 in the presence of NaN(CN)2 and Cu(II) complex [Cu(Qr)N3(CH3OH)(H2O)] (complex 2) which is developed by the condensation reaction of quercetin and CuCl2 in presence of NaN3, are thoroughly examined in relation to their use in biomedicine. The results of several spectroscopic studied confirm the structure of both the complexes and the Density Functional Theory (DFT) study helps to optimize the structure of complex 1 and 2. After completion of the identification process, DNA and Human Serum Albumin (HSA) binding efficacy of both the investigated complexes are performed by implementing a long range of biophysical studies and a thorough analysis of the results unveils that complex 1 has better interaction efficacy with the macromolecules than complex 2. The binding efficacy of complex 1 is comparatively higher towards both macromolecules because of its pure groove binding mode during interaction with DNA and the presence of an extra H-bond during connection with HSA. The experimental host-guest binding results is fully validated by molecular docking study. Interestingly complex 1 shows better antioxidant properties than complex 2, as well as quercetin, and it has strong anticancer property with minimal damage to normal cells, which is proved by the MTT assay study. Better DNA and HSA binding efficacy of 1 may be the reason for the better anticancer property of complex 1