The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two ...The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two compounds were characterized by elemental analyses and spectroscopic methods. Their structures were determined by X-ray diffraction study. Crystal data for 1: C24H20N6, Mr = 392.5, monoclinic, P21/c, a = 13.871(3), b = 13.510(2), c = 12.153(2) ? b = 112.97(2)? Z = 4, V = 2094.1(6) ?, Dc = 1.245 g/cm3, m(MoKa) = 0.078 mm-1, F(000) = 824, the final R = 0.0545 and wR = 0.0557 for 2048 observed reflections (I > 2s(I)); for BDPM: C24H24N6, Mr = 396.49, monoclinic, C2/c, a = 21.411(3), b = 8.053(1), c = 11.868(1) ? b = 92.63(1)? Z = 4, V = 2044.2(4) 3, Dc = 1.288 g/cm3, m(MoKa) = 0.080 mm-1, F(000) = 840, the final R = 0.0401 and wR = 0.0939 for 1673 observed reflections (I > 2s(I)).展开更多
Separation of lithium and sodium is a topic of substantial scientific and industrial importance.Regarding Li/Na perchlorates,which are not only environmental hazards but also useful oxidants in chemical synthesis,an e...Separation of lithium and sodium is a topic of substantial scientific and industrial importance.Regarding Li/Na perchlorates,which are not only environmental hazards but also useful oxidants in chemical synthesis,an efficient Li-Na perchlorate separation method has not been reported due to lack of a ligand which can selectively coordinate with one of the two.Herein,we report an efficient Li-Na perchlorate separation by using our hexadentate ligand N,N′,N″-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane(DETAN),which can selectively coordinate with LiClO_(4)at room temperature to form a monomer in excellent yield but does not coordinate with NaClO_(4)even at elevated temperature.The structure of the monomeric complex,[LiClO_(4)(DETAN)](1),was characterised by single-crystal X-ray diffraction and NMR spectroscopy.展开更多
We report a detailed investigation of the potential of Fe(Ⅲ)complexes with H_(4)EDTA derivatives containing different spacers as magnetic resonance imaging(MRI)contrast agents:trans-cyclohexane-1,2-diamine(t-H_(4)CDT...We report a detailed investigation of the potential of Fe(Ⅲ)complexes with H_(4)EDTA derivatives containing different spacers as magnetic resonance imaging(MRI)contrast agents:trans-cyclohexane-1,2-diamine(t-H_(4)CDTA),cis-cyclohexane-1,2-diamine(c-H_(4)CDTA),propane-1,3-diamine(H_(4)PDTA),benzene-1,2-diamine(H_(4)PhDTA),trans-cyclopentane-1,2-diamine(H_(4)CpDTA)and trans-cyclobutane-1,3-diamine(H_(4)CBuDTA).The Fe(Ⅲ)complex of the related hexadentate ligand H_(2)CBuDEDPA(6,6’-(((trans-cyclobutane-1,3-diyl)bis(azanediyl))bis(methylene))dipicolinic acid)is also reported for comparative purposes.The X-ray structure of[Fe(1,3-CBuDEDPA)](PF_(6))·H_(2)O evidences the six-coordination of the ligand to the metal ion and displays a distorted octahedral polyhedron.All complexes show reversible or quasi-reversible cyclic voltammograms in aqueous 0.15 M NaCl due to the Fe(Ⅲ)/Fe(Ⅱ)pair,with E1/2 values in the range of +97 to 136 mV(vs.NHE)for the complexes with t-H_(4)CDTA,c-H_(4)CDTA,H_(4)PhDTA and H_(4)CpDTA.The longer spacers of H_(4)PDTA and H_(4)CBuDTA induce a stabilization of the Fe(Ⅱ)complex(E_(1/2)=260 and 294 mV vs.NHE,respectively).The Fe(Ⅲ)complexes of H_(4)PDTA and H_(4)CBuDTA do not contain innersphere water molecules.Thus,their ^(1)H nuclear magnetic relaxation dispersion(NMRD)profiles were analysed using an outer-sphere model.The complexes of c-H_(4)CDTA and H_(4)PhDTA display relaxivities that indicate the presence of a water molecule coordinated to the metal ion.A set of 17O NMR transverse relaxation rates and chemical shifts obtained at different temperatures provided information on the water exchange kinetics.Subsequently,the analysis of the ^(1)H NMRD profiles provided information on the rotational dynamics of the complexes and electronic relaxation.The integrated approach reported here includes a computational DFT and CASSCF study and provides insights into the structural and dynamic parameters affecting the efficiency of these complexes as MRI contrast agents.展开更多
This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diami...This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diamines.Notably,these complexes uniquely prefer a trigonal prism geometry,presenting a novel approach to synthesizing complexes with this distinctive shape.The compounds were characterized by elemental analysis,FT-IR spectroscopy,and single-crystal and powder XRD techniques.Furthermore,the magnetism was investigated by DC and AC magnetic measurements and also complemented by X-band EPR spectroscopy.The results reveal that the prepared complexes behave as field-induced single-molecule magnets,characterized by a substantial negative axial zero-field splitting D-parameter and spin reversal energetic barrier U_(eff) reaching values up to 72 K.The theoretical methods based on CASSCF/NEVPT2 calculations were applied to rationalize their magnetic properties.Moreover,these complexes hold promising potential for further functionalization,offering opportunities to enhance their properties,particularly towards developing zero-field single-molecule magnets as evidenced by the slow relaxation of magnetization in zero static magnetic field observed for the zinc-diluted complex 1Zn.展开更多
基金This work was financially supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars State Educational Ministry
文摘The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two compounds were characterized by elemental analyses and spectroscopic methods. Their structures were determined by X-ray diffraction study. Crystal data for 1: C24H20N6, Mr = 392.5, monoclinic, P21/c, a = 13.871(3), b = 13.510(2), c = 12.153(2) ? b = 112.97(2)? Z = 4, V = 2094.1(6) ?, Dc = 1.245 g/cm3, m(MoKa) = 0.078 mm-1, F(000) = 824, the final R = 0.0545 and wR = 0.0557 for 2048 observed reflections (I > 2s(I)); for BDPM: C24H24N6, Mr = 396.49, monoclinic, C2/c, a = 21.411(3), b = 8.053(1), c = 11.868(1) ? b = 92.63(1)? Z = 4, V = 2044.2(4) 3, Dc = 1.288 g/cm3, m(MoKa) = 0.080 mm-1, F(000) = 840, the final R = 0.0401 and wR = 0.0939 for 1673 observed reflections (I > 2s(I)).
基金Leverhulme Trust for their generous financial support via two Research Grant projects RPG-2023-159(R.J.A.,E.L.and M.E.L.)RPG-2022-231(J.M.H.,J.A.D.and E.L.)+1 种基金Newcastle University,University of Birmingham and the EPSRC for a PhD studentship via the Doctoral Training Partnerships(DTP)the Faraday Institution for funding(ReLiB project FIRG085).
文摘Separation of lithium and sodium is a topic of substantial scientific and industrial importance.Regarding Li/Na perchlorates,which are not only environmental hazards but also useful oxidants in chemical synthesis,an efficient Li-Na perchlorate separation method has not been reported due to lack of a ligand which can selectively coordinate with one of the two.Herein,we report an efficient Li-Na perchlorate separation by using our hexadentate ligand N,N′,N″-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane(DETAN),which can selectively coordinate with LiClO_(4)at room temperature to form a monomer in excellent yield but does not coordinate with NaClO_(4)even at elevated temperature.The structure of the monomeric complex,[LiClO_(4)(DETAN)](1),was characterised by single-crystal X-ray diffraction and NMR spectroscopy.
基金A.R.-R.(Grant PID2019-108352RJ-I00)Ministerio de Ciencia e Innovación(Grant PID2019-104626GB-I00)+1 种基金Xunta de Galicia(Grant ED431B 2020/52)for generous financial supportXunta de Galicia(Grant ED481A-2018/314)for funding her Ph.D.contract.
文摘We report a detailed investigation of the potential of Fe(Ⅲ)complexes with H_(4)EDTA derivatives containing different spacers as magnetic resonance imaging(MRI)contrast agents:trans-cyclohexane-1,2-diamine(t-H_(4)CDTA),cis-cyclohexane-1,2-diamine(c-H_(4)CDTA),propane-1,3-diamine(H_(4)PDTA),benzene-1,2-diamine(H_(4)PhDTA),trans-cyclopentane-1,2-diamine(H_(4)CpDTA)and trans-cyclobutane-1,3-diamine(H_(4)CBuDTA).The Fe(Ⅲ)complex of the related hexadentate ligand H_(2)CBuDEDPA(6,6’-(((trans-cyclobutane-1,3-diyl)bis(azanediyl))bis(methylene))dipicolinic acid)is also reported for comparative purposes.The X-ray structure of[Fe(1,3-CBuDEDPA)](PF_(6))·H_(2)O evidences the six-coordination of the ligand to the metal ion and displays a distorted octahedral polyhedron.All complexes show reversible or quasi-reversible cyclic voltammograms in aqueous 0.15 M NaCl due to the Fe(Ⅲ)/Fe(Ⅱ)pair,with E1/2 values in the range of +97 to 136 mV(vs.NHE)for the complexes with t-H_(4)CDTA,c-H_(4)CDTA,H_(4)PhDTA and H_(4)CpDTA.The longer spacers of H_(4)PDTA and H_(4)CBuDTA induce a stabilization of the Fe(Ⅱ)complex(E_(1/2)=260 and 294 mV vs.NHE,respectively).The Fe(Ⅲ)complexes of H_(4)PDTA and H_(4)CBuDTA do not contain innersphere water molecules.Thus,their ^(1)H nuclear magnetic relaxation dispersion(NMRD)profiles were analysed using an outer-sphere model.The complexes of c-H_(4)CDTA and H_(4)PhDTA display relaxivities that indicate the presence of a water molecule coordinated to the metal ion.A set of 17O NMR transverse relaxation rates and chemical shifts obtained at different temperatures provided information on the water exchange kinetics.Subsequently,the analysis of the ^(1)H NMRD profiles provided information on the rotational dynamics of the complexes and electronic relaxation.The integrated approach reported here includes a computational DFT and CASSCF study and provides insights into the structural and dynamic parameters affecting the efficiency of these complexes as MRI contrast agents.
基金financial support from the PalackýUniversity Olomouc project IGA_PrF_2022_006E.Č.was supported by the Slovak Research and Development Agency,contract no.APVV-22-0172 and APVV-18-0197。
文摘This article presents a series of six mononuclear Co(II)complexes 1-6 featuring ligands derived from a hexadentate Schiff base family,originating from the condensation of(2-formylphenoxy)acetic acid with various diamines.Notably,these complexes uniquely prefer a trigonal prism geometry,presenting a novel approach to synthesizing complexes with this distinctive shape.The compounds were characterized by elemental analysis,FT-IR spectroscopy,and single-crystal and powder XRD techniques.Furthermore,the magnetism was investigated by DC and AC magnetic measurements and also complemented by X-band EPR spectroscopy.The results reveal that the prepared complexes behave as field-induced single-molecule magnets,characterized by a substantial negative axial zero-field splitting D-parameter and spin reversal energetic barrier U_(eff) reaching values up to 72 K.The theoretical methods based on CASSCF/NEVPT2 calculations were applied to rationalize their magnetic properties.Moreover,these complexes hold promising potential for further functionalization,offering opportunities to enhance their properties,particularly towards developing zero-field single-molecule magnets as evidenced by the slow relaxation of magnetization in zero static magnetic field observed for the zinc-diluted complex 1Zn.
