Core/Shell Oligometallic Template Synthesis of Macrocyclic Hexaoxime

Akine, Shigehisa; Sunaga, Shuichi; Taniguchi, Takanori; Miyazaki, Hayato; Nabeshima, Tatsuya

doi:10.1021/ic062327s

Cited by 107 publications

(80 citation statements)

References 19 publications

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“…The six phenoxo oxygen atoms are in equatorial positions around a central Ln III ion, and hence an equatorial LF is produced. We have reported syntheses and structures of mixed-metal tetranuclear complexes constructed with L2 6À , [9] of which the oxime ligand showed a slight deviation from an ideal plane because of the longer NÀN distance of the diamine. Hence, we decided to employ an ethylenediamine derivative to achieve a more planar structure of the complex.…”

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confidence: 99%

Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

et al. 2011

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Single-molecule magnets (SMMs) [1][2][3][4][5][6] are chemically and physically interesting compounds that exhibit hitherto unobserved magnetic properties. To prevent reversal of the molecular magnetic moment, the use of heavy lanthanide ions is becoming popular because of their large spin multiplicity and large magnetic anisotropies in the ground state. [3][4][5][6] Lanthanide ions exhibit flexibility in magnetic anisotropy, which is another advantage of Ln III -based SMMs that is attributable to the flexible design and control of the ligandfield (LF) anisotropy. These anisotropies are correlated through Stevens factor q m as B [ We found that phenoxo oxygen donors have higher negative charges than other donor atoms.[5] To achieve an equatorial LF, we focused on the macrocyclic Schiff base and oxime ligands shown in Scheme 1, which provide a metallacrown coordination environment [3j, 8] for the central metal ion with six phenoxo oxygen donors and have a rigid and planar framework owing to the p-conjugated moieties. The ligands are formed by condensation of 2,3-dihydroxybenzene-1,4-dicarbaldehyde and a diamine in the presence of metal ions as templates. The six phenoxo oxygen atoms are in equatorial positions around a central Ln III ion, and hence an equatorial LF is produced. We have reported syntheses and structures of mixed-metal tetranuclear complexes constructed with L2 6À , [9] of which the oxime ligand showed a slight deviation from an ideal plane because of the longer NÀN distance of the diamine. Hence, we decided to employ an ethylenediamine derivative to achieve a more planar structure of the complex.The wheel-shaped tetranuclear complex [Er III Zn II 3 (L1)-(OAc)(NO 3 ) 2 (H 2 O) 1.5 (MeOH) 0.5 ] (1) was synthesized by reaction of Er(NO 3 ) 3 ·6 H 2 O, 2,3-dihydroxybenzene-1,4-dicarbaldehyde, (R,R)-1,2-diphenylethylenediamine, and Zn-(OAc) 2 ·2 H 2 O in 1:3:3:3 ratio (see Experimental Section; Scheme 1. Structures of macrocyclic ligands.

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Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

et al. 2011

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“…We have already demonstrated that a binding selectivity trend of alkali metal << Zn 2+ < alkaline earth < rare earth metal ions was observed in the shorter L 1 Zn2M system [57] and related complexes [79][80][81][82][83] without chiral auxiliary. If the longer L 4 Zn3M system having a chiral auxiliary also shows a similar selectivity trend, Ba 2+ in the L 4 Zn3Ba can be efficiently replaced by La 3+ .…”

Section: Helicity Inversion By Metal Exchangementioning

confidence: 92%

Dynamic Helicity Control of Oligo(salamo)-Based Metal Helicates

Akine

2018

Inorganics

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Much attention has recently focused on helical structures that can change their helicity in response to external stimuli. The requirements for the invertible helical structures are a dynamic feature and well-defined structures. In this context, helical metal complexes with a labile coordination sphere have a great advantage. There are several types of dynamic helicity controls, including the responsive helicity inversion. In this review article, dynamic helical structures based on oligo(salamo) metal complexes are described as one of the possible designs. The introduction of chiral carboxylate ions into Zn 3 La tetranuclear structures as an additive is effective to control the P/M ratio of the helix. The dynamic helicity inversion can be achieved by chemical modification, such as protonation/deprotonation or desilylation with fluoride ion. When (S)-2-hydroxypropyl groups are introduced into the oligo(salamo) ligand, the helicity of the resultant complexes is sensitively influenced by the metal ions. The replacement of the metal ions based on the affinity trend resulted in a sequential multistep helicity inversion. Chiral salen derivatives are also effective to bias the helicity; by incorporating the gauche/anti transformation of a 1,2-disubstituted ethylene unit, a fully predictable helicity inversion system was achieved, in which the helicity can be controlled by the molecular lengths of the diammonium guests.

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“…41 . On the other hand Ni(II) complex showed three absorption bands at 13,500-14500, 15,600-17000 and 23,500-25000 cm -1 , which are attributed to 1 …”

Section: Electronic Spectral Studiesmentioning

confidence: 96%

“…Transition metal ions with Schiff-bases have been extended enormously and embraced wide and diversified subjects comprising vast areas of organometallic compounds 1 and various aspects of biocoordination chemistry 2 . Schiff base ligands with donors N, O, S etc., have structural similarities with natural biological systems and imports and rasemination reaction in biological systems due to presence of imine (-N=CH-) group 3 .…”

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confidence: 99%

Synthesis, Characterization and Biological Studies of Homobimetallic Schiff Base Cu(II) and Ni(II) Complexes

2013

Chem Sci Trans

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.4(OAc) (4) respectively. The four new homobimetallic complexes have been characterized by spectral techniques like elemental analysis, NMR, IR, UV Visible absorption, magnetic measurements, thermal, EPR, electrochemical studies and molar conductance. IR spectral data shows that the ligands are bidentate and the binding sites are azomethine nitrogen and free primary amine groups. Molar conductance measurements show that the complexes are electrolytes. EPR values and electronic spectral data suggest that it possesses square planar geometry. The Schiff base ligands and metal complexes were evaluated for antimicrobial activity against gram positive bacteria and gram negative bacteria. The ligands and its metal complexes were found to be biologically active. All the complexes show higher antimicrobial activity than the ligand and streptomycin.

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Core/Shell Oligometallic Template Synthesis of Macrocyclic Hexaoxime

Cited by 107 publications

References 19 publications

Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

Dynamic Helicity Control of Oligo(salamo)-Based Metal Helicates

Synthesis, Characterization and Biological Studies of Homobimetallic Schiff Base Cu(II) and Ni(II) Complexes

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Core/Shell Oligometallic Template Synthesis of Macrocyclic Hexaoxime

Cited by 107 publications

References 19 publications

Wheel‐Shaped ErIIIZnII3 Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

Wheel‐Shaped ErIIIZnII3 Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

Dynamic Helicity Control of Oligo(salamo)-Based Metal Helicates

Synthesis, Characterization and Biological Studies of Homobimetallic Schiff Base Cu(II) and Ni(II) Complexes

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Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy

Wheel‐Shaped Er^IIIZn^II₃ Single‐Molecule Magnet: A Macrocyclic Approach to Designing Magnetic Anisotropy