Encapsulation of a magnesium hydroxide cubane by a bowl-shaped polypyrrolic Schiff base macrocycle

Hydrolysis of a Pacman-shaped binuclear magnesium complex of a polypyrrolic Schiff base macrocycle results in the formation of a new magnesium hydroxide cubane that is encapsulated by the macrocyclic framework through both coordinative and hydrogen-bonding interactions.     

Synthesis and characterization of new azo containing Schiff base macrocycle

Fully conjugated Schiff base macrocycle has been prepared through a simple and mild condition,a one-pot cyclization procedure of four-component without using a template.The condensation reaction of related bis（hydroxybenzaldehyde） with phenylenediamines to prepare a conjugated[2 + 2]Schiff base macrocycle has been investigated and fluorescent[2 + 2]Schiff base macrocycles with N₂O₂ binding pockets has been prepared and characterized by elemental analysis,¹H NMR,IR,fluorescent,UV-visible and MALDI mass spectroscopies.     

Formation of a silicon‐containing macrocycle with a pyridoxalimine Schiff base ligand

The reaction of dichlorodiphenylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2‐hydroxyaniline yields the macrocyclic centrosymmetric silicon compound 9,27‐dimethyl‐3,3,21,21‐tetraphenyl‐2,4,20,22‐tetraoxa‐8,13,26,31‐tetraaza‐3,21‐disilapentacyclo[30.4.0.0^6,11.0^14,19.0^24,29]hexatrideca‐1(32),6,8,10,12,14,16,18,24,26,28,30,33,35‐tetradecaene‐10,28‐diol chloroform tetrasolvate, C₅₂H₄₄N₄O₆Si₂·4CHCl₃. The asymmetric unit contains half of the macrocycle and two molecules of chloroform, with C—H...O and C—H...N contacts binding the two guests to the host in the crystal structure. This macrocyclic silicon compound represents a promising host for molecular‐recognition processes and for the construction of nanostructures.     

Positive homotropic allosteric binding of silver(I) cations in a Schiff base oligopyrrolic macrocycle

The binuclear silver(I) complex of a Schiff base oligopyrrolic macrocycle was prepared in high yield and fully characterized. UV-visible absorption and 1H NMR spectroscopic analyses reveal that coordination of Ag(I) cations is subject to a strong positive homotropic allosteric effect.     

A Schiff base expanded porphyrin macrocycle that acts as a versatile binucleating ligand for late first-row transition metals

The coordination chemistry of the Schiff base polypyrrolic octaaza macrocycle 1 toward late first-row transition metals was investigated. Binuclear complexes with the divalent cations Ni(II), Cu(II), and Zn(II) and with the monovalent cation Cu(I) were prepared and characterized. Air oxidation of the Cu(I) ions in the latter complex to their divalent oxidation state resulted in a change in the coordination mode relative to the macrocycle.     

Double template effect in [4 + 4] Schiff base macrocycle formation; an ESI-MS study

The mechanism of self-assembly of a polynuclear complex of a [4 + 4] Schiff base iminomethylenediphenolate macrocycle [BaCu(4)(4 + 4)](2+) via a non-macrocyclic dialdehyde intermediate has been followed using ESI-MS of the reaction solutions. Both assembly of the intermediate and Schiff-base condensation with diamine give rise to single products; formation of the intermediate metallacycle is fast but Schiff-base condensation is much slower. Both intermediate complex and macrocyclic product have been structurally characterised.     

冠醚化Schiff碱

综述了冠醚化Schiff碱的合成、配位和某些仿生性能的研究进展。     

Metal-Salen Schiff base complexes in catalysis: practical aspects

Schiff base ligands are considered "privileged ligands" because they are easily prepared by the condensation between aldehydes and imines. Stereogenic centres or other elements of chirality (planes, axes) can be introduced in the synthetic design. Schiff base ligands are able to coordinate many different metals, and to stabilize them in various oxidation states, enabling the use of Schiff base metal complexes for a large variety of useful catalytic transformations. Practical guidelines for the preparation and use of different Schiff base metal complexes in the field of catalytic transformations are discussed in this tutorial review.     

Cooperative self-assembly of a macrocyclic Schiff base complex

A metal template approach affords in high yield a tetra-Zn(salphen) macrocycle (3) which shows strong and cooperative self-assembly mediated by the formation of Zn(salphen) dimer units held together via μ(2)-phenoxo interactions. A cooperative binding mode for the tetranuclear Zn(4) macrocycle 3 is supported by comparison of UV-vis and fluorescence titration data recorded for 3 when compared with respective mononuclear and dinuclear Zn(salphen) model compounds. UV-vis dilution experiments carried out for Zn(4) macrocycle 3 and its Pd(4) analogue 4, as well as comparative TEM studies involving the same tetranuclear macrocycles further support the strong assembly behavior of 3. This self-assembly seems to be primarily dictated by its ability to form multiple, self-assembled dimeric [Zn(salphen)](2) units.     

Quinoxaline-based Schiff base transition metal complexes: review

The literature survey highlights spectra and biological activity of transition metal complexes derived from Schiff bases of quinoxaline. The extensive studies of synthesis, spectral, structural characterization, and biological activities of the metal complexes with heterocyclic Schiff bases of quinoxaline are reviewed.     

Schiff base derivatives of lanthanons

Bifunctional tridentate Schiff bases such as, $$\begin{gathered} HOC_6 H_4 C(CH_3 ) : NCH_2 CH_2 OH, \hfill \\ HOC_6 H_4 C(CH_3 ) : NCH_2 CH_2 (OH)CH_3 , \hfill \\ HOC_6 H_4 C(H) : NCH_2 CH_2 OH \hfill \\ \end{gathered} $$ and HOC₆H₄C(H)∶NCH₂CH(OH)CH₃ react with La(III), Pr(III) and Nd(III) isopropoxides to 1∶1 and 2∶3 derivatives of the type,Ln(O?i-C₃H₇)(OC₆H₄C[R]∶NR′O) andLn ₂(OC₆H₄C[R]∶ NR′O)₃ [where,Ln=La(III), Pr(III) or Nd(III); R=CH₃ or H and R′=CH₂?CH₂ or CH₂CHCH₃] in dry benzene. The labile nature of the isopropoxy groups in the 1∶1 derivatives has been shown by exchange reactions with an excess oft-butyl alcohol leading to the formation ofLn(O?t-C₄H₉)(OC₆H₄C[R]∶NR′O); (where R=CH₃ and R′=CH₂CHCH₃) type derivatives in almost quantitative yield. The IR spectra of the resulting derivatives have been recorded in the range of 4000–400 cm^?1, ν C=N frequency bands appear at ≈ 1620 cm^?1 and almost no change has been noted in their positions on complexation. Some new peaks are, however, observed in the range of 700–600 cm^?1 and these may be ascribed to the ring deformation coupled with both theLn?O stretching and C?CH₃ stretching modes.     

Uranyl stabilized Schiff base complex

Uranyl Schiff base complex [(UO(2))(2)(Salpro)(OH)(Solvent)(2)] (1) in the presence of excess of ethylenediamine (EDA) does not undergo nucleophilic addition (hydrolysis) and substitution (transamination) reactions due to an extended chelation [2N, 3O + OH] by the flexible backbone.     

Synthesis and characterization of a pyridine-containing Schiff base oligomer

The oligomer of 4-(4-pyridylmethylideneimino)phenol was formed during oxidative polycondensation in aqueous alkaline medium using oxygen as the oxidant. Optimum conditions of the oxidative polycondensation and the main parameters of the process were found. The maximum yield of the oligomer was 52.4%. The product was characterized by elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and ¹H NMR spectroscopy. The molecular weight distribution was determined by size exclusion chromatography. Thermogravimetric and differential thermal analyses were carried out for 4-(4-pyridylmethylideneimino)phenol and its oligomer. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1785–1788, October, 2006.     

Silicon-containing Schiff base and benzimidazole derivatives

Investigations were undertaken to obtain information for use in the development of new heat-stable polymers. Model silicon-containing Schiff base and benzimidazole derivatives were synthesized by reaction of p-(triphenylsilyl)-benzaldehyde with phenylenediamines. The structure and thermal stability of the products were studied. The reaction of p-(triphenylsilyl)benzaldehyde and o-phenylenediamine yielded N-p-(triphenylsilyl)benzylidene-o-phenylenediamine which readily oxidizes to form 2-p-(triphenylsilyl)phenylbenzimidazole. The di-Schiff bases, which most probably exist in trans-trans configurations, were obtained from reaction of the aldehyde derivative with m- and p-phenylenediamine. In contrast to similar Schiff bases without silicon, the products are soluble in organic solvents. The good resistance of the di-Schiff base and benzimidazole derivatives to thermal decomposition suggests that polymers with repeating units of such structures would also be heat-stable and might possess useful properties.     

New Schiff base complexes of tetrachlorouranium

Summary Tetrachlorouranium complexes containing a Schiff base ligand, p-XC₆H₄NH=CHC₆H₄OH(L), derived from p-XC₆H₄NH₂ and salicylaldehyde, have been prepared. Atris complex was obtained when X=NO₂ andbis complexes for the other p-substituted Schiff bases when X=Cl, Br, OH and Me.