Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands

Abstract

The mono-dentate, pyridyl containing, nitro naphthalimide ligands N-(4-pyridyl)-4-nitro-1,8-naphthalimide (L 1 ) and N-(3-pyridyl)-4-nitro-1,8-naphthalimide (L 2 ) were prepared and complexed with a selection of copper salts [Cu(OAc) 2 , Cu(CF 3 SO 3 ) 2 and Cu(ClO 4 ) 2 ]. Crystallographic studies were undertaken and revealed that dinuclear acetate bridged complexes resulted from reactions with Cu(OAc) 2 , while mononuclear systems resulted from reactions with Cu(CF 3 SO 3 ) 2 and Cu(ClO 4 ) 2 . Despite the differing coordination environments the naphthalimide based ligands provided a range of interesting π-based interactions in the form of π⋯π, anion⋯π, nitro⋯π, solvent⋯π and CvO⋯π associations. Solid state EPR spectra were in agreement with the coordination environments observed from crystallography.

Rare Supramolecular Assemblies of a Dicopper(II)‐tetracarboxylate Stabilized by (Methanol)6, Dimethyl Sulfoxide and 4,4′‐Azobipyridyl Bridges

“…The spectra consist of a strong band centered around g =1.44 with two additional weak bands. These spectra closely match the EPR spectra of antiferromagnetically coupled dicopper(II)‐tetracarboxylate complexes reported earlier in the literature …”

Effect of the Pyridine Substituent on the Role of the Phenol Functional Group in [Cu(pOHBz)2(dPy)2] Complexes (pOHBz: p‐Hydroxybenzoate, dPy= 4‐Phenylpyridine, 4‐Benzylpyridine, 3‐Phenylpyridine).

“…The non‐bridging carboxylate adopts a bonding mode from a clearly asymmetric chelating to monodentate. The Cu(2)‐N bond lengths are also in good agreement with the values reported for similar compounds …”

Structural and magnetic properties of dinuclear Cu(II) complexes featuring triazolyl-naphthalimide ligands

“…In line with our previous studies [35] our primary aim was to probe the ability of L 1 and L 2 to develop higher order supramolecular architectures in combination with metal salts and here we have employed Cu(II) for this purpose.. In doing so we have shown that these simple ligands generate systems where structure extension occurs through π···π and anion···π interactions.…”

“…The Cu(II) ions are 2.651(2) Å apart, similar to other copper paddlewheel complexes. [35] The copper ions are adopt a near perfect square-based pyramidal geometry with the degree of trigonality (τ) being 0. [43] Bond lengths and angles are also consistent with other axially elongated square-based pyramidal structures where the equatorial acetate oxygen Cu-O bond lengths average 1.968(2) Å whilst the axial triazole nitrogen atom Cu-N bond length is 2.180(2) Å (Table 2).…”