Mono- and ditopic hydroxamate ligands towards discrete and extended network architectures

Abstract

A family of mono- and ditopic hydroxamic acids has been employed in the synthesis and structural and physical characterisation of discrete (0D) and (1- and 2-D) extended network coordination complexes. Examples of the latter include the 1-D coordination polymer {[Zn(II)(L₃H)₂]·2MeOH}_n (5; L₃H₂ = 2-(methylamino)phenylhydroxamic acid) and the 2-D extended network {[Cu(II)(L₂H)(H₂O)(NO₃)]·H₂O}_n (5; L₂H₂ = 4-amino-2-(acetoxy)phenylhydroxamic acid). The 12-MC-4 metallacrown [Cu(II)₅(L₄H)₄(MeOH)₂(NO₃)₂]·3H₂O·4MeOH (7) represents the first metal complex constructed using the novel ligand N-hydroxy-2-[(2-hydroxy-3-methoxybenzyl)amino]benzamide (L₄H₃). Variable temperature magnetic susceptibility studies confirm strong antiferromagnetic exchange between the Cu(II) centres in 7. Coordination polymer 5 shows photoluminescence in the blue region (λ_PL ∼ 421–450 nm) with a bathochromic shift of the emission (∼15–30 nm) from solution to the solid state.