Syntheses, structures and photoluminescence of a series of metal-organic complexes with 1,3,5-benzenetricarboxylate and pyrazino[2,3-f][1,10]-phenanthroline ligands

Abstract

A series of new metal-organic coordination complexes, [Co₂(HBTC)₂(Pyphen)₂(H₂O)₄]·4H₂O (1), [Mn(HBTC)(Pyphen)(H₂O)] (2), [Cd₂(OH)(BTC)(Pyphen)₂]·H₂O (3), [Cu₂(OH)(BTC)(Pyphen)] (4), and [Zn₂(OH)(BTC)(Pyphen)] (5) were prepared through hydrothermal reactions of pyrazino[2,3-f][1,10]-phenanthroline (Pyphen) and 1,3,5-benzenetricarboxylic acid (H₃BTC) with different metal salts. All these compounds were structurally determined by X-ray single-crystal diffraction. In the dinuclear Co(II) compound (1) π–π interactions exist between Pyphen and HBTC²⁻ ligands, resulting in interesting 2D supramolecular layers. For complex (2), the Mn(II) centers are linked by HBTC²⁻ ligands to form a 2D (4,4) coordination layer, and these layers are interdigitated in pairs. Polymer (3) also possesses a 2D network structure composed of the tetrametallic clusters [Cd₄(µ₂-OH)₂], which is extended to 3D arrays through the π–π interactions between Pyphen ligands. The isostructural coordination polymers (4) and (5) show the same 3D framework structure. Solid-state luminescent spectra of the Cd(II) and Zn(II) complexes indicate intense fluorescent emissions.