Mixed-ligand Co^II and Cd^II complexes with 4-aminoantipyrine

Abstract

Self-assembly of 4-aminoantipyrine (AAP) and 5-nitroisophthalic acid (H₂NIP) with Co(CH₃COO)₂ or Cd(NO₃)₂ in CH₃OH–H₂O at room temperature generated {[Co₂(AAP)(NIP)(H₂O)₈][Co(AAP)(NIP)₂(H₂O)₂](H₂O)_4.5} (1) and {[Cd(AAP)(NIP)(H₂O)](H₂O)} _n (2), which were further characterized by X-ray diffraction, IR spectra, elemental analysis and solid-state fluorescence spectra. The structure analysis indicates that 1 contains two individual fragments, one NIP-bridged six-coordinate binuclear Co^II cation and a mononuclear Co^II dianion. The binuclear units are connected into 1-D chains via O–H ··· O hydrogen bond interactions, which were further assembled into a 2-D supramolecular layer bridged by the mononuclear Co^II unit. Complex 2 is a linear NIP bridged seven-coordinate Cd^II polymeric chain with the terminal AAP ligands as decorations, and are further extended into 2-D network by classic hydrogen bonds and π ··· π stacking interactions. Both solid complexes exhibit emission spectra from intraligand electron transfer at room temperature.

Keywords:

• Crystal structures
• 4-Aminoantipyrine
• Self-assembly
• Metal-organic coordination polymers

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 20571056), the National Fundamental Research Project of China (2005CCA01200) and Natural Science Foundation of Tianjin (No. 06YFJMJC03900), which are gratefully acknowledged.