Metal-directed self-assembly of M₃L₂ (M=Zn, Cd) metal-organic architectures with a tripodal tris-bidentate chelator

Abstract

Two discrete M₃L₂ metal-organic architectures, 1 and 2, have been constructed by reaction of a newly designed tripodal tris-bidentate ligand L with M(NO₃)₂ (1: M=Zn; 2: M=Cd). Both complexes together with L have been structurally elucidated by single-crystal X-ray crystallography. Complex 1 exhibits a cationic M₃L₂ coordination architecture bearing three positive charges balanced by three uncoordinated nitrates, while 2 shows a neutral M₃L₂. 1 and 2 both adopt a compressed trigonal prism shape but show no internal cavity due to close ligand-to-ligand interactions. They display totally different intermolecular packing modes in the solid state, which strongly influence the intermolecular π–π interactions. Complex 1 has been arrayed such that each M₃L₂ is surrounded by three neighboring C₃-symmetry related ones, whereas 2 exhibits a columnar molecular stacking. The distinctive intermolecular packing modes in the solid state between 1 and 2 bring about a small but discernible red shift (4 nm) corresponding to the π–π^∗ electronic absorption.

Keywords:

• Metal-organic polyhedra
• Tripodal
• Crystal structure
• Photophysical property

Supplementary material

CCDC-908644 (for 1), -908645 (for 2) and -908646 (for L) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: [phone]; or E-mail: [email protected]).

Acknowledgments

We acknowledge the financial support from the National Natural Science Foundation of China (No. 21171036) and the Teaching and Research Program for the Excellent Young Teachers of Southeast University.