Preparation and Analyses of the Multifunctional Properties of 2D and 3D MOFs Constructed from Copper(I) Halides and Hexamethylenetetramine

In this article, two two-dimensional
and three-dimensional metal–organic
frameworks are synthesized by the self-assembly of copper­(I) halide
and the hexamethylenetetramine (hmt) ligand. Compound 1 is a two-dimensional metal–organic framework composed of
a pyramidal Cu4I5 cluster and hexamethylenetetramine,
in which hmt-bridged Cu clusters form a two-dimensional (4,4)-connected
net with a point symbol of (44·62) (44·62). Compound 2 is a homochiral
three-dimensional metal–organic framework material generated
through an unusual spontaneous crystallization from achiral precursors.
The two compounds were characterized by a series of analyses such
as infrared spectroscopy, elemental analysis, circular dichroism spectroscopy,
and powder X-ray diffraction. Both of them exhibit unexpected stability
under a wide range of conditions of acid and base. In addition, the
fluorescence intensity changes regularly under acid–base conditions.
Stokes shift shows a good linear relationship with −log [H+], which makes them become promising acid–base sensors.
Compounds 1 and 2 also display selective
adsorption and a significant degradation effect on the organic dye
methylene blue. In addition, the fluorescence study indicated that
compound 2 could be used as a sensor to detect Cr3+.