Two Silver Coordination Network Compounds with Colorful Photoluminescence

The excitation-wavelength-dependent
photoluminescence (EWDP) property
of flexible organic ligand 1,4-bis­(2-methyl-imidazol-1-yl)­butane (Bmib)
was observed. Herein, Bmib was chosen as a bridge linker to react
with AgX (X = Br and I) to synthesize novel coordination network compounds
(CNCs) with interesting EWDP properties. As anticipated, under the
same hydrothermal synthesis conditions, two new isomorphic CNCs, i.e.
[Ag2(Bmib)­Br2]∞ (IAM16-1) and [Ag2(Bmib)­I2]∞ (IAM16-2), as the first
examples of CNCs showing EWDP properties, have been obtained. The
EWDP properties may be attributed to the stretch and rotation of the
long -(CH2)4- chains of Bmib and the spatial
orientation adjustment of the methyl group of each imidazole ring
at different excitation wavelengths. It is a great challenge to point
out the emission mechanisms of CNCs merely from the experimental results
due to their multiple charge transfer routes. To address this issue,
we adopt DFT calculations to pursue in-depth investigation of the
emission mechanisms for IAM16-1 and IAM16-2, respectively.