  Azobenzene has become a ubiquitous component of functional molecules and
polymeric materials because of the light-induced trans-cis isomerization of the
diazene group. In contrast, there are very few applications utilizing
azobenzene luminescence, since the excitation energy typically dissipates via
nonradiative pathways. Inspired by our earlier studies with
2,2'-bis[N,N'-(2-pyridyl)methyl]diaminoazobenzene (AzoAMoP) and related
compounds, we investigated a series of five aminoazobenzene derivatives and
their corresponding silver complexes. Four of the aminoazobenzene ligands,
which exhibit no emission under ambient conditions, form silver coordination
polymers that are luminescent at room temperature. AzoAEpP
(2,2'-bis[N,N'-(4-pyridyl)ethyl]diaminoazobenzene) assembles into a
three-dimensional coordination polymer (AgAAEpP) that undergoes a reversible
loss of emission upon the addition of metal-coordinating analytes such as
pyridine. The switching behavior is consistent with the disassembly and
reassembly of the coordination polymer driven by displacement of the
aminoazobenzene ligands by coordinating analytes.
