Three new heterometallic metal organic
frameworks, [{[Ca6(H2O)18][Ag6(mna)6]2}·[Ag6(Hmna)6]·20H2O], 1,
{[Sr3(H2O)10][Ag6(mna)6]·12H2O}, 2,
and {[Ba3(H2O)10][Ag6(mna)6]·8H2O}, 3, have
been synthesized following hard–soft
acids–bases principle. Compounds 1 and 2 have three-dimensional structures with cor and pcu (α-Po) topology, whereas compound 3 has a two-dimensional sql topology. Smaller calcium
and strontium ions form a simple dimer (Ca2/Sr2, 1/2) and tetramer units (Sr4, 2), whereas the larger
barium ion forms infinite Ba–O–Ba chains. The presence
of the electron-rich mna ligand in all the compounds paved the way
for the detection of electron-deficient hazardous nitroaromatics employing
photoluminescence quenching methods. The luminescence intensities
of the compounds are strongly quenched by picric acid, p-nitro phenol, and 2-nitro toluene at low concentration, which indicates
that these compounds are excellent materials for the detection of
these nitroaromatics in solution.