Abstract:
Two cadmium-based 3D luminescent MOFs {[Cd2(SA)2(L)2] H2O}n (Cd-MOF-1) and [Cd(CDC)(L)]n
(Cd-MOF-2) (H2SA = succinic acid, H2CDC = 1,4-cyclohexanedicarboxylic acid, L = [3,30-azobis(pyridine)])
have been assembled by employing organic dicarboxylic acid linkers with an unexploited azofunctionalized
N,N0 spacer via a room temperature slow evaporation process, and they are characterized
by single crystal X-ray analysis, TGA, FT-IR, PXRD and elemental analysis. The topological analysis reveals
that Cd-MOF-1 features a 6c-uninodal rare ‘rob’ topology with the point symbol {48 66 8}, whereas
Cd-MOF-2 shows a ‘pcu’ alpha-Po primitive cubic topology with the point symbol {412 63}. These MOFs
are highly emissive at 382 nm and 398 nm when excited at 305 nm and 312 nm, respectively. The
exposed azo groups are presumed to act as functional sites for the recognition of metal ions through
quenching of fluorescence intensity. The fluorescence measurements show that these MOFs can
selectively and sensitively detect Fe3+ as well as Al3+ and thus, they demonstrate potential as dualresponsive
luminescent probes for metal-ion sensing. EDS elemental mapping, PXRD of loaded MOF
materials, and a plausible quenching mechanism have been discussed. More importantly, both the MOFs
exhibit rapid response times toward sensing of Fe3+ and Al3+.
