Synthesis, photoluminescence and forensic applications of blue light emitting azomethine-zinc (II) complexes of bis(salicylidene)cyclohexyl-1,2-diamino based organic ligands

Various azomethine-zinc(II) complexes (3a-c) of bis(salicylidene)cyclohexyl-1,2-diamino organic ligands were synthesized by one pot reaction of salicylaldehydes/2-hydroxy-1-naphthaldehyde (2 eq), cyclohexyl-1,2-diamine (1 eq) and zinc acetate (1 eq) in methanol solvent at reflux temperature. The synthesized complexes were characterized by FTIR, 1H NMR, and SEM. Their photophysical properties such as Photoluminescence (PL) and Diffused Reflectance Spectra (DRS) were studied. PL studies revealed that the emission peaks of the complexes in both solution and solid states appeared to occur at 395-600 nm and emitted blue light. The band gap energies determined from DRS were 2.98 eV (3a), 2.91 eV (3b), and 2.73 eV (3c). Based on these results, we ascertain that these Zn(II) complexes can serve as a suitable non-dopant blue light emitting compound for flat panel display applications. Latent fingerprint detection study indicated that the powder compounds show good adhesion and finger ridge details without background staining. The demonstrated method can be applied to detect fingerprints on all types of smooth surfaces.