Spectral properties of new N,N′-bis-alkyl-1,4,6,8-naphthalenediimide complexes

The photophysical properties of two N,N′-bis-alkyl-1,4,6,8-naphthalenediimide (DCN1 and DCN2) have been studied in chloroform and N,N-dimethylformamide solvents. The ability of DCN2 in N,N-dimethylformamide to detect metal cations have been monitored by the fluorescence emission spectroscopy. It has been shown that the fluorescent intensity is very sensitive to the concentration of Fe3+ cations. The reaction of iodine with N,N′-bis-alkyl-1,4,6,8-naphthalenediimide in chloroform solution have been investigated by spectrophotometric method. The results indicate the formation of two CT-complexes [(DCN1)I]+·I3− and [(DCN2)I]+·I3− at donor:acceptor molar ratio of 1:2. The [(DCN1)I]+·I3− shows the characteristic absorptions of I3− ion at 290 and 360 nm while the charge-transfer transition of [(DCN2)I]+·I3− occurs at 310 nm. Three characteristic bands at the far infrared region in each iodine complex are observed around 135, 105 and 85 cm−1 due to νas (I–I), νs (I–I) and δ (I3−), respectively with C2v symmetry. The values of the complex formation constant, K, and the absorptivity, ɛ have been calculated.