Investigation of the spectral properties of a squarylium near-infrared dye and its complexation with Fe(III) and Co(II) ions

摘要

The spectral features of the squarylium near-infrared (NIR)dye NN525 in different solutions and its complexation with several metalions were investigated.The absorbance maximum of the dye is #lambda#=663 nm in methanol.This value matches the output of a commercially available laser diode (650 nm),thus making use of such as source practicalfor excitation.The emission wavelength of he dye in methanol is #lambda#_cm=670 nm.The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye.The Stern-Volmer quenching constant,K_sv,was calculated from the Stern-Volmer plot to be K_(sv)=2.70*10~7 M~(-1) for Co(II) ion.The K_sv value for Fe(III) ion could not be established due to the non-linearity of the Stern-Volmer plot and the modified Sstern-Volmer plot for this ion. The detection limit is 6.24*10~(-8) M for Fe(III) ion and 1.55*10~(-5)M for Co(III) ion.The molar ratio of the metalto the dye was established to be 1:1 for both metal ions.The stability constant,K_s, of the metal-dye complex was calculated to be 3.14*10~6 M~(-1) for the Fe-dye complex and 2.64*10~5 M~(-1) for the Co-dye complex.