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A new imidazo[4,5-f][1,10]phenanthroline (imp) derivative imidazo-N5,N6-bis((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenyl)methylene)-1,10-phenanthroline-5,6-diamine (impap) was synthesized in five steps starting from bare phenanthroline (phen) precursors. The novel compound was fully characterized by 1H-NMR, IR, elemental analysis and electrospray ionization mass spectroscopy (ESI-MS) techniques. Solid state emission spectrum of impap showed two distinct strong emission maxima with large Stokes shifts. The ground state gas phase geometry of impap was predicted by DFT calculations. Excited state properties of the molecule were examined through TD-DFT calculations conducted at the optimized geometry. Responsible transitions for the strong fluorescence of impap were assigned to single component charge transfer transitions with large oscillator strengths based on the ground state calculated molecular orbital contributions.

The traditional spectrophotometric determination of stability constants of complexation involves finding a wavelength at which only one of the components has absorbance without any spectroscopic interference of the other reaction components. But this method fails when there is not selective wavelength for at least one of the component. Multivariate data analysis involving soft and/or hard model analysis can be used in these cases. In the present work, firstly, multivariate curve resolustion-alternative least squares which is a model free analysis, was used to estimate the chemical model of data variation and then a robust multi-wavelength model-based method has been developed to determine the stability constants of formed complex(s) regardless to the spectra overlapping of the components. By applying such model, not only the stability constants of the formed complex(s) can be calculated, but also the pure spectra of all contributed components are extracted well. The complexations of 1,10-phenanthroline-5,6-dione ligand with several metalic cations [Cu(II), Ni(II), Co(II), Zn(II)] were studied using proposed multi-wavelength spectrophotometric method in non-aqueous solution at 25 °C. It was found that there is a 2:1 stoichiometry between ligand with studied metalic cations and also their stability constants were calculated. DOI: http://dx.doi.org/10.4314/bcse.v28i3.6