有機溶媒中에서 Cr(II)과 p-Aminoazobenzene 및 그 誘導體와의 錯物에 關한 硏究 = A Study on Complexes between Cr(II)and p-Aminoazobenzene and their Derivativies in Organic Solvents

다국어 초록 (Multilingual Abstract)

The study of the complexes between an acceptor molecule Cr(Ⅱ) and donor molecules, p-aminoazobenzene(AAB), N-methylarninoazobenzene (MAAB) and N.N-dimethylaminoazobenzene, was accomplished through UV-Vis spectrophotometric method. The complexes were formed in pure methanol, acetonitrile and mixed solvents of both, of which volume ratios were 3 : 1, 1 : 1, 1 : 3, respectively.
Looking into absorption spectra of donors, as the polarity of solvent was increased, maximum absorption wavelength showed hypsochromic shift in AAB and MAAB, and bathochromic shift in DMAB. This is because the donor molecules in AAB and MAAB at the ground state are more polar than that at the excited state, while the donor molecules in DMAB at the existed state are more polar than that at the ground state.
The complexes formed between green Cr(Ⅱ) and yellow donors showed red color, which are longer wavelength than acceptor and donors. As the solvent's polarity increased, absorption spectra of each complex showed bathochromic shift. This is because the effect of methyl group's electron donating effect increased the basicity of donors through interaction between methyl groups and p-aminoazobenzene. Therefore the basicity order between AAB and derivatives is AAB < MAAB < DMAB.
The stability constants(K) and molar extinction coefficient (ε max) of each complex were calculated by using Benesi-Hildebrand method. This method and mole ratio results and the values of showed 103~105 L/mol·㎝ were considered to be 1:1 or 1:2 ratio complex. As the H atoms of NH2 are substituted by CH3, the stability constants increased. Regarding the donors' electron donating effect, the complex resulted from reactions between Cr(Ⅱ) and donors is considered ligand-to-metal charge transfer complex.