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The absorption and fluorescence spectra of 1,5-diaminoanthraquinone(1,5-DAAQ) have been investigated in organic solvents-Benzene(BZ), Ethanol (ETOH), Acetonitrile (AN), Dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO). There is an intra molecular hydrogen bond formed between quinoid oxygen and the substituents NH(2) [C = O...H-N]. The interaction of the hydrogen atom of - NH(2) leads to red shift in both absorption and fluorescence spectra. The dipole moment ratio of 1,5 DAAQ in ground and excited states was calculated from stokes shift obtained from optical absorption and fluorescence spectra. Photo physical properties of 1,5-DAAQ dye was studied using this absorption and fluorescence spectroscopy techniques in binary liquid mixtures(AN + DMF, AN + DMSO, AN + ETOH and BZ + ETOH).

Optical absorption and fluorescence emission spectra of 2,3-bis(chloromethyl)-1,4-anthraquinone (DCMAQ) in single solvents namely, carbon tetrachloride, acetonitrile, chloroform, propan-2-ol and its binary mixtures [carbon tetrachloride/chloroform, chloroform/acetonitrile, chloroform/propan-2-ol] have been investigated. The preferential solvation of DCMAQ in above mixtures has been studied by monitoring the absorption and fluorescence spectra of DCMAQ. The spectral features indicate that DCMAQ is preferentially solvated by CHCl(3) in the above mixtures. This can be elucidated from the local mole fraction, non-linearity in transition energy plot, preferential solvation index (delta (s2)) and (f2/f1) values. Molecular recognition properties of p-tert-butylcalix[4]arene (tBC) to DCMAQ via hydrogen bonding and pi-pi interaction were sensed successfully on the basis of absorption and fluorescence emission spectroscopies, by which the stoichiometry ratio and the binding constant of the tBC-DCMAQ complex were determined.

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