A spectroscopic investigation of the photophysical behaviour of 9-aminoacridine hydrochloride hydrate in presence of organic amines in homogeneous and heterogeneous media

Abstract

Photoinduced interactions of 9-aminoacridine hydrochloride hydrate (9AA-HCl) with aromatic and aliphatic amines, N,N'-dimethylaniline (DMA) and triethylamine (TEA) respectively have been investigated in homogeneous water–acetonitrile (1:1) mixture as well as in heterogeneous cetyltrimethyl ammonium bromide (CTAB) micellar media using UV–vis absorption, steady-state as well as time-resolved fluorescence spectroscopies and laser flash photolysis technique associated with a weak external magnetic field (MF). Differential modes of fluorescence quenching of 9AA-HCl with DMA and TEA corroborated with absorption studies reveal their disparity in the mechanism of interactions. Excited state proton transfer (ESPT) and photoinduced electron transfer (PET) are the phenomenon that have been found to be involved in with DMA, whereas with TEA ground-state complex formation, ground-state proton transfer and PET are prevalent. Discrepancy in pH of the interfacial and hydrophobic regions of CTAB facilitates the partitioning of the protonated and neutral forms of 9AA-HCl leading to differential occupational sites of the acceptor and donor moieties in the micellar medium, thus making the study more intriguing. Another important aspect of the present study is the use of MF to confirm the occurrence of PET, authenticate the spin-state of the intermediates thus formed and also to resolve the process of PET and ESPT.