Excimer of 9-Aminoacridine Hydrochloride Hydrate in Confined Medium: An Integrated Experimental and Theoretical Study

详细信息    查看全文

• 作者：Piyali Mitra ; Brotati Chakraborty ; Dhananjay Bhattacharyya ; Samita Basu
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：February 21, 2013
• 年：2013
• 卷：117
• 期：7
• 页码：1428-1438
• 全文大小：561K
• 年卷期：v.117,no.7(February 21, 2013)
• ISSN：1520-5215

文摘

We aim to find out the extent of stability of the excimer of 9-aminoacridine hydrochloride hydrate (9AA), a prospective PDT drug, in different confined media with varying cavity size. When confined in cetyltrimethyl ammonium bromide micelles, although at low concentration of 9AA, only a single distinct peak (位_max at 460 nm) with a shoulder at 485 nm is observed in steady-state fluorescence spectrum, yet with increase in concentration the peak and the shoulder merge with simultaneous emergence of another peak at 535 nm, which is assigned to excimer. Similar behavior is also observed in Triton-X, crown ether, 伪-cyclodextrin, 尾-cyclodextrin, and homogeneous aqueous medium. The formation of excimer, which reflects the extent of confinement of 9AA, is maximum in 尾-cyclodextrin followed by others. Steady-state and time-resolved fluorescence studies along with TRES and TRANES analyses coupled with anisotropy data and transient absorption studies reveal the presence of monomer鈥揹imer equilibrium of 9AA in the excited state. Molecular modeling indicates that the structure of excimer is stabilized by locking of the two monomeric species via four hydrogen bonds formed between the amino-H and imino-N of 9AA monomers, whereas the dimer in the ground state has only two such hydrogen bonds.