Coordination between lanthanide (III) ions and organic ligands of natural pharmaceutical containing lactone group probed by DAOSD approach

Two-dimensional (2D) correlation spectroscopy provides an important approach to the study of subtle spectral variations caused by intermolecular interactions. In our previous work, DAOSD (Double Asynchronous Orthogonal Sample Design) scheme was introduced to analyze subtle spectral variations of characteristic peaks of substance under intermolecular interactions. In this paper, we apply DAOSD scheme to probe weak coordination between lanthanide (III) ions and lactone group of organic ligands from natural pharmaceutical. Weak coordinative interaction between Nd3+ and carbonyl group in Nd(ClO4)(3)/artemisinin in acetonitrile solutions is characterized by using 2D UV/IR hetero-correlation spectroscopy. Experimental results demonstrate that subtle band-shift and variation on the absorptivity can be observed on both carbonyl band of artemisinin and f-f transition band of Nd3+ ions upon coordination.