[Investigation on the molecular structures and electronic absorption spectra of Tanshinone II A and Tanshinone II A -Cu(II) complex].

Using an intensified spectroscopic detector CCD, the UV-Vis absorption spectra of tanshinone II A and Tanshinone II A-Cu(II) complex were acquired. The stable geometric structures of Tanshinone II A and Tanshinone II A -Cu(II) complex were obtained by using density functional theory method. Based on the optimized geometric structures, the electronic absorption spectra of Tanshinone II A and Tanshinone II A-Cu(II) complex in gas phase and in ethanol solution were calculated by using time-dependent density functional theory. Results show that the solvent effect induces the red shift of spectrum for Tanshinone II A and the blue shift of spectrum for Tanshinone II A-Cu(II) complex. The calculated absorption spectra including the solvent effect are in good agreement with the experimental results. The present work first measured and computed the electronic absorption spectra of Tanshinone II A-Cu(II) complex.