Synthesis and Spectroscopic Properties of 1 H -Cyclohepta[2,1- b :3,4- b’ ]diindole and Molecular Structure of its Protonated Species

The title compound 9 was synthesized by condensation of 2,2’-biindole and 1-chloro-3-( N,N -dimethylamino) propenium chloride in 1,2-dichloroethane. NMR and UV-vis absorption spectra of 9 under neutral, acidic and basic conditions were discussed in respect of its protonation and deprotonation. A crystal structure of its protonated species, 9H + TfO – , was determined by X-ray diffraction analysis, indicating its planar and symmetrical structure. Change of absorption spectra of 9 in the presence of a large excess of various metal ions was studied to find out a mode of interaction between 9 and metal ion.