Studies on Inclusion Complexes of Nitrosubstituted Indole Derivatives

A number of [arylidenamino]-1,3,4-thiadiazino[6,5b]indoles with nitro groups have been synthesized in their purest form starting from indole-2,3-dione and using ortho, meta and para nitro benzaldehyde. In order to increase the solubility of these compounds in polar medium, their inclusion complexes have been prepared with β-cyclodextrin. The formation of compounds and their inclusion complexes have been ascertained from elemental analysis and study of spectral characteristics. The stability of inclusion complexes is known from the study of thermodynamics parameters like change in free energy, change in enthalpy and change in entropy. The results clearly suggest existence of noncovalent intermolecular forces in between the guest compounds and host β-cyclodextrin during inclusion complex formation.