Applications of novel triptycene based ligands and chitosan polymer in organic chemistry

Abstract

One-pot synthesis of triptycene based non-chiral and chiral macrocyclic ligands was successfully accomplished in high yields and characterized by IR, 1H NMR, 13C NMR and HRMS. Theoretical calculations were performed to ascertain their heartshaped cavity decorated with moderate intra-molecular hydrogen bonding. The hydrophilic nature was mapped with electrostatic potential surfaces representing high electron density on the surface of cavity. DFT studies evidences for the co-existence of their enol-imine and keto-enamine tautomers and electrostatic intramolecular hydrogen bonding which was also evidenced by broadened peaks in the solution-phase NMR. Novel triptycene based conjugated macrocyclic fluorophores showed high solvatochromic effect and large stokes shifts. These were developed as efficient and selective chemosensors for copper ion sensing in water. Determination of Cu2+ ions in real water samples also provided reliable results with the recovery range of 85-120 %. Type IV nitrogen adsorption-desorption BET isotherms representing mesoporous nature make them potential candidates as OMIMs for adsorption applications. The novel triptycene based chiral cobalt complexes were explored as asymmetric transition metal catalysts for various C-C and C-N bond forming enantioselective organic transformations such as aldol condensation, nitro-aldol reaction and epoxide opening ring opening reactions. Aldol products were achieved in quantitative yields with excellent diastereoselectivity but with moderate enantioselectivity. Epoxide ring opening reaction showed high chemosselectivity with poor stereo-control. In addition to this, we have successfully established two eco- friendly catalytic systems i.e. chitosan in water and aqueous inclusion complex as efficient heterogeneous and selective organocatalytic systems for the C-C bond formation reactions to obtain the products in high yields. newline