Madhushree Sarkar

Coordination polymers of Ag(I) with di-Schiff base and diaminoalkanes: double helix, ladder, CdSO4 and zigzag-chain networks

A new di-Schiff base ligand has been prepared from 3-acetylpyridine and 1,2-diaminoethane and its structure has also been characterized by single crystal X-ray diffraction. Furthermore, the ligand was found to form a 1 : 1 complex with Ag(NO3) in CH3CN. The crystal structure of the complex exhibits a 1D-double helix with the pitch length of 10 A. In these reactions, the ligand was found to disintegrate into the individual components to form a crystal of a 3D-network which comprised of Ag(NO3) and 1,2-diamino ethane. Nitrate ions occupied the channels and form several N–H⋯O hydrogen bonds with the walls of the channels. Interestingly, the topology of the 3D-network was found to be similar to that of the CdSO4. This structure prompted us to study the reactions of Ag(NO3) with 1,2-diaminoethane, 1,2-diaminopropane and 1,3-diaminopropane. The crystal structures of these complexes reveal that 1,2-diaminoethane forms the 3D-network similar to the above reaction, whereas 1,2-diaminopropane and 1,3-diaminopropane form a ladder and 1D-zigzag chain, respectively.

Photophysical properties of di-Schiff bases: evaluating the synergistic effect of non-covalent interactions and alkyl spacers in enhanced emissions of solids

Photophysical properties of di-Schiff base compounds in the solution and solid states are explored. The di-Schiff bases with alkyl spacers (ethyl, butyl and hexyl) showed enhanced light emitting properties in the solid state, while quenching was observed for di-Schiff bases with a hydrazine spacer. The photoluminescence spectra and the crystal structure were compared with bis-pyridyl-ethyl-di-imine and bis-pyridyl-butyl-di-imine. The crystal structure analysis of the compounds rationalizes the observed results. The concentration dependent 1H-NMR and NOESY spectra showed the aggregation behaviour of the compounds.

Effects of non covalent interactions in light emitting properties of bis-pyridyl-alkyl-di-imines

The crystal structures of three bis-pyridyl-alkyl-di-imines are studied. The non-covalent interactions lead to the packing of the crystals of the compounds in such a way that crystallization induced emission (CIE) is observed for bis-pyridyl-ethyl-di-imine and bis-pyridyl-butyl-di-imine, while for bis-pyridyl-di-imines, with no alkyl spacer, the luminescence is absent in the solid state. The enhanced emission in the solid state is attributed to the collective effects of planarization and the specific arrangement of molecules.