Crystal Engineering of Co ordination Polymers CPs Derived from Bis pyridyl amides and Analyzing Their Structural Transformations Triggered by External Stimulus

Abstract

The thesis entitled Crystal Engineering of Co-ordination Polymers (CPs) Derived from Bis-pyridyl amides and Analyzing Their Structural Transformations Triggered by External Stimulus deals with the synthesis of flexible reverse bis-pyridyl-bis-amide ligands having different alkyl spacer and their co-ordination polymers (CPs) with Cu(II) and Cd(II). The detailed structures of the co-ordination polymers are determined using single crystal XRD technique. The chapter 1 of thesis provides the literature survey on structure of the CPs, their post synthetic modification and various applications related to porous nature. The different networks of 4.4 -Bipyridine and other bidentate ligands are discussed and the effect of introducing hydrogen bonding moiety in the ligand on the network geometry is analyzed. The intermolecular interactions i.e. hydrogen bonding, and#960;-and#960; interactions, co-ordinate bond interaction and their strength and role in organizing supramolecular geometry is also discussed. Chapter 2 deals with the instrumental techniques, used by us in our work for characterization of CPs. newlineChapter 3 of thesis is about the synthesis CP of ligand 1a with Cu(II) salts, where the ligand 1a is a bis-pyridyl-bis-amide with ethyl spacer. The ligand 1a formed 1D-looped chain network (CP1) with Cu(PF6)2, where the anion PF6- involved in hydrogen bonding with the amide and resulted in unavailability of space for guest inclusion in the loops. The exchange of PF6and#8722; ion with ClO4and#8722; ion resulted in the intake of aromatic guest molecules, which were monitored by IR and UV-Vis spectroscopy. The capability of the flexible ethyl spacer of 1a to adjust the conformation according to the requirements of the other components of the networks is observed in this chapter. This resulted in reversible inclusion and removal of guest molecules triggered by the exchange of anions. In Chapter 4, CPs of ligand 1b with Cu(ClO4)2 resulted 2D network (CP3), which showed two-fold parallel interpenetration; whereas with Cd(ClO4)2 is a 1D network