Synthesis and Characterization of Acid-Responsive Luminescent Fe(II) Metallopolymers of Rigid and Flexible Backbone N-Donor Multidentate Conjugated Ligands.

In this report we have disclosed the syntheses and properties of two new conjugated organic moieties bearing the same coordination sites but possessing different backbone rigidities and rotational flexibilities. Two new metallopolymers have been synthesized from the corresponding ligands under identical reaction conditions, and they have been thoroughly characterized through different techniques to understand the effect of backbone rigidity on the evolution of different properties in these metallopolymers. A FESEM micrograph of the rigid metallopolymer confirms the formation of a rigid nanorod type structure, while long agglomerated nanofiber strands are visible on the substrate in the case of the flexible analogue. All of the newly synthesized materials are fluorescence active. An Fe(II) metallopolymer of the flexible ligand showed huge changes in emission properties in the presence of different acids and showed a possibility of it being used as a thin film acid vapor sensor. All of the materials showed reversible electrochemical activity, and both of these polymers have shown electroluminescence when an appropriate potential is applied.