| dc.description.abstract | Organometallic polymers have been identified as a class of materials useful in various advanced applications due to their promising electrical, magnetic, optical and catalytic properties. Such properties depend on the orbital interactions between metal ions and ligands, which allow for a mechanism for electronic tuning of the metal environment and properties. [2.2]Paracyclophane has been extensively studied due its unusual structural and electronic properties that arise from the co-facial arrangement of two benzene rings bridged by ethano groups. In this work, ferrocenyl Schiff’s bases derived from [2.2]paracyclophane were synthesized to study the electronic behavior of iron centers in ferrocene mediated through the [2.2]paracyclophane moiety. A Schiff’s base ligand of 4-amino[2.2]paracyclophane has also been synthesized and studied with regards to its geometric constraints. Attempts were also made to synthesize polymeric copper Schiff’s base complexes to study the electronic coupling of copper atoms mediated through [2.2]paracyclophane.
It has been well understood that the [2.2]paracyclophane moiety behaves as an electron donating group but how it behaves when attached to a redox center has not been explored or quantified. We report here the synthesis and electrochemical study of a series of ferrocenyl imine Schiff’s bases, including the Schiff’s base derived from 4-amino[2.2]paracyclophane. All these ferrocenyl Schiff’s bases showed one-electron redox behavior in their cyclic voltammograms, and their redox potentials were found to correlate linearly with Hammett substituent constants (σ) and (σ+), where the reaction constant (ρ) values were found to be ca. 0.95 and 0.8, respectively. A detailed discussion of the interaction of the [2.2]paracyclophane moiety with the iron redox center will be presented.
Understanding the electronic ability of the [2.2]paracyclophane to modify the redox behavior of ferrocene, we report the synthesis and electronic interactions between the two iron centers in a bis(ferrocenyl Schiff’s base) separated by [2.2]paracyclophane. This study was carried out using cyclic voltammetry, to monitor the electrochemical behavior. A mixed-valent state was observed in this system and the electronic effect of one iron center on the other iron center mediated through [2.2]paracyclophane was determined by calculating comproportionation constant (Kc), which is equal to 240. The result showed weak interactions between the two iron centers mediated through [2.2]paracyclophane moiety.
In another study, Schiff’s base ligands of [2.2]paracyclophanes were synthesized by condensation reactions of amino[2.2]paracyclophanes with salicylaldehyde. Geometrical constraints were studied for the Schiff’s base ligand derived from 4-amino-[2.2]paracyclophane using UV-visible spectroscopy and computational methods. The ligand geometry was found to be distorted from planarity with the [2.2]paracyclophane unit. Studies were carried out on the synthesis of copper complexes of Schiff’s base ligands based on 4-amino[2.2]paracyclophane and pseudo-para-4,12-diamino[2.2]paracyclophane isomers.
Finally, the electrochemical growth of poly(2,2’-bithiophene) (PBT) from 2,2’-bithiophene in sodium dodecylsulfate (SDS) aqueous media was studied using cyclic voltammetry. Different concentrations of SDS and BT were used to optimize the polymer growth. The optimization of such growth depends on the number of BT molecule per SDS micelles in aqueous media and the mechanism for film growth is discussed in detail. | en_US |
