Quantum mechanical calculations of different monomeric structures with the same electroactive group to clarify the relationship between structure and ultimate optical and electrochemical properties of their conjugated polymers

Abstract

Quantum mechanical calculations can clarify the relationship between structure and ultimate optical and electrochemical properties of conjugated polymers and produce a ground for the design of advanced materials for futuristic applications. Herein, we have examined the structural geometries and electronic properties of different monomeric structures with the same electroactive group to provide a relationship between calculated electronic properties of the monomers with the observed optical and electrical properties of their conjugated polymers. For this purpose, three different amide substituted 2,5-di(2-thienyl)-1H-pyrrole compounds containing a different number of electroactive groups have been synthesized and molecular structure optimizations have been carried out with the Density Functional Theory (DFT) calculations. FT-IR and NMR spectra of optimized geometries have been compared with experimental data. Furthermore, electronic properties of the monomeric structures such as chemical hardness/softness, ionization potential, HOMO-LUMO energy levels, electronegativity have been revealed and molecular electrostatic potential (MEP) surface has been calculated to determine the electrophilic and nucleophilic reactive attack regions of the molecules considered in this study. Finally, Total Density of State (TDOS), Partial Density of State (PDOS) and Mulliken charge analyses of these molecules have been carried out. Our calculations based on ab-initio methods for the monomers have been compared with the optical and electrical properties of their conductive polymers in order to understand interrelationship between monomer structure and polymer properties.