Quantum Chemical Studies On The Properties Of Several Conjugated Conducting Polymers

In this paper, pyridine, poly(2,5-pyridinediyl)(PPY), 5,10-dimethylene-5,10-dihydroindolo[6,5-f]indole (DDI) and its polymer(trans-PDDI and cis-PDDI) are studied by means of the Density Functional Theory(DFT). According to the calculated results, the relationship between structure and conductivity for the organic conductors is analyzed in detail.1 Quantum Chemical Studies on the Properties of Poly (2,5-pyrid-inediyl)The geometries of pyridine and its several oligomers (as shown in figure 1, n is from 2 to 8), are optimized at the B3LYP/6-31G^* level by means of quantum chemistry methods. Population analysis and thermodynamic calculations are also carried out based on the optimized structures. The band structure and density of states of PPY are calculated with the same basis sets. The results show pyridine molecule has planar structure and PPY has stable chain structure. PPY is easy to form the N-type doped polymer. Moreover, the calculations suggested that the PPY can be doped due to the present of protonic acid. It is predicted that the zero point energy (ZPE), heat capacity (C_v<sup>o) and entropy (S^o) of pyridine oligomers (C_5nH_3n+2Nn) increase linearly with the increase of n value. In addition, our results indicate that the capability of conductivity for these studied systems will become more excellent with the increase of the polymerization degree of PPY. However, it is finite to enhance conductivity of PPY through this method. 2 Quantum chemical studies on the 5,10-dimethylene-5,10-dihydroindolo[6,5-f]indole and its polymersIn this section, the geometries of DDI,trans-PDDI and cis-PDDI are optimized by means of the density functional theory (DFT), using the B3LYP functional. Considering the relationship between the precision and efficiency, basis sets 6-31G^* are chosen for the studied systems. In order to obtain the information about the conductivity, the band structures of trans-PDDI and cis-PDDI are investigated by the one-dimensional periodic boundary condition. The calculated results predicted that the DDI and its oligomers have planar geometries, and the trans-PDDI and cis-PDDI polymers possess the conjugatedπbonds. According to the results from the calculations of the band structures and electronic properties, it is predicted that the trans-PDDI and eis-PDDI have potential good conductivity, and the conductivity of the cis-PDDI is better than the trans-PDDI.