Effect of backbone conformation and its defects on electronic properties and assessment of the stabilizing role of π–π interactions in aryl substituted polysilylenes studied by DFT on deca[methyl(phenyl)silylene]s

Abstract

BackgroundRecent efforts in the field of mesoscale effects on the structure and properties of thin polymer films call to revival interest in conformational structure and defects of a polymer backbone which has a crucial influence on electronic properties of the material. Oligo[methyl(phenyl)silylene]s (OMPSi) as exemplary molecules were studied theoretically by DFT in the form of optimal decamers and conformationally disrupted decamers (with a kink).ResultsWe proved that transoid backbone conformation is true energy minimum and that a kink in the backbone causes significant hypsochromic shift of the absorption maximum (λmax), while backbone conformation altering from all-eclipsed to all-anti affects λmax in the opposite way. π–π stacking was investigated qualitatively through optimal geometry of OMPSi and mutual position of their phenyls along the backbone and also quantitatively by an evaluation of molecular energies obtained from single point calculations with functionals, which treat the dispersion effect in the varying range of interaction.ConclusionsThe kink was identified as a realistic element of the conformational structure that could be able to create a bend in a real aryl substituted polysilylene chain because it is stabilized by attractive π–π interactions between phenyl side groups.Graphical abstract.Electronic supplementary materialThe online version of this article (doi:10.1186/s13065-016-0173-0) contains supplementary material, which is available to authorized users.

An experimental and theoretical study of the structural ordering of the PTB7 polymer at a mesoscopic scale

“…A specific threshold in optoelectronic behaviour can be observed between nano-and microscale, situated at about several hundred nm as shown in our previous work [21,22] on thin films as well as reported for physical parameters of photovoltaic diodes (conjugated polymerfullerene based heterojunction diodes) by other authors [23]. The effect of the polymer chain conformational disorder was also investigated in theoretical studies [24,25]. Also, the dielectric properties of insulating films (polyimides) are found to be sensitive to the polymer chain orientations' dependence on the thickness scale threshholding between one hundred and one thousand nanometers [26].…”