Substituted <i>p</i>-phenylene vinylene oligomers are bright molecules which display strong solvatochromism in the photoluminescence spectrum. Solvatochromic shifts range from 10 to over 100 nm, depending on substituent. The mechanism of these shifts is thought to be mainly due to aggregation effects, but the role of solvent dielectric effects has not been ruled out. To confirm this, we explored the excited state potential energy surfaces of substituted PPVOs in various solvent with excited state molecular dynamics (ESMD). These adiabatic ESMD use a time-dependent Hartree-Fock scheme with semiempirical model chemistry. The role of dielectric solvent effects is simulated in absorption and fluorescence by using an implicit solvent model which simulates a dielectric cavity, in this case the conductor-like polarizable continuum model. Simulated fluorescence solvatochromism is due to dielectric effects only. Results are compared with single point time-dependent density functional theory calculations to confirm our method accuracy. It is found that very little solvatochromism is attributable to dielectric effects, such that the mechanism of large solvatochromic shift is safely assigned to aggregate emission. Future applications of ESMD with implicit solvent are discussed and suggestions for further improvements on ESMD with implicit solvent are given.

Simulations of fluorescence solvatochromisms in substituted <i>p<</i>-phenylene vinylene oligomer derivatives: Excited state molecular dynamics with implicit solvent

249th National Meeting (2015)

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Simulations of fluorescence solvatochromisms in substituted p<-phenylene vinylene oligomer derivatives: Excited state molecular dynamics with implicit solvent