Abstract

The polycyclic p-quinodimethanes are proposed to be the novel candidates of the high-performance nonlinear optical (NLO) materials because of their large third order polarizabilities (γ). We investigate the switchable NLO responses of a series of polycyclic p-quinodimethanes with redox properties by employing the density functional theory (DFT). The polycyclic p-quinodimethanes are forecasted to exhibit obvious pure diradical characters because of their large y 0 index (the y 0 index is a value between 0 [closed-shell state] and 1 [pure biradical state]). The γ values of these polycyclic p-quinodimethanes and their corresponding one-electron and two-electron reduced/oxidized species are calculated by the (U)BHandHLYP method. The γ values of polycyclic p-quinodimethanes and their corresponding one-electron reduced species are all positive and significantly different. The large differences of the γ values are due to a change in the transition energy and are related to the different delocalization of the spin density, which demonstrates that the NLO switching is more effective on one-electron reduction reactions. Therefore, the study on these polycyclic p-quinodimethanes provides a guideline for a molecular design of highly efficient NLO switching. FigureThe NLO switching is more effective on one-electron reduction reaction Electronic supplementary materialThe online version of this article (doi:10.1007/s00894-013-2035-1) contains supplementary material, which is available to authorized users.

Highlights

  • Over the last two decades, high-performance nonlinear optical (NLO) materials have been designed and synthesized [1,2,3,4,5,6]

  • The ΔE S−T values decrease gradually from 1 to 3, which means that the diradical characters of molecules 1 –3 increase progressively

  • These molecules can be viewed as third order redox NLO switching

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Summary

Introduction

Over the last two decades, high-performance nonlinear optical (NLO) materials have been designed and synthesized [1,2,3,4,5,6]. We present the detailed quantum-chemical analysis of the origin of the third order NLO responses for the molecules 1, 2, and their corresponding one-electron and two-electron reduced/ oxidized species. In order to verify the reliability and accuracy of the method, we chose diradical molecule 1 and its one-electron reduced specie 1a as examples to calculate the γ values by CAM-B3LYP and BHandHLYP functionals.

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