Chromophore Planarity, –BH Bridge Effect, and Two-Photon Activity: Bi- and Ter-Phenyl Derivatives as a Case Study
Swati Singh Rajput, Robert Zaleśny, Md. Mehboob Alam
Abstract
High Resolution Image Download MS PowerPoint Slide In this work, we have employed electronic structure theories to explore the effect of the planarity of the chromophore on the two-photon absorption properties of bi- and ter-phenyl systems. To that end, we have considered 11 bi- and 7 ter-phenyl-based chromophores presenting a donor−π–acceptor architecture. In some cases, the planarity has been enforced by bridging the rings at ortho-positions by −CH 2 and/or –BH, –O, –S, and –NH moieties. The results presented herein demonstrate that in bi- and ter-phenyl systems, the planarity achieved via a −CH 2 bridge increases the 2PA activity. However, the introduction of a bridge with the –BH moiety perturbs the electronic structure to a large extent, thus diminishing the two-photon transition strength to the lowest electronic excited state. As far as two-photon absorption activity is concerned, this work hints toward avoiding –BH bridge(s) to enforce planarity in bi- and ter-phenyl systems; however, one may use −CH 2 bridge(s) to achieve the enhancement of the property in question. All of these conclusions have been supported by in-depth analyses based on generalized few-state models.