Synthesis of Oxazolones with Extended Conjugation and Evaluation of their Linear and Nonlinear Optical Photochemistry

Abstract

Oxazolones or azlactones are small heterocyclic systems that can be easily functionalized with a double bond directly attached to their structure. In addition, they can be substituted on the opposite side of the heterocycle with styrenyl groups to extend their conjugation. This allows for versatile tuning of their linear and non‐linear optical properties. In this work, eight doubly substituted oxazolones including different push‐pull or pull‐pull designs were synthesized, and their linear and non‐linear photophysical properties were studied. As we show, the two‐photon activity of these systems is dependent on the donor‐acceptor pattern, where a methoxy substitution on the styrene end of the molecule and an acetyl group on the other end shows two‐photon Z‐E conversion properties with an important two photon absorption cross section of 308 GM. Most oxazolones shown in this study undergo picosecond relaxation to the electronic ground state, releasing the biphotonic energy to their surrounding environment. The results obtained in this work are indicative of potential applications of these molecules in schemes where high spatial patterning or thermalization is required.