Hitting two birds with one stone: DPAC derivatization with o-carborane resulted in improved photochemical stability and enhanced sensing performance

Abstract

Innovative design of sensing materials is pivotal for the development of high-performance fluorescence film sensors (FFSs). In this work, we combined one or two o-carboranyl units into the skeleton of N,N′-diphenyldihydrodibenzo[a,c]phenazine (DPAC), a well-known fluorophore, and obtained two new DPAC derivatives, CbDPAC-Ph and bis-CbDPAC-Ph. We found incorporation of o-carborane not only enriches the stacking of DPAC, enhancing photostability and increasing the Stokes shift, but also facilitates analyte mass transfer in the fluorescent active layer due to increased molecular channels. Further studies revealed that the FFSs based on bis-CbDPAC-Ph exhibit outstanding cyclic stability and are highly sensitive to acrylonitrile (ACN), with a detection limit of 22 ppb, significantly lower than the 450-ppb threshold value recommended by the Risk Assessment Committee (RAC) of Europe for workplaces. Moreover, with a response time within 2 s and a full recovery time of less than 2 min, this device shows promising potential for developing into a portable ACN detector.