Tetraphenylethene– and diphenyldibenzofulvene–anthracene-based fluorescence sensors possessing photo-induced electron transfer and aggregation-induced emission enhancement characteristics for detection of water?

New Journal of Chemistry Pub Date: 2018-07-05 DOI: 10.1039/C8NJ02522C

Abstract

We have designed and developed a tetraphenylethene (TPE)–anthracene–(aminomethyl)-4-cyanophenylboronic acid ester (AminoMeCNPhenylBPin) structure (RS-1) and a diphenyldibenzofulvene (DPDBF)–anthracene–AminoMeCNPhenylBPin structure (RS-2) possessing PET (photo-induced electron transfer) and AIEE (aggregation-induced emission enhancement) characteristics as PET/AIEE hybrid fluorescence sensors for detection of water in the low and high water content regions in solvents, where the TPE or DPDBF unit is directly attached to the 10-position on the anthracene skeleton. For both RS-1 and RS-2 the enhancement of the fluorescence band at around 430 nm in the low water content region below 1.0 wt% is attributed to the fluorescence emission originating from the anthracene skeleton due to the formation of PET inactive species RS-1(H2O) and RS-2(H2O), respectively, upon addition of water molecules. Furthermore, the appearance of new and broad fluorescence bands at around 450 nm for RS-1 and 530 nm for RS-2 in the high water content region of over 60–70 wt% is attributed to the AIEE characteristics due to the restricted intramolecular rotation (RIR) of the TPE or DPDBF unit associated with aggregate formation (RS-1(H2O)-A and RS-2(H2O)-A). It is worth noting that a big difference in the enhancement of the fluorescence band originating from the anthracene skeleton due to the suppression of the PET characteristics and the appearance of a fluorescence band due to the AIEE characteristics with aggregate formation between RS-1 and RS-2 was observed: for RS-2 the separation of fluorescence peak wavelengths originating from the anthracene skeleton (at ～430 nm) and due to the RIR of the DPDBF unit with the aggregate formation (at ～530 nm) is clear, but for RS-1 the separation of fluorescence peak wavelengths is completely indistinct. Consequently, this work indicates that RS-2 having a DPDBF unit on the anthracene skeleton can act as a PET/AIEE hybrid-based dual-fluorescence emission sensor for detection of water in the low and high water content regions in solvents.

Graphical abstract: Tetraphenylethene– and diphenyldibenzofulvene–anthracene-based fluorescence sensors possessing photo-induced electron transfer and aggregation-induced emission enhancement characteristics for detection of water
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