title: Tetraphenylethene-Based Conjugated Fluoranthene: A Potential Fluorescent Probe for Detection of Nitroaromatic Compounds.
abstract: This study reports the synthesis and photophysical properties of a star-shaped, novel, fluoranthene-tetraphenylethene (TFPE) conjugated luminogen, which exhibits aggregation-induced blue-shifted emission (AIBSE). The bulky fluoranthene units at the periphery prevent intramolecular rotation (IMR) of phenyl rings and induces a blueshift with enhanced emission. The AIBSE phenomenon was investigated by solvatochromic and temperature-dependent emission studies. Nanoaggregates of TFPE, formed by varying the water/THF ratio, were investigated by SEM and TEM and correlated with optical properties. The TFPE conjugate was found to be a promising fluorescent probe towards the detection of nitroaromatic compounds (NACs), especially for 2,4,6-trinitrophenol (PA) with high sensitivity and a high Stern-Volmer quenching constant. The study reveals that nanoaggregates of TFPE formed at 30 and 70% water in THF showed unprecedented sensitivity with detection limits of 0.8 and 0.5 ppb, respectively. The nanoaggregates formed at water fractions of 30 and 70% exhibit high Stern-Volmer constants (Ksv=79,998 and 51,120 M(-1), respectively) towards PA. Fluorescence quenching is ascribed to photoinduced electron transfer between TFPE and NACs with a static quenching mechanism. Test strips coated with TFPE luminogen demonstrate fast and ultra-low-level detection of PA for real-time field analysis.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India), Fax.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Chandrasekaran
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India), Fax.
authors.forename: Nutalapati
authors.identifier: http://orcid.org/0000-0003-0235-2707
authors.initials: N
authors.lastname: Venkatramaiah
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India), Fax. satish@sscu.iisc.ernet.in.
authors.forename: Satish
authors.initials: S
authors.lastname: Patil
keywords: aggregation; conjugation; fluorescence; sensors; structure-activity relationships