title: Gelation-induced enhanced fluorescence emission from organogels of salicylanilide-containing compounds exhibiting excited-state intramolecular proton transfer: synthesis and self-assembly.
abstract: Self-assembly structure, stability, hydrogen-bonding interaction, and optical properties of a new class of low molecular weight organogelators (LMOGs) formed by salicylanilides 3 and 4 have been investigated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV/Vis absorption and photoluminescence, as well as theoretical studies by DFT and semiempirical calculations with CI (AM1/PECI=8) methods. It was found that salicylanilides form gels in nonpolar solvents due to pi-stacking interaction complemented by the presence of both inter- and intramolecular hydrogen bonding. The supramolecular arrangement in these organogels predicted by XRD shows lamellar and hexagonal columnar structures for gelators 3 and 4, respectively. Of particular interest is the observation of significant fluorescence enhancement accompanying gelation, which was ascribed to the formation of J-aggregates and inhibition of intramolecular rotation in the gel state.
authors.affiliation: Department of Chemistry, Texas A&M University at Qatar, PO Box 23874, Doha, Qatar.
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Nayak
authors.forename: Byung-Hwa
authors.initials: BH
authors.lastname: Kim
authors.forename: Ji Eon
authors.initials: JE
authors.lastname: Kwon
authors.forename: Sanghyuk
authors.initials: S
authors.lastname: Park
authors.forename: Jangwon
authors.initials: J
authors.lastname: Seo
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Chung
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Park