Supramolecular phosphorescent trinuclear copper(I) pyrazolate complexes for vapochromic chemosensors of ethanol

• Main Authors: Lintang, H. O., Ghazalli, N. F., Yuliati, L.
• Format: Article
• Language: English
• Published: Gadjah Mada University 2017
• Subjects: QC Physics
• Online Access: http://eprints.utm.my/id/eprint/74913/1/HendrikOktendyLintang_SupramolecularPhosphorescentTrinuclearCopper.pdf; http://eprints.utm.my/id/eprint/74913/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026679390&doi=10.22146%2fijc.22553&partnerID=40&md5=2f5b8ecfd0019518733ac8a6259b33cf
• Institution: Universiti Teknologi Malaysia

We highlight that by using supramolecular single crystals of phosphorescent trinuclear copper(I) pyrazolate complexes with different molecular structures (2A-E), vapochromic chemosensors were successfully designed for sensing ethanol with high sensing capability. These complexes 2A-E were synthesized from non-side chain, 3,5dimethyl, 3,5-bis(trifluoromethyl), 3,5-diphenyl and 4-(3,5-dimethoxybenzyl)-3,5-dimethyl pyrazole ligands (1A-E) in 83, 97, 99, 88 and 85% yields, respectively. All complexes showed emission bands centered at 553, 584, 570 and 616 nm upon an excitation at 280 nm for complexes 2A-C,E, respectively and 642 nm upon an excitation at 321 nm for complex 2D with lifetime in microseconds, indicating a large Stoke shift for phosphorescent compounds. These emission spectra were in good agreement with their colors from green to red upon exposure to a UV lamp with an excitation at 254 nm in dark room. Upon exposure to ethanol in 5 min, quenching, photoinduced energy transfer and shifting of emission intensities were observed for chemosensors 2A-C, 2D and 2E, respectively. Interestingly, chemosensor 2E only showed completely and autonomously recovery of its original emission intensity. Such novel finding in sensing capability might be caused by a weak intermolecular hydrogen bonding interaction of ethanol to oxygen atoms at dimethoxybenzyl side-chains of the pyrazole ring.