Fluorescence emission studies of an azlactone derivative embedded in polymer films - An optical sensor for pH measurements
Küçük Resim Yok
Tarih
2000
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Science Sa
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Azlactone molecules can be protonated in acidic media, and the process of protonation is irreversible due to ring opening in solutions. A new fully reversible pH sensor has been developed 4-(p-N,N-dimethylamino phenyl methylene)-2-phenyl-5-oxazolone (DPO), an azlactone derivative, embedded in a plasticized PVC polymer film. The sensor membrane is completely transparent and exhibits pH induced color change which is capable of measuring of pH in the range 1-7 and has a pK(a) value of 3.4. In agreement with crystal phase studies, DPO displays enhanced fluorescence emission quantum yield, Q(f) = 0.52, and fluorescence emission lifetime, tau (f) = 1.35 ns, in immobilized PVC film matrix, compared to Q(f) congruent to 0.03 and tau (f) = 0.02-0.03 ns in solutions. Stokes shift decreased to 46 nm in plasticized PVC film, with respect to Stokes shift of 81 nm in acetonitrile solution. Singlet energy, E-s = 60.4 kcal mol(-1), of DPO in PVC film, which is 1.1-1.4 kcal mol(-1) lower with respect to solutions, is taken as evidence of lessened singlet-triplet crossings in excited state of DPO in immobilized phase, and result in enhanced fluorescence emissions. (C) 2000 Elsevier Science B.V All rights reserved.
Açıklama
Anahtar Kelimeler
optical sensor, fluorescence emission, azlactone, pH, polymer film
Kaynak
Journal of Photochemistry and Photobiology A-Chemistry
WoS Q Değeri
Q3
Scopus Q Değeri
Cilt
137
Sayı
02.Mar
