TY - JOUR
T1 - Time-resolved photoluminescence of 6-thienyl-lumazine fluorophores in cellulose acetate nanofibers for detection of mercury ions
AU - Al-Shamsi, Noura
AU - Laptenok, Sergey P.
AU - Bufaroosha, Muna S.
AU - Greish, Yaser E.
AU - Saleh, Na'il
N1 - Funding Information:
All authors thank the research program in United Arab Emirates University for financial grant numbers ECEER-1-2017 .
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/11/5
Y1 - 2019/11/5
N2 - Time-resolved photoluminescence measurements were used to characterize the photophysical properties of 6-thienyllumazine (TLm) fluorophores in cellulose acetate nanofibers (NFs) in the presence and absence of mercuric acetate salts. In solution, excited-state proton transfer (ESPT) from TLm to water molecules was investigated at pH from 2 to 12. The insertion of thienyl group into lumazine introduces cis and trans conformers while keeping the same tautomerization structures. Global and target analyses were employed to resolve the true emission spectra of all prototropic, tautomeric, and rotameric species for TLm in water. The results support the premise that only the cis conformers are related to the ESPT process. However, no ESPT from TLm to a nearby water molecule was observed in NFs. The addition of NFs increases the excited-state lifetime of TLm in the solid state because of combined polarity/confinement effects. The solid-state fluorescence of TLm (in NFs) was quenched by mercuric acetate through different mechanisms—dynamic and static—depending on the applied pressure—atmospheric and vacuum, respectively. The new solid-state sensor is simple, ecofriendly, and instantly fabricated. TLM-loaded NFs can detect mercuric ions at a concentration of 50 picomolar. The formation of non-fluorescent ground-state complex between TLm molecules and mercuric ions inside the pores of NFs was achieved under vacuum condition.
AB - Time-resolved photoluminescence measurements were used to characterize the photophysical properties of 6-thienyllumazine (TLm) fluorophores in cellulose acetate nanofibers (NFs) in the presence and absence of mercuric acetate salts. In solution, excited-state proton transfer (ESPT) from TLm to water molecules was investigated at pH from 2 to 12. The insertion of thienyl group into lumazine introduces cis and trans conformers while keeping the same tautomerization structures. Global and target analyses were employed to resolve the true emission spectra of all prototropic, tautomeric, and rotameric species for TLm in water. The results support the premise that only the cis conformers are related to the ESPT process. However, no ESPT from TLm to a nearby water molecule was observed in NFs. The addition of NFs increases the excited-state lifetime of TLm in the solid state because of combined polarity/confinement effects. The solid-state fluorescence of TLm (in NFs) was quenched by mercuric acetate through different mechanisms—dynamic and static—depending on the applied pressure—atmospheric and vacuum, respectively. The new solid-state sensor is simple, ecofriendly, and instantly fabricated. TLM-loaded NFs can detect mercuric ions at a concentration of 50 picomolar. The formation of non-fluorescent ground-state complex between TLm molecules and mercuric ions inside the pores of NFs was achieved under vacuum condition.
KW - ESPT
KW - Fluorescence quenching
KW - Lumazine
KW - Nanofibers
KW - Time-resolved photoluminescence
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U2 - 10.1016/j.saa.2019.117189
DO - 10.1016/j.saa.2019.117189
M3 - Article
C2 - 31177004
AN - SCOPUS:85066740507
SN - 1386-1425
VL - 222
JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
M1 - 117189
ER -