Enhanced Luminescence Based Response towards pH in Highly Acidic Environments by the Silver Nanoparticles and Ionic Liquids

PubMed ID: 30919129Correct measurement of the pH in highly acidic environments is still a challenge. In such conditions most of the pH indicators suffer from instability in air or leaching from host matrices due to the solubility considerations. In this work, two different fluorescent probes were used along with silver nanoparticles (AgNPs) and ionic liquid (IL) in the polymeric matrices for sensing of the pH in harsh conditions. The pH sensitivities of the probes were tested after exposure to strong acid vapors by steady-state, lifetime based and kinetic mode measurements. The sensing materials were fabricated in form of thin films and electrospun nanofibers. The ionic liquid; 1-butyl-3-methylimidazolium tetrafluoroborate was exploited as additive to enhance the stability as well as response towards pH. Spectral changes were tested in a large scale; between pH 3.00–12.00. Utilization of the dyes in ethyl cellulose and polymethyl methacrylate along with AgNPs in form of electrospun fibers resulted in many advantages such as enhanced long term stability, sensitivity and improvement in all sensor dynamics. Sensing characteristics of the offered designs were tested after exposed to vapors of HCl, H2SO4 and HNO3, respectively. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Türkiye Bilimsel ve Teknolojik Araştirma Kurumu, TÃ?BITAKWe gratefully acknowledge that funding of this project was provided by the Scientific and Technological Research Council of Turkey (TUBITAK) (Research Fellowship Program for National Researchers, 2210-C). We also thank to the Scientific Research Funds of Dokuz Eylul University (project number: 2014. KB. FEN.040). -

Fiber optic pH sensing with long wavelength excitable Schiff bases in the pH range of 7.0-12.0

PubMed ID: 17386792Most of the fluorescent pH probes work near neutral or acidic regions of the pH scale. In this work, two different fluorescent Schiff bases, chloro phenyl imino propenyl aniline (CPIPA) and nitro phenyl imino propenyl aniline (NPIPA), have been investigated for pH sensing in the alkaline region. Absorption and emission based spectral data, quantum yield, fluorescence lifetime, photostability and acidity constant (pKa) of the Schiff bases were determined in conventional solvents and in PVC. The long wavelength excitable immobilized Schiff bases CPIPA (?ex = 556 nm) and NPIPA (?ex = 570 nm) exhibited absorption and emission based optical response to proton in the pH range of 8.0-12.0 and 7.0-12.0, respectively. Response of the CPIPA was fully reversible within the dynamic working range. The response times were between 3-13 min. A relative signal change of 95% and 96% have been achieved for sensor dyes of CPIPA and NPIPA, respectively. The CPIPA displayed better fluorescence quantum yield (?{symbol}F = 3.7 × 10-1) and higher matrix compatibility compared to NPIPA (?{symbol}F = 1.6 × 10-1) in immobilized PVC. The CPIPA and NPIPA exhibited a slight cross sensitivity to the ions of Hg+ and Fe3+, respectively. © 2007 Elsevier B.V. All rights reserved.104M268We thank Prof. Dr. Jean-Marie Salmon and Dr. Anne-Cecile Ribou for allowing time resolved based studies in their laboratory. Funding for this research was provided by the TUBITAK (Kariyer Project—104M268) and Scientific Research Funds of Dokuz Eylul University (Project No.: 2005 KB Fen 18). -

A long wavelength excitable fluorophore; Chloro Phenyl Imino Propenyl Aniline (CPIPA) for selective sensing of Hg (II)

In this study, a very sensitive and highly selective irreversible optical chemical sensor (optode) for mercury ions was described. The sensing scheme was based on the interaction of Hg (II) with a newly synthesized fluoroionophore; chloro phenyl imino propenyl aniline (CPIPA) in plasticized PVC membrane. The sensor membranes were tested for the determination of mercury ion in aqueous solutions by batch and flow-through methods. The optodes allow determination of Hg (II) in the working range of 1.0×10 -9-1.0×10 -5 M with a detection limit of 4.3 ppb. The sensor exhibited excellent selectivity for Hg (II) with respect to several common alkali, alkaline earth and transition metal ions. The association constant of the 1:1 complex formation for Hg (II) was found to be K a=1.86 × 10 5 M -1. The CPIPA exhibited high fluorescence quantum yield, long excitation and emission wavelength and high Stokes' shift values in the solid matrix which makes it compatible with solid state optics. © 2009 Springer Science+Business Media, LLC.Faculty of Arts and SciencesAcknowledgements The work was done in the laboratories of Dokuz Eylul University, Department of Chemistry, Faculty of Arts and Science and supported by the project of 2007 KB Fen 024. We also thank to the Scientific and Technological Research Council of Turkey (TUBITAK). -

Structure-Property Relationship in Amber Color Light-Emitting Electrochemical Cell with TFSI Counteranion: Enhancing Device Performance by Different Substituents on N^N Ligand

PubMed: 336670702-s2.0-85103451693Amber color emitting novel Ir(III) complexes were synthesized: [Ir(Meppy)2(Fpbpy)][PF6] (1bPF6), [Ir(Meppy)2(Fpbpy)][TFSI] (1bTFSI), [Ir(Meppy)2(MeObpy)][PF6] (2bPF6) and [Ir(Meppy)2(MeObpy)][TFSI] (2bTFSI), where Meppy = 2-(p-methylphenyl)-pyridine (b), Fpbpy = 4,4?-bis(4-fluorophenyl)-2,2?-bipyridine (1), and MeObpy = 4,4?-bis(4-methoxy)-2,2?-bipyridine (2). The photophysical and X-ray results showed that the complexes have aggregation-induced phosphorescent emission (AIPE) and a salt-induced polymorphism effect. The highest photoluminescence intensity was observed in complex 2bTFSI compared to other complexes in the solid state. Their theoretical absorption and phosphorescence emission transitions in acetonitrile were also investigated by using double- and triple-? basis sets with B3LYP and PBE0 hybrid functional. The best light-emitting electrochemical cell (LEC) performance was exhibited by complex 2bTFSI, and the data obtained were as follows: Luminance, current density, luminous efficiency, turn-on time, power efficiency, and external quantum efficiency were measured as 16 156 cd/m2, 554 mA/cm2, 8.49 cd/A, 17 s, 3.95 lm/W and 6.37%, respectively. The investigation of crystallographic characteristics have shown that the LEC performance of these complexes depends on cationic-anionic interaction which has a significant influence on molecular stacking of the molecules. Because, complex 2bTFSI, with weak cationic-anionic interactions, shows strong ?···?stacking interactions between the adjacent molecules, it is the best lighting application candidate among the complexes. © 2021 American Chemical Society.17 GEE 004 16DPT002 Dokuz Eylül Üniversitesi: KB.FEN.13We thank the Ege University Solar Energy Institute for photophysical, NMR, CV analysis, and optoelectronic measurements (grant no. 17 GEE 004 and TUBITAK: 16DPT002). We also thank Izmir Katip Celebi University Central Research Laboratory for TGA analysis. We are grateful to Dokuz Eylul University for crystallographic measurements (Agilent Xcalibur Eos diffractometer, grant no. 2010.KB.FEN.13). We also thank Hacettepe University and TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources) for DFT and TD-DFT calculations

Structure-Property Relationship in ?-Conjugated Bipyridine Derivatives: Effect of Acceptor and Donor Moieties on Molecular Behavior

2-s2.0-85072577584Here, we reported the photophysical studies, single-crystal X-ray crystallography, and density functional theory (DFT) calculations of two bipyridine derivative molecules. In addition, thermal gravimetric analysis and cyclic voltammetry studies were also performed for both compounds. According to crystallographic data, the ?-conjugated molecules have high-quality crystal structures as a result of intramolecular and intermolecular hydrogen bonds occurring through the molecules of the compound. It was determined that when the functional groups (F- and CH3O-) were introduced to the para positions, the molecules adopted slipped stacking (J-aggregate) and antiparallel cofacial stacking (H-aggregate). It was observed that these two bipyridine derivatives disclose the relationship between molecular conformation-molecular packing modes and photophysical behavior of organic solids. The results of DFT calculations supported the structural, spectroscopic, and photophysical data and confirmed the compositions of frontier molecular orbitals in both molecules. © 2019 American Chemical Society.Ege Üniversitesi Dokuz Eylül Üniversitesi: 17 GEE 004, 2010, KB.FEN.13This work was supported by the Ege University, Izmir Katip Celebi University, and Dokuz Eylul University. The authors acknowledge the Izmir Katip Celebi University Central Research Laboratory for the cyclic voltammetry measurement and TGA analysis, Ege University for NMR measurement and photophysical studies (grant no. 17 GEE 004), and Dokuz Eylul University for the use of the Agilent Xcalibur Eos diffractometer (purchased under University Research grant no. 2010.KB.FEN.13)