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21.
In recent years squarines received attention as fluorescent labels. Their very promising spectral properties such as long wavelength absorption and emission, high extinction coefficients and quantum yields could lead novel sensing technologies. In this work newly synthesized fluoroinophores named bis[4-N-(1-aza-4,7,10,13-tetraoxacyclopentadecyl)-3,5-dihydroxyphenyl]squaraine, azacrown-1 and 2 bis[4-N-(1-aza-4,7,10,13,16-pentaoxacyclooctadecyl)-3,5-dihydroxyphenyl]squaraine, azacrown-2 have been used for sodium and potassium sensing in plasticized PVC matrix. The squaraine derivatives exhibited fluorescence emission based optical responses to sodium and potassium with a detection limit of 1.10(-9) M. The sensor compositions exhibited wide response ranges between 10(-9) and 10(-5) M Na(+)or K(+), and, therefore, may be an alternative method to flame emission spectroscopy. The sensor is fully reversible within the dynamic range and the response time is 3 min under batch conditions. Cross sensitivity to pH is negligible in the pH range of 6.2-7.3. Throughout fiber optic based studies a relative signal change of 54-56% has been achieved. The azacrown dyes have the advantage that they can be excited with long wavelength light and, are, therefore, LED compatible. The cross sensitivity of azacrown-1 and -2 to Ba(2+), Ca(2+) and NH(4)(+)were also tested in separate solutions. 相似文献
22.
H. Temel B. Ziyadanogullari H. Alp I. Aydın F. Aydın S. İlhan 《Russian Journal of Coordination Chemistry》2006,32(4):282-286
The Cu(II) and Zn(II) complexes of aromatic bidentate diamines were prepared and characterized by different analytical and
spectral methods. Thermodynamic parameters of complexes of Cu(II) and Zn(II) cations with 1,3-bis(p-aminophenoxy)propane were determined in 60 vol. % DMF-H2O at various ionic strengths (0.07, 0.13, 0.2 M NaNO3) and different temperatures (45, 50, 55, 60 ± 0.1°C) using a spectrophotometric method. The NaNO3 solution was used to maintain the ionic strength. The stability constants show an inverse relationship with ionic strengths.
The thermodynamic parameters of 60 vol. % DMF-H2O (ΔG°, ΔH°, ΔS°) based on these formation constants were determined.
The text was submitted by the authors in English. 相似文献
23.
Sevinc Z. Topal Kadriye Ertekin Derya Topkaya Serap Alp Berrin Yenigul 《Mikrochimica acta》2008,161(1-2):209-216
Room temperature ionic liquids doped with tris(2,2′-bipyridyl)ruthenium(II)chloride together with chemically and biochemically
inert perfluoro chemicals (PFCs) have been used for the first time for optical O2 sensing purposes.
The response to oxygen of the Ru complex in 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium
bromide (RTIL-II) has been evaluated in terms of sensitivity, stability, regeneration ability and response time. The response
times were 2 and 5 s, respectively, and the signal changes were reversible. Better oxygen solubility, enhanced molar absorption
coefficients and photostabilies were found for the RTILs. The stability the Ru complex in RTILs was tested over 12 months
and it is when stored in the ambient air of the laboratory.
Correspondence: Kadriye Ertekin, Fen-Edebiyat Fakultesi, Dokuz Eylul Universitesi, Kimya Bolumu, 35160 Buca, Izmir, Turkey 相似文献
24.
The entropy generation during the transient laminar natural convection in a square enclosure that is partially heated from a vertical lateral wall is numerically investigated. The active sites referring to the main irreversibility locations are determined. The Boussinesq approximation is used in the natural convection modelling. The effects of Prandtl (Pr) and Rayleigh (Ra) number combinations on the entropy generation are investigated. The study is restricted to the fluids of Prandtl number from 0.01 to 1.0, and Rayleigh numbers in the range of 102–108. It is found that the upper corner of the heated part of the side wall is the active site where the entropy generation initiates due to irreversibilities representing the energy loss. 相似文献
25.
Hemamalini Madhukar Kestek İrem Çınar Emine Berrin Agar Ayşen Alaman Dege Necmi Josekavitha Savaridasan Rajakannan Venkatachalam 《Crystallography Reports》2021,66(6):1023-1030
Crystallography Reports - The title Schiff base compound (I), C17H19BrN2O, has been synthesized by the reaction of 4-(diethylamino)-2-hydroxybenzaldehyde and 3-bromoaniline. The dihedral angle... 相似文献