Search results for "luminescence."

Molecular connectivity as a relevant new tool for predicting analytical behavior: A survey of chemiluminescence and chromatography

2005

Abstract We present a critical presentation and discussion on molecular connectivity applied to analytical fields, giving special attention to predicting the chemiluminescent behavior of pharmaceuticals and pesticides. Molecular connectivity has been largely applied to predict the therapeutic effects of pharmaceuticals and rarely to predictions in analytical chemistry – basically to chromatographic processes and recently to liquid-phase chemiluminescence.

Flow Methods in Pharmaceutical Analysis

2008

Inhibition of the system luminol-H2O2-Fe(CN)63− chemiluminescence by the Mn(II) indirect determination of isoniazid in a pharmaceutical formulation

1998

A flow injection procedure for the indirect chemiluminescent determination of isoniazid is proposed. The method is performed in a flow-injection manifold provided with a solid-phase reactor. The reactor was made from manganese dioxide physically entrapped by polymerization; the redox reaction isoniazid-manganese dioxide released Mn(II) which was monitored through its inhibitory effect on the reaction between luminol and hydrogen peroxide in presence of potassium hexacyanoferrate (III). The procedure resulted in a linear calibration graph over the range 5-15 mg/L of isoniazid with a sample throughput of 43 samples/h. The influence of foreign compounds was studied and the method was applied t…

Effects of ultrahigh dilutions of 3,5-dichlorophenol on the luminescence of the bacterium Vibrio fischeri.

2003

Abstract There is a great need for research in the field of homeopathy for laboratory test systems to investigate the actions of ultrahighly diluted biological effectors. With this in mind, we used the luminescent bacterium Vibrio fischeri, which is used throughout the world in testing water quality. Luminescence inhibition is utilized as a test parameter for the toxicity of a sample. We used ultrahigh dilutions (UHD) of 3,5-dichlorophenol as effector and adapted the standard test procedure for water toxicity in a way that let us evaluate very minute effects. Three groups of samples were prepared and then blinded: 45 dilutions of 3,5-dichlorophenol in steps of 10, starting with 4.2×10−2 M, …

Measurement of the Md3+/Md2+ Reduction Potential Studied with Flow Electrolytic Chromatography

2013

The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By application of the appropriate potentials on the chromatography column, the more stable Md(3+) is reduced to Md(2+). The reduction potential of the Md(3+) + e(-) → Md(2+) couple was determined to be -0.16 ± 0.05 V versus a normal hydrogen electrode.

Cover Feature: A Strongly Luminescent Chromium(III) Complex Acid (Chem. Eur. J. 48/2018)

2018

Strong circularly polarized luminescence of an octahedral chromium(iii) complex

2019

The chiral spin-flip luminophore [Cr(ddpd)2]3+ can be resolved into enantiopure material by chiral HPLC. The corresponding enantiomers show very high luminescence dissymmetry factors of up to ∣glum ∣≈ 0.093 in circularly polarized luminescence (CPL) measurements for the "ruby-like" phosphorescence transition 2E/2T1 → 4A2 in the near-IR region around λ ≈ 775 nm.

Effect of annealing temperature on persistent luminescence of Y3Al2Ga3O12:Cr3+ co-doped with Ce3+ and Pr3+

2021

Abstract Y3(Al,Ga)5O12 (YAGG) materials doped with Ce3+, Cr3+ and Pr3+ were synthesized by using a modified Pechini method and subsequently annealed in air at selected temperatures between 900 and 1500 °C. According to X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) analyses, the particles and size distributions become large and broad, respectively, due to sintering and agglomeration at high annealing temperatures. Based on infrared (FTIR) spectra and calculation of multi-phonon de-excitation probabilities, the high energy O–H vibrations are not causing significant multi-phonon de-excitation of the emitting 5d level of Ce3+ if the annealing temperature is above 90…

ChemInform Abstract: Photoluminescence of Chromium(III)-Doped Silicoaluminophosphate with AFI Structure.

2010

Luminescent P-Chirogenic Copper Clusters

2013

P-chirogenic clusters of the cubanes [Cu4I4L4] (L = chiral phosphine) were prepared from (+)- and (-)-ephedrine with L = (S)- or (R)-(R)(Ph)(i-Pr)P (with R = CH3 (seven steps) or C17H35 (10 steps)) with e.e. up to 96%. The X-ray structure of [Cu4I4((R)-(CH3)(Ph)(i-Pr)P)4] confirmed the cubane structure with average Cu···Cu and Cu···I distances of 2.954 and 2.696 Å, respectively. The cubane structure of the corresponding [Cu4I4((S)-(CH3)(Ph)(i-Pr)P)4] was established by the comparison of the X-ray powder diffraction patterns, and the opposite optical activity of the (S)- and (R)-ligand-containing clusters was confirmed by circular dichroism spectroscopy. Small-angle X-ray scattering patterns…