24 research outputs found
The specialized twin-solution method for selective Pd(II) ions determination and methyl orange removal
Tropaeolin OO as a Chemical Sensor for a Trace Amount of Pd(II) Ions Determination
The selective determination of metals in waste solutions is a very important aspect of the
industry and environmental protection. Knowledge of the contents and composition of the waste can
contribute to design an efficient process separation and recovery of valuable metals. The problematic
issue is primarily the correct determination of metals with similar properties such as palladium and
platinum. Thus this paper focuses on the development of a selective method that enables Pd(II)
determination in the presence of Pt(IV) ions using the azo-dye tropaeolin OO (TR). For this purpose,
the process of the metalorganic complex formation and Pd(II) ions determination were studied by
using UV–Vis spectrophotometry under different conditions: solvents (water and B-R buffer), pH
(2.09–6.09), temperature (20–60 ◦C), anions and cations concentrations. The formed metalorganic
complex between Pd and tropaeolin OO allows for distinguishing Pd(II) ions from both platinum
complexes, i.e. Pt(II), Pt(IV). Moreover, the proposed method can be applied to solutions containing
both chloride and chlorate ions. The obtained characteristic spectrum with two maxima allows the
determination of palladium even in the presence of other cations (Na, K, Mg, Zn, Co, Ni, Al) and
changed concentrations of Pt(IV) ions. Furthermore, the developed spectrophotometric method
for the Pd(II) ions determination using tropaeolin OO is characterized by high selectivity towards
palladium ions
Application of Vibrational Spectroscopy Supported by Theoretical Calculations in Identification of Amorphous and Crystalline Forms of Cefuroxime Axetil
UV-visible and NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors
Four model thiosemicarbazide anion chemosensors containing three N
–
H bonds, substituted with phenyl
and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide,
fl
uoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in
DMSO and 9 : 1 DMSO
–
H
2
O by UV-visible absorption and
1
H/
13
C/
15
N NMR spectroscopic techniques and
corroborated with DFT studies. Signi
fi
cant changes were observed in the UV-visible absorption spectra
with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye.
These changes were determined to be due to the deprotonation of the central N
–
H proton and not due
to hydrogen bonding based on
1
H/
15
N NMR titration studies with acetate in DMSO-
d
6
–
0.5% water. Direct
evidence for deprotonation was con
fi
rmed by the disappearance of the central thiourea proton and the
formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the
central N
–
H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation
mechanism of the central N
–
H proton rather than by hydrogen bonding as is often reported
Towards "computer-on-a-particle" devices : optoelectronic 1:2 demultiplexer based on nanostructured cadmium sulfide
Unconventional molecular scale logic devices
Semiconducting nanoparticles offer a versatile platform for various logic devices. Wide band gap semiconductors modified with molecular species are materials with unique optical and electronic properties. The most intriguing property of such systems is photoelectrochemical photocurrent switching (PEPS) effect. The polarity of photocurrent generated within these materials depends on many variables (light, electrode polarization, redox processes). Materials showing the PEPS effect can be used for construction of simple logic gates and other devices