MSc (Chemistry) / Department of Chemistry

Eine Reihe 3-(p-X-phenyl)-Thiophenmonomeren (X = -H, -CH3, -OCH3, -COCH3, -COOC2H5, -NO2) wurde elektrochemisch polymerisiert, um Filme zu erhalten, die umkehrbar reduziert und oxidiert werden konnten (n-und p-dotiert wurden). Die Oxidationspotentiale der Monomere und die formalen Potentiale der n und p-Dotierprozesse der Polymere wurden mit Resonanz- und induktiven Effekten der Substituenten (Hammett konstanten) am Phenylring sowie semiempirisch errechneten Bildungswärmen der Monomereradikalkationen korreliert. Außerdem wurden die Oxidationspotentiale mit den Ionisierungspotentialen der Monomere verglichen, die über die Dichtefunktionialtheorie (DFT) errechnet wurden, die der Energie für das Erzeugen der Radikalkationen entsprechen. Um theoretische Grundlagen für die Einstufen-Bildung regioregulär -konjungierter Oligo- und Polythiophene zu erhalten, wurden die elektronischen Zustände von 3-Phenylthiophen-Derivaten anhand von Molekülorbitalberechnungen auf Grundlage der Dichtefunktionaltheorie mit Becke’s Drei-Parameter-Funktion (B3LYP), sowie mit den Basissätzen 6-31G(d) und 3-21G(d) erklärt. Die Reaktivität der Verknüpfung von mono- und oligo-3-Phenylthiophenen wurde von den berechneten ungepaarten Elektronenspindichten der entsprechenden Radikal-Anionen abgeleitet. Die Ionisierungspotentiale, die den Energien zur Erzeugung der Radikal-Anionen während der Oxidation entsprechen, wurden abgeschätzt. Die aus den 3-Phenylthiophenen entstandenen regioselektiven Hauptprodukte können gut durch die Größe der Spindichten erklärt werden. Da die Verknüpfungsreaktion an der zwei-Position des Thiophnrings (C-2) sterisch durch die Phenylgruppe und den Thiophenring gehindert ist, startet die Initiierung der 3-Phenylthiophene über die Bildung eines Kopf-Schwanz-Dimers. Folglich spielt das Kopf-Schwanz-Dimer eine wichtige Rolle bei den Wachstumsreaktionen der 3-Phenylthiophene. Die Ursache dafür liegt darin, dass das Kopf-Schwanz-Dimer in 5-Position die höchste Spin-Dichte besitzt und die Wahrscheinlichkeit einer Kopf-Kopf-Verknüpfung aufgrund der sterischen Hinderung zwischen dem Thiophenring und der Phenylgruppe gering ist. Polymerfilme von 3-Phenylthiophenderivaten, die durch elektrochemische Polymerisation synthetisiert wurden, sind in situ und ex situ durch Resonanz-Raman-Spektroskopie bei verschiedenen Anregungswellenlängen, sowie durch in situ und ex situ UV-Vis Spektroskopie analysiert wurden. Die Entwicklung der in situ UV-Vis-Spektren der Polymer von 3-Phenylthiophene nach der Dotierung wird durch ähnliche Eigenschaften gekennzeichnet, wie für viele Polythiophene mit einem hohen Grad der Konjugation beobachtet. Während der schrittweisen Oxidation der Poly-3-phenylthiophen Filme verringert sich die Intensität der Absorption wegen des Überganges bei 450-566 nm und ein neues ausgedehntes Absorptionsband, das auf (bi)polaron Zustände bezogen wird erscheint bei ungefähr 730-890 nm. Andererseits wird während der Oxidation (p-Dotierung) des Poly3-phenylthiophen Filmes eine blau/hypsochrome Verschiebung für beide Absorptionsbänder beobachtet . Es wird durch die Tatsache erklärt, dass ein Polymer eine Verteilung der Kettenlängen enthält und die längste Polymer kette (dessen Absorption bei niedriger Energie auftritt), bei niedrigeren Potentialen zu oxidieren beginnt. Die elektrochemischen Bandlücken der Derivate von 3-Phenylthiophen sind durch zyklische Voltametrie gemessen worden. Der Effekt der Substituenten auf den Oxidations-/Reduktions- potentiale wird besprochen. Bei Bandlücken, die durch zyklische Voltammetrie erhalten wurden, hat sich herausgestellt, dass sie im Allgemeinen höher liegen als optische Bandlücken. Erste Resultate der in situ Resonanz-Raman-Spektroskopie, von dem elektrochemisch erzeugten Polymerderivate von 3-Phenylthiophen Filmen auf einer Platinelektrode, in einer organischen Elektrolytlösung, werden berichtet. Beobachtete Raman Banden werden zugewiesen; gegründet auf diesen Resultaten werden die zuvor angenommenen molekularen Strukturen diskutiert. / A series of 3-(p-X-phenyl) thiophene monomers (X= –H, –CH3, –OCH3, –COCH3, –COOC2H5, –NO2) was electrochemically polymerized to furnish polymer films that could be reversibly reduced and oxidized (n- and p-doped). The oxidation potentials of the monomers and formal potentials of the n- and p-doping processes of polymers were correlated with resonance and inductive effects (Hammett constants) of the substituents on the phenyl ring as well as the semiempirically calculated heats of formation of the monomer radical cations. Moreover, the oxidation potentials of the monomers were correlated with the ionization potentials of the monomers calculated via density functional theory (DFT), which correspond to the energies for generating radical cations during oxidative processes. For obtaining a theoretical basis for the one-step formation of regioregular –conjugated oligo-and polythiophenes, the electronic states of 3-phenylthiophene derivatives were elucidated by molecular orbital calculations using density functional theory with the Becke-type three parameters functional (B3LYP), the 6-31G(d), and 3-21G(d) basis sets. The reactivity for coupling reaction of mono- and oligo-3-phenylthiophenes are inferred from the calculated unpaired electron spin densities of the respective radical cations, and the ionization potentials which correspond to the energies for generating radical cations during oxidative processes were estimated. The major regioselective products of the oligomerization of 3-phenylthiophene can be well understood in terms of the magnitude of spin densities. Since the steric hindrance between the phenyl group and thiophene ring interferes with the coupling reaction occurring between 2-postions (C–2) of thiophene rings, the initiating reaction of 3-phenylthiophene is generaton of a head-to-tail (HT) dimer. Thus, the head-to-tail (HT) dimer plays an important role in the propagation reactions of 3-phenylthiophene. This originates from the highest spin density at the 5- position of the HT dimer and low probability of the HH coupling due to the steric hindrance between thiophene ring and phenyl group. Polymer films of the 3-phenylthiophene derivatives prepared by electrochemical polymerization were analyzed, in situ and ex situ, with resonance Raman spectroscopy using several excitation wavelengths as well as in situ and ex situ UV-Vis-spectroscopy. The evolution of the in situ UV-Vis-spectra of poly 3-phenylthiophene derivatives upon doping is characterized by similar features as observed for many polythiophenes with high degree of conjugation. During stepwise oxidation of the poly-3-phenylthiophene films the intensity of the absorption due to the transition around 450–566 nm decreases and a new broad absorption band related to (bi)polaron states appears around 730-890 nm. On the other hand, during the oxidation (p-doping) of the poly-3-phenylthiophene films a blue/hypsochromic shift is observed for both absorption bands. It is explained by the fact that a polymer contains a distribution of chain lengths, and the longest polymer chains (the absorption of which occurs at lower energies) start to oxidize at lower potentials. The electrochemical bandgaps of 3-phenylthiophene derivatives have been measured by cyclic voltammetry. The effect of substituents on the oxidation / reduction potentials is discussed. Bandgaps obtained by cyclic voltammetry have been found to be in general higher than optical bandgaps. Preliminary results of in situ resonance Raman spectroscopy of electrochemically generated poly-3-phenylthiophene derivatives films on a platinum electrode exposed to an organic electrolyte solution are reported. Observed Raman bands are assigned; based on these results previously suggested molecular structures are discussed.

Tetrathiafulvalene derivatives are remarkable molecules, with various application, reported relatively recently. The radical cation of these compounds has very inter- esting optical, electronic, electrocatalytic superconducting and magnetic properties that have been intensively studied recently. Quantitative in-situ EPR voltammetric spectroelectrochemistry studies of 2-(2-hydroxyethylsulfanyl)-3-(benzylsulfanyl)-6,7- bis(octadecylsulphanyl)tetrathiafulvalene (TTF-Der3) have been carried out with the aim to confirm the oxidation sites, follow-up reactions (after the first electron transfer), and electrochemical behaviour. The diffusion process was confirmed by the depen- dence of current on the square root of the scan rate. It was claimed that the ratio of the number of generated radicals to transferred charge (electrons) for two representative TTF derivatives was determined to 5.5:500 for and 7:500 for TTF, indicating the follow- up reactions. Experiments were performed using the commercially available EPR standards, calibrated for this method (experimental setup). The latter was validated by quantitative EPR with standard 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical concentration (1·10−4 mol dm−3). For the ratios the confidence interval was reported for the first time for TTF-Der3 it was...

Voltammetric methods for the determination amphenicol antibiotic chloramphenicol (CAP) and quinolone antibiotic Ofloxacin (OFL) were developed. TTechniques differential pulse voltammetry (DPV) and DC voltammetry (DCV) for determination of both substances at boron doped diamond film electrode (BDDFE) were used. The effect of pH of Britton-Robinson buffer was tested and the stability of the signal with repeated measurements was monitored. Optimal pH 6 was used for determining of CAP by both, DPV and DCV techniques. Media of pH 4 for determining of OFL by DPV and DCV was optimal. Under these conditions linear dependences in the calibration concentration region 1.10 -6 - 1.10-4 mol.l -1 were obtained. The limit of determination for the method for CAP by DPV at 3.10 mol.l , by -6 -1 DCV at 3.10 mol.l and for -6 -1 OFL by DPV at 1.10 mol.l -6 -1 and by DCV at 4.10 mol.l -7 -1 was found. The developed methods were used for the determination of CAP in the drug samples Spersadex comp. and OFL determination in drug samples Zanocin 200. Method for solid phase extraction of OFL from samples of urine with voltammetric detection was developed with limit of determination at 7.10 mol.l . -6 -1

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The electrochemical behavior of nickel (Ni) in different concentrations of sulfuric acid (H2SO4) was studied via cyclic voltammetry (CV) over a range of potentials (0.0 V– 3.0 V) at room temperature. The presented work displays novel experiments where external forcing by a platinum (Pt) electrode changed the proton concentration at a Ni electrode surface in order to control the frequency and magnitude of periodic oscillations produced. When studying unique phenomena such as the Ni phenomena in this thesis, efficient, durable, and inexpensive technology is always beneficial. A coupled microelectrode array sensor or CMAS which has been used for over four decades to study pitting corrosion, crevice corrosion, intergranular corrosion, galvanic corrosion, and other heterogeneous electrochemical processes were fabricated in a novel, systematic, inexpensive, and time efficient process. The presented work shows how to make the CMAS and proved that they functioned properly.

Today's society is currently developing lithium-ion batteries to eventually replace the use of fossil fuels. High entropy oxides is a new type of material to use as an anode in the lithium-ion battery. These high entropy oxides may consist of a few different transition metals including lithium and oxygen. In this report was (MgCoNiZn)1-xLixO synthesized with a method called Pechini with a molar fraction of x=0.35. This study compares the results from a reference study that has shown the potential of the electrochemical characteristics of (MgCoNiZn)1-xLixO for application as anode in a lithium-ion battery.  The synthesis starts with a heating step to remove all the organics in the composition. The powder consists of several structures and, therefore goes through a calcination step to dissolve all of the intermediate phases into the rock-salt structure. The structure of the powder had a lattice constant of 4,138Å. The powder was made into a slurry containing Carbon black, PVDF and NMP to later get coated by a Dr. Blade. After drying the coating the cell was then assembled with lithium as metal cathode and 1M LiPF6 in 1:1 EC/DMC as electrolyte. After the cell was assembled it, went through electrochemical properties test using a potentiostat and the cell being inside a in a climate chamber at 25°C.  7 cycles were done to plot a cyclic voltammetry graph as well as a discharge-charge test was performed. The cyclic voltammetry and discharge-charge test was run with a voltage range of 0,053 V. The discharge-charge test was run at a current density of 100 mA/g and a constant current of 42,68 mA. / Dagens samhälle genomgår en stor utveckling av litium-jon batterier för att kunna ersätta användningen av fossila bränslen. Höga entropi oxider är ny typ av material som används som anod material för litiumjonbatterier. Dessa höga entropi oxider kan bestå av en rad olika övergångsmetaller inklusive litium och syre i sammansättningen. I den här rapporten var (MgCoNiZn)1-xLixO syntetiserad med en metod som heter Pechini med ett molbråk på x=0,35. En studie har visat potentialen i dem elektrokemiska beetenden av (MgCoNiZn)1-xLixO till applicering som en anode i ett litiumjon batteri.  Syntetiseringen började med ett uppvärmningsteg för att bränna bort alla organiska föreningar. Resulterade pulvret bestod av olika strukturer, och till ett kalcinerings steg för att lösa upp mellanfaserna till NaCL-struktur. Strukturen på pulvret hade en gitter constant på 4,138 Å. Pulvret gjordes till en slurry som innehåller amorft kol, PVDF och NMP för att sedan belägga elektroden med en Dr.Blade. Efter beläggningen har fått torka monterades cellen med litium som katod och 1M LiPF6 in 1:1 EC/DMC som elektrolyt. Tester utfördes på cellen med hjälp av en potentiostat medans cellen var förvaren i en klimatkammare i 25°C.  7 stycken cykler kördes för att plotta en cyklisk voltametri graf samt en urladdning-laddning prov utfördes. Cykliska voltametrin och urladdning-laddnings prov utfördes med ett spänningsintervall på 0,05-3,0V. Urladdning-laddnings provet hade en strömtäthet på 100 mA/g och en konstant ström på 42,68 mA.

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The major directions of this dissertation involve (1) the syntheses and characterization of molecular polygons incorporating sp1hybridized carbon linkers and L2Pt corners (L2 = cis-1,3-diphosphine), (2) the development of protected carbon chain complexes featuring fluorous phosphine ligands and (3) click reactions of metal terminal polyynyl complexes and further metallations of the resulting triazole rings. A brief overview is provided in Chapter I. Chapter II details the syntheses of molecular squares containing bidendate diphosphine ligands of the formula R2C(CH2PPh2)2 where R = Me, Et, n-Bu, n-Dec, Bn, and p-tolCH2 (general designation dppp*), in which the R2 groups are intended to circumvent the solubility issues encountered by others. Their syntheses involve double substitutions of the dimesylate compounds R2C(CH2OMs)2 using KPPh2. Building blocks of the formulae (dppp*)PtCl2 and (dppp*)Pt((C≡C)2H)2 are synthesized and characterized, including one crystal structure of the latter. The target complexes are accessed by reactions of (dppp*)PtCl2 with (dppp*)Pt((C≡C)2H)2 under Sonogashira type conditions. Six new squares of the formula [(R2C(CH2PPh2)2)Pt(C≡C)2]4 are characterized including two crystal structures. Further topics include approaches to higher homologues and cyclocarbon synthesis. Chapter III focuses on carbon chain complexes bearing fluorous phosphine ligands of the formula P((CH2)mRfn)3 (Rfn = (CF2)n-1CF3; m/n = 2/8, 3/8, and 3/10). Precursors of the formula trans-(C6F5)((Rfn(CH2)m)3P)2PtCl are synthesized and characterized, including one crystal structure, which reveals phase separation of the fluorous and non-fluorous domains. Reactions with butadiyne give trans-(C6F5)((Rfn(CH2)m)3P)2Pt(C≡C)2H. Oxidative homocouplings afford the target complexes trans,trans-(C6F5)((Rfn(CH2)m)3P)2Pt(C≡C)4(C6F5)(P((CH2)mRfn)3)2Pt. Cyclic voltammetry indicates irreversible oxidations of the title compounds, in contrast to partially reversible oxidations of non-fluorous analogues. Chapter IV focuses on multimetallic complexes achieved by click reactions in metal coordination spheres. The copper catalyzed click reaction between trans-(C6F5)(p-tol3P)2Pt(C≡C)2H (1) and (η5-C5H4N3)Re(CO)3 affords the bimetallic 1,2,3-triazole trans-C6F5)(p1tol3P)2PtC≡CC=CHN((η51C5H4)Re(CO)3)N=N. Further reactions with Re(CO)5OTf and Re(CO)5Br give trimetallated adducts, which represent the first species of this type. An alternative route to a trimetallic complex involves the twofold cycloaddition of the diazide (η5-C5H4N3)2Fe and 1, giving (η5-C5H4NN=N-C(trans-(C≡C)Pt(Pp-tol3)2(C6F5)=CH)2Fe. The crystal structures of the di and trimetallic complexes are compared, but attempts to achieve a fourth metallation involving the =CH groups are unsuccessful. However, when the triazolium salt [trans-(C6F5)(p-tol3P)2PtC≡CC=CHN(CH2C6H5)N=N(Me)]+ I– is treated with Ag2O and [Rh(COD)Cl]2, a =CRh adduct is obtained. The success of =CH metallation is correlated to the 1H NMR chemical shift, indicative of an electronic effect.

Optimum detergent dosage during a washing process depends on water quality, degree of pollution and quantity of laundry. Particularly, water quality is an important factor. Other parameters like carbonate- or non-carbonate hardness and calcium / magnesium (Ca / Mg) ratio in addition to total hardness of water have an impact on the amount of detergent. This work discusses the possibilities realizing a detergent sensor that measures important parameters for the washing process and assess the ideal necessary amount of detergent during the washing process. The approach is to combine impedance spectroscopy with cyclic voltammetry in order to determine both water quality and concentration of detergent in the suds which build up the basis for an optimum detergent dosage. The results of cyclic voltammetry show that it is possible to identify the Ca / Mg ratio and the carbonate hardness separately, which is necessary for the optimization of the washing process. Impedance measurements identify total hardness and detergent concentrations.