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231	X-ray spectroscopic and magnetic investigations of selected manganese-containing molecularhigh-spin complexes Prinz, Manuel 08 July 2009 (has links) The presented thesis includes investigations to fully characterize the electronic structure and magnetic properties ofselected manganese containing high-spin molecules by means of various X-ray spectroscopic, magnetic and theoretical methods. The investigations on the Mn4 star-shaped molecule havelead to a number of interesting results. Magneto-chemical studies exhibit very weak exchange coupling constantsbetween the four Mn(II) ions, leading to complicated low lying states in which the ground state is not well separated, resulting from a dominant weak ferromagnetic coupling and a giant moment of up to 20 µB/f.u. XMCD measurements revealed that almost the completemagnetic moment is located around the Mn(II) ions.This is in agreement with only a few charge transfer states foundwithin the detailed X-ray absorption spectroscopic study. The electronic structure and detailed magnetic properties of the star-shaped heteronuclear CrIIIMnII3 complex have been precisely investigated.With XPS the homovalency of Mn and Cr have been verified. The XA-spectra of the manganese and chromium L edges were measured and compared to earlier investigated Mn4 spectra.The combination high-magnetic field magnetic measurements and element selective XMCD of Mn and Cr L edges and quantum model calculations lead to a complete analysis of the magnetic structure of the CrMn3 magnetic core. The III valence state of the manganese ions in MnIII6O2Salox has been verified. From X-ray diffraction, typical Jahn-Teller distorted oxygen octahedra have been found for Mn(III) ions. Comparisons of XPS and XAS spectra of the complex to corresponding spectraof maganite and tetranuclear manganese(II) cluster it was definitely possible to identify MnIII6O2Salox as a pure Mn(III) compound. molecular magnetism high-spin molecules maganese XPS XAS XMCD 29 - Physik, Astronomie 75.50.Xx - Molecular magnets 78.70.Dm - X-ray absorption spectra 87.64.Kn ddc:540
232	Synthesis of Thiophene-Vinyl-Benzothiazole Based Ligand Analogues for Detection of Aβ and Tau Pathology in Alzheimer's Disease Johansson, Joel January 2024 (has links) As of today, Alzheimer’s disease is the leading cause of dementia among neurodegenerative disorders, affecting many millions of people worldwide. As the average life span of populations increase, more and more people succumb to the illness each year. Like other neurodegenerative disorders, Alzheimer’s disease can be attributed to the accumulation of protein aggregates in the brain. These amyloid-β peptides and tau proteins can presumably be detected in the brain many years before the onset of clinical symptoms. Development of fluorescent ligands, capable of binding to these neuropathological hallmarks and highlighting them, could serve as molecular diagnostic tools and facilitate an early diagnosis of the disease. The method could also be useful in studying disease progression and evaluating the effects of novel treatments. One such ligand is HS-259. The aim of this project was to synthetize different analogues of HS-259, and test their selectivity towards the aforementioned aggregates in brain tissue from an individual with Alzheimer’s disease. Staining of tissue samples with analogue solution enables visualization of aggregate sites through fluorescence imaging. In the end, five analogues were synthetized, albeit in relatively low overall yields. Synthetic methods included Suzuki-Miyara cross-couplings, Ullmann-type arylations and condensations. Liquid Chromatography-Mass Spectrometry (LC-MS) and Nuclear Magnetic Resonance (NMR) were used for analysis of the compounds. Two of the five analogues could be tested for staining of aggregates and assessed for photophysical characteristics, i.e. absorption- and emission spectra. One analogue stained both amyloid-β aggregates and some tau aggregates, whereas the other stained neither. Since only two analogues were tested and rendered inconsistent results, further studies are needed to assess the binding properties of HS-259 analogues in general. Alzheimer's disease neurodegenerative disorders protein aggregates molecular ligands amyloid-β Aβ amyloid-beta tau diagnosis HS-259 staining brain tissue Suzuki coupling Ullmann arylation condensation NMR nuclear magnetic resonance LC-MS liquid chromatography neuropathological hallmarks absorption spectra emission spectra synthesis plaques symptoms neuropathology thiophene-vinyl-benzothiazole TVBT ligand analogues N-arylation Knoevenagel preparative LC PBS phosphate buffered saline treatments AD mechanisms thiophene benzothiazolium fluorescence imaging bTVBT bi-thiophene-vinyl-benzothiazole detection Suzuki-Miyara Organic Chemistry Organisk kemi

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X-ray spectroscopic and magnetic investigations of selected manganese-containing molecularhigh-spin complexes

Synthesis of Thiophene-Vinyl-Benzothiazole Based Ligand Analogues for Detection of Aβ and Tau Pathology in Alzheimer's Disease