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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

1H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe2+ complex

Petzold, Holm, Djomgoue, Paul, Hörner, Gerald, Speck, J. Matthäus, Rüffer, Tobias, Schaarschmidt, Dieter 15 September 2016 (has links) (PDF)
A series of Fe2+ spin crossover (SCO) complexes [Fe(5/6)]2+ employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2′-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe2+ and Zn2+ complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) 1H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe2+ complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT 1H NMR spectroscopy. An alternative scheme using a linear correction term C1 to model chemical shifts for Fe2+ SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)]2+ obtained by VT 1H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)]2+ were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
2

1H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe2+ complex

Petzold, Holm, Djomgoue, Paul, Hörner, Gerald, Speck, J. Matthäus, Rüffer, Tobias, Schaarschmidt, Dieter 15 September 2016 (has links)
A series of Fe2+ spin crossover (SCO) complexes [Fe(5/6)]2+ employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2′-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe2+ and Zn2+ complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) 1H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe2+ complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT 1H NMR spectroscopy. An alternative scheme using a linear correction term C1 to model chemical shifts for Fe2+ SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)]2+ obtained by VT 1H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)]2+ were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
3

Designrekommendationer för 3D-interiör : En kvalitativ studie för 3D-applikationer

Lind, Olof January 2021 (has links)
I dagens samhälle är digitalisering en självklarhet genom olika former av applikationer vilka samspelar med människan. Det ställer höga krav på både användare och utvecklare, att de ska vara anpassningsbara. Inom fastighetsbranschen är visualisering ett väl etablerat verktyg för att kommunicera information, och en del av digitaliseringen sker genom mjukvaror som 3D-applikationer. Det är givet att dessa visualiseringsapplikationer måste förhålla sig till ett antal punkter som vilken information som ska presenteras, hur det ska förmedlas samt vilken nivå av abstraktion att bistå. På senare tid har begreppet användarbarhet blivit väldigt populärt där det grundläggande är att designa med människan i centrum. Det är en strategi för interaktiv utveckling där fokus är användarna och definierar vad folk har för kunskap, vad de arbetar med, gör och känner. Vid utveckling av dessa mjukvaror är det viktigt att just fokusera på individen för att en produkt eller tjänst ska bli så god som möjligt, vilket underlättar acklimatiseringen för slutanvändarna. Denna undersökning har fokuserat på användarupplevelsen av design som koncept samt existerande teorier vilket behandlar principer och element i 3D. Målgruppen har varit utvecklare av 3D-applikationer där undersökningen gjorts på fastighetsspekulanter, deras åsikter har legat som grund för viktiga funktioner inom en mjukvara. Datainsamlingen har skett enligt kvalitativa intervjuer, litteraturstudie och en benchmarkundersökning. Undersökningen har visat att respondenterna i det stora hela bekräftar tidigare forskning, med mindre bortfall. I studien har det framkommit ytterligare delar som är viktiga både från undersökningen med respondenterna och genom benchmarkingen.

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