The chiral vicinal diamine moiety is “privileged” and is widely found in catalysts and bio-active compounds. A series of seven chiral vicinal diamines with heterocyclic substituents have been synthesized with great enantiospecificity via the resonance assisted hydrogen bond driven diaza-Cope rearrangement reaction using 1,2-bis(2-hydroxyphenyl)-1,2-diaminoethane and heterocyclic aldehydes as starting materials. This thesis will also discuss the development of a new guanidine-based chiral shift rea-gent for determining the enantiopurity and the absolute configuration of α-amino acids by proton nuclear magnetic resonance (1H NMR) spectroscopy. The chiral shift reagent is easily synthesized from the commercially-available 1,2-diphenyl-1,2-diaminoethane. This method is advantageous over many previously described procedures for determining amino acid enantiopurity as it does not require prior derivatization of the analyte.

The chiral vicinal diamine moiety is “privileged” and is widely found in catalysts and bio-active compounds. A series of seven chiral vicinal diamines with heterocyclic substituents have been synthesized with great enantiospecificity via the resonance assisted hydrogen bond driven diaza-Cope rearrangement reaction using 1,2-bis(2-hydroxyphenyl)-1,2-diaminoethane and heterocyclic aldehydes as starting materials. This thesis will also discuss the development of a new guanidine-based chiral shift rea-gent for determining the enantiopurity and the absolute configuration of α-amino acids by proton nuclear magnetic resonance (1H NMR) spectroscopy. The chiral shift reagent is easily synthesized from the commercially-available 1,2-diphenyl-1,2-diaminoethane. This method is advantageous over many previously described procedures for determining amino acid enantiopurity as it does not require prior derivatization of the analyte.

There is considerable current interest in the design and synthesis of new phosphorus ligands and their transition metal complexes in view of their potential applications in homogeneous catalysis. The present study is concerned with the synthesis of new chiral and achiral “ diphosphazanes”, which constitute a class of versatile short-bite bidentate phosphine ligands, and studying their reactivity towards late transition metals (Ag, Pd and Ru). Symmetrical diphosphazane ligands, MeN{P(OR)2}2 (R = (1R, 2S, 5R)-menthyl) and MeN{P(SR)2}2, (R = C6H5) and unsymmetrical diphosphazane ligands, Ph2PN(Pri)PPhY, (Y =OC6H3Me2-2,6 or NMePh) have been synthesized and structurally characterized. The reactivity of these ligands towards the transition metal precursors viz., [PdCl2(COD)] and [CpRu(PPh3)2Cl] has been investigated. The reaction of [Ru(bipy)2Cl2] with the diphosphazane, PriN(PPh2)2 in the presence of AgOTf to synthesize [Ru(bipy)2{PriN(PPh2)2}2]OTf led to an unexpected entry into the Ag(I) chemistry of this ligand. By optimizing the reaction conditions, several mononuclear, dinuclear and trinuclear complexes such as [Ag(K2-PriN(PPh2)2)2]X, [Ag(µ-PriN(PPh2)2)X]2 and [Ag3(µ-(Cl)2(µ-PriN(PPh2)2)3]X (X = NO3, OTf or PF6) have been synthesized. A polymeric complex, [Ag2(µ-PriN(PPh2)2)( µ-NO3)2]n in which the ligand adopts a unique ‘Cs’ geometry has also beenstructurally characterized. This polymeric complex is used to synthesize a helical polymer,[Ag2{µ-PriN(PPh2)2}(DABCO)(NO3)2]n and π- π stacked supramolecular assemblies such as [Ag2(NO3)2(µ-Ph2PN(Pri)PPh2)(2,2'-bipy)2] and [Ag2{µ-PriN(PPh2)2}(1,10-phen)2](NO3)2]. The reaction of a sterically bulky diphosphazane ligand, EtN{P(OC6H3(Pri)2-2,6)2}2 (L) with[(η3-1-R,R’-C3H3)Pd(µ-Cl)]2 in the presence of NH4PF6 gives the cationic complex, [(η 3-1-R,R’-C3H3)Pd(L)]PF6 (R = H; R’= H or Me) as the sole product. In the absence of NH4PF6, theinitially formed cationic complex, [(η 3-C3H5)Pd(L)]PF6 is transformed into a mixture of chlorobridged complexes over a period of 96 h. An octa-palladium complex [(η3-C3H5)(2-Cl- η3-C3H4)Pd4(µ-Cl)4(µ-L)]2 is formed as a result of nucleophilic substitution by a chloride ligand at the central allyl carbon atom. The reaction of L with [(η3-C3H5)Pd(µ-Cl)]2 in the presence of K2CO3 yields a dinuclear complex, [(η3-C3H5)Pd2(µ-L)Cl] containing a coordinatively unsaturated T-shaped palladium center. This complex exhibits high catalytic activity and large“turn-over numbers” in the catalytic hydrophenylation of norbornene. Reactions of diphosphazanes with cyclometalated palladium complexes of the general formula [Pd( k2-(C,N)-Me2NCHMe(C6H4))(solvent)2]PF6 derived from a chiral amine, (S)-N,N-dimethyl-1-phenethylamine give chelate complexes of the type [Pd{ k2-(C,N)-Me2NCHMe(C6H4)}(LL)] PF6, (L-L = diphosphazane). Chiral racemic diphosphazanes give a mixture of diastereomeric(S,R and S,S) complexes which could not be separated. These cyclometalated complexes show moderate catalytic activity in C−C bond forming reactions (hydrophenylation /Suzuki coupling).

Chiral bisphosphinites are well-documented alternatives for chiral bisphosphines as ligands that can be exploited in various asymmpetric syntheses. Particularly, vicinal biarylphophinite ligands give a seven membered chelate ring similar to the successful DIOP on coordination to the metal. RajanBabu and coworkers have described asymmetric bisphosphinites obtained by functionalization of sugars and have shown their utility in enantioselective hydrogenation, hydrovinylation and hydrocynation reactions. Despite the interesting reactions demonstrated by bisphosphinites, not much attention has been paid to their synthesis and catalysis. This is probably due to the known moisture and oxygen sensitivity that makes their use limited. In the present thesis, a series of C1 an C2 symmetric bisphosphinite complexes of Pd(II) and Pt(II) have been synthesized directly from various naturally occurring chiral alcohols using a modified template method. A number of asymmetric catalytic reactions have been developed such as allylation of imines, allylation of aldehydes, allylic allylation, allylic alkylation, hydrosilylation of alkenes and regioselective allylation of oxiranes. Allylation of imines was carried out in essentially neutral conditions using Pd(II) catalysts and water was shown to accelerate the reaction. Interestingly acetic acid was required as a promoter in asymmetric allylation of cinnamaldehyde in the Pt(II) catalyzed reaction whereas water was a deterrent. Hydrosilylation reaction was carried out in solvent free conditions with high turnover numbers (.1000). Ascorbic acid based complexes produced the highest enantioselectivity for the asymmetric allylic alkylation reaction (97 % ee) and hydrosilylation of styrene (98% ee). These enantioselectivity results are the best obtained using ligands directly prepared from natural products.

<p>This thesis deals with the design and syntheses of chiral,enantiopure pyridinecontaining ligands and their applicationsin asymmetric catalyis.</p><p>Chiral pyridyl pyrrolidine ligands and pyridyl oxazolineligands were synthesized and employed in thepalladium-catalysed allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate. Theinfluence of the steric properties of the ligands wereinvestigated.</p><p>Ditopic ligands, containing crown ether units as structuralelements, were synthesized and some of the ligands were used asligands in the palladiumcatalysed allylic alkylation of1,3-diphenyl-2-propenyl acetate with dimethyl malonate. A smallrate enhancement was observed, compared with analogous ligandslacking the crown ether unit, when these ditopic ligands wereused in dilute systems.</p><p>A modular approach was used to synthesize chiralenantiomerically pure pyridyl alcohols and C2-symmetric2,2’-bipyridines, with the chirality originating from thechiral pool. Electronic and steric properties of the compoundswere varied and they were used as ligands in theenantioselective addition of diethylzinc to benzaldehyde. Thesense of asymmetric induction was found to be determined by theabsolute configuration of the carbinol carbon atom. Theelectronic properties of the ligands had a minor influence onthe levels of enantioselectivity induced by the ligands.</p><p>Chiral pyridyl phosphinite ligands and pyridyl phosphiteligands were synthesized from the pyridyl alcohols andevaluated as ligands in palladiumcatalysed allylic alkylations.With the phosphinite ligands, the sense of chiral induction wasfound to be determined by the absolute configuration of theformer carbinol carbon atom. A kinetic resolution of theracemic starting material was observed with one of thephosphite ligands. Moderate enantioselectivities wereachieved.</p><p><b>Kewords:</b>asymmetric catalysis, chiral ligand, chiralpool, oxazoline, crownether, ditopic receptor, bipyridine,pyridyl alcohol, modular approach, P,Nligand, diethylzinc,allylic alkylation.</p>

Ziel der durchgeführten Arbeiten war die Etablierung neuer Synthesestrategien zur Gewinnung chiraler metall-organischer Gerüstverbindungen (engl: Metal-Organic Frameworks, MOFs). Hierfür wurden drei verschiedene Ansätze verfolgt. Zunächst sollte die Einbringung einer chiralen Dicarbonsäure mit einem 2,2´-Spirobiindan-Gerüst in ein MOF-Netzwerk untersucht werden. Im Rahmen einer Kooperation wurden neue mit chiralen Oxazolidinonen substituierte 4,4´,4´´-Benzol-1,3,5-triyl-tribenzoesäuren H3ChirBTB-n (n = 1, 2) entwickelt, die ebenfalls zur Synthese neuer chiraler MOFs dienten. Die Modifizierung bekannter nicht-chiraler metall-organischer Gerüstverbindungen mit koordinativ ungesättigten Metallatomen durch Anbindung chiraler Amine stellte die dritte Synthesestrategie dar. Im Rahmen der letztgenannten Syntheseroute wurde für MIL-101 (MIL = Matérial Institut Lavoisier) eine sehr hohe katalytische Aktivität in der Cyanosilylierung von Benzaldehyd nachgewiesen. Die Umsetzung mit chiralen Aminen führte jedoch nicht zu einem enantioselektiven Katalysator. Im Gegensatz dazu konnten die ersten beiden Synthesewege zur Gewinnung neuer chiraler metall-organischer Gerüstverbindungen erfolgreich beschritten werden. Durch solvothermale Reaktion von (S)-2,2´-Spirobiindan-5,5´-dicarbonsäure ((S)-H2Spiro-BIDC) mit Zinknitrat in N,N-Dimethylformamid (DMF) wurde eine neue chirale metall-organische Gerüstverbindung namens DUT-7 (DUT = Dresden University of Technology) der Zusammensetzung Zn4O((S)-Spiro-BIDC)3 dargestellt. Neben einer unerwarteten, zweifach interpenetrierten Netzwerkstruktur mit hexagonalen Kanälen weist DUT-7 eine für MOFs bislang noch nicht beobachtete temperaturinduzierte, reversible Strukturänderung auf. Die zweite neue Strategie zur Gewinnung chiraler MOFs beinhaltete die Umsetzung der chiralen Tricarbonsäuren H3ChirBTB-n, die entweder (S)-4-iso-Propyl- (n = 1) oder (S)-4-Benzyl-1,3-Oxazolidin-2-on-Substituenten (n = 2) tragen. Die beiden gewonnenen Verbindungen Zn3(ChirBTB-1)2 und Zn3(ChirBTB-2)2 weisen trotz gleicher Zusammensetzung völlig unterschiedliche Kristallstrukturen auf. Beide Materialien wurden erfolgreich in der Mukaiyama-Aldol-Reaktion von Benz- bzw. 1-Naphthaldehyd mit 1-Methoxy-2-methyl-1-(trimethylsiloxy)propen eingesetzt, wobei ihre katalytische Aktivität mit verschiedenen Referenzkatalysatoren verglichen wurde. Die erzielten Enantiomerenüberschüsse (ee) liegen zwischen 6 und 16%. Auf der Suche nach neuen, für die Einbringung der ChirBTB-n-Liganden geeigneten MOF-Strukturen wurde auch die Umsetzung der reinen, nicht chiralen 4,4´,4´´-Benzol-1,3,5-triyl-tribenzoesäure (H3BTB) untersucht. Die Reaktion mit Nickelnitrat führte zur Bildung einer neuen hochporösen Verbindung namens DUT-9 mit der Zusammensetzung Ni5O2(BTB)2(DEF,DMF)4(H2O)4. DUT-9 weist neben den auf dem Gebiet der MOF-Forschung bislang unbekannten Ni5O2-Clustern eine noch nicht beschriebene dreidimensionale (3,6)-Netzwerktopologie auf. Das neue Material zeigt zudem exzellente Speicherkapazitäten für Wasserstoff, Methan und Kohlenstoffdioxid. / The present work aims on the search for new synthesis strategies towards chiral Metal-Organic Frameworks (MOFs). Three different approaches were pursued. Initially, the integration of a chiral dicarboxylic acid with a 2,2´-spirobiindane backbone into a MOF network was investigated. Within a cooperation, new 4,4´,4´´-benzene-1,3,5-triyl-tribenzoic acids H3ChirBTB-n (n = 1,2) with chiral oxazolidinone substituents were developed which were also used for the assembly of chiral MOFs. The third synthesis strategy involved the tethering of chiral amines to coordinatively unsaturated metal atoms of known non-chiral Metal-Organic Frameworks. Within the last-mentioned approach, the very high catalytic activity of MIL-101 (MIL = Matérial Institut Lavoisier) towards the cyanosilylation of benzaldehyde was demonstrated. Treatment with chiral amines did not lead to an enantioselective catalyst. In contrast, the first two synthesis strategies could be performed successfully. A new MOF named DUT-7 (DUT = Dresden University of Technology) with composition Zn4O((S)-Spiro-BIDC)3 was obtained by solvothermal reaction of (S)-2,2´-spirobiindane-5,5´-dicarboxylic acid ((S)-H2Spiro-BIDC) with zinc nitrate in N,N-dimethylformamide (DMF). Besides an unexpected, two-fold interpenetrated framework structure with hexagonal channels, DUT-7 shows a temperature induced, reversible structure transformation not yet observed. The other new strategy to obtain chiral Metal-Organic Frameworks involved the conversion of the chiral tricarboxylic acids H3ChirBTB-n bearing either a (S)-4-iso-propyl- (n = 1) or a (S)-4-benzyl-1,3-oxazolidin-2-one substituent (n = 2). Though having the same framework composition, the new compounds Zn3(ChirBTB-1)2 and Zn3(ChirBTB-2)2 exhibit completely different crystal structures. Both materials were tested in the Mukaiyama aldol reaction between benzaldehyde or 1-naphthaldehyde, respectively, and 1-methoxy-2-methyl-1-(trimethylsiloxy)propene and their catalytic activity was compared to different reference catalysts. Enantiomeric excess values (ee) between 6 and 16% were obtained. In search of new MOF structures being suitable for the integration of the ChirBTB-n linkers, the conversion of the pure, non chiral 4,4´,4´´-benzene-1,3,5-triyltribenzoic acid (H3BTB) was investigated. The reaction with nickel nitrate lead to the formation of a new, highly porous compound Ni5O2(BTB)2(DEF,DMF)4(H2O)4 named DUT-9. Besides Ni5O2 clusters which are a novelty in MOF chemistry, DUT-9 exhibits a three dimensional (3,6)-network topology not yet described. In addition, the new material shows excellent storage capacities for hydrogen, methane and carbon dioxide.

Le ligand nacnacxylH (xyl = C6Me2H3) et les ligands dikétimines N-alkyle substitués (nacnacCH(Me)PhH, nacnacBnH and nacnaciPrH) ont été préparés avec de bons rendements à l’exception du nacnaciPrH (23%) en utilisant un protocole en une étape et à l’aide d’un montage Dean-Stark. La réaction du S,S-nacnacCH(Me)PhH et du nacnacBnH avec le nBuLi dans le THF conduit au S,S-nacnacCH(Me)PhLi(THF) et au nacnacBnLi(THF). Les tentatives de bromation de ces composés par le N-bromosuccinimide conduisent plutôt aux ligands S,S-succnacnacCH(Me)PhH et succnacnacBnH (succ = succinimido) substitués par un groupement succinimido sur le carbone  La chloration par le N-chlorosuccinimide conduit au produit désiré, mais avec des impuretés. La réaction de ces ligands avec le CuOtBu (ou bien MesCu, où Mes = C6Me3H2, et une quantité catalytique de CuOtBu) en présence de bases de Lewis donne les (nacnacxylCu)2(-toluène), nacnacxylCuCNC6H3(Me)2, nacnacCH(Me)PhCuL (L = PPh3, PMe3, CNC6H3(Me)2, DMAP, lutidine, Py, MeCN), nacnacBnCuL (L = PPh3, CNC6H3(Me)2, styrène, trans-stilbene, phenylvinylether, acrylonitrile, diphenylacetylène), nacnaciPrCuL (L = PPh3, CNC6H3(Me)2, MeCN) et le succnacnacCH(Me)PhCuL (PPh3, CNC6H3(Me)2, pyridine). Tous ces complexes sont jaunes et sensibles à l’air et à l’humidité. En l’absence de fortes bases de Lewis, on n’observe pas de réaction entre les précurseurs de cuivre et les ligands N-alkyle substitués. Les études RMN des complexes dans le C6D6 ne présentent pas de complexe de toluène mais un mélange à l’équilibre du (nacnacxylCu)2(-C6D6) et nacnacxylCu(C6D6) dans une proportion de 2 pour 1. Alors que l’addition de plus de cinquante équivalents soit de THF, soit de toluène n’induit aucun changement des spectres RMN, l’addition de 2 équivalents de MeCN conduit instantanément au complexe nacnacxylCu(MeCN). De plus, le (nacnacxylylCu)2(-C6D6) ne se coordone ni ne réagit avec le N2O, même après avoir été chauffé à 60°C pendant treize jours. En présence de DPA (diphenylacétylène), la réaction du nacnacBnH avec le CuOtBu conduit au dimère ponté (nacnacBnCu)2(µ-DPA). L’addition d’un excès de DPA (10-12 équivalents) transforme le dimère ponté en complexe lié en position terminale nacnacBnCuDPA. Les nacnacRH (R = CH(Me)Ph et i-Pr) ne forment pas de complexe ni avec les oléfines ni avec le DPA. Une réactivité similaire a été observée avec les complexes de nacnacCH(Me)PhCu(NCMe) et nacnaci-PrCu(NCMe). Tandis que le complexe lié en position terminale par MeCN a été isolé et caractérisé, l’équilibre en solution nous laisse suspecter la formation d’un complexe d’acétonitrile ponté. Des études de réactivité comparatives ont été menées sur quelques complexes de cuivre. La Morpholine ne réagit pas avec le nacnacBnCu(acrylonitrile) contrairement à l’acrylonitrile libre. L’expérience de l’échange d’oléfine montre que l’acrylonitrile (une oléfine électro-attractrice) se lie plus fortement que les autres oléfines, mettant ainsi en évidence l’importance de la rétrodonation  face à la donation La rétrodonation est cependant faible comparée aux autres complexes de styrène structurellement caractérisés. Les complexes nacnacCH(Me)PhCuL (L = PPh3 et MeCN) ont été employés dans la cyclopropanation catalytique du styrène et dans l’addition conjuguée du ZnEt2 sur la 2-cyclohexénone, mais les résultats indiquent que le ligand dikétimine est éliminé avant son entrée dans le cycle catalytique. Par conséquent, il n’y a pas d’induction chirale. Les complexes tétra coordinées de cuivre avec les nacnacRCu(phen) (R = Bn, CH(Me)Ph et Phen = 1,10-phenanthroline, 2-Mes-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline (dmp) et 2,9-diphenyl-1,10-phenanthroline (dpp)) ont été synthétisés. Ces complexes sont d’une intense couleur bleue et des interactions d’empilement entre l’un des cycles phényle des ligands nacnac et la phénanthroline ont été observées dans les structures à l’état solide. Les mesures en absorption UV-visible ont été effectuées dans le toluène et les bandes MLCT sont déplacées vers le rouge par rapport à celles des complexes de cuivre et bisphénanthroline. Tous ces composés émettent à l’état solide mais les complexes 1,10-phenanthroline et 2-Mes-1,10-phenanthroline n’émettent pas en solution. Pour renforcer les interactions d’empilement , les nouveaux ligands nacnacRH (R = CH2C6H2(OMe)3, CH2C6F5) et leurs complexes de cuivre respectifs ont été préparés avec du dmp et dpp. Afin de permettre la comparaison, le nacnaciBuCu(dmp) a été synthétisé. Alors que les complexes dmp montrent une augmentation des interactions intramoléculaires - avec les substituants phényle du ligand dikétimine et de la phénanthroline, les complexes dpp ne révèlent pas de telles interactions. Les complexes perfluorés montrent, en absorption et en émission, un déplacement significatif vers le bleu, alors que les complexes substitués par un groupements isobutyle présentent des transitions déplacées vers le rouge. Alors que les intensités de luminescence et les durées de vie sont faibles, les déplacements réduits de Stokes et les pics étroits de luminescence comparables indiquent une réduction des distorsions de l’état excité. / The ligand nacnacxylH (xyl = C6Me2H3) and the N-alkyl substituted diketimine ligands (nacnacCH(Me)PhH, nacnacBnH and nacnaciPrH) have been prepared in good yields except nacnaciPrH (23%) using a one-step procedure with the help of a Dean-Stark apparatus. Reaction of S,S-nacnacCH(Me)PhH and nacnacBnH with nBuLi in THF gave S,S-nacnacCH(Me)PhLi(THF) and nacnacBnLi(THF). Attempts to brominate these THF adducts with N-bromosuccinimide gave instead the -carbon substituted succinimido ligands S,S-succnacnacCH(Me)PhH and succnacnacBnH (succ = succinimido). Chlorination with N-chlorosuccinimide, afforded the desired product albeit with significant amounts of impurities. Reaction of these ligands with CuOtBu (or MesCu and catalytic amounts of CuOtBu, Mes = C6Me3H2) in the presence of Lewis bases gave (nacnacxylCu)2(-toluene), nacnacxylCuCNC6H3(Me)2, nacnacCH(Me)PhCuL (L = PPh3, PMe3, CNC6H3(Me)2, DMAP, lutidine, Py, MeCN), nacnacBnCuL (L = PPh3, CNC6H3(Me)2, styrene, trans-stilbene, phenylvinylether, acrylonitrile, diphenylacetylene), nacnaciPrCuL (L = PPh3, CNC6H3(Me)2, MeCN) and succnacnacCH(Me)PhCuL (PPh3, CNC6H3(Me)2, pyridine). All complexes are yellow and sensitive to air and moisture. There was no reaction between the copper precursors and the N-alkyl substituted ligands in the absence of strong Lewis bases. NMR studies of the complex (nacnacxylCu)2(-toluene) in C6D6, showed no toluene adduct but an equilibrium mixture of (nacnacxylCu)2(-C6D6) and nacnacxylCu(C6D6) in a ratio of 2:1. While addition of up to 50 equiv of either toluene or THF did not cause any significant change in the 1H NMR spectrum, addition of 2 equiv MeCN gave instantaneously the nacnacxylCu(MeCN) complex. In addition, (nacnacxylylCu)2(-C6D6) did not coordinate or react with N2O even after heating at 60 oC for thirteen days. In the presence of DPA (diphenylacetylene), reaction of nacnacBnH with CuOtBu yields the bridged dimer (nacnacBnCu)2(µ-DPA). Addition of excess DPA (10-12 equiv) converts the bridged dimer to the terminally bound complex nacnacBnCuDPA. NacnacRH (R = CH(Me)Ph and i-Pr) did not form complexes with olefins or with DPA. Similar reactivity was observed in nacnacCH(Me)PhCu(NCMe) and nacnaci-PrCu(NCMe) complexes. While the terminally bound MeCN complex was isolated and characterized, equilibrium in solution led us to suspect the formation of a bridged acetonitrile adduct. Reactivity and comparative studies were performed with several copper complexes. Morpholine did not react with nacnacBnCu(acrylonitrile) while free acrylonitrile does. Olefin exchange experiment showed that acrylonitrile (an electron withdrawing olefin) binds stronger than the other olefins examined, showing the importance of -backbonding relative to -donation. -Backbonding is, however, still low when compared other structurally characterized transition metal styrene complexes. Complexes nacnacCH(Me)PhCuL (L = PPh3 and MeCN) have been employed in catalytic cyclopropanation of styrene and the conjugate addition of ZnEt2 to 2-cyclohexenone, but results indicate that the diketimine ligand is lost before it enters the catalytic cycle. Hence, there was no chiral induction. Four-coordinate copper(I) complexes of the form nacnacRCu(phen) (R = Bn, CH(Me)Ph and Phen = 1,10-phenanthroline, 2-Mes-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline (dmp) and 2,9-diphenyl-1,10-phenanthroline (dpp)) were also prepared. The complexes are intensely blue in colour and intramolecular -stacking interactions between one of the phenyl rings of nacnac ligand with the phenanthroline were observed in the solid state structures. UV-vis absorption measurements were performed in toluene and the MLCT bands are red-shifted relative to those of bisphenanthroline copper complexes. All compounds are emissive in the solid state, but 1,10-phenanthroline and 2-Mes-1,10-phenanthroline complexes do not emit in solution. To buttress the -stacking interactions, the new ligands nacnacRH (R = CH2C6H2(OMe)3, CH2C6F5) and their respective copper complexes with dmp and dpp were prepared. For the sake of comparison, nacnaciBuCu(dmp) was prepared. While the dmp complexes showed enhanced -intramolecular interactions with both phenyl substituents of the diketimine ligand and the phenanthroline, dpp revealed no such interactions. The perfluorinated complex showed a significant blue-shift in absorption and emission spectra when compared to the other complexes, while the isobutyl substituted complex displayed red-shifted transitions. While luminescence intensities and lifetimes were low, reduced Stoke shifts and comparable sharp luminescence peaks indicate reduced distortions in the excited state.

Optically active helical microparticles are studied in the forms of thin films, suspensions and powders. From fabricated helical porous thin films, microparticle suspensions are obtained by removing the microparticles (film columns) from their substrates and dispersing them into water. For removing microparticles, four methods are explored and compared: sacrificial NaCl layer, gold (Au) layer, buffered oxide etching, and direct ultrasonic agitation. The primary film material studied in this work is amorphous silicon (Si). Physical morphology of the microparticles is examined with scanning electron microscopy (SEM). Methods employed to characterize optical activity of the microparticles include: polarimetry, spectrophotometry, and spectroscopic ellipsometry (SE). The produced chiral microparticles exhibit optical activity: optical rotation (OR) and circular dichroism (CD - in the form of differential circular transmission (DCT)). Significant findings include: (a) we observe the largest optical rotatory power ever reported in scientific literature, 11◦/μm at 610 nm wavelength for a Si film; (b) for the helical thin films, there is one dominant DCT band in the measured wavelength range; however for microparticle suspensions and powders, there exist two DCT bands: one broad band at long wavelengths, and one narrow band in the short wavelength range; compared to their thin film forms, microparticle suspensions and powders have inverted sign for the broad DCT band. A discrete dipole approximation (DDA) model is employed to calculate optical response (e.g. extinction, scattering, and absorption cross-sections) of the microparticles, so as to enable us to understand the effects of different structural parameters of the microparticles on their optical response. Calculation confirms that optical activity of chiral microparticles is due to coherent light scatterings with the chiral structures of the particles. The inversion in sign of the broad DCT bands of microparticle suspensions and powders is likely due to the averaging effect from random orientation of the helical microparticles, as is indicated both from experimental results and from calculation. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-07-06 09:59:20.751

Les travaux présentés dans ce mémoire décrivent une nouvelle voie de synthèse d'aminoalcools 1,2 à partir de γ-bromo-β-cétosulfoxydes, dans lesquels seul le centre stéréogène du soufre est défini. Cette synthèse s'appuie sur deux processus hautement stéréocontrôlés dirigés par le groupement sulfoxyde : le dédoublement cinétique dynamique lors de la substitution nucléophile du brome par la dibenzylamine et la réduction diastéréosélective du carbonyle. Les syn-γ-N,N-dibenzylamino-β-hydroxysulfoxydes correspondants ont été obtenus avec des excès diastéréoisomériques supérieurs à 95%. Les syn-γ-N,N-dibenzylamino-β-hydroxysulfoxydes se sont avérés être des intermédiaires très intéressants pour la synthèse de produits comportant le motif aminoalcool 1,2. Ainsi, nous avons décrit la préparation d'un 3-N,N-dibenzylamino-1,2-diol et son utilisation dans une nouvelle stratégie de déprotection régiodivergente d'acétals cycliques. Nous avons également décrit un nouvel accès aux cis-2-méthyl-6-alkylpipéridin-3-ols, via l'ouverture de cycle d'un 3-N,N-dibenzylamino-1,2-époxyde par l'azaénolate dérivé d'une hydrazone, et l'avons appliqué à la synthèse d'un alcaloïde, la (+)-déoxocassine. Parallèlement, nous avons débuté une étude de synthèse d'aminoalcools 1,3 par la réduction diastéréosélective d'une oxime dérivée d'un δ-céto-β-hydroxysulfoxyde. / In this thesis manuscript, we report on a new pathway to 1,2-aminoalcohols starting from chiral nonracemic γ-bromo-β-ketosulfoxides. This two-step approach, where the stereo control is provided by the sulfoxide group, relies on a highly stereocontrolled nucleophilic substitution of the bromine by dibenzylamine, combined with a dynamic kinetic resolution process, and the reduction of the carbonyl group. The corresponding syn-γ-N,N-dibenzylamino-β-hydroxysulfoxides were obtained with more than 95% diasteroisomeric excess. These syn-γ-N,N-dibenzylamino-β-hydroxysulfoxides turned out to be very useful intermediates for the synthesis of aminoalcohol containing products. Thus, we described the preparation of a 3-N,N-dibenzylamino-1,2-diol, and its use in an original strategy of regiodivergent cyclic acetals deprotection. We also developed a new access to "all cis"-2-methyl-6-alkylpiperidin-3-ols, by the mean of a 3-N,N-dibenzylamino-1,2-epoxide ring opening reaction with the azaenolate derived from an hydrazone. We applied this methodology to the synthesis of an alkaloid, (+)-deoxocassine. In addition, we studied a synthesis of 1,3-aminoalcohols using a diasteroselective reduction of a δ-keto-β-hydroxysulfoxyde-derived oxime.

Dans ce travail de thèse, nous avons d'abord développé deux études basées sur des unités dites ''stilbène rigide'' qui sont connues pour s'interconvertir de manière réversible entre deux formes trans et cis grâce à la lumière. La première étude correspond à des photocommutateurs chiraux à base d'hélicènes, l'autre à des complexes photocommutables alcynyles d'or(I). Ensuite, nous avons examiné la synthèse et la caractérisation de complexes de Dy(III) à base d'hélicène-bipyridine comme nouveaux types d'aimants moléculaires (SMM) chiraux et comparé la différence des propriétés magnétiques entre les SMM racémique et énantiopurs. Enfin, nous avons développé la première utilisation de la cycloaddition réversible d'hélicènes racémiques sur le [60]fullerène et de sa rétrocycloaddition ultérieure comme une stratégie alternative efficace pour le dédoublement énantiomérique d'un hélicène-carboxaldéhyde. / In this PhD work, we firstly developed two studies based on the so-called ''stiff stilbene'' units that are known to reversibly interconvert between two trans and cis forms through light. The first study corresponds to photoresponsive chiral switches based on helicenes, the other one to photoresponsive gold(I) complexes. Then, we dealt with the synthesis and characterization of helicene-bipyridine based Dy(III) complexes as novel kinds of chiral single molecule magnets (SMMs) and compared the difference of the magnetic properties between racemic and enantiopure SMMs. Finally, we developed the first use of the reversible sterodivergent cycloaddition of racemic helicenes onto [60]fullerene with its subsequent retro-cycloaddition as an efficient alternative strategy for the enantiomeric resolution of a helicene-carboxaldehyde.