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URN: urn:nbn:de:bsz:25-opus-85758
URL: http://www.freidok.uni-freiburg.de/volltexte/8575/

Maclaren, Jana K.

Synthesis and charactarization of chiral coordination polymers

Synthese und Charakterisierung von chiralen koordinations Polymeren

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Kurzfassung in Englisch

The work discussed in this thesis involves chiral transition coordination polymers. Enantiopure ligands and racemic mixtures of ligands were used, as well as mixed ligand systems of enantiopure and non-chiral ligands, to obtain new chiral coordination polymers.
In this context, Cu(II) halides were reacted with enantiopure amino alcohols (LH= 2-amino-ethan-1-ol (ae), (R)-2-amino-propan-1-olate (ap), (R)-2-amino-butan-1-olate (ab), (R)-2-amino-2-phenyl-ethanolate (aPhe)) in the presence of base. Enantiopure trinuclear Cu-amino alcoholate SBUs {Cu3(µ-L)4X2} can be reproducibly obtained. Supramolecular interactions aggregate the SBU into 2D-layers with a polar hydrophilic interior and ‘hydrophobic exterior’ nonpolar groups oriented away from both sides. Thus, thin crystal plates form along the charge-assisted Cu(2+)∙∙∙(–)Br, N-H···(–)O and N-H···(–)Br bond orientation. A magnetic study of the two compounds {Cu3(µ-L)4X2} (X=Br, L=ae and ab) showed a ferromagnetic coupling, which is in agreement with their structural parameters (mainly the Cu−O−Cu bond angle). A very good agreement for {Cu3(µ-L)4X2} between the experimental and theoretical magnetic J,j coupling constants indicates that an interaction between the terminal copper(II) ions in these linear trinuclear systems is present.
The presence of a base was crucial to the formation of the {Cu3(µ-L)4X2} SBUs. From the mother liquors (lower concentration of the amino alcohol), crystals of compound 1D-[{Cu2(µ-ab)2Br2}2{(µ3-Br)Cu(abH)2Br}{(µ3-Br)Cu(abH)(CH3OH)Br}] and 1D-[{Cu2(µ-ab)2Cl2}2{(µ3-Cl)Cu(abH)(CH3CH2OH)Cl}2] were obtained. The concentration dependence and the different possibilities to form complexes from Cu(II), halide and amino alcohol ligands were investigated. Comparing all the structures including [Cu(aeH)2X2][Cu2(ae)2X2] (with X=Cl or Br)[281] shows that several coordination modes are possible, depending on the metal-ligand concentration and ratio in the solution, with the different building blocks in an equilibrium.
In a combinatorial approach, 19 different amino acids and 18 different bridging ligands were combined with transition metal(II) nitrates (Cu, Cd, and Ni). Five new coordination polymers were obtained: two 1D copper-amino acid coordination polymers, two 2D cadmium-amino acid coordination polymers, and one cadmium-amino-4,4’-bipy coordination polymer. In the first four cases, characterization was performed using single crystal X-ray diffractometry, powder X-ray diffractometry, IR spectroscopy and Raman spectroscopy.
While the cadmium structures consist of 2D-network layers, the copper structures consist of square pyramids build up from Cu(AA)2 units, which are linked through an axial bond to give helical polymers. They can be compared to the structures of the cadmium, which consist of distorted octahedrons built up from Cd(AA)2 units, linked through axial bonds to give a 2D polymer. Taking the long Jahn-Teller interactions of the Cu-compound into account, the four structures are fairly similar. The mixed ligand compound 3D-{[Cd(μ2-4,4’-bipy)( μ-D-Phe)H2O][NO3]}∞ is built up from 1D helices connected to a 2D layer through charge-assisted H-bonds. Those 2D layers are connected from the linking ligand 4,4’-bipy to a 3D network; chirality is transferred into the H-bond network and the 4,4’-bipy ligand exhibits axial chirality.
The achiral mesoxalato ligand (H2mesox2) was used and yielded spontaneously in eleven isostructural extended homochiral MOFs 2D-[Ln2(μ-H2mesox)3(H2O)6] structures [with Ln(III) = La (1), Ce(2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Er (10), Yb (11) and H4mesox = mesoxalicacid]. The isostructurality was deduced by means of powder and single crystal X-ray diffraction analysis. Single crystal X-ray analysis was carried out for 7 of the compounds (1,2,3,4,7,10 and 11). The Ln(II) ions are covalently connected by the mesoxalato ligands into a corrugated grey arsenic-type (6,3)-net (layer) with chair-shaped six-membered rings. The Ln(III) ions exhibit Δ/Λ-configured coordination spheres. Luminescence measurements show strong emission bands characteristic for isolated Eu(III) ions. This dominating intensity of the hypersensitive transition within trivalent europium (5D0 / 7F2) reacts strongly to the absence of a local inversion and reflects the chirality of the structures. Magnetic susceptibility measurements show typical deviations from the Curie law. This is mainly because of the split of the ground term due to ligand field or crystal field. In the case of Sm(III) and Eu(III) compounds, spin-orbit coupling determines the magnetic behaviour.
The mesox ligand was used in another 3D coordination network. The 3D-{[K(H2O)6]0.5[K(18-crown-6)]0.5[MnCu3(Hmesox)3]·5.25H2O} compound (16) is built from the SBU, [Cu3(Hmesox)3]3−. This SBU acts as a planar 3-connecting node and, combined with the 3-connected Mn2+ node, yields the anionic chiral 3D [MnCu3(Hmesox)3]− (10,3)-a network. It crystallizes in a doubly interpenetrated network, with both P and M (10,3)-a anionic nets in a racemic centrosymmetric crystal structure and with the disordered [K(H2O)6]+ and [K(18-crown-6)]+ cations in small cavities.
Three new neutral bridging ligands with two [1,2,4]triazoyl groups connected through aliphatic bridges were synthesised: 1,2-bis[1,2,4]triazol-4-yl-propane (BTTiP), 1,3-bis[1,2,4]triazol-4-yl-propane (BTRP), 1,4-bis[1,2,4]triazol-4-yl-butane (BTRB). Four new coordination polymers with these ligands were obtained and their structure was determined through single crystal X-ray crystallography.
In the zinc compound {Zn(μ5-btc)2(μ4-BTRB)∙[(H2O)(dmf)]0.8(H2O[NH2(CH3)2] [OH])0.2}∞ (3.4-1) the two ligands connect a trinuclear SBU to a 3D network. The SBU consists of zinc atoms μ-bridged from the carboxylic groups and the triazol groups to give a linear rod. The coordination sphere is octahedral for the central zinc atom and tetrahedral for the external zinc atoms. The 3D compound {[Cd2(μ4-BTRB)3(NO3)6]2-(H+)2∙(H2O)x}∞ (3.4-2) was obtained from a mixed ligand synthesis of Cd(NO3)2, BTRB and chiral bridging acids such as camphoric acid, mandelic acid or ascorbic acid. However, these bridging acids did not co-crystallize. Their presence was crucial for the formation of the compound by influencing the pH of the reaction mixture. The compound is build up from μ-bridged Cd chains connected by the BTRB ligand to built triangular channels with nitrate anions are located along the wall of these channels, resulting an overall negatively charged frame. This negative charge is balanced by delocated protonated water inside the channels.
The two structures {Cd(μ2-BTRE)(μ2-Camph)}∞ (3.4-3) and {Cd(μ2-BTRiP)(μ2-Camph)·[H2O]}∞ (3.4-4) crystallize in very similar corrugated 2D sheets with alternating Λ- and Δ-coordination of the Cd cations. The protruding methyl group of the BTRiP has some influence on the coordination sphere of the Cd atom closer to the methyl group, as the coordination sphere becomes more trigonal prismatic. The bigger influence of the methyl group, however, is on the packing of the corrugated layers. While in 3.4-3 the layers are stacked on top of each other with a translational symmetry operation, the layers in 3.4-4 are stacked alternating through an inversion and a C2 rotation and water molecules enclose between every second layer, translational symmetry occurs only after four layers.
Another new neutral bridging ligand with a triazoyl group connected to a pyridyl group was synthesised: 4-(pyrid-4-yl)-1,2,4-triazole (pytz). The new ligand can coordinate terminally to a metal atom by its Npyridine donor atom or bridge between metal atoms by Npyridine- and Ntriazole-coordination. The structure of a mononuclear complex [Cd(dca)2(κNpy-pytz)2(H2O)2], a 1-D chain coordination polymer [ZnBr2(μ-κNpy,Ntz-pytz)] ∞and a 3D network [Cd(μ-SCN)4(μ-pytz)2] were investigated. The bridging through a SCN-anion was necessary for the 3D network. The molecular complexes and the 1D chain structure feature hydrogen bonds for the 3D supramolecular packing, which involve the pytz Ntriazole atom (not involved in the metal coordination) as an acceptor. This way, adjacent chains in 1D-[ZnBr2(μ-κNpy,Ntz-pytz)] are connected through C–H···Br and C–H···Ntriazole hydrogen bonds to a supramolecular 3D network.
The structure of six different Ag(I) and one Cu(I) compounds with the 1,2,4-triazolo[1,5-a]pyrimidine (tp), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) and 7-amine-1,2,4-triazolo[1,5-a]pyrimidine (7atp) ligands and different counter anions was determined using single crystal X-ray diffractometry. The dinuclear [Ag2(μ-tp)2]2+ building units are featured in all silver complexes, independently of the counterion used. These dimers are present as discrete entities in four of the Ag(I) compounds. However, in two cases, these species are connected to each other leading to 1D and 3D polymers. The 3D polymer is built from a cationic 3D silver(I) metal–ligand network with NbO topology.
The Cu(I) compound [Cu2(μ-tp)(CH3CN)(μ-I)(μ3-I)]n is a 2D-polymer with a bridging mode of the tp ligand via N1 and N3 between chair-like [Cu4I4] units.
The single crystal X-ray structures of the molecular half-sandwich η5-cyclopentadienylpalladium (η5-C5H5)Pd(C6F5)(AsPh3), (η5-C5Ph4H)Pd(C6F5)(AsPh3), (η5-C5Bn5)Pd(C6F5)(AsPh3), PdBr0.23Cl0.77(C6F5)(AsPh3)2 and Pd(C6F5)Cl(bpzm*) [bpzm* = bis(3,5-dimethylpyrazol-1-yl)methane] were determined and discussed.
New ligands were synthesised. Several different ligands (including the new ligands) and ligand combinations were successfully investigated for the formation of new 1D to 3D coordination polymers. The structures of many new chiral and some non-chiral coordination polymers and their properties were investi

Kurzfassung in Deutsch

In der vorliegenden Arbeit werden neue 1D-, 2D- und 3D-Koordinationspolymere vorgestellt. Enantiomerenreine und racemische Mischungen von Liganden und Kombinationen von nicht chiralen Brückenliganden und chiralen Liganden wurden verwendet um neue chirale Koordinationspolymere zu synthetisieren.

Die dreikernige sekundäre Baueinheit (SBU) {Cu3(µ-L)4X2} ist aus chelatierendem, O-verbrückendem Aminoalkoholat (µ-L) und terminalen Halogenidliganden aufgebaut (X = Br oder Cl; L = 2-Aminoethan-1-olat (ae), (R)-2-Aminopropan-1-olat, (R)-2-Aminobutan-1-olat (ab) oder (R)-2-Amino-2-phenylethanolat). Durch Verbrückung via Halogenidliganden entsteht ein homochirales 2D-Polymer. Die Kristallstrukturen und ihr Einfluss auf die Kristallmorphologie der 6 isomorphen 2D-[Cu3(µ-L)4(µ3-X)2]∞ Verbindungen werden untersucht und diskutiert. Der pH-Wert und das Reaktandenverhältnis ist wichtig für die Synthese der 2D-Koordinationspolymere. Eine niedrige Liganden- oder Basenkonzentration führt zu 1D-Polymeren, die aus einer Mischung aus zweikernigen {Cu2(µ-L)2X2} und einkernigen {(µ3-X)Cu(LH)(S)X} und {(µ3-X)Cu(LH)2X} (mit S=Lösungsmittel) Baueinheiten aufgebaut sind. Die Kristallstruktur der beiden 1D-Koordinationspolymere [{Cu2(µ-ab)2Br2}2{(µ3-Br)Cu(abH)2Br}{(µ3-Br)Cu(abH)(CH3OH)Br}], [{Cu2(µ-ab)2Cl2}2{(µ3-Cl)Cu(abH)(CH3CH2OH)Cl}2] und des Nebenproduktes {[Cu(rac-abH)(rac-ab)H2O]ClO4}2 wurden bestimmt und werden diskutiert. Das Gleichgewicht zwischen den einkernigen, zweikernigen und dreikernigen Baueinheiten wurde untersucht und wird diskutiert. Temperatur-abhängige magnetische Suszeptibilitätsmessungen der Verbindungen [Cu3(µ-L)4(µ3-X)2]∞ (L=ae; X=Br) zeigen ferromagnetische Kupplung, aber keine magnetische Ordnung, jedoch mit einsetzender Fernordnung bei Temperaturen unter 3K. Weitere AC-magnetische Messungen mit verschiedenen Frequenzen bei Temperaturen zwischen 1,9 K und 5 K zeigen, dass die magnetische Fernordnung erst bei niedrigeren Temperaturen eintritt. Sehr gute Übereinstimmung zwischen experimentell bestimmten und theoretisch (DFT) berechneten J,j Kopplungskonstanten zeigt, das die Wechselwirkung zwischen den terminalen Cu(II)-Ionen in den linearen dreikernigen Baueinheiten nicht vernachlässigt werden darf.

Aus einem kombinatorischen Ansatz, in dem 19 verschiedene Aminosäuren (AA) und 18 verschiedene Brückenliganden mit Übergangsmetallnitraten (Cu(II), Cd(II), Ni(II)) kombiniert wurden, konnten fünf neue Koordinationspolymere erhalten werden: zwei 1D-[Cu(AA)2]∞ -Polymere, zwei [Cd(AA)2]∞ -Polymere und das Mischliganden-Polymer {[Cd(μ2-4,4’-bipy)(AA)H2O][NO3]}∞. Die Verbindungen wurden mit Einkristallröntgenstrukturanalyse, Röntgenpulveranalyse, IR-Spektroskopie und Raman-Spektroskopie charakterisiert .

Aus dem achiralen Mesoxalato-Ligand (H2mesox2) bilden sich spontan homochirale 2D-Koordinationspolymere 2D-[Ln2(μ-H2mesox)3(H2O)6] (mit Ln(III) = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb und H4mesox = CO2HC(OH)2CO2H). Die Isostrukturalität dieser elf Verbindungen wurde mit Röntgenpulveranalyse bestätigt. Einkristallstrukturanalyse konnte an 7 Verbindungen durchgeführt werden (La, Ce, Pr, Nd, Gd, Er and Yb). Der Mesoxalat-Ligand verbindet die Ln(II)-Ionen zu einem (6,3)-Netz vom Typus des grauen Arsen. Die Ln(II)-Ionen haben eine Δ/Λ-konfigurierte Koordinationssphäre. Lumineszenzmessungen bestätigen die chirale Koordinationssphäre und magnetische Suzeptibilitätsmessungen zeigen typische Abweichungen vom Curie-Gesetz. Eine weitere Mesoxalatstruktur ( {[K(H2O)6]0.5[K(18-crown-6)]0.5[MnCu3(Hmesox)3]·5.25H2O}) wurde bestimmt und diskutiert.

Neue neutrale verbrückende Triazolliganden (1,2-Bis[1,2,4]triazol-4-yl-ethane (BTRE), 1,2-Bis[1,2,4]triazol-4-yl-propane, 1,3-Bis[1,2,4]triazol-4-yl-propane, 1,4-Bis[1,2,4]triazol-4-yl-butane (BTRB) und 4-(pyrid-4-yl)-1,2,4-triazole (pytz)) wurden synthetisiert. Diese wurden verwendet um die neuen mehrdimensionalen Koordinationspolymere ((3D-{Zn(μ5-BTC)2(μ4-BTRB)∙[(H2O)(dmf)]0.8(H2O[NH2(CH3)2][OH])0.2}∞, 3D-{[Cd2(μ4-BTRB)3(NO3)6]2-(AH+)2∙(H2O)x}∞, 2D-{Cd(μ2-BTRE)(μ2-Camph)}∞, 2D-{Cd(μ2-BTRiP)(μ2-Camph)·[H2O]}∞, (mit BTC=Trimesinsäure und AH+= protoniertes Kristallwasser)) herzustellen. Die Strukturen wurden mit Einkristall-Röntgenstrukturanalyse bestimmt. Weitere Strukturen mit Triazolliganden wurden bestimmt und werden diskutiert ([Cd(dca)2(κNpy-pytz)2(H2O)2], 1D-[ZnBr2(μ-κNpy,Ntz-pytz)] und 3D-[Cd(μ-SCN)4(μ-pytz)2]).

SWD-Schlagwörter: Koordinationspolymer
Freie Schlagwörter (deutsch): chiral
Freie Schlagwörter (englisch): chiral , coordination polymer
Institut: Institut für Anorganische und Analytische Chemie
Fakultät: Fakultät für Chemie, Pharmazie und Geowissenschaften
DDC-Sachgruppe: Chemie
Dokumentart: Dissertation
Erstgutachter: Janiak, Christoph (Prof. Dr.)
Sprache: Englisch
Tag der mündlichen Prüfung: 04.05.2012
Erstellungsjahr: 2012
Publikationsdatum: 03.09.2012