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Acknowledgment I extend my sincere gratitude and appreciation to many people who made this doctoral thesis possible. Special thanks are due to my supervisor Prof. Ryan Richards for his timely advices and cooperation. Thanks are also due to my former and current lab mates Mr. A. Suchopar for help with experiment organisation, Dr. K. Zhu and Dr. L. D’Souza and Dr. F. Pozgan, for many useful advices and directing, Dr. J. C. Hu and Mrs. L. F. Chen for general help and cooperation in lab work, Mr. L. Zhi and Mrs. Helga van Eys-Schaefer with Mrs. Kirsten Töbe (Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung, Bremen) for very important and high quality TEM photographs. Author thanks Prof. Gerard Buono and Dr. Didier Nuel of Université Aix-Marseille III, France for providing the quiphos and quiphos-spider ligands and for useful discussion concerning the quiphos modifier, Dr. Virginie Ratovelomanana-Vidal (Laboratoire de Chimie Organique, E.N.S.C.P., UMR) for providing the synphos ligand and her colleague Dr. Véronique Michelet for useful discussion about synphos ligand. I would like to thank Prof. U. Kortz (International University Bremen, Bremen) and Dr. E. Kirilina (Physikalisch-Technische Bundesanstalt, Berlin) for useful discussions about NMR spectra, Prof. Thomas Nugent (International University Bremen, Bremen) and Prof. S. Tautz (International University Bremen, Bremen) for useful discussions about organic chemistry and surface science, correspondingly, as well as for being my work supervisors, Dr. T. Mallat and Prof. A. Baiker (Swiss Federal Institute of Technology, Zurich) for useful discussions about cinchonidine on Pd and Pt systems, Dr. Achim Gelessus (International University Bremen, Bremen) for help with work with Gaussian 03 software, Dr. L. G. Gordeeva (Boreskov Institute of Catalysis, Novosibirsk) for discussions about surface chemistry of alumina and silica materials, Dr. A. G. Okunev (Boreskov Institute of Catalysis, Novosibirsk) for discussion about kinetics of heterogeneous reactions, Dr. Serguei Soubatch (International University Bremen, Bremen) for discussions about chemical physics of surfaces. I am highly indebted to Dr. Yu.I.Aristov (Boreskov Institute of Catalysis, Novosibirsk), Prof. S. A. Dzuba and Mrs. R. I. Ratushkova (Chair of Chemical and Biological Physics, Novosibirsk State University, Novosibirsk) for introducing me to the world of science and right directing and general support. My gratitude goes to the International University Bremen for providing me a financial support during my Ph.D. studies and making this work possible. Finally, my special gratitude goes to my wife Mrs. Liliya Kulishova and my family for their cooperation, support and encouragement. iv
Abstract Studies of the interactions of organic substrates with nanoscale metals and metal oxides are of fundamental importance for both fundamental scientific understanding and the development of commercial applications. Additionally, the development of heterogeneous (solid/liquid or solid/gas) enantioselective catalysts is of great interest for the pharmaceutical industry. Here, the adsorption of chiral ligands on metal surfaces to develop heterogeneous asymmetric catalysts is presented. Functionalizing metal nanoparticles with chiral ligands facilitates increased surface coverage and the observed activity of these catalysts is significantly higher than their conventional phase counterparts. The first two chapters are an introduction to the enantioselective catalysis and nanosized materials. As described in the chapter 3, the primary objectives of this work are 1. to synthesize Pt and Pd nanoclusters modified by specific chiral ligands by `bottom up' chemical synthesis, 2. to determine the geometric orientation of adsorbed modifier with respect to the metal surface via DRIFTS (Diffuse Reflectance Infra-red Fourier Transform Spectroscopy) and molecular modeling, 3. test enantioselective activity of the obtained samples in the hydrogenation of ethyl pyruvate. The special effort has been given for investigation of cinchonidine as modifier (chapter 4, 5, 6). Among the following chiral ligands: quiphos (chapter 7), “quiphos-spider” (chapter 8), binap and synphos (chapter 10), only diop (chapter 9) was found to be able to induce low enantioselectivity, that was qualitatively explained through comparison with cinchonidine/Pt system. v
Page 1 and 2: Preparation and Characterization of
Page 3: 5.4 Summary 66 Chapter 6 Cinchonidi
Page 7 and 8: many compounds are biologically act
Page 9 and 10: Fig. 1-7. Hexahelicene [3]. 7. Chir
Page 11 and 12: R H COOH C OH CH 3 H COO - Bricine-
Page 13 and 14: Catalyst activity, expressed in the
Page 15 and 16: In fact, there are only two heterog
Page 17 and 18: similar way as relative abundance o
Page 19 and 20: surface concentration of cinchonidi
Page 21 and 22: site on Pt surface formed by a adso
Page 23 and 24: Chapter 2 Introduction to the nanos
Page 25 and 26: Triangular prism 5 4 Comments: A -
Page 27 and 28: precursors and building-up. This me
Page 29 and 30: 2.3 Preparation of nanoclusters on
Page 31 and 32: Paris Marseille Ljubljana Synphos Q
Page 33 and 34: Chapter 4 Cinchonidine modified Pt
Page 35 and 36: dihydrocinchonidine (355 mg or 1.2
Page 37 and 38: Table 4-1. Comparison between 5 % P
Page 39 and 40: widening can be used in estimation
Page 41 and 42: 1 Absorbance 0.1 2 1600 1400 1200 1
Page 43 and 44: the focus of these prior experiment
Page 45 and 46: Fig. 4-11. Tilted adsorbed cinchoni
Page 47 and 48: sci., QL. comp. 768 (str) 756 (str)
Page 49 and 50: Conversion, % 100 80 60 40 ITP time
Page 51 and 52: 6A c 10 19.5 B, 20 61 0 3 0.18 0.51
Page 53 and 54: pressure, exposing time, cinchonidi
Page 55 and 56:
Fig. 4-16. Linear relationship betw
Page 57 and 58:
1 , 1209 cm -1 and 1382 cm -1 remai
Page 59 and 60:
Our results are in line with previo
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eaction. The stability of the catal
Page 63 and 64:
Table 5-1. Ee and reaction rate ind
Page 65 and 66:
Enantiomeric excess, % 85 80 75 A2
Page 67 and 68:
35 30 Before After Percent of parti
Page 69 and 70:
catalyst activation seems to indica
Page 71 and 72:
Table 5-3. Assignment of some vibra
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6.2 Experimental Materials Cinchoni
Page 75 and 76:
Fig. 6-3. TEM image of cinchonidine
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From the results of EP and EB hydro
Page 79 and 80:
enhancement. However the exact fact
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Further, this family of man-made li
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Fig. 7-2. TEM of quiphos modified P
Page 85 and 86:
of quiphos adsorbed on Pt and Pd an
Page 87 and 88:
Fig. 7-8 Flat adsorbed quiphos via
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comp., H 11,12,13,14 2 C b., 2 P 11
Page 91 and 92:
Chapter 8 “Quiphos-spider” modi
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flat crystal surface due to the hig
Page 95 and 96:
Chapter 9 Diphos and diop modified
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Table 9-1. Average crystal size of
Page 99 and 100:
Fig. 9-4. Conformation of diphos mo
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ings. Due to these reasons we can n
Page 103 and 104:
Fig. 9-9. Proposed orientation of a
Page 105 and 106:
The model of adsorption of diop on
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The calculation of energy of formin
Page 109 and 110:
For the preparation of synphos modi
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1 2 20 40 60 80 2Θ Fig. 10-3. XRD
Page 113 and 114:
The DRIFT spectra of synphos (Fig.
Page 115 and 116:
peaks which can be used for analysi
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References [1] G.E. Tranter, J. Che
Page 119 and 120:
[64] A. Szabo, N. Kunzle, T. Mallat
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[128] J.D. Aiken III, R.G. Finke, J
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[189] K. Umezawa, T. Ito, M. Asada,
Page 125:
I declare that the current Ph.D. th
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