Metal complexes of amino acids which form tridentate N

91 Pages·2005·6.19 MB·English

Metal complexes of amino acids which form tridentate
N-chelates

Metallkomplexe mit Dreizähnig Chelatisirenden
Aminosäuren

Den Naturwissenschaftlichen Fakultäten
der Friedrich-Alexander-Universität Erlangen-Nürnberg
zur Erlangung des Doktorgrades

Vorgelegt von
Slobodan Novokmet
aus Kragujevac, Serbien und Montenegro.
Als Dissertation genehmigt von den
Naturwissenschaftlichen Fakultäten der Universität
Erlangen-Nürnberg

Tag der mündlichen Prüfung: 22.12.2005

Vorsitzender der
Promotionskommission: Prof. Dr. D. –P. Häder

Erstberichtstatter: PD Dr. R. Alsfasser

Zweiteberichtstatter: Prof. Dr. Dr. h. c. R. van Eldik
Acknowledgements

This work was carried out from August 2002 until September 2005 at the Institute of
Inorganic Chemistry at the Friedrich–Alexander–University of Erlangen–Nürnberg
under supervision of PD Dr. Ralf Alsfasser to whom I would especially like to thank for
a very productive time in his group, his permanent interest in my work, and his financial
support during my work. Sincere thanks are given to my group co-workers Dipl. Chem.
Christian Schickaneder and Dr. Nicole Niklas for having a good time during the work in
the lab, useful discussions, and advices.
I would like to thank to Prof. Dr. Dr. h. c. Rudi van Eldik for his great support and the
possibility to finish my work in his group.
Special thanks are also given to: Dr. Frank Heinemann for x-ray analyses, Dr. Achim
Zahl for NMR measurements, Susanne Hoffmann for IR measurements, Christina
Wrona for elemental analyses, Dr. Jörg Sutter and Martin Bachmüller for mass
spectrometry measurements, Prof. Dr. Paul Müller and Sahabul Alam (Department of
Physics) for the STM measurements, the people from workshop of the Institute and
glassblower Mr. Zöbelein, for their excellent technical support. Dr. Jürgen Limmer, Dr.
Anton Neubrand, Dr. Carlos Dücker-Benfer, Dr. Ivana Ivanovic-Burmazovic, PD Dr.
Roland Meier, Ariane Brausam, David Sarauli, Hakan Ertürk, Joachim Maigut, Nadine
Summa, Patrick Witte, Peter Illner, Wolfgang Schiessel, Usrula Niegratschka (secretary
of the institute) for their continuous support during my work. Dr. Diana Utz and Dr.
Markus Weitzer for a wonderful time that we spent toghether on lunch-brakes. Prof. Dr.
Živadin Bugarčić (University of Kragujevac) for helping me to get the oportunity to
study in Germany.
City of Erlangen and Germany for hosting me and my family during my PhD studies.
Finally, I would like to thank my familly, wife Danijela and son Aleksa, that supported
me all of this PhD-time.
"Labor praebet quod natúra negat"

I dedicate this thesis to my wife Danijela and son Aleksa.
List of publications

1. Z. Bugarčić, S. Novokmet, Ž. Senić, Ž. Bugarčić, Chem. Mon., 2000, 131(7),
799-802.

2. S. Novokmet, V. Mujović, V. Jakovljević, D. Djurić, Perfusion, 2001, 2, 93-94.

3. Z. Bugarčić, S. Novokmet, V. Kostić, J. Serb. Chem. Soc., 2005, 70(5), 681-686.

4. S. Novokmet, S. Alam, V. Dremov, F. W. Heinemann, P. Müller, R. Alsfasser,
Angew. Chem. Int. Ed. Engl., 2005, 44, 803-806.

5. S. Novokmet, F. W. Heinemann, A. Zahl, R. Alsfasser, Inorg. Chem., 2005,
44(13), 4796-4805.

Conference contributions

1. Annual meeting of the German Atherosclerosis Society, 29.03.-31.03.2001,
Blaubeuren, Germany.

2. Annual meeting of the German Chemical Society, 06.10–11.10. 2003, Munich,
Germany.

3. The 2004 Yonger European Chemists’ Conference, Short-talk, 25.08-
29.08.2004, Torino, Italy.

4. Joint SFB Workshop, SFB 436, SFB 583, SFB 623, SFB 624, "Advances ion
Molecular Catalysis", 12-14.10.2004, Lauterbad (Schwarzwald), Germany.

5. SFB 583-Minisymposium, February 2005, Erlangen, Germany.
Table of Contents

Chapter 1
1. General Introduction 1
1.1. Aromatic Interactions 1
1.1.2. π–π Interactions 2
1.1.3. Cation–π Interactions 2
1.1.4. Investigation of aromatic interactions in peptide model systems 3
1. 2. Coordination Polymers 4
1.3. Preliminary work done in our research group 6
1.3.1. Synthesis of peptide type metal complexes: chelating ligand + biomolecule- metal 6
1.3.2. Helical Coordination Polymers 7
1.3.3. pH dependent switch of peptidic amide group from oxygen to anionic nitrogen
coordination 8
1.4. Goals and tasks of this work 9
1.4.1. Dipeptide Ligands Containing the Amino Acid Dipicolylglycine (Dpg) 9
1.5. References and Notes 11
Chapter 2
2. The Deposition of Metallopeptide Based Coordination Polymers on Graphite
Substrates: Effects of Side Chain Functional Groups and Local Surface Structure 13
2.1. Introduction 13
2.2. Results and Discusion 14
2.3. Experimental Section 20
2.4. References and Notes 26
Chapter 3 27
Aromatic Interactions in Unusual Backbone N-Coordinated Zinc Peptide
3. Complexes: A Crystallographic and Spectroscopic Study 27
3.1. Introduction 27
3.2. Results and discussion 29
3.3. Conclusions 38
3.4. Experimental Section 39
3.4.1. General Methods 39
Table of Contents

3.4.2. Bromoacetylated Amino Acid Esters. 40
3.4.3. Ligands 43
3.4.4. [(Dpg-Xaa-OMe)(H O)Zn](CF SO ) 45
2 3 3 2
3.4.5. Synthesis of [(Dpg-Xaa)-HZn] 47
3.4.6. X-ray crystallography 51
3.4.7. Apendix 55
3.5. References and Notes 57
Chapter 4
4.1. Synthesis of chiral quadridentate ligands derived from L-alanine and L-leucine 61
4.1.1. Bromoacetylated Amino Acid Esters 61
4.1.2. Ligands 62
4.2. Synthesis of chiral quadridentate ligands Dpg-Xaa – type 63
4.3. Synthesis of Zn(II) complexes using chiral quadridentate ligands Dpg-Ala-OMe
and Dpg-Leu-OMe 67
4.4. Synthesis of Zn(II)peptide based coordination polymer and N-anionic coordinated
monomer derived from leucine 70
4.5. Synthesis of Cu(II)peptide based coordination polymer derived from leucine 72
4.6. Synthesis of Ni(II)peptide based coordination dimer derived from phenylalanine 74
4.7. Synthesis of Cd(II), Co(II) and Mn(II) complexes using chiral quadridentate
ligand Dpg-Phe-OMe 76
5. Summary 81
6. Zusammenfassung 82
7. Curiculum Vitae 83

Chapter 1

1. General Introduction

1.1. Aromatic Interactions

Aromatic rings are important structural and functional elements both in biological and
in synthetic supramolecular architectures, and contribute to the intramolecular
stabilization of structures such as enzyme-substrate complexes. Aromatic interactions
play a key role in biomolecular recognition processes1 and protein aggregation. The
redox-active aromatic amino acids tyrosine and tryptophan are known to participate in
metalloenzyme-catalysed substrate oxidations. Recent results demonstrate their
importance for the activation of coordinated ligands.2 In model complexes, aromatic
rings are well known to form close contacts with metal centers in planar complexes.3
They can thereby significantly contribute to the stabilization of ternary amino acid
complexes. Depending on the nature of the rings, aromatic groups can interact in one of
several geometries. Those interactions are expected to be strong in water because of the
hydrophobic component of the interaction, and the interaction should be selective if the
electrostatic component is significant. Several geometries have been proposed on the
basis of the electrostatic component of the interaction (Figure 1).4

a b c

Figure 1. Geometries of aromatic interactions:
(a) edge-face; (b) offset stacked; (c) face-to-face stacked.
1
The edge-face geometry (Figure 1a), which can be considered a CH–π interaction, is
found in benzene in the solid state, and is commonly observed between aromatic
residues in proteins. The face-to-face stacked orientation (Figure 1b) is observed with
donor–acceptor pairs and compounds that have opposite quadrupole moments. The
offset stacked orientation (Figure 1c) represents the geometry of base stacking in DNA,
and is also found in proteins. Two types of aromatic interactions have been described
and characterized.

1.1.2. π–π Interactions

The interaction between two aromatic rings consists of van der Waals, hydrophobic and
electrostatic forces.5 Such aromatic–aromatic interactions, including the edge–face and
offset stacked geometries, are commonly observed in proteins. The interactions between
two aromatic rings may be intra- and intermolecular. π-π-Stacking between aromatic
rings is crucially involved in the stabilization of the double helical structure of DNA,
the packing of aromatic molecules in crystals, and the tertiary structures of proteins.6

1.1.3 Cation–π Interactions

The ion–quadrupole interaction between a positively charged group, such as an
ammonium or guanidinium group, and the electron-rich π-cloud of an aromatic ring,
represents the cation-π interaction.

Figure 2. Cation–π interaction

2