Tuning Reactivity of Platinum(II) Complexes

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the hydrolysis of the complex, whereas the non-hydrolysable and sterically demanding lipophilic chelating amine (dach) ligand makes the complex less polar. This has been proposed to contribute to a better cellular uptake. 60 In addition, the dach ligand prevents the binding of the DNA repair proteins by pointing into the major DNA groove (Figure 1.6). These adducts shield the inhibition of DNA replication, resulting in apoptosis and cell death. Oxaliplatin and carboplatin both have bidentate leaving groups that reduce the severity of the side effects by slow ligand exchange reaction with plasma proteins. Figure 1.6: DNA adducts formed by oxaliplatin 13 . Sterically Hindered Platinum(II) Complex (ZD0473) One of the main mechanisms of cisplatin-resistance is an increase in intracellular thiol- mediated detoxification by peptides and proteins such as glutathione and metallothionines (see section 1.3.2.5). Cis-ammninedichlorido(2-methylpyridine)Pt(II), (ZD0473) (Figure 1.7) is the first drug to be administered orally. It is sterically hindered platinum(II) complex and is in phase II clinical trials. 61 Crystal structures of the complex have shown that the pyridine ring is tilted at 102.7° with respect to the PtN2Cl2 coordination square-plane. 62 This introduces steric hindrance directly above the platinum coordination plane, limiting the axial attack by the incoming nucleophile to 11
one side of the coordination square-plane. 63 In addition; this steric hindrance makes it less susceptible to deactivation by the S-containing proteins than cisplatin. This is essential in retarding in vivo cellular detoxification reaction by ubiquitous deactivating scavengers like GSH and MT. This feature is also linked to its ability to overcome cisplatin/drug resistance mechanisms. H 3 N N ZD0473 Figure 1.7: Structure of a sterically hindered platinum(II) complex (ZD0473) that circumvents cisplatin resistance. 1.3.3.2 Platinum(IV) Complexes Platinum(II)-based complexes: cisplatin, carboplatin and oxaliplatin are associated with poor saline solubility, high reactivity and therefore, poor bioavailability and lower pharmaco-stability. In addition, these drugs can only be administered intravenously, making them expensive. An oral drug must be neutral, lipophylic, water soluble and stable to survive in the gastrointestinal media. 64 As a result, octahedral Pt(IV) complexes were developed. Notable examples are satraplatin (JM216) (see Figure 1.2), which has entered phase III of clinical trials for the treatment of ovarian and small lung cancers; and LA-12. These complexes display greater advantages that include 12 Pt i. Greater stability to ligand substitution reactions and bioreductive activation which allows a greater proportion of the drug to arrive at its target the DNA. 65 ii. Higher solubility in aqueous solution enables them to be administered orally. iii. Moderate lipophilic properties due to the presence of bulky non-leaving groups enable them to circumvent resistance caused by decreased Pt accumulation. iv. Exhibition of lower nephrotoxicity and neurotoxicity, besides better sensitivity in cisplatin resistant cell-lines than cisplatin. Cl Cl
Page 1 and 2: Tuning Reactivity of Platinum(II) C
Page 3 and 4: Declaration This thesis report is b
Page 5 and 6: Abstract Systematic kinetic and the
Page 7 and 8: Table of contents Acknowledgements
Page 9 and 10: 2.5.5 Effect of Non-participating G
Page 11 and 12: 5.2.1 Chemical and Solutions ......
Page 13 and 14: 7.2 Experimental Section ..........
Page 15 and 16: procurements, Messers P. Forder and
Page 17 and 18: Figure 2.2 Potential energy profile
Page 19 and 20: Figure 4.6 Concentration dependence
Page 21 and 22: Figure 6.1 Spectrophotometric titra
Page 23 and 24: List of Tables Table 2.1 A selectio
Page 25 and 26: Table 6.4 Summary of rate constants
Page 27 and 28: TU thiourea DMTU 1,3-dimethyl-2-thi
Page 30 and 31: Table of Contents-1 Chapter 1 .....
Page 32 and 33: 1.0 Introduction 1.1 Cancer Disease
Page 34 and 35: toxic potential. The most well-know
Page 36 and 37: 1.3.2.2 Cellular Uptake Cisplatin i
Page 38 and 39: H 3N OH 2 Pt H 3N OH 2 Active Pt(II
Page 40 and 41: transformational pathways that comp
Page 44 and 45: 1.3.4 Terpyridine Platinum(II) Comp
Page 46 and 47: H 3 N Cl Pt NH 3 H 3 N NH 2 (CH 2 )
Page 48 and 49: 1.4 Kinetic Interest The platinum-b
Page 50 and 51: 3. The effect of varying the positi
Page 52 and 53: 17 R. A. Henderson, The Mechanism o
Page 54 and 55: Altona J. H. van Boom, G. A. van de
Page 56 and 57: 76 (a)J. Kašpárková, J. Zehnulov
Page 58 and 59: Table of Contents-2 Chapter Two ...
Page 60 and 61: List of Tables Table 2.1: A selecti
Page 62 and 63: The mononuclear Pt(II) complexes 1-
Page 64 and 65: Potential Energy R + X RX 1 transit
Page 66 and 67: For the associative mechanism (A),
Page 68 and 69: the concentration of one of the rea
Page 70 and 71: k obs , s -1 0.00030 0.00025 0.0002
Page 72 and 73: k = Ae -Ea/RT 2.14 lnk = lnA - E a
Page 74 and 75: = 23.76 + R Hence, a plot of ln ⎛
Page 76 and 77: iii. # Δ V ≈ 10 cm3 mol-1 featur
Page 78 and 79: conventional methods are classical
Page 80 and 81: Figure 2.6: Schematic diagram of a
Page 82 and 83: The light transmitted from the samp
Page 84 and 85: c. Oxidizability: Ligands that are
Page 86 and 87: Table 2.1: A selection of n o pt va
Page 88 and 89: eaction with different nucleophiles
Page 90 and 91: eaction site from direct attack by
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PEt 3 PEt 3 R PEt 3 Pt Pt Y Y Cl R
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direct displacement of the leaving
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therefore, weaken the bond of the l
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σ-Donation According to classical
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References 1 (a) J. Reedijk, Chem.
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34 R. B. Jordan, Reaction Mechanism
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Table of Contents-3 Chapter 3.The
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Chapter 3 The π-Acceptor Effect in
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In order to extend our understandin
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after which water was added to quen
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O CH 3 + I + N O oH - N O O 7 CH 3
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84% (34.7 mg, 0.0618 mmol). 1 H NMR
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PhCN PhCN Pt Cl Cl + N N CH 3 N CH
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Complex Structure HOMO LUMO PtCl CH
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The geometry-optimised structures i
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against the concentration of the in
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Table 3.2: Summary of the second-or
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constants of CH3PhisoqPtCl decrease
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with π*-orbitals of the ligand. Th
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3.6 References 1 D. Rosenberg, L. V
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30 Microcal TM Origin TM Version 5.
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Figure S3.1: Kinetic trace at 448 n
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ln(k 2 /T) -6.0 -7.5 -9.0 -10.5 -12
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Table S3.3b: Average observed rate
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Table S3.5b: Temperature dependence
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Table S3.8: DFT calculated electros
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List of Figures Figure 4.1: Structu
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Table 4.2: Summary of pKa values fo
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4.1 Introduction Platinum compounds
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cis geometry, leading to dramatic c
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ligand was added to the [{cis-PtCl(
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spectra were measured in and refere
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4.3.1 DFT calculated Optimized Stru
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Table 4.1: A summary of the DFT cal
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H2O-Pt-L-Pt-OH2 H2O-Pt-L-Pt-OH2 H2O
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electrophilicity and acidity of the
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(A) 18 Absorbance 0.08 0.07 0.06 0.
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k obs(3 rd ) , s -1 -5 6.00x10 TMTU
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4.3.4 Kinetics with NMR The substit
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ln([ML] t ) 4.0 3.5 3.0 2.5 2.0 1.5
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ln(k 2(1 st ) /T) -3.5 -4.0 -4.5 -5
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Comple x Table 4.4: Summary of Acti
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The decrease in reactivity of 2,6pz
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Table 4.5: DFT calculated (NBO) cha
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eaction proceeds via bimolecular pa
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References 1 T. Storr, K. H.Thomson
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36 D. Jaganyi, D. Reddy, J.A. Gerte
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Appendix 4 THE INFLUENCE OF THE PYR
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Absorbance at 368. 0 nm 0. 0 8 0. 0
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Table S4.3: Average observed rate c
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k nd obs(2 ) , s-1 0.003 TU DMTU TM
Page 194 and 195:
Page 196 and 197:
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k obs2 , s -1 2.40x10 -4 2.20x10 -4
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Table S4.13: Average observed rate
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Page 204 and 205:
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k obs(1 st ) , s -1 0.06 0.04 0.02
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ln(k 2(3 rd ) /T) -10.0 -10.5 -11.0
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SpinWorks 2.5: 2,6 pznClO4 in D2O N
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Table of Contents-5 Chapter 5 .....
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List of Tables Table 5.1: A summary
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5.1 Introduction Multinuclear plati
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onding. For this reason, pKa titrat
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400-300 cm -1): 3308, 3117, 3071 (N
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5.2.6 Spectrophotometric pKa Titrat
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Table 5.1: A summary of DFT-calcula
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However, because the highest occupi
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Table 5.2: Acid dissociation consta
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Table 5.3: A summary of DFT calcula
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H3N 6 eq TU 0 eq TU Ha NH3 Ha Cl TU
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third step due to the trans-effect
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[H 2 O-Pt-(NN)-Pt-OH 2 ] +4 [NU-Pt-
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k obs(1st) / s -1 0.20 TU DMTU TMTU
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thiourea nucleophile is large enoug
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ln(k st 2(1 ) /T) -3 -4 -5 -6 -7 -8
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is the same as the electron-withdra
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associative mode of substitution me
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16 H. Ertürk, J. Maigut, R. Puchta
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43 (a) D. Jaganyi, A. Hofmann and R
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276 nm Absorbance 0 . 6 5 0 . 6 4 0
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k obs(1 st ) , s -1 0.4 0.3 0.2 0.1
Page 258 and 259:
Page 260 and 261:
ln(k 2(2 nd ) /T) -8.0 TU -8.5 -9.0
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pzn PPM -1750.0 -1850.0 -1950.0 -20
Page 264 and 265:
Page 266 and 267:
Figure S5.13: UV/Visible spectra fo
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k obs(1 st ) in s -1 0.030 0.025 0.
Page 270 and 271:
Page 272 and 273:
ln(k 2(2 nd ) /T) -10 -11 -12 -13 -
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9.61 ppm Ha PPM 9.8 9.6 9.4 9.2 9.0
Page 276 and 277:
Page 278 and 279:
k obs(3rd) / s -1 -5 8 .00 x 10 T U
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ln(k st 2(1 ) /T) -1.5 TU DMTU TMTU
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ln(k rd 2(3 ) /T) -8.5 -9.0 -9.5 -1
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SpinWorks 2.5: znPt(II)-OP4 in D2O
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Figure S5.31: Mass spectrum for com
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Page 290 and 291:
Page 292 and 293:
ln(k st 2(1 ) /T) -4 -5 -6 -7 -8 -9
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SpinWorks 2.5: phtPt(II)-OP2 in D2O
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Figure S5.41: Mass spectrum for com
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List of Figures Figure 6.1: Spectro
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Chapter 6 Tuning Reactivity of Plat
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Against this background, several re
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6.2.2 Instruments Microanalyses wer
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Metal Complex Pt3 Yield: 52.5 mg (0
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6.3 Results 6.3.1 Synthesis and Cha
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The pKa values obtained are summari
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Table 6.2: DFT-calculated parameter
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that of dinuclear Pt(II) complexes
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It can be concluded that substituti
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ate constants, kobs(1 st /2 nd ), w
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Table 6.3: Summary of rate constant
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6.3.6 Activation Parameters The act
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pKa1 values become smaller. In addi
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of steric influence is felt by the
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6.5 Conclusion The present study ha
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17 O. F. Wendt and L. I. Elding, 19
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51 Y. Iwadata, K. Kawamura, K. Igar
Page 334 and 335:
Page 336 and 337:
Table S6.4(b): Average observed rat
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ln(k 2(2 nd ) /T) -4 -6 -8 -10 -12
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45.0 40 35 30 25 20 %T 15 10 5 0 -5
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k st obs(1 ) in s-1 0.30 Br TU 0.25
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-2304.16 ppm H 3N PPM -2200.0 -2220
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Page 350 and 351:
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Absorbance 1.6 1.4 1.2 1.0 0.8 0.6
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SH N SH + Mechanism Br N + CO 3 2-
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Figure 7.5: 195Pt NMR spectra of mi
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linker remained coordinated to the
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complexes, have a lower charge and
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ange 326-400 cm -1 (weak) for Pt-Cl
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ButPt, HexPt, OctPt and DecPt, were
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7.3 Results 7.3.1 DFT Calculations
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Structure HOMO LUMO EnPt (C2h) Prop
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Absorbance Table 7.2: Summary of pK
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coordination to the soft Pt(II) cen
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observed at -2962.4 and -3024.1 ppm
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H 3N NH 3 Pt NH 2 OH 2 n NH 3 NH 2
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k obs2 , in s -1 -3 TU 1.2x10 DMTU
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7.3.4 Activation Parameters The tem
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density is located on the metal cen
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acetylmethionine, which reported th
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References 1 (a) B. Rosenberg, L. V
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32 N. Summa, J. Maigut, R. Puchta a
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Appendix 7 Table S7.1: Summary of s
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k obs(2 nd ) , in s -1 0.00020 0.00
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ln(k 2(2 nd ) /T) -8.5 -9.0 -9.5 -1
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k obs(1 st ) , in s -1 0.06 TU DMTU
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ln(k 2(1 st ) /T) -3.2 TU DMTU TMTU
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Table S7.11: Summary of kobs(2 nd )
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%T 22.0 20 18 16 14 12 10 8 6 4 2 0
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k st obs(1 ) , in s-1 0.10 0.08 0.0
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ln(k st 2(1 ) /T) -4.0 TU DMTU TMTU
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Figure S7.23: Mass spectra for HexP
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Table S21: Average observed rate co
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Table S7.23: Summary of kobs(2 nd )
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90.0 80 70 60 50 40 30 20 %T 10 0 -
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Figure S7.37: Mass spectrum for Hex
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Chapter 8 Tuning Reactivity of plat
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dinuclear Pt(II) complexes to relea
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finally Pt2. The order of reactivit
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• prolonged survival in the cell
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Tuning Reactivity of Platinum(II) Complexes

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