Tuning Reactivity of Platinum(II) Complexes

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6.3.6 Activation Parameters The activation parameters were determined through systematic variation of temperature within the range 15-35 °C, at 5 °C interval. The Eyring plots depicted in Figure 6.7 and 6.8 (also Figures S6.3-S6.4 and S6.11-S6.12, Appendix 6) resulted in the activation parameters: activation enthalpy, ΔH ≠ (1 st /2 nd ) from the slopes, and activation entropy, ΔS ≠ (1 st /2 nd ) from the intercept. The values obtained are tabulated in Tables 6.3 and 6.4. ln(k st 2(1 ) /T) -4.5 -5.0 -5.5 -6.0 -6.5 -7.0 -7.5 -8.0 -8.5 -9.0 -9.5 -10.0 0.00325 0.00330 0.00335 0.00340 0.00345 1/T,K -1 23 TU DMTU TMTU SCN Br Figure 6.7: Plots of ln(k2(1 st )/T) versus (1/T) for the first step reaction of Pt1 with a series of different nucleophiles at varying temperatures.
ln(k 2/2 nd)/T) -8.0 -8.2 -8.4 -8.6 -8.8 -9.0 -9.2 -9.4 -9.6 -9.8 -10.0 -10.2 -10.4 -10.6 SCN TU DMTU TMTU 0.00325 0.00330 0.00335 0.00340 0.00345 0.00350 1/T, K -1 Figure 6.8: Plots of ln(k2(2 nd )/T) versus (1/T) for the second step reaction of Pt1 with a 6.4 Discussion series of different nucleophiles at varying temperatures. 6.4.1 pKa Determination for the Diaqua Complexes The thermodynamic data in Table 6.1 demonstrates that the pKa values of the coordinated aqua moieties are dependent on the nature of the linker. The pKa1 values of the studied dinuclear complexes Pt1, Pt2 and Pt3 (ranging from 4.86 ± 0.05 to 5.19 ± 0.02) are lower than that of the mononuclear analogue Pt4 (pKa = 5.63 ± 0.01) and those of the Pt(II) amphiphiles recently published: 48 [Pt(H2O)(N,N-bis(2-pyridylmethyl)- NCH2)n-CH3; NH] +2 n = 1, 2, 3, 4, 5, 9 (pKa = 5.45 ± 0.05 to 5.52 ± 0.02); signifying an increase in acidities of the coordinated water molecules in these dinuclear complexes. This is in agreement with what has been reported in other studies which have shown that Pt atoms in dinuclear complexes are more acidic than the Pt atoms of the mononuclear complexes. 24,25,48 A higher overall positive charge of +4 on the Pt atoms coupled with higher electrophilicity is the reason for the lower pKa value observed in the dinuclear complexes than that found for +2 charged Pt(II) centres of the mononuclear complexes. Furthermore, a short distance between the Pt(II) centre of the dinuclear complexes, results in single charge additions (controlled by in-space electrostatic forces and/or H-bond) on the platinum atoms that increases the effective positive charge at the metal centre. 25(b & c) This explains why with decreasing Pt---Pt separation distance the 24
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Tuning Reactivity of Platinum(II) C
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Declaration This thesis report is b
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Abstract Systematic kinetic and the
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Table of contents Acknowledgements
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2.5.5 Effect of Non-participating G
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5.2.1 Chemical and Solutions ......
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7.2 Experimental Section ..........
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procurements, Messers P. Forder and
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Figure 2.2 Potential energy profile
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Figure 4.6 Concentration dependence
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Figure 6.1 Spectrophotometric titra
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List of Tables Table 2.1 A selectio
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Table 6.4 Summary of rate constants
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TU thiourea DMTU 1,3-dimethyl-2-thi
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Table of Contents-1 Chapter 1 .....
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1.0 Introduction 1.1 Cancer Disease
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toxic potential. The most well-know
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1.3.2.2 Cellular Uptake Cisplatin i
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H 3N OH 2 Pt H 3N OH 2 Active Pt(II
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transformational pathways that comp
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the hydrolysis of the complex, wher
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1.3.4 Terpyridine Platinum(II) Comp
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H 3 N Cl Pt NH 3 H 3 N NH 2 (CH 2 )
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1.4 Kinetic Interest The platinum-b
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3. The effect of varying the positi
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17 R. A. Henderson, The Mechanism o
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Altona J. H. van Boom, G. A. van de
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76 (a)J. Kašpárková, J. Zehnulov
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Table of Contents-2 Chapter Two ...
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List of Tables Table 2.1: A selecti
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The mononuclear Pt(II) complexes 1-
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Potential Energy R + X RX 1 transit
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For the associative mechanism (A),
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the concentration of one of the rea
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k obs , s -1 0.00030 0.00025 0.0002
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k = Ae -Ea/RT 2.14 lnk = lnA - E a
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= 23.76 + R Hence, a plot of ln ⎛
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iii. # Δ V ≈ 10 cm3 mol-1 featur
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conventional methods are classical
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Figure 2.6: Schematic diagram of a
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The light transmitted from the samp
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c. Oxidizability: Ligands that are
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Table 2.1: A selection of n o pt va
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eaction with different nucleophiles
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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
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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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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
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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
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Figure S5.13: UV/Visible spectra fo
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k obs(1 st ) in s -1 0.030 0.025 0.
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Page 272 and 273: ln(k 2(2 nd ) /T) -10 -11 -12 -13 -
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Page 276 and 277: Table S5.22: Average observed rate
Page 278 and 279: k obs(3rd) / s -1 -5 8 .00 x 10 T U
Page 280 and 281: ln(k st 2(1 ) /T) -1.5 TU DMTU TMTU
Page 282 and 283: ln(k rd 2(3 ) /T) -8.5 -9.0 -9.5 -1
Page 284 and 285: SpinWorks 2.5: znPt(II)-OP4 in D2O
Page 286 and 287: Figure S5.31: Mass spectrum for com
Page 292 and 293: ln(k st 2(1 ) /T) -4 -5 -6 -7 -8 -9
Page 294 and 295: SpinWorks 2.5: phtPt(II)-OP2 in D2O
Page 296 and 297: Figure S5.41: Mass spectrum for com
Page 298 and 299: List of Figures Figure 6.1: Spectro
Page 300 and 301: Chapter 6 Tuning Reactivity of Plat
Page 302 and 303: Against this background, several re
Page 304 and 305: 6.2.2 Instruments Microanalyses wer
Page 306 and 307: Metal Complex Pt3 Yield: 52.5 mg (0
Page 308 and 309: 6.3 Results 6.3.1 Synthesis and Cha
Page 310 and 311: The pKa values obtained are summari
Page 312 and 313: Table 6.2: DFT-calculated parameter
Page 314 and 315: that of dinuclear Pt(II) complexes
Page 316 and 317: It can be concluded that substituti
Page 318 and 319: ate constants, kobs(1 st /2 nd ), w
Page 320 and 321: Table 6.3: Summary of rate constant
Page 324 and 325: pKa1 values become smaller. In addi
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Page 328 and 329: 6.5 Conclusion The present study ha
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Page 334 and 335: Table S6.3: Average observed rate c
Page 336 and 337: Table S6.4(b): Average observed rat
Page 338 and 339: ln(k 2(2 nd ) /T) -4 -6 -8 -10 -12
Page 340 and 341: 45.0 40 35 30 25 20 %T 15 10 5 0 -5
Page 342 and 343: k st obs(1 ) in s-1 0.30 Br TU 0.25
Page 344 and 345: Table S6.9: Average observed rate c
Page 346 and 347: -2304.16 ppm H 3N PPM -2200.0 -2220
Page 352 and 353: Absorbance 1.6 1.4 1.2 1.0 0.8 0.6
Page 354 and 355: SH N SH + Mechanism Br N + CO 3 2-
Page 356 and 357: Figure 7.5: 195Pt NMR spectra of mi
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Page 360 and 361: complexes, have a lower charge and
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Page 364 and 365: ButPt, HexPt, OctPt and DecPt, were
Page 366 and 367: 7.3 Results 7.3.1 DFT Calculations
Page 368 and 369: Structure HOMO LUMO EnPt (C2h) Prop
Page 370 and 371: 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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