WWW.BOOK.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Books, abstracts, thesis
 
<< HOME
CONTACTS

Pages:     | 1 || 3 | 4 |   ...   | 18 |

«A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of ...»

-- [ Page 2 ] --

Thermal ellipsoids are drawn with 50% probability.

Figure 4.5.

1H NMR spectra as a function of time after crystals of the E′ isomer of [Re(CO)3(5,5′-Me2bipy)(HNC(CH3)NHCH(CH3)2)]BF4 (2) were dissolved in acetonitrile-d3 at 25 °C.

x Figure 4.6.

1H NMR spectrum of [Re(CO)3(5,5′-Me2bipy)(HNC(CH3)NHCH(CH3)2)] BF4 (2) in acetonitrile-d3 at 25 °C

Figure 4.7.

1H-1H COSY NMR spectrum of [Re(CO)3(5,5′-Me2bipy)(HNC(CH3) NHCH(CH3)2)]BF4 (2) in acetonitrile-d3 at 25 °C.

Figure 4.8.

1H NMR spectra illustrating the distribution of E′, E, and Z isomers of [Re(CO)3(5,5′-Me2bipy)(HNC(CH3)NHCH(CH3)2)]BF4 (2) in CD2Cl2 (with percent acetonitriled3 noted on trace) and acetonitrile-d3 at 25 °C. Note: the bottom two spectra were recorded before equilibrium was reached

Figure 5.1.

ORTEP plot of [Re(CO)3(CH3CN)3]PF6. Thermal ellipsoids are drawn with 50% probability.

Figure 5.2.

ORTEP plots of the cations of (a) [Re(CO)3(bipy)(HNC(CH3)OCH3)]BF4 (2), (b) [Re(CO)3(4,4′-Me2bipy)(HNC(CH3)OCH3)]BF4 (3), (c) [Re(CO)3(5,5′-Me2bipy) (HNC(CH3) OCH3)]BF4 (4) and (d) [Re(CO)3(6,6′-Me2bipy)(HNC(CH3)OCH3)]BF4 (5). The uncomplexed 6,6′-Me2bipy ligand in 5 is omitted for clarity. Thermal ellipsoids are drawn with 50% probability.

Figure 5.3.

Relative orientations of [Re(CO)3L(HNC(CH3)OCH3)]BF4 when the structures are viewed with the aromatic rings in the plane and the acetimidate ligand projected toward the viewer. L = bipy (a), 4,4′-Me2bipy (b), 5,5′-Me2bipy (c), and 6,6′-Me2bipy (d)

Figure 5.4.

Overlay of Re, N3, and O4 atoms of the acetimidate ligands of [Re(CO)3(bipy)(HNC(CH3)OCH3)]BF4 (gold) and [Re(CO)3(6,6′-Me2bipy) (HNC(CH3)OCH3)]BF4 (purple) when the structure is viewed with the aromatic ring of the least distorted structure on the plane and the iminoether ligand projected along the y axis (r.m.s. = 0.033).

Figure 6.1.

Ligands used in this study: N,N-di(2-picolyl)methanesulfonamide (N(SO2Me)dpa), N,N-di(2-picolyl)-2,4,6-trimethylbenzenesulfonamide (N(SO2tmb)dpa), N,N-di(2-picolyl)-5dimethylamino)-naphthalene-1-sulfonamide (N(dansyl)dpa)

Figure 6.2.

ORTEP plots of the cations in [Re(CO)3(N(SO2Me)dpa)]PF6 (1). Thermal ellipsoids are drawn with 50% probability

Figure 6.3.

ORTEP plots of the cations in [Re(CO)3(N(SO2tmb)dpa)]PF6 (2). Thermal ellipsoids are drawn with 50% probability

Figure 6.4.

ORTEP plots of the cations in [Re(CO)3(N(dansyl)dpa)]BF4 (3). Thermal ellipsoids are drawn with 50% probability

Figure 6.5.

Comparison of the 1H NMR spectra of T(N(SO2C6H4)dpa)P (bottom) and [{Re(CO)3}4T(N(SO2C6H4)dpa)P](BF4)4 (top) in DMSO-d6 at 25 °C.

–  –  –

fac-[ReI(CO)3L]n complexes serve as models for short-lived fac-[99mTcI(CO)3L] imaging tracers. Dangling groups on L, needed to achieve desirable biodistribution, complicate the NMR spectra, which are not readily understood. In fac-[ReI(CO)3L]+ with less complicated L, NH groups (exo-NH) projecting toward the L face sometimes showed an upfield shift attributable to steric shielding of the exo-NH group from the solvent by the chelate rings. To investigate whether exo-NH groups in six-membered rings exhibit the same effect and whether the presence of dangling groups alters the effect, we prepared new fac-[Re(CO)3L]n complexes that allow direct comparisons of exo-NH shifts for six-membered vs. five-membered chelate rings. The use of anions as probes, including the new use of the [ReBr6]2– anion as a paramagnetic outer-sphere H-bonding shift reagent, establishes that these NH protons are not well solvated. Lack of solvation, induced by chelate ring bulk, accounts for the upfield shift.

To evaluate syntheses of fac-[Re(CO)3L]+ complexes in organic solvents, we treated facRe(CO)3(CH3CN)3]PF6/BF4 in acetonitrile with triamine ligands (L). When L had two primary or two tertiary terminal amine groups, the expected fac-[Re(CO)3L]+ complexes formed.

Treatment of fac-[Re(CO)3(CH3CN)3]+ with various tridentate amine ligands has produced several novel compounds, which most likely arise from reaction of the coordinated nitrile with ligand terminal amines. The new compounds advance our understanding of the spectral and structural properties of Re analogues of 99mTc radiopharmaceuticals.

In fac-[Re(CO)3(5,5′-Me2bipy)(HNC(CH3)NHR)]BF4 complexes, the monodentate amidine ligand adopts the E, E′, and Z, but not the Z′ configuration in solution. Both amidine CN bonds have double-bond character, leading to slow isomerization on the NMR time scale.

–  –  –

occur.

The structural characterization of fac-[Re(CO)3L]+ complexes bearing novel ligands having a central sulfonamide group and two pyridine rings has revealed that the central N of the tertiary sulfonamide group binds to Re. These are among the few structurally characterized complexes with a tertiary (neutral) sulfonamide bound to a metal. We show that a sulfonamide can be used to conjugate the fac-{Re(CO)3}+ unit to a porphyrin. The new ligands may be used eventually in 99mTc imaging.





–  –  –

diagnostic and therapeutic agents are some notable examples.2-4

1.1 Metalloradiopharmaceuticals Radiopharmaceuticals are used as modern, powerful tools in nuclear medicine to diagnose and treat many common diseases. Various imaging agents are in use today but the need

–  –  –

Metalloradiopharmaceuticals consist of a metal nuclide and ligands. The metal nuclides of most interest are 99mTc, and 186/188Re.

99m Tc (E = 141 keV, t1/2 = 6h) is the most widely used radionuclide in nuclear medicine with over 7 million scans performed each year.5,6 The 141 keV gamma ray emission is close to optimal for imaging, and commercially available gamma cameras may be used. The 6 h half-life

–  –  –

MeV, t1/2 = 17 h) are used for therapeutic applications and aim at delivering therapeutic doses of radiation to target tissues without adversely affecting normal tissue.4,8

1.2 fac-{MI(CO)3}+ (M = 99mTc, Re) Core The seminal contributions of Alberto and co-workers to technetium-carbonyl chemistry

–  –  –

fundamental chemistry based on the fac-{MI(CO)3}+ core is important to guide efforts to develop new radiopharmaceuticals.8,11 Radiopharmaceuticals containing the {99mTcI(CO)3}+ core show promise in the advancement of new clinically useful imaging agents12,13 and the fac-Re(CO)3L analogue approach (L is a facially coordinated tridentate ligand) has aided in the development of technetium complexes as potential radiopharmaceuticals.14-16 Several studies, including those from our laboratory, have been instrumental in developing a better understanding of NMR spectral features of fac-Re(CO)3L complexes bearing simple donor ligands.17-22 Renal imaging agents with some target ligands such as polyamino-polycarboxylic ligands form isomers under the aqueous conditions under which they are synthesized.18,23 We reasoned that reactions in organic media could be more easily followed in real time by using NMR spectroscopy. Thus, precursors such as fac-[Re(CO)3(CH3CN)3]+ and fac-[Re(CO)3(DMSO)3]+ which are organic soluble, may be utilized.

Another class of fac-[Re(CO)3L(L′)]n complexes of interest includes the bisimine complexes, which have recently been shown to be useful as cell imaging agents in fluorescence microscopy.24 Relative lipophilicity is a desired feature of Re complexes to be used for cell imaging because it leads to cell membrane permeability.24 Numerous other applications exist for these bisimine complexes, such as precursors in supramolecular chemistry for the design and construction of molecular scale devices for information storage and transfer.25-28 A theme of this work has been to understand the solution structure of novel fac-Re(CO)3 complexes and how NMR spectroscopy could be utilized for this purpose. The first part of this work describes the synthesis in water and detailed analysis of fac-[Re(CO)3L]n+ complexes having six-membered chelate rings and use of small anions to probe solution structure of these complexes.

In the second part, to evaluate syntheses of fac-[Re(CO)3L]+ complexes in organic solvents, the fac-[Re(CO)3(CH3CN)3]+ precursor was utilized; some unusual ReI amidine complexes formed by attack of primary or secondary amine terminal groups of polyamines on coordinated acetonitrile, in one case giving a seven-membered chelate ring. Because an important goal is to interpret how structure affects the NMR spectra of the fac-[ReI(CO)3L]n complexes, we evaluate the interaction of Cl– with some of the new fac-[Re(CO)3L]n complexes that have unusual NH groups. To further assess ReI amidine chemistry, we move on to investigate amidine products formed by treating fac-[Re(CO)3(5,5′-Me2bipy)(CH3CN)]BF4 (a complex with only one coordinated acetonitrile) with ammonia and amines. The configuration is influenced primarily by electronic and steric effects because the ligand is monodentate and the configuration is not restricted.

–  –  –

these complexes. This model is also extended to include a Re-porphyrin conjugate.

1.3 References

1. Orvig, C.; Abram, M. J. Chem. Rev. 1999, 99, 2201-2203.

2. Lippard, S. J.; Berg, J. M. Principles of Bioinorganic Chemistry; University Science Books:

Mill Valley, CA, 1994.

3. Roat-Malone, R. M. Bioinorganic Chemistry: A Short Course; John Wiley & Sons, Inc., 2002.

4. Volkert, W. A.; Hoffman, T. J. Chem. Rev. 1999, 99, 2269-2292.

5. Liu, S. Chem. Soc. Rev. 2004, 33, 445-461.

6. Bartholomä, M.; Valliant, J.; Maresca, K. P.; Babich, J.; Zubieta, J. Chem. Commun.

(Cambridge, U.K.) 2009, 493-512.

7. Schibli, R.; Schubiger, A. P. Eur. J. Nucl. Med. Mol. Imaging 2002, 29, 1529-1542.

8. Schibli, R.; Bella, R. L.; Alberto, R.; Garcia-Garayoa, E.; Ortner, K.; Abram, U.; Schubiger, A. P. Bioconjugate Chem. 2000, 11, 345-351.

9. Alberto, R.; Schibli, R.; Egli, A.; Schubiger, A. P.; Abram, U.; Kaden, T. A. J. Am. Chem.

Soc. 1998, 120, 7987-7988.

10. Alberto, R.; Ortner, K.; Wheatley, N.; Schibli, R.; Schubiger, A. P. J. Am. Chem. Soc. 2001, 123, 3135-3136.

11. Alberto, R.; Schibli, R.; Waibel, R.; Abram, U.; Schubiger, A. P. Coord. Chem. Rev. 1999, 190-192, 901-919.

12. Alberto, R.; Schibli, R.; Schubiger, A. P.; Abram, U.; Pietzsch, H. J.; Johannsen, B. J. Am.

Chem. Soc. 1999, 121, 6076-6077.

13. Lipowska, M.; He, H.; Malveaux, E.; Xu, X.; Marzilli, L. G.; Taylor, A. T. J. Nucl. Med.

2006, 47, 1032-1040.

14. He, H.; Lipowska, M.; Xu, X.; Taylor, A. T.; Marzilli, L. G. Inorg. Chem. 2007, 46, 3385He, H. Y.; Lipowska, M.; Christoforou, A. M.; Marzilli, L. G.; Taylor, A. T. Nucl. Med.

Biol. 2007, 34, 709-716.

16. Tzanopolou, S.; Pirmettis, I. C.; Patsis, G.; Paravatou-Petsotas, M.; Livaniou, E.;

Papadopoulos, M.; Pelecanou, M. J. Med. Chem. 2006, 49, 5408-5410.

17. Christoforou, A. M.; Marzilli, P. A.; Fronczek, F. R.; Marzilli, L. G. Inorg. Chem. 2007, 46, 11173-11182.

18. Lipowska, M.; Cini, R.; Tamasi, G.; Xu, X.; Taylor, A. T.; Marzilli, L. G. Inorg. Chem.

2004, 43, 7774-7783.

19. Christoforou, A. M.; Fronczek, F. R.; Marzilli, P. A.; Marzilli, L. G. Inorg. Chem. 2007, 46, 6942-6949.

20. Christoforou, A. M.; Marzilli, P. A.; Fronczek, F. R.; Marzilli, L. G. J. Chem. Crystallogr.

2008, 38, 115-121.

21. Banerjee, S. R.; Levadala, M. K.; Lazarova, N.; Wei, L.; Valliant, J. F.; Stephenson, K. A.;

Babich, J. W.; Maresca, K. P.; Zubieta, J. Inorg. Chem. 2002, 41, 6417-6425.

22. Perera, T.; Marzilli, P. A.; Fronczek, F. R.; Marzilli, L. G. Inorg. Chem. 2010, 49, 5560Lipowska, M.; He, H.; Xu, X.; Taylor, A. T.; Marzilli, P. A.; Marzilli, L. G. Inorg. Chem.

2010, 49, 3141-3151.

24. Amoroso, A. J.; Coogan, M. P.; Dunne, J. E.; Fernandez-Moreira, V.; Hess, J. B.; Hayes, A.

J.; Lloyd, D.; Millet, C.; Pope, S. J. A.; Williams, C. Chem. Commun. 2007, 3066-3068.

25. Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S. Chem. Rev. 1996, 96, 759-833.

26. Slone, R. V.; Yoon, D. I.; Calhoun, R. M.; Hupp, J. T. J. Am. Chem. Soc. 1995, 117, 11813Casanova, M.; Zangrando, E.; Munini, F.; Iengo, E.; Alessio, E. Dalton Trans. 2006, 5033Ziessel, R.; Juris, A.; Venturi, M. Inorg. Chem. 1998, 37, 5061-5069.

–  –  –



Pages:     | 1 || 3 | 4 |   ...   | 18 |


Similar works:

«Connecting Across Language and Distance: Linguistic and Rural Access to Legal Information and Services Karen Cohl and George Thomson December 2008 Connecting Across Language and Distance: Linguistic and Rural Access to Legal Information and Services Final report of the Linguistic and Rural Access to Justice Project This is the report of the Linguistic and Rural Access to Justice Project conducted by Karen Cohl and George Thomson at the request of The Law Foundation of Ontario. We would like to...»

«BIOMECHANICAL EVALUATION OF MODIFIED TRACK SHOES A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural Mechanical College in partial fulfillment of the requirements for the Degree of Master of Science in Industrial Engineering in The Department of Construction Management and Industrial Engineering By Marlon Alberetos Greensword B.S., L.S.U., 2007 B.A., L.S.U., 2005 May 2010 ACKNOWLEDGMENTS I must first give thanks to God the Father, Jesus the Son and the...»





 
<<  HOME   |    CONTACTS
2016 www.book.xlibx.info - Free e-library - Books, abstracts, thesis

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.