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LOYOLA  COLLEGE (AUTONOMOUS), CHENNAI-600 034.

M.Sc. DEGREE  EXAMINATION  – chemistry

fourth  SEMESTER  – APRIL 2003

CH  4950/CH 1054 ADVANCED COORDINATION  chemistry 

23.04.2002

1.00 – 4.00                                                                                          Max: 100 Marks

 

part – A                                                       (10 ´ 2 = 20)

 

1. What is slipped Sandwich?   Cite an example.
2. Define coordination template effect. Cite a dinuclear complex synthesized by

the method.

3. Justify the formation of coordination compounds of different geometries by d-

block metal ion with the help of angular overlap model.

4. What is tetragonal splitting parameter? How is it evaluated?
5. Differentiate CE and EC mechanisms.
6. Give the structure of (a) Potassium ethylxanthate

(b) Dipheylphosphinoethane (dppe).

7. How are he optical isomers of [Co (NH₃)₄ Cl₂]⁺ distinguished?
8. [NiCl₄]^2- has a magnetic moment of 2.84 B.M. Predict the geometry with hybridization of the metal atom.
9. How are the complexes [Cr(NH₃]₄ Cl₂]Cl and [Cr(NH₃)₃Cl₃] distinguished by NQR spectroscopy?
10. What role is  played by cisplatin in the cancer therapy?

 

PART- B                                           (8 ´ 5 = 40 Marks)

 

11. Explain the principles of angular overlap model.
12. What are compartmental ligands? Explain the different methods of syntheizing compartmental ligands and their polynuclear complexes.
13. Explain the electronic spectral features of high-spin octahedral and tetrahedral complexes.
14. Give an account of spectroelectrochemical techniques in studying electrogenerated species.
15. Explain the principle of AC polarography. How is this technique useful to study the reversible redox couples?
16. Explain with an example the experimental method of studying static dynamic Jahn-Teller effect.
17. Explain that the isomer shift value of [Fe (CN)₆]^4– is more negative than that of

[Fe (H₂O)₆]²⁺ . D E_Q of the former is zero and the later has a D E_Q value of 3.3 mm s^-1.

 

 

 

 

 

18. Suggest a method of synthesis for

(a) [Co (NH₃)₆]Cl₃ from CoCl₂.6H₂O                                                                                     (2)

(b) Cis and trans – [Pt(NH₃)₂Cl₂]                                                               (1 ½  + 1 ½)

 

19. Discuss the different sampling methods used in EPR spectroscopy. Bring out their advantages.
20. How do the quantum yields vary in a photoanation reactions? Discuss with a suitable example.
21. Discuss the coordination around iron in cytochrome and the role played by it in the biological processes.
22. How is N(1s) photoelectron spectrum useful in the study of [Co(NH₃)₅ N₃](NO₃)₂

 

PART – C                                         (4 ´10 = 40 Marks)

 

23. (a) Derive the Marcus-Hush equation for electron transfer.

• Explain how do the crystal field effect influence the rate of electron

transfer reactions.

24. (a) Explain the electronic spectral features of  low -spin d⁶ metal ion and

the  method of computing Dq^xy and Dq^z values.

• How is spin crossover studied experimentally?
• Give an account of NMR spectra of paramagnetic compounds.

 

26. Discuss the role played by the metal atoms in the Nitrogen fixation. Write a note

on  biomimic coordination. cluster complexes of nitrogenase.

 

27. (a) Explain the  Mossbauer spectrum of FeF₃ recorded at 4K.                         (5)

• Describe Krammer’s degeneracy choosing an example.

 

28. (a) Discuss in detail the EPR spectrum of [Cu (salimine)₂] along with the

hyperfine splitting by the ligand.                                                                 (7)

 

(b)   How does Cr(CO)₆ undergo photochemical decomposition?                      (3)

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

LM 56

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2007

CH 4956 – ADVANCED COORDINATION CHEMISTRY

 

 

 

Date & Time: 23/04/2007 / 9:00 – 12:00   Dept. No.                                           Max. : 100 Marks

 

 

Part-A

Answer all questions. Each question carries two marks 

 

1. Explain the EPR spectrum of [Mo(CN)₈]^3-.
2. Mention the features of the Mossbauer spectrum of K₄[Fe(CN)₆].
3. Explain the ¹⁹FNMR spectrum of TiF₄(base)₂.
4. Mention the number of peaks and their ratio in N(1s) PES of [Rh(NH₃)₅(NO₂)](NO₃)₂.
5. Draw the unit structure of rubredoxin.
6. What is nephelauxetic series? How is it constructed?
7. According to crystal field formalism pseudooctahedral complexes of d^1,4,6,9 metal ions are expected to exhibit one spin-allowed d-d transition, but they often exhibit many transitions in close proximity. Rationalize.
8. What is dendrimer-encapsulated catalysis? Mention one such reaction.
9. Differentiate calix[4]arene and calix[6]arenes.
10. What is supramolecular self assembly? Depict such a supramolecular assembly.

 

Part-B

Answer any eight questions. Each question carries five marks 

 

11. Discuss the EPR spectrum of [Mn(H₂O)₆]²⁺ and explain Kramer’s degeneracy.
12. Discuss the temperature variation ¹H NMR spectral features of Ni(CH₂=CH-CH₂)₂.
13. Discuss the g and A terms in EPR spectroscopy and bring out their significance.
14. How are the following ligands prepared? (a) salen and (b) dibenzo-18-crown-6.
15. Calculate the m_J value of Ce(III).
16. Write a note on copper blue protein.
17. How do you differentiate low-spin and high-spin octahedral complex of a d⁵ metal ion by electronic spectroscopy?
18. Explain the feature of Tanabe Sugano diagrams. Compare it with Orgel diagrams.
19. What are pseudorotoxanes? Explain the synthesis of two such systems.
20. Explain supramolecular assembly with an example. Comment upon the role of bridging ligands in the construction of supramolecular assemblies.
21. What are metallodendrimers? Mention the different kinds of metallodendrimers.
22. Mention the different kinds of supramolecular interactions. Cite two supramolecular assemblies constructed by any two such interactions.

 

 

Part-C

Answer four questions. Each question carries ten marks 

 

23. Discuss the significances of isomer sciff (d) and quadrapole splitting (DE_Q) in Mossbauer spectrum. How is p-back bonding inferred from the d value?
24. Discuss the biological role and structure of ferredoxin along with model complexes.
25. Discuss the temperature variation magnetic susceptibility studies to understand the spin-cross over systems.
26. (a) Explain the method of synthesising of PAMAM dendrimer.

(b) Write a note on molecular wires.

27. (a) Explain the electronic spectral feature of tetragonally distorted octahedral complex of low spin d⁶ metal ion. How do you compute the ligand field parameters.

(b) Compare the above spectrum with that of a pseudooctahedral complex of high spin d⁶ metal ion.

28. Explain the methods of synthesizing and self assembling catenanes and rotaxanes.

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

LM 50

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2007

CH 4953 – ADVANCED COORDINATION CHEMISTRY

 

 

Date & Time: 23/04/2007 / 9:00 – 12:00  Dept. No.                                           Max. : 100 Marks

 

Part-A

 

Answer all questions. Each question carries two marks

 

1. How do you infer tetragonal distortion in transition metal complexes by electronic spectroscopy?
2. What is intensity stealing? Mention its consequences.
3. The CN stretching vibrations in cyano complexes occur at higher energy than that of free cyanide ion. Explain.
4. Metal carbonyls are formed by metals in their lower oxidation states. Give reason.
5. What are optically transparent electrodes? Mention their uses.
6. EPR spectra of transition metal complexes are recorded by doping onto diamagnetic host at low temperature. Give reason.
7. The rate constant for outer-sphere ectron transfer in [Fe(H₂O)₆]^2+/3+ is low as compared to that in [Fe(bpy)₃]^2+/3+. Give reason?
8. What is an internal electrochemical standard? Cite two examples.
9. How do the iron center in cytochromes differ from that of Fe-S proteins?
10. What is Wilson’s disease? What chelating agent is used to cure this disease?

 

Part-B

 

Answer eight questions. Each question carries five marks

 

11. Justify the position of CN-in the spectrochemical series with the help of MO theory.
12. What are compartmental ligands? Explain the synthesis of such ligands from phenol and pyridine head units.
13. How is thiocyanato- and isothiocyanato complexes differentiated by IR spectroscopy?
14. What are Orgel diagrams? Construct the Orgel diagram for d^3,8 metal ions in Oh and T_d  geometries.
15. What is spectroelectrochemistry? Explain the application of this technique in the study of cooordination compounds.
16. What is static dynamic Jahn-Teller effect? Explain the method of studying it by spectroscopic method.
17. The epr spectrum of bis(salyciladimine)copper(II) consists of four sets of eleven lines each. Interpret the spectrum and substantiate your result with the help of experimental evidences.
18. Compute D_o values in T_d geometry by angular overlap model.
19. Illustrate the importance of cation-cavity best fit in the synthesis of macrocyclic complexes.
20. Explain Marcus-Hush theory of electron transfer reactions.
21. Explain the mechanism of in “in vivo nitrogen fixation”.
22. Explain the principle of AC polarography. How do you evaluate the reversibility of the redox couple by this technique?

 

 

 

 

 

 

 

 

 

 

 

 

Part-C

 

Answer four questions. Each question carries ten marks

 

23a.  What is coordination template effect? Differentiate between kinetic and thermodynamic  coordination template effects.

1. Explain the synthesis of complexes of Schiff base macrocycles by this method.

24a.  Explain the principle and methodology of cyclic voltammetry.

1. How is the reversibility of a redox couple evaluated by this technique?

25a.  Explain the electronic spectral features of a low-spin d⁶ metal ion in a tetragonally distorted octahedral geometry.

1. How do you evaluate the D_q^xy and D_q^z  values in this geometry.

26a.  Identify the metal orbitals and LGOs suitable for s-bonding in an O_h geometry.  Construct  a qualitative MO energy level diagram for            s-bonding in an O_h geometry.

1. Compare the D_o values of [CoF₆]^3- and [Co(bpy)₃]³⁺ in the light of MO theory.

27a.  Give a brief account of the electronic spectral features of high-spin O_h complexes of transition metal ions.

1. Construct the Orgel diagram for high-spin d⁸ O_h complex. Explain the spectral features of the corresponding low-spin complex with the help of Tanabe-sugano diagram.

28a.  What are cytochromes? How are they classified?

1. Explain the biological roles and structural aspects of rubredoxins and feredoxins.

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

GH 49

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2008

    CH 4956 – ADVANCED COORDINATION CHEMISTRY

 

 

 

Date : 25/04/2008            Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

 

PART-A

Answer all questions. Each question carries two marks  (10 x 2 = 20)

 

1. Give the term symbol of a d² metal ion for the ground state.
2. What is nephelauxetic series? How is it constructed?
3. Sketch the EPR spectrum of [VO(glycollate)₂]^2-.
4. Explain the ¹⁹F NMR spectrum of SbF₅.base adduct.
5. Draw the structural unit of (a) 2Fe-2S (b) 4Fe-4S proteins.
6. Illustrate transmetallation reaction with an example.
7. Explain metal ion induced ring contraction in the synthesis of macrocycles.
8. What are optically transparent electrodes?
9. What is rotaxane? Cite an example.
10. Cite an A-ET-E device involving a lanthanide metal ion.

 

 

PART-B

Answer eight questions. Each question carries five  marks  (8 x 5 = 40)

 

11. How is the electronic spectrum of [Ti(H₂O)₆]³⁺ interpreted using Orgel diagram.
12. Write a note on charge transfer transition in metal complexes.
13. What are Racah parameters? Explain their significance.
14. Explain the application of Mossbauer spectroscopy in the study of p-back bonding in transition metal complexes?
15. Discuss the role of manganese cycle in splitting water during photosynthesis.
16. How do metal porphyrin complexes act as model systems for electron transfer processes?
17. Explain the synthesis of dendrimer-encapsulated gold nanoparticles.
18. Explain the synthetic strategies of (a) a molecular grid and (b) a molecular rectangle.
19. What are the general methods of constructing rotaxanes? Explain the construction of such assemblies by each method.
20. Explain the template synthesis of catenanes with illustrative examples.
21. What are molecular shuttles? Explain the synthesis of such species controlled by (a) electrochemical methods, (b) pH, and (c) redox process.
22. Define molecular machine. Explain the synthesis of a molecular gear.

 

 

 

PART-C

Answer four questions. Each question carries ten marks    (4 x 10 = 40)

 

23. Discuss the ¹H NMR spectral studies of two organometallic fluxional molecules.

24a. Explain zero field splitting and hyperfine splitting.

1. Explain the EPR spectrum of [Mn(H₂O)₆]²⁺ with the help of hyperfine splitting energy level diagram.
2. Discuss the photo- and redox chemistry involved in photosystem-I.

26a.  Explain the principle and methodology of cyclic voltammetry.

1. The cyclic voltammogram of a Co(III) complex consists of two cathodic waves at     E_pc = -0.65  and -0.42 V and two anodic waves at E_pa = -0.52  and -0.35 V at the scan rate of 50 mV s^-1 with i_pc values of 25 and 19 mA, and i_pa values of 23 and 19 mA. Explain the electrochemical behavior of the system from the computed parameters.
2. Explain template synthesis of macrocyclic ligands and their mono- and dinuclear complexes with illustrative examples.

27a. Explain the principle and methodology of constructing a dye sensitized solar cell.

1. Give an account of Ru(II) polypyridyl complexes used in the construction of solar cells.

28a.  Explain the synthesis of dendrimers with two examples.

1. Give an account of the application potential of dendrimers.

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

GH 61

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2008

    CH 4953 – ADVANCED COORDINATION CHEMISTRY

 

 

 

Date : 06/05/2008            Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART-A

Answer all questions. Each question carries 2 marks                                  (10 x 2 = 20)

 

1. What are compartmental ligands? Give an example.
2. Electron transfer for Cr(II)/Co(III) system follows inner-sphere mechanism whereas the V(II)/Ru(III) system follows outer-sphere mechanism. Give reason.
3. What are optically transparent electrodes?
4. Explain photosubstitution reaction with an example.
5. ‘Contrary to the usual observation, the CN stretching vibration of coordinated cyanide appears at higher energy than that of the free cyanide’. Rationalize.
6. Octahedral complexes of high-spin d5metal ions are feebly colored whereas octahedral complexes of low-spin d5 metal ions are intensely colored. Explain.
7. Mention the purpose of using internal electrochemical standard. Cite two examples.
8. What is intensity stealing?
9. Lower oxidation states of transition metal ions are stabilized by p-acids. Offer a resonable explanation.
10. How does change in the angular orientation of the ligand with respect to the metal ions affect the magnitude of s- and p-bonding?

PART-B

Answer eight questions. Each question carries 5 marks                                        (8 x 5 = 40)

 

11. Illustrate with examples the study of fluxional isomerism by NMR spectroscopy with two examples.
12. Derive Marcus-Hush equation to compute the rate constant of electron transfer reactions.
13. Explain the mechanism of in vivo nitrogen fixation?
14. Write a short note on charge transfer photochemistry.
15. Explain Adamson’s rule in the photosubstitution of metal complexes with an example.
16. Explain template synthesis of macrocyclic complexes with two examples.
17. What is spin crossover? Explain the experimental methods of studying it.
18. Illustrate static-dynamic Jahn Teller effect with an illustrative example.
19. Explain the electronic absorption spectral features of high spin octahedral and tetrahedral complexes of transition metal ions.
20. Explain photoisomerization reaction with examples.
21. What are Orgel diagrams? Construct Orgel diagram for high-spin d3and d7 O_h and T_d complexes.
22. How do you differentiate thiocyanato- and isothiocyanato complexes by IR spectroscopy.

 

PART-C

Answer four questions. Each question carries 10 marks                                   (4 x 10 = 40)

 

23. According to MO theory, p-donation by ligands lowers the magnitudes of 10D_q values whereas p-back bonding increases its magnitude. Explain with a qualitative MO energy level diagrams.

24a.  Explain the structural features and biological role of Fe-S proteins.                 (6)

1. Write a note on synthetic oxygen carriers.                                                         (4)

25a.  Explain the structural features of cytochromes.                                                (5)

1. Explain the role of cytochromes as bio-redox agents.                                       (5)
2. A six-coordinate low-spin cobalt(III) complex of a quadridentate ligand with two thiocyanate ions exhibits electronic transitions at 660 nm (Î = 76.5 L mol-1cm-1), 525 nm (Î = 1260 L mol-1 cm-1), 415 nm (Î = 396 L mol-1 cm-1), and 290 nm (Î = 10658 L mol-1 cm-1). Assign these transitions, predict the geometry, and compute the field strength of the ligands.

27a.  Explain the principle of angular overlap model. How s- and p-bonding are quantified in this model?                                                                                                  (3)

1. Prove that 4/9D_o = D_t  with usual notations.                                          (7)
2. Explain the template synthesis of macrocyclic ligands and mono- and dinuclear complexes.

 

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       LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

WD 52

FOURTH SEMESTER – April 2009

CH 4956 – ADVANCED COORDINATION CHEMISTRY

 

 

 

Date & Time: 28/04/2009 / 9:00 – 12:00     Dept. No.                                              Max. : 100 Marks

 

 

PART-A

Answer all questions. Each question carries two marks

 

1. Define relaxivity. What are contrast enhancing agents for MRI?
2. The direct excitation of lanthanide ions does not give rise to significant emission. Comment.
3. Mention the structural components of dendrimers and cite a few functional dendrimers.
4. How do you differentiate low-spin and high-spin octahedral complexes of Fe(II)?
5. How do you infer spin-orbit coupling from electronic spectroscopy? Mention one example where such an effect is very predominant.
6. Illustrate transmetallation reaction with an example.
7. What are radiopharmaceuticals? Cite two examples.
8. What are optically transparent electrodes? Where is it employed?
9. What is pseudorotaxane? Cite an example.
10. Define quantum-up and quantum-down conversion processes.

 

PART-B

Answer eight questions. Each question carries five  marks

 

11. Explain the theory of relaxivity by Gd(III)-based contrast agents for MRI and highlight the parameters of relaxivity optimization.
12. Explain the synthetic strategies of polynuclear supramolecular assemblies involving d,d– and d,f -metal ions.
13. Explain the synthesis of any three supramolecular architectures.
14. What are the general methods of constructing rotaxanes? Explain the construction of such assemblies by each method.
15. The ³¹P NMR spectrum of [Rh(PPh₃)₃Cl₃] consists of two triplets and two doublets. Interpret the spectrum and comment upon its geometry.
16. Explain the principle and methodology of constructing a dye sensitized solar cell.
17. Explain the synthesis and properties of dendrimer-encapsulated gold nanoparticles.
18. Discuss the structural features of ferredoxins and rubredoxins.
19. Explain the electronic spectral features of tetragonally distorted octahedral complexes of low-spin Co(III) with a qualitative energy level diagram.
20. Explain the template synthesis of catenanes with illustrative examples.
21. Explain template synthesis of macrocyclic ligands and their complexes with illustrative examples.
22. Define molecular machine. Explain the construction of two such devices.

 

 

 

 

 

PART-C

Answer four questions. Each question carries ten marks

 

23. What is an A-ET-E molecular device?

Explain the photochemistry of encapsulated complexes of Eu(II) and Tb(III).

24a.Explain zero field splitting and hyperfine splitting.

1. The EPR spectrum of a high spin Mn(II) complex doped onto a diamagnetic host consists of 30 lines. Explain the spectrum with the help of hyperfine splitting energy level diagram.
2. Explain the synthetic strategies for compartmental macrocyclic- and macroacyclic ligands and their complexes of lanthanides and actinides.
3. What are molecular shuttles? Give an account of the construction of molecular shuttles controlled by (a) electrochemically, (b) pH, and (c) redox process.

27a. Explain the principle and methodology of cyclic voltammetry.

b.The cyclic voltammogram of a Co(III) complex consists of two cathodic waves at     E_pc = -0.65  and -0.42 V and two anodic waves at E_pa = -0.52  and -0.35 V at the scan rate of 50 mV s^-1 with i_pc values of 25 and 19 mA, and i_pa values of 23 and 19 mA. Explain the electrochemical behavior of the system from the computed parameters.

28a. Explain the synthesis of dendrimers with two examples.

1. Give an account of the application potential of dendrimers.

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2011

CH 4956 – ADVANCED COORDINATION CHEMISTRY

 

 

Date : 09-04-2011             Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

Part-A

Answer all questions. Each question carries two marks 

 

1. Define an A-ET-E device.
2. How does change in the angular orientation of a ligand with respect to the metal ions affect the magnitude of s- and p-bonding?
3. Give two examples of gadolinium-based contrast reagents for MRI.
4. Mention the prominent emission bands of europium(III) and terbium(III).
5. What are the different kinds of metallodendrimers.
6. How is the kinetic lability of alkali- and alkaline earth metal complexes of macrocycles exploited in the synthesis of the corresponding transition metal complexes?
7. How do you convert complex of a ring contracted macrocycle into that of the ring expanded one?
8. Mention the causes of electrochemical irreversibility in the case of transition metal complexes.
9. Define quantum down-conversion.
10. Complexes of d¹⁰ metal ions are often spectroscopically silent. Comment

 

 

Part-B

Answer eight questions. Each question carries five marks 

 

11. Illustrate a pH controlled molecular shuttle.
12. Construct a molecular break.
13. Explain the method of synthesizing dendrimers with examples.
14. Explain the synthesis of compartmental macrocyclic complexes by coordination template method with examples.
15. Explain acid/base driven threading and dethreading motions in supramolecular assemblies.
16. p-Back bonding by ligands increases the magnitudes of 10D_q values. Explain with a qualitative MO energy level diagram.
17. What is cation-cavity “best fit”? Illustrate with examples.
18. Explain the electronic spectral features of low-spin transition metal ions in O_h and T_d geometries.
19. Give a brief account of the photochemistry of lanthanides.
20. Explain the template synthesis of 2- and 3-catenanes.
21. Explain the principles of spectroelectrochemistry. Highlight the limitations of this technique.
22. Construct the Orgel diagram for high-spin d³ and d⁷ metal ions in O_h geometry. Explain the features of their Tanabe-Sugano diagrams.

 

 

 

 

 

 

 

Part-C

Answer four questions. Each question carries ten marks  

 

23a. Explain the EPR spectrum of bis(salicylaldimine)copper(II) and justify your interpretation with experimental evidences.                                                                   (7)

1. What is zero field splitting? Mention its causes for transition metal complexes.      (3)
2. Explain the different synthetic strategies employed for symmetric and unsymmetric compartmental macrocyclic ligands and their complexes.

25a. Explain the principle of angular overlap model.                                            (3)

1. With the help of angular overlap model show that D_t = 4/9D_o.                                (7)

26a. Explain the principle and methodology of cyclic voltammetry.

1. The cyclic voltammogram of a dinuclear Cu(II)/Ni(II) complex consists of two cathodic waves at E_pc = -0.56 and -0.34 V and two anodic waves at E_pa = -0.5   and               -0.25 V at the scan rate of 100 mV s^-1 with i_pc values of 25 and 19 mA, and i_pa values of 23 and 19 mA. Compute the electrochemical parameters and explain the electrochemical behavior of the system.

27a. Explain the principle and methodology of constructing a dye sensitized solar cell.  (6)

1. Give an account of Ru(II) polypyridyl complexes used in the construction of solar cells.                                                                                      (4)

28a. Mention the different kinds of rotaxanes.                                                                  (3)

1. Explain the construction of such assemblies by various synthetic methods.             (7)

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2012

CH 4956 – ADVANCED COORDINATION CHEMISTRY

 

 

Date : 20-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

 

Part-A

Answer all questions. Each question carries 2 marks

1. What is dendritic catalysis? Cite two reactions catalyzed by a dendritic catalyst.
2. Define relaxivity. Cite two FDA approved contrat agents for MRI.
3. How do you compute the field strength of low-spin octahedral complex of cobalt(III)?
4. Mention the different kinds of supramolecular interactions.
5. What is supramolecularself assembly? Cite an example.
6. How do you evaluate diffusion controlled process by cyclic voltammetry?
7. Octahedral complexes of high-spind⁵ metal ions are feebly colored whereas octahedral complexes of low-spin d⁵ metal ions are intensely colored. Rationalize.
8. Encapsulated lanthanide complexes emit with high intensity. Comment.
9. Illustrate transmetalation reaction with an example.
10. What is quantum up-conversion?

Part-B

Answer eight questions:   Each question carries 5 marks

11. p-Back bonding by ligands increases the magnitudes of 10D_q values. Explain with a qualitative MO energy level diagram.
12. Explain the method of constructing rotaxanes and pseudorotaxanes with examples.
13. What are catenanes? Explain the methods of synthesizing catenanes.
14. Illustrate a supramolecular assembly functioning like a molecular gear.
15. Explain the construction of two photochemical supramolecular assemblies.
16. Illustrate the importance of cation-cavity best fit in the synthesis of Schiff base macrocycles.
17. Explain the electronic spectral features of tetragonally distorted low-spin octahedral cobalt(III) complexes.
18. Explain the working principle of dye-sensitized photovoltaic cells.
19. Explain the biological roles and structural features of rubredoxins and ferredoxins.
20. Give an account of the photochemistry of lanthanide macrocyclic complexes. How do the photochemistry of lanthanides differ from that of ruthenium(II)?
21. Write a note on spectroelectrochemistry.
22. Write a note on the applications of dendrimers and metallodendrimers.

Part-C

Answer four questions. Each question carries 10 marks

23. A six-coordinate low-spin cobalt(III) complex of a quadridentate ligand with two thiocyanate ions exhibits electronic transitions at 660, 525, 415, and 290 nm. Assign these transitions, predict the geometry, and compute the field strength of the axial and equatorial ligands.

24a. The epr spectrum of a high-spin manganese(II) complex doped into a diamagnetic host consists of 30 lines (five sets of six lines each).      Interpret the spectrum with the appropriate energy level diagram.                                                                                             (7)

1. Mention the causes of zero field splitting in transition metal complexes.                       (3)

25a. Explain the principle of cyclic voltammetry and the method of evaluating the reversibility of a redox couple. Mention the causes of electrochemical irreversibility of a redox couple.

1. The cyclic voltammogram of a pseudooctahedral cobalt(III) complex consists of two reduction waves at -0.34 and -1.22 V and two oxidation waves at -1.16 and -0.29 V versus Ag/Ag⁺. Explain the electrochemical behavior of this complex.

26a. Differentiate thermodynamic and kinetic coordination template effects.                      (3)

1.   Explain the template synthesis of macrocyclic and compartmental macrocyclic ligands and their mono- and dinuclear complexes by coordination template effect.                            (7)
2. What are molecular shuttles? Explain their synthesis by chemical, electrochemical, and photochemical methods.

28a. Explain the mechanism of water proton relaxation by gadolinium(III)-based contrast enhancing agents for MRI.

1. Explain the synthetic strategies employed for the polyazacarboxylate ligands used for the development of contrast agents for MRI and diagnostic radiopharmaceuticals.

 

 

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