Organic spin clusters: Annelated macrocyclic polyarylmethyl polyradicals and a polymer with very high spin S = 6-18

Chemistry - A European Journal

Volumn 10, Issue 13, 2004, Pages 3144-3157

  Rajca, Andrzej ^a   Wongsriratanakul, Jirawat ^a   Rajca, Suchada ^a   Cerny, Ronald L ^a  

^a UNIVERSITY OF NEBRASKA LINCOLN   (United States)

Author keywords

High spin systems; Macrocycles; Magnetic properties; Polymers; Radicals

Indexed keywords

ANNEALING; CHEMICAL ANALYSIS; DISPERSIONS; FERROMAGNETIC MATERIALS; LOW TEMPERATURE EFFECTS; MAGNETISM; MAGNETIZATION; NEUTRON SCATTERING; POLYETHERS; SYNTHESIS (CHEMICAL);

CHEMICAL DEFECTS; MONODISPERSITY;

FREE RADICALS;

CALIXARENE; ETHER DERIVATIVE; FERROMAGNETIC MATERIAL; MACROCYCLIC COMPOUND; POLYCYCLIC AROMATIC HYDROCARBON DERIVATIVE; POLYETHER DERIVATIVE; POLYMER; RADICAL;

ARTICLE; CROSS COUPLING REACTION; ELECTRON; LOW TEMPERATURE; MAGNETIC FIELD; MAGNETISM; MASS; MASS SPECTROMETRY; NEUTRON SCATTERING; PROTON NUCLEAR MAGNETIC RESONANCE; QUANTITATIVE ANALYSIS; ROOM TEMPERATURE; SYNTHESIS;

FREE RADICALS; MACROCYCLIC COMPOUNDS; MAGNETIC RESONANCE SPECTROSCOPY; MAGNETICS; MOLECULAR STRUCTURE; POLYMERS; SPECTROMETRY, MASS, FAST ATOM BOMBARDMENT;

EID: 3042845688     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/chem.200306036     Document Type: Article

References (38)

1. A. Rajca, Chem. Eur. J. 2002, 8, 4834-4841.
2. K. Itoh in Molecular Magnetism, New Magnetic Materials (Ed.: M. Kinoshita), Gordon and Breach, Kodansha, 2000, pp. 1-337.
3. P. M. Lahti, Magnetic Properties of Organic Materials, Marcel Dekker, New York, 1999, pp. 1-713.
4. A. Rajca, Chem. Rev. 1994, 94, 871-893.
5. H. Iwamura, N. Koga, Acc. Chem. Res. 1993, 26, 346-351.
6. K. Matsuda, N. Nakamura, K. Inoue, N. Koga, H. Iwamura, Bull. Chem. Soc. Jpn. 1996, 69, 1483-1494.
7. T. Michinobu, J. Inui, H. Nishide, Org. Lett. 2003, 5, 2165-2168.
8. H. Nishide, T. Ozawa, M. Miyasaka, E. Tsuchida, J. Am. Chem. Soc. 2001, 123, 5942-5946.
9. R. J. Bushby, D. Gooding, J. Chem. Soc. Perkin Trans. 2 1998, 1069-1075.
10. M. M. Murray, P. Kaszynski, D. A. Kaisaki, W. Chang, D. A. Dougherty, J. Am. Chem. Soc. 1994, 116, 8152-8161.
11. K. K. Anderson, D. A. Dougherty, Adv. Mater. 1998, 10, 688-692.
12. N. Mataga, Theor. Chim. Acta 1968, 10, 372-376.
13. A. Aharoni, Introduction to the Theory of Ferromagnetism, 2nd ed., Oxford University Press, Oxford 2000, Chapter 4, pp. 76-79.
14. a) For isotropic exchange coupling involving the Heisenberg Hamiltonian based models (generally applicable to organic polyradicals), the absence of ferromagnetism or antiferromagnetism in one or two-dimensions was rigorously proven: N. D. Mermin, H. Wagner, Phys. Rev. Lett. 1966, 17, 1133-1136;
15. b) The Mermin-Wagner theorem was extended to additional models: P. Bruno, Phys. Rev. Lett. 2001, 87, 137203-1-4.
16. For selected models, based upon anisotropic exchange coupling (e.g., Ising Hamiltonian), ferromagnetism in two-dimensional system is possible, see for example: R. P. Feynman, Statistical Mechanics, Benjamin/Cummings, Reading, MA, 1972, Chapter5, pp. 127-150.
17. The magnetic dipole-dipole interactions may lead to ferromagnetism in two dimensions, though only at relatively low temperatures: Y. Yafet, J. Kwo, E. M. Gyorgy, Phys. Rev. B 1986, 33, 6519-6522.
18. A. Rajca, J. Wongsriratanakul, S. Rajca, Science 2001, 294, 1503-1505.
19. For a report on organic spin clusters addressing the possible source of magnetic anisotropy (shape anisotropy) in polymer 1 see: "Organic Spin Clusters: Dendritic-Macrocyclic Polyarylmethyl Polyradical with Very High-Spin of S = 10 and its Derivatives: Synthesis, Magnetic Studies, and Small Angle Neutron Scattering": S. Rajca, A. Rajca, J. Wongsriratanakul, P. Butler, S. Choi, J. Am. Chem. Soc. in press.
20. For a report on organic spin clusters addressing the development of net ferri- or ferromagnetic correlations in polymer 1 see: "Organic Spin Clusters: Macrocyclic-Macrocyclic Polyarylmethyl Polyradicals with Very High Spin S = 5-13": A. Rajca, J. Wongsriratanakul, S. Rajca, J. Am. Chem. Soc. in press.
21. A. Rajca, S. Rajca, J. Wongsriratanakul, J. Am. Chem. Soc. 1999, 121, 6308-6309.
22. In the other limiting mode of annelation, the calix[4]arene macrocyles are connected through the diagonal benzene rings.
23. A. Rajca, K. Lu, S. Rajca, J. Am. Chem. Soc. 1997, 119, 10335-10345.
24. A. R. Forrester, J. M. Hay, R. H. Thomson, Organic Chemistry of Stable Free Radicals, Academic Press, London, 1968, Chapter 2, pp. 55-110.
25. A. Rajca in Encyclopedia of Polymer Science and Technology, 3rd ed. (Ed: J. I. Kroschwitz), Wiley, Online Posting Date: October, 2002.
26. 2 was carried out only once on the 4 μmol scale and involved addition of only 2 drops of the solution of tBuLi; this may contribute to the low yield of the product.
27. Such "mono-demethylated" polyethers were observed by FAB-MS in other instances (e.g., ref. [19]).
28. 2.
29. n were obtained under identical conditions.
30. 42 were resolved, as well.
31. gq < 1.10. The SANS experiments and the data handling are described in detail ref. [18]; a short summary may be found in the Supporting Information.
32. s, may be found in ref. [20] (note 21).
33. This approximate mean-field approach is justified for such small values of |θ|.
34. Most likely, polymer 6 possesses net ferromagnetic couplings with a wide distribution of strengths.
35. E. Beloritzky, P. H. Fries, J. Chim. Phys. Phys.-Chim. Biol. 1993, 90, 1077-1100.
36. At higher magnetic field, H = 0.5 Tesla, the low temperature downward turn in the χT versus T plot is dominated by paramagnetic saturation; this is overestimated at low temperatures by the fit with the perfect S = 7 polyradical (J/k > 0), while S ≈ 6 is found for the sample. At lower fields, the paramagnetic saturation nearly vanishes and antiferromagnetic interactions become detectable for the J/k > 0 case. At lower magnetic fields, the need for additional correction for diamagnetism may be caused by a low signal-to-noise ratio for the paramagnetic component, especially at higher temperatures.
37. A. Rajca, J. Wongsriratanakul, S. Rajca, J. Am. Chem. Soc. 1997, 119, 11674-11686.
38. These two-parameter percolation fits possess relatively large values of parameter dependence, approaching 0.99, making them less reliable than the two-parameter fits to a single Brillouin function.