Karl Seff

Professor Emeritus

University of Hawaii at Manoa
Department of Chemistry
2545 The Mall, Honolulu,
HI 96822-2275

Phone: (808) 956-7665
Fax: (808) 956-5908
Email: seff@hawaii.edu

 
 

Karl Seff received his B.S. degree from the University of California at Berkeley in 1959 and his Ph.D. from the Massachusetts Institute of Technology in 1964. After three years of post-doctoral work at U.C.L.A., he joined the faculty of the chemistry department at the University of Hawaii. In 1988-89, he spent a year in Oxford, England studying pulsed-neutron diffraction from zeolite powders. His efforts in X-ray and neutron crystallography are directed mostly at the determination of the structures of chemically modified zeolites, to identify new species synthesized in intrazeolitic voids.

 
 

    A novel chemistry is observable crystallographically within the rigid porous anionic aluminosilicate frameworks of variously ion- exchanged, desolvated and chemically treated zeolites. The ions D+, Na+, K+, Rb+, Cs+, Tl+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ have been found at positions of extreme coordinative unsaturation, which is the very basis of many of the valuable properties that activated zeolites have, such as selective sorption and catalysis. Intrazeolitic redox processes involving Cu and Ag have been observed simply upon desolvation, in the latter case to give the new molecule hexasilver, Ag6 (no charge), the smallest possible fully developed single crystal of silver (see figure). These can also be prepared by the reduction of Ag+ with Cs(g) or Rb(g).

 

    By the sorption of metal vapors, the following species were synthesized within zeolites and seen for the first time crystallographically: (Na5)4+, (K3)2+, (K4)3+, (Rb3)+, (Rb3)2+, (Cs4)3+, Cd+, (Cd2)2+, and Cd2. More interestingly, the zeolite sometimes begins to fill with vapor metal atoms to give, not small isolated clusters, but positively charged two- or three- dimensional continua, with formulae like (Cs122)86+ per unit cell. The properties of these cationic continua, which appear to be a new class of metals or semi-metals, remain to be established.

    In addition, small molecules sorbed by desolvated (activated) zeolites have been found complexed to cations within zeolite A. Some of those molecules are C2H2, C2H4, C3H6, NO, NO2, CO, CH3OH, Cl2, Br2, CS2 and H2S. We believe that the new molecules N3H5 (triazane) and N3H3 (cyclotriazane) have been synthesized and are stabilized within the zeolite by complexation to Ag+.

    In other work, linear (Pb-S-Pb)2+ ions were found in zeolite Y, and near cubic (Pb7O(OH)3)9+ ions were found in zeolite A. Atoms of Ar and Kr have been found encapsulated in partially Cs+-exchanged zeolite A. Ca2+,Ag+-zeolite A was exposed to Cs(g) at 250 ºC: for reasons of Cs atom size and Ag+ cation immobility, we observed the quantitative intrazeolitic reduction of Ca2+ to Ca while Ag+ remained entirely unreacted! To make possible the preparation of many new zeolite compositions, we are seeking to identify non-aqueous solvents which may be used for ion exchange.

 

Nanoclusters of Ag4I4 in the Sodalite Cavities of Zeolite A.

The following short paper will be published in the Proceedings of the Fourteenth International Zeolite Conference to be held in Capetown South Africa in April, 2004. It announces the discovery that elements can disproportionate in a very interesting way upon sorption into a zeolite. This has become a major new research theme in my group.

Recent Publications:

The following publications have appeared in print in this millenium. This is the most recent portion of my publication list.

  1. Zhen, S.; Bae, D.; Seff, K., Zn+ Cations, Probable Tl4Zn12 and Tl6 Clusters, and Zeolite Desilication (Less Likely Dealumination). Crystallographic Study of the Incomplete Reaction of Zn Vapor with Tl+- Exchanged Zeolite X, J. Phys. Chem. B 2000, 104, 515-525. Errata: ibid. 2001, 105, 12222.

  2. Park, H.S.; Seff, K., Crystal Structures of Fully La3+-Exchanged Zeolite X. An Intrazeolitic La2O3 Continuum. Hexagonal Planar and Trigonally Monocapped Trigonal Prismatic Coordination, J. Phys. Chem. B 2000, 104, 2224-2236.

  3. Lee, S.H.; Kim, Y.; Seff, K., Crystal Structure of Partially Pd2+-Exchanged Zeolite X Dehydrated in Oxygen at 400 C. Formation of Linear Pd2O3 Clusters Proposed to be HO-Pd(IV)-O-Pd(IV)-OH in (Pd2+)14(HOPdOPdOH4+)8(Na+)32-Si100Al92O384, J. Phys. Chem. B 2000, 104, 2490-2494.

  4. Zhen, S.; Seff, K., Structures of Organic Sorption Complexes of Zeolites, Microporous Mesoporous Mater. 2000, 39, 1-18.

  5. Zhu, L.; Seff, K., Rate of Tl+ Exchange into Single Crystals of Zeolite X, Microporous Mesoporous Mater. 2000, 39, 187-193.

  6. Bae, D.; Seff, K., Crystal Structure of Zeolite X Nickel(II)-Exchanged at pH 4.3 and Partially Dehydrated, Ni2(NiOH)35(Ni4AlO4)2(H3O)46-Si101Al91O384, Microporous Mesoporous Mater. 2000, 40, 219-232.

  7. Bae, D.; Seff, K., Extensive Intrazeolitic Hydrolysis of Zn(II). Partial Structures of Partially and Fully Hydrated Zn(II)-Exchanged Zeolite X, Microporous Mesoporous Mater. 2000, 40, 233-245.

  8. Choi, E.Y.; Kim, Y.; Han, Y.W.; Seff, K., Structure of a Cyclopropane Sorption Complex of Dehydrated Fully Mn2+-Exchanged Zeolite X, Microporous Mesoporous Mater. 2000, 40, 247-255.

  9. Heo, N.H.; Jung, S.W.; Park, S.W.; Park, M.; Lim, W.T.; Seff, K., Crystal Structures of Fully Indium-Exchanged Zeolite X, J. Phys. Chem. B 2000, 104, 8372-8381.

  10. Zhu, L.; Seff, K., Cation Crowding in Zeolites. Reinvestigation of the Crystal Structure of Dehydrated Potassium-Exchanged Zeolite X, J. Phys. Chem. B 2000, 104, 8946-8951. Errata: ibid. 2001, 105, 12221.

  11. Zhen, S.; Seff, K., Crystallographic Study of the Reaction of Zn Vapor with Fully Cd2+-Exchanged Zeolite X. Complete Reduction of Cd2+ by Zn, Extraction of SiO44- and AlO45- from the Zeolite Framework, and Reduction of Si4+ to Si, J. Phys. Chem. B 2000, 104, 9811-9816.

  12. Lee, S.H.; Kim, Y.; Seff, K., Weak Ag+-Ag+ Bonding in Zeolite X. Crystal Structures of Ag92Si100Al92O384 Hydrated and Fully Dehydrated in Flowing Oxygen, Microporous Mesoporous Mater. 2000, 41, 49-59. Errata: ibid. 2002, 52, 61-63.

  13. Choi, E.Y.; Kim, Y.; Seff, K. Structure of a Cyclopropane Sorption Complex of Dehydrated Fully Cd2+-Exchanged Zeolite A, Microporous Mesoporous Mater. 2000, 41, 61-68.

  14. Lee, S.H.; Kim, Y.; Seff, K., A Cationic Rubidium Continuum in Zeolite X, J. Phys. Chem. B 2000, 104, 11162-11167.

  15. Bae, D.; Seff, K., Some Chemical Treatments Diminish the Long Range Ordering in the Aluminosilicate Framework of Zeolite X, Microporous Mesoporous Mater. 2001, 42, 299-306.

  16. Zhu, L.; Seff, K., Verification of Linear Na32+ Clusters in Zeolite X, Microporous Mesoporous Mater. 2001, 46, 111-113.

  17. Witzke, T.; Zhen, S.; Seff, K.; Doering, T.; Nasdala, L.; Kolitsch, U., Ronneburgite, K2MnV4O12, a New Mineral from Ronneburg, Thuringia, Germany: Description and Crystal Structure, Am. Mineral. 2001, 86, 1081-1086.

  18. Heo, N.H.; Jung, S.W.; Park, S.W.; Noh, J.S.; Lim, W.T.; Park, M.; Seff, K., Preparation, Characterization, and Crystal Structures of Fully Indium-Exchanged Zeolite X, Studies in Surface Science and Catalysis, 135, Elsevier, New York, 2001. pp 1478-1485.

  19. Heo, N.H.; Chun, C.W.; Park, J.S.; Lim, W.T.; Park, M.; Li, S.-L.; Zhou, L.-P.; Seff, K., Reaction of Fully Indium-Exchanged Zeolite A with Hydrogen Sulfide. Crystal Structures of Indium-Exchanged Zeolite A Containing In2S, InSH, Sorbed H2S, and (In5)7+, J. Phys. Chem. B 2002, 106, 4578-4587.

  20. Choi, E.Y.; Kim, Y.; Seff, K., Crystal Structure of a Mesitylene Sorption Complex of Dehydrated Fully Ca2+-Exchanged Zeolite X. Sorbed Mesitylene Appears to be Significantly Nonplanar, J. Phys. Chem. B 2002, 106, 5827-5832.

  21. Choi, E.Y.; Lee, S.H.; Kim Y.; Han, Y.W.; Seff, K., Crystal Structure of a Cadmium Sorption Complex of Dehydrated Fully Cd(II)-Exchanged Zeolite X, Studies in Surface Science and Catalysis, 135, Elsevier, New York, 2001. pp 1447-1454; Crystal Structure of a Cadmium Sorption Complex of Dehydrated Fully Cd2+-Exchanged Zeolite X Containing Cd2+, Cd+ and Cd0, J. Phys. Chem. B 2002, 106, 7569-7573.

  22. Heo, N.H.; Park, J.S.; Kim, Y.J.; Lim, W.T.; Jung, S.W.; Seff, K., A Spatically Ordered Quantum Dot Array of Indium Nanoclusters in Fully Indium-Exchanged Zeolite X, J. Phys. Chem. B 2003, 107, 1120-1128.

  23. Song, M.K.; Kim, Y.; Seff, K., Disproportionation of an Element in a Zeolite. I. Crystal Structure of a Sulfur Sorption Complex of Dehydrated Fully Cd2+ Exchanged Zeolite X. Synthesis of Tetrahedral S44+ and n-S42+, Two New Polyatomic Cations of Sulfur, J. Phys. Chem. B 2003, 107, 3117-3123.
  24. Kim, S.Y.; Kim, Y.; Seff, K., Two Crystal Structures of Fully Dehydrated Fully Ag+-Exchanged Zeolite X. Dehydration in Oxygen Prevents Ag+ Reduction. Without Oxygen, Ag (Td) and cyclo-Ag (near S4) Form, J. Phys. Chem. B 2003, 107, 6938-6945. Errata: ibid. 10320.

  25. Choi, E.Y.; Kim, S.Y.; Kim, Y.; Seff, K., Crystal Structure of an Ethylene Sorption Complex of Fully Dehydrated, Fully Oxidized, Fully Ag+-Exchanged Zeolite X, Microporous Mesoporous Mater. 2003, 62, 201-210.

  26. Bae, M.N.; Song, M.K.; Kim, Y.; Seff, K., Crystal Structure of a Hydrogen Sulfide Complex of Fully Dehydrated Mn2+-Exchanged Zeolite X, Mn46Si100Al92O384-89H2S, Microporous Mesoporous Mater. 2003, 63, 21 31.

  27. Song, M.K.; Choi, E.Y.; Kim, Y.; Seff, K., Disproportionation of an Element in a Zeolite. II. Crystal Structure of an Iodine Sorption Complex of Dehydrated Fully Cd2+-Exchanged Zeolite X Containing n-I5- as I--I3+-I- and Square cyclo-I42+, J. Phys. Chem. B 2003, 107, 10709-10714.

  28. Heo, N.H.; Kim, H.S.; Lim, W.T.; Kim, B.J.; Seff, K., Synthesis and Crystal Structure of Ag4I4 Nanoclusters in the Sodalite Cavities of Fully K+-Exchanged Zeolite A, J. Phys. Chem. B 2004, 108, in press.

  29. Ryu, K.S.; Bae, M.N.; Kim, Y.; Seff, K., Further Crystallographic Confirmation that Cs+ Ions Can Occupy Sodalite Cavities and Double Six-Rings in FAU. Crystal Structure of Dehydrated Partially Cs+-Exchanged Zeolite X,| Cs45Na47|[Si100Al92O384]-FAU, Microporous Mesoporous Mater. 2004, in press.

  30. Jeong, G.H.; Kim, Y.; Seff, K., Crystal Structure of a Methylamine Sorption Complex of Dehydrated Fully Ca2+-Exchanged Zeolite X, |Ca46(CH3NH2)16|[Si100Al92O384]-FAU, Langmuir, submitted for publication.
Last updated 09 September 2008