New Crystalline Layered Zinc Phosphate with 10-Membered-Ring Channels Perpendicular to Layers Lei Liu, † Stanislav Ferdov, ‡,§ Cristina Coelho, ‡ Ying Kong, † Lu  is Mafra, ‡ Jin P. Li, † Jin X. Dong, † Uwe Kolitsch, ^ Rute A. S  a Ferreira, z Ekkehart Tillmanns, # Jo ~ ao Rocha, ‡ and Zhi Lin* ,‡ † Research Institute of Special Chemicals, Taiyuan University of Technology, 030024 Taiyuan, People’s Republic of China, ‡ Department of Chemistry, CICECO, University of Aveiro, Aveiro 3810-193, Portugal, § Department of Physics, University of Minho, Campus de Azur em, 4800-058 Guimar ~ aes, Portugal, ^ Mineralogisch- Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, A-1010 Wien, Austria, z Department of Physics, CICECO, University of Aveiro, Aveiro 3810-193, Portugal and # Institut f :: ur Mineralogie and Kristallographie, Universit :: at Wien, Geozentrum, Althanstrasse 14, A-1090 Wien, Austria Received January 19, 2009 A novel layered zinc phosphate, [N 2 C 6 H 12 ] 2 [Zn 7 H 3 (HPO 4-x ) 5 (PO 4 ) 3 ] H 2 O, with unique 10-membered-ring ellipsoidal channels running perpendicularly to ladder-shaped tetrahedral layers, has been synthe- sized ionothermally via in situ generation of 1,4-diazabicyclo[2.2.2] octane. Layered materials have versatile applications in catalysis, adsorption, and ion exchange. 1 Recently, layered materials have been used as precursors in the preparation of nano- composites. 2 Layered materials with perforated sheets are particularly interesting 3 and have been used as selectivity- enhancing additives in polymer membranes. 2 Zincophosphates are an important subset of the large phosphate family. Although over 20 different zincopho- sphates with various structural dimensionalities and stoichio- metries have been synthesized and characterized, 4-8 the preparation of zinc phosphates with novel structures is still possible. 9-11 Most of these structures are built up from vertex-linked ZnO 4 and PO 4 tetrahedra, and connectivity between two or more ZnO 4 tetrahedra through Zn-O-Zn linkages is rare. 12 These materials are typically synthesized hydrothermally using a zinc salt and phosphoric acid, together with an organic amine acting as a template or structure-directing agent. Recently, ionothermal synthesis has been used in the preparation of aluminophosphate molecular sieves, among other materials. 13 The term “ionothermal synthesis” was proposed to describe a reaction using ionic liquids or eutectic mixtures as solvents to distinguish it from hydrothermal synthesis. 13 One class of deep eutectic solvents (DESs), formed between a variety of quaternary ammonium salts and carboxylic acids or urea-based amines, 14,15 exhibits unusual solvent properties that are very similar to those of ionic liquids and can be used in ionothermal syntheses as an alternative to ionic liquids. 13,16 Among these DESs, the carboxylic acid/quaternary ammonium salt DESs seem to be stable and usually do not contribute decomposition products as templates to the reactions, 16 while the ionic liquid acts as both a solvent and a template provider in ionothermal syntheses. Quaternary ammonium salts, such as TMABr, TEABr, TPABr, TBABr, and choline chloride, have been much used as structure-directing agents in the hydrothermal synthesis of molecular sieves. Different quaternary ammo- nium cations may template dissimilar frameworks. The above-mentioned quaternary ammonium salts may be mixed with oxalic acid to form DES, with melting points *To whom correspondence should be addressed. E-mail: zlin@ua.pt. (1) Corma, A. Chem. Rev. 1997, 97, 2373. (2) Choi, S.; Coronas, J.; Jordan, E.; Oh, W.; Nair, S.; Onorato, F.; Shantz, D. F.; Tsapatsis, M. Angew. Chem., Int. Ed. 2008, 47, 552. (3) Jeong, H.-K.; Nair, S.; Vogt, T.; Dickinson, L. C.; Tsapatsis, M. Nat. Mater. 2003, 2, 53. (4) Rao, C. N. R.; Natarajan, S.; Neeraj, S. J. Am. Chem. Soc. 2000, 122, 2810. (5) Choudhury, A.; Natarajan, S.; Rao, C. N. R. Inorg. Chem. 2000, 39, 4295. (6) Ng, H. Y.; Harrison, W. T. A. Microporous Mesoporous Mater. 2001, 50, 187. (7) Harrison, W. T. A.; Philips, M. L. F. Chem. Mater. 1997, 9, 1837. (8) Yang, G. Y.; Sevov, S. C. J. Am. Chem. Soc. 1999, 121, 8389. (9) Chang, W.-M.; Cheng, M.-Y.; Liao, Y.-C.; Chang, M.-C.; Wang, S.-L. Chem. Mater. 2007, 19, 6114. (10) Yang, Y.; Zhao, Y. N.; Yu, J. G.; Wu, S. Z.; Wang, R. J. Inorg. Chem. 2008, 47, 769. (11) Jensen, T. R.; Goncalves, A.; Hazell, R. G.; Jakobsen, H. J. Micro- porous Mesoporous Mater. 2008, 109, 383. (12) Song, T. Y.; Hursthouse, M. B.; Chen, J. S.; Xu, J.; Abdul Malik K. M.; Jones, R. H.; Xu, R. R.; Thomas, J. M. Adv. Mater. 1994, 6, 679. (13) Parnham, E. R.; Morris, R. E. Acc. Chem. Res. 2007, 40, 1005 and references cited therein. (14) Abbitt, A. P.; Boothby, D.; Capper, G.; Davies, D. L.; Rasheed, R. K. J. Am. Chem. Soc. 2004, 126, 9142. (15) Abbitt, A. P.; Capper, G.; Davies, D. L.; Rasheed, R. K.; Tambyrajah, V. Chem. Commun. 2003, 70. (16) Drylie, E. A.; Wragg, D. S.; Parnham, E. R.; Wheatley, P. S.; Slawin, A. M. Z.; Warren, R. E.; Morris, R. E. Angew. Chem., Int. Ed. 2007, 46, 7839. Inorg. Chem. 2009, 48, 4598–4600 4598 DOI:10.1021/ic900107p © 2009 American Chemical Society Published on Web 4/20/2009 pubs.acs.org/IC