MS16-P02 Tunable crystal structure and proton conductivity of lanthanide nitrilotris-methylphosphonates Inés Ruiz Salcedo (Departamento Química Inorgánica, Cristalografía y Mineralogía. Facultad de Ciencias. Universidad de Málaga., Málaga, Spain) Aurelio Cabeza Díaz (Departamento Química Inorgánica, Cristalografía y Mineralogía. Universidad de Málaga., Málaga, Spain) Montse Bazaga García (Departamento Química Inorgánica, Cristalografía y Mineralogía. Universidad de Málaga., Málaga, Spain) Rosario Mercedes Pérez Colodrero (Wolverhampton School of Sciences. Faculty of Science and Engineering. University of Wolverhampton., Wolverhampton, United Kingdom) Gary Hix (Wolverhampton School of Sciences. Faculty of Science and Engineering. University of Wolverhampton., Wolverhampton, United Kingdom) Enrique Ramírez Losilla (Departamento Química Inorgánica, Cristalografía y Mineralogía. Universidad de Málaga., Málaga, Spain) Pascual Olivera Pastor (Departamento Química Inorgánica, Cristalografía y Mineralogía. Universidad de Málaga., Málaga, Spain)email: inesrs@uma.esMetal phosphonates are multifunctional solids with remarkable stability and proton conducting properties owing to their structure is usually composed of extended hydrogen-bond networks that favor proton transfer pathways [1]. Moreover, these properties can be enhanced by appropriate modification of the synthesis conditions [2, 3].
 
In this communication, a new family of isostructural 2D layered compounds based on lanthanide nitrilotris-methylphosphonates is reported. These compounds have been isolated at room temperature and have the general formula Ln[N(CH2)3(PO3H2)2(PO3H)(H2O)]SO4·2H2O (Ln= Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb). The coordination environment of Ln3+ is composed by eight oxygen atoms from three different ligands and two oxygens from bound waters. This connectivity creates positive charged layers connected to sulfate ions through hydrogen-bonds. These compounds show promising proton conductivity with values ranging between 7.6·10-2 and 3.8·10-2 S·cm-1 at 80 °C and 95% RH and low activation energy corresponding to Grotthuss-type proton transfer mechanism. In addition, a structural transformation occurs at T > 70 °C accompanied by a remarkable enhanced conductivity. Studies on the structure-properties relationships will be discussed.
References:

[1] Metal phosphonate Chemistry: from synthesis to applications. 1st ed., edited by A. Clearfield, K. D. Demadis, RSC-Publishing, Cambridge.



[2] M. Bazaga-García, G. K. Angeli, K. E. Papathanasiou, I. R. Salcedo, P. Olivera-Pastor, E. R. Losilla, D. Choquesillo-Lazarte, Gary B. Hix, A. Cabeza, K. Demadis. (2016). Inorganic Chemistry, 55, 7414-7424.



[3] A. Cabeza, P. Olivera-Pastor, R. M. P. Colodrero. (2015). Tailored Organic-Inorganic Materials. Eds. E. Brunet, J. L. Colón, A. Clearfield. Ed. John Wiley & Sons, Inc. Ch. 4, 137-191.

Keywords: metal phosphonates, proton conductivity, crystal structure