Three lanthanum MOF polymorphs: insights into kinetically and thermodynamically controlled phases.
RPF-4 is a family of polymeric frameworks prepared with rare-earth elements and the versatile ligand 4,4'-(hexafluoroisopropylidene)bis(benzoic acid). We have found that during the synthesis procedure up to three different polymorphs can be obtained. Their crystal structures are here presented. The three networks have unusual topologies, the three being uninodal penta-coordinated, two of them unknown up to now, and the other named hxg-d-5-Imma. They are here described and compared. DFT calculations of the relative energies for the three polymorphs show that the most often obtained structure is a metastable phase, which appears to be, next to others, thermodynamically more stable.
Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain.
Felipe
F
Gándara
Víctor A
VA
de la Peña-O'Shea
Francesc
F
Illas
Natalia
N
Snejko
David M
DM
Proserpio
Enrique
E
Gutiérrez-Puebla
M Angeles
MA
Monge
D003198:Computer Simulation; D007700:Kinetics; D007811:Lanthanum / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013816:Thermodynamics
D008024:Ligands; D009942:Organometallic Compounds; D007811:Lanthanum