title: Crystal phase competition by addition of a second metal cation in solid solution metal-organic frameworks.
abstract: Herein we report a synthetic study focused on the preparation of solid-solution metal-organic frameworks, MOFs, with the use of two kinds of linkers. In particular, we have explored the system composed by zinc, cobalt, 1,2,4-triazole and 4,4′-hexafluoroisopropylidenebisbenzoic acid (H2hfipbb). During this study, four new MOFs have been isolated, denoted TMPF-88 [M3(hfipbb)2(triazole)2(H2O)], TMPF-90 [M2(triazole)3(OCH2CH3)], TMPF-91 [M2(hfipbb)(triazole)2(H2O)] and TMPF-95 [M5(hfipbb)4(triazole)2(H2O)] (TMPF = transition metal polymeric framework, M = Zn, Co, or mixture of them). The study demonstrates that the addition of a second metal element during the MOF synthesis has a major effect in the formation of new phases, even at very high Zn/Co metal ratios. Furthermore, we show that during the MOF formation reaction, there is a competition among different crystal phases, where kinetically favoured phases of various compositions crystallize in short reaction times, precluding the formation of the pure solid-solution phases of other energetically more stable MOFs.
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: C
authors.initials: C
authors.lastname: Castillo-Blas
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: N
authors.initials: N
authors.lastname: Snejko
authors.affiliation: IMDEA Energy Institute, Móstoles Technology Park, Av. Ramón de la Sagra 3, 28935 Móstoles, Madrid, Spain.
authors.forename: V A
authors.initials: VA
authors.lastname: de la Peña-O'Shea
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: J
authors.initials: J
authors.lastname: Gallardo
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: E
authors.initials: E
authors.lastname: Gutiérrez-Puebla
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: M A
authors.initials: MA
authors.lastname: Monge
authors.affiliation: Department of New Architectures in Materials Chemistry - Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain. gandara@icmm.csic.es amonge@icmm.csic.es.
authors.forename: F
authors.initials: F
authors.lastname: Gándara