RESEARCH ARTICLE 1 How to cite: Angew. Chem. Int. Ed. 2021, 60, 12001–12006 International Edition: doi.org/10.1002/anie.202100507 German Edition: doi.org/10.1002/ange.202100507 A multifunctional Dysprosium-carboxylato 2D metallorganic framework Jonay González, [a] Pablo Sevilla, [b] Guillem Gabarró-Riera, [a,f] Jesús Jover, [a,c] Jorge Echeverría, [a,c] Sara Fuertes, [d] Ana Arauzo [e] , Elena Bartolomé,* [b] E. Carolina Sañudo* [a,f] [a] J. González, G. Gabarró-Riera, Dr. J. Jover, Dr. J. Echeverría, Dr. E. C. Sañudo Secció de Química Inorgànica, Departament de Química Inorgànica i Orgànica, Universitat de Barcelona C/Martí i Franquès, 1-11, 08028 Barcelona, Spain E-mail: esanudo@ub.es [b] Dr. P. Sevilla, Dr. E. Bartolomé Department of Mechanical Engineering. Escola Universitària Salesiana de Sarrià (EUSS). Passeig de Sant Joan Bosco, 74, 08017, Barcelona, Spain E-mail: ebartolome@euss.es [c] Dr. J. Jover, Dr. J. Echeverría Institut de Química Teòrica i Computacional, Universitat de Barcelona 08028, Barcelona, Spain [d] Dr. Sara Fuertes Departamento de Química Inorgánica, Facultad de Ciencias, Instituto de Síntesis Química y Catalisis, Homogénea (ISQCH), CSIC−Universidad de Zaragoza, Spain [e] Dr. A. Arauzo Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain. E-mail: arauzo@unizar.es [f] G. Gabarró, Dr. E. C. Sañudo Institut de Nanociència i Tecnologia, Universitat de Barcelona IN2UB C/Martí i Franquès, 1-11, 08028 Barcelona, Spain Supporting information for this article is given via a link at the end of the document. Abstract: We report the microwave assisted synthesis of a bidimensional (2D) MOF of formula [Dy(MeCOO)(PhCOO)2]n (1) and its magnetically diluted analogue [La0.9Dy0.1(MeCOO)(PhCOO)2] (1d). 1 is a 2D material with single-ion-magnet (SIM) behaviour and 1d is a multifunctional, magnetic and luminescent 2D material. 1 can be exfoliated into stable nanosheets by sonication. Introduction The study of matter at the nanoscale has opened huge possibilities in technological advances towards faster, smaller and more energy-efficient technological devices. The development of 2D materials poses new challenges but also offers exciting possibilities for the study of physical phenomena and properties at the 2D limit. Current interest in 2D materials is concerned mainly with the possible application in ultrathin devices, catalysis, sensing [1] and magnetism. [2] Most well studied 2D materials are inorganic solids, or the very well-known graphene. [3] Advances in inorganic 2D materials have allowed the study of superconductivity at the 2D limit [4] or the layer-dependent ferromagnetism in Van der Waals crystals. [5] Inorganic 2D materials are used to exploit proximity effects on graphene, being magnetic 2D metal organic frameworks (MOFs) an alternative to the known 2D inorganic materials. [6] The chemical control provided by coordination chemistry can be exploited in this area, making possible defect-free 2D nanosheets, to tune aggregation of the nanosheets, as shown by Choi and co- workers, by modifying the ligand in ways that do not affect the binding sites [7] , to form 2D materials for planar qubits [8] , or to provide multifunctional properties to the material by ligand functionalization, as is currently done for coordination complexes that combine multiple properties like magnetism and luminescence [9–15] or photochromism. [16,17] There are already several examples of 2D MOFs, usually relying in polytopic planar ligands or molecules that afford a coordination network in two dimensions with suitable linkers. [18–20] In many cases, these 2D MOFs are formed of charged layers with the counter ions in the lamellar space [21] , which makes them brittle and difficult to exfoliate. For exfoliation, neutral 2D MOFs, organized in three dimensions by weak Van der Waals (VdW) forces would be preferred. The non-covalent bonding between layers would allow the exfoliation without disturbing the bonding within the layer. Exfoliation of the bulk 2D MOF material into nanosheets is an important step for the use of these nanoobjects in devices or materials, and the most relevant techniques are reviewed in several papers. [22–24] For 2D MOFs formed of neutral VdW stacked nanosheets exfoliation by sonication in a liquid matrix should result in nanosheets stable towards aggregation, as observed for some 2D materials. [1,25] This last point is very relevant for further manipulation of the nanosheets, for surface deposition, or for the formation of multilayer heterostructures. Among other groups, in our laboratory we have pioneered the use of microwave assisted synthesis in coordination chemistry. [26– 32] Many groups have also used microwave assisted synthesis for the preparation of MOFs [33] due to the advantages of this technique: the very short reaction times and the isolation of a single, pure product. Herein, we present a simple method for the microwave assisted synthesis of a 2D MOF formed by neutral nanosheets stacked into microcrystals by Van der Waals interactions and its structural, thermo-magnetic and optical characterization. Experimental All chemicals and solvents were purchased from comercial sources and used as received. Synthesis of 1. 0.0883 g of hydrated Dy(MeCOO)3·xH2O (0.26 mmol) and 0.063 g of PhCOOH (0.52 mmol) were placed in a microwave reactor tube with 4 mL of a MeOH:MeCN mixture in 1:1 proportion. A pulse of 150 W is applied and the reaction kept for 10 minutes at a maximum temperature of 125ºC. The reaction is cooled to room temperature and a colorless precipitate is filtered off. The solution is left for 9 days at 40ºC; after this time