A microfluidic chip has been used to prepare fibres of a porous polymer with high structural order, setting a precedent for the generation of a wide variety of materials using this reagent mixing approach that provides unique materials not accessible easily through bulk processes. The reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in acetic acid under continuous microfluidic flow conditions leads to the formation of a highly crystalline and porous covalent organic framework (hereafter denoted as MF-COF-1), consisting of fibrillar micro-structures, which have mechanical stability that allows for direct drawing of objects on a surface ; Financial support from Spanish Government (Projects MAT2013-46753-C2-1-P and CTQ2014-53486-R) and FEDER are acknowledged. A. A. and J. P. L. would like to thank the financial support from the Swiss National Science Foundation (SNSF) through the project no. 200021_160174
To date, crystallization studies conducted in space laboratories, which are prohibitively costly and unsuitable to most research laboratories, have shown the valuable effects of microgravity during crystal growth and morphogenesis. Herein, an easy and highly efficient method is shown to achieve space-like experimentation conditions on Earth employing custom-made microfluidic devices to fabricate 2D porous crystalline molecular frameworks. It is confirmed that experimentation under these simulated microgravity conditions has unprecedented effects on the orientation, compactness and crack-free generation of 2D porous crystalline molecular frameworks as well as in their integration and crystal morphogenesis. It is believed that this work will provide a new "playground" to chemists, physicists, and materials scientists that desire to process unprecedented 2D functional materials and devices. ; N.C.-P., D.R.-S.-M., C.F. contributed equally to this work. This work was supported by the European Research Council Starting Grant microCrysFact (ERC-2015-STG No. 677020), the Horizon 2020 FETOPEN project SPRINT (No. 801464), the Swiss National Science Foundation (project no. 200021_181988), grant MAT 2015-70615-R from the Spanish Government funds and by the European Regional Development Fund (ERDF). The ICN2 is funded by the CERCA programme/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). N.C.-P. acknowledges support from "laCaixa" Foundation (fellowship ID 100010434). The fellowship code is LCF/BQ/ES17/11600012. N.C.-P. also acknowledges the financial support of COST action MP1407. R.P. acknowledges support from the Marie Curie Cofund, Beatriu de Pinós Fellowship AGAUR 2017 BP 00064. The GIWAXS experiments were conducted on the NCD-SWEET beamline of the ALBA synchrotron, Spain and on the SAXS/WAXS beamline of the Australian Synchrotron, ANSTO, Australia. GIWAXS experiments of Ni3(HITP)2 and COF-TAPB-BTCA were performed at the NCD-SWEET beamline at ALBA Synchrotron with the collaboration of ALBA staff. The authors acknowledge the support of the ANSTO, in providing the facilities for the GIWAXS experiments used for the characterization of COF-TAPB-BTCA in this work. ; Peer reviewed
2D materials have opened a new field in materials science with outstanding scientific and technological impact. A largely explored route for the preparation of 2D materials is the exfoliation of layered crystals with weak forces between their layers. However, its application to covalent crystals remains elusive. Herein, a further step is taken by introducing the exfoliation of germanium, a narrow-bandgap semiconductor presenting a 3D diamond-like structure with strong covalent bonds. Pure α-germanium is exfoliated following a simple one-step procedure assisted by wet ball-milling, allowing gram-scale fabrication of high-quality layers with large lateral dimensions and nanometer thicknesses. The generated flakes are thoroughly characterized by different techniques, giving evidence that the new 2D material exhibits bandgaps that depend on both the crystallographic direction and the number of layers. Besides potential technological applications, this work is also of interest for the search of 2D materials with new properties ; The authors acknowledge the financial support from the Spanish Ministry of Science and Innovation, through the "María de Maeztu" Programme for Units of Excellence in R&D (CEX2018-000805-M and CEX2019-000919-M) and MINECO-FEDER projects PID2019-111742GB-C31, PID2019-111742GB-C32, PCI2018-093081, PID2019-109539GB-C43, MAT2015-666888-C3-3R, MICINN projects FIS2017-82415-R, RTI2018- 097895-B-C43 and PID2019-111742GA-I00, the Comunidad Autónoma de Madrid through S2018/NMT-4321 (NanomagCOST-CM), the Generalitat Valenciana (CIDEGENT/2018/001 grant and iDiFEDER/2018/061 co-financed by FEDER) and the Deutsche Forschungsgemeinschaft (DFG, FLAG-ERA AB694/2-1), the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. The authors thank the European Research Council (ERC Starting Grant 2D-PnictoChem 804110 to G.A.). W.S.P. acknowledges the computer resources and assistance provided by the Centro de Computación Científica of the Universidad Autónoma de Madrid and the computer resources at MareNostrum and technical support provided by Barcelona Supercomputing Center (FI-2019-2-0007)
Covalent organic frameworks (COFs) are commonly synthesized under harsh conditions yielding unprocessable powders. Control in their crystallization process and growth has been limited to studies conducted in hazardous organic solvents. Herein, we report a one-pot synthetic method that yields stable aqueous colloidal solutions of sub-20 nm crystalline imine-based COF particles at room temperature and ambient pressure. Additionally, through the combination of experimental and computational studies, we investigated the mechanisms and forces underlying the formation of such imine-based COF colloids in water. Further, we show that our method can be used to process the colloidal solution into 2D and 3D COF shapes as well as to generate a COF ink that can be directly printed onto surfaces. These findings should open new vistas in COF chemistry, enabling new application areas. ; This work was supported by the European Union (ERC-2015-STG microCrysFact 677020), the Swiss National Science Foundation (Project No. 200021_181988), ETH Zürich and Ministry of Science, Innovation and Universities MICINN (MAT2016-77608-C3-1P). R.P. acknowledges the Spanish MINECO (Grant No. CTQ2017—88948-P). A.E.P.P. acknowledges a TALENTO grant (2017-T1/IND5148) from Comunidad de Madrid. I.S. acknowledges the Ministry of Human Capacities of Hungary (20391-/2018/FEKUSTRAT). G.M.P. acknowledges the funding received by the Swiss National Science Foundation (SNSF grant number 200021_175735) and by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 818776 - DYNAPOL). D.M. acknowledges financial support from the European Union (ERC-Co 615954). ICN2 is supported by the Severo Ochoa program from the Spanish MINECO (Grant No. SEV-2017-0706). S.P. acknowledges funding from a Consolidator Grant from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 771565). We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Synchrotron X-ray diffraction experiments with COF-TAPB-BTCA were carried out at the beamline P02.1 PETRA III under the proposal I-20170717 EC. We acknowledge Jaume Caelles for SAXS/WAXS measurements performed at IQAC–CSIC. ; Peer reviewed
