Novel functionalization methods of 1D and 2D materials and their applications

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 31-01-202

A MoS2 platform and thionine-carbon nanodots for sensitive and selective detection of pathogens

This work focuses on the combination of molybdenum disulfide (MoS2) and à la carte functionalized carbon nanodots (CNDs) for the development of DNA biosensors for selective and sensitive detection of pathogens. MoS2 flakes prepared through liquid-phase exfoliation, serves as platform for thiolated DNA probe immobilization, while thionine functionalized carbon nanodots (Thi-CNDs) are used as electrochemical indicator of the hybridization event. Spectroscopic and electrochemical studies confirmed the interaction of Thi-CNDs with DNA. As an illustration of the pathogen biosensor functioning, DNA sequences from InIA gen of Listeria monocytogenes bacteria and open reading frame sequence (ORF1ab) of SARS-CoV-2 virus were detected and quantified with a detection limit of 67.0 fM and 1.01 pM, respectively. Given the paradigmatic selectivity of the DNA hybridization, this approach allows pathogen detection in the presence of other pathogens, demonstrated by the detection of Listeria monocytogenes in presence of Escherichia coli. We note that this design is in principle amenable to any pathogen for which the DNA has been sequenced, including other viruses and bacteria. As example of the application of the method in real samples it has been used to directly detect Listeria monocytogenes in cultures without any DNA Polymerase Chain Reaction (PCR) amplification processAuthors thank the financial support from the Comunidad de Madrid (NANOAVANSENS, S2013/MIT-3029, MAD2D-CM Program, S2013/ MIT-3007 and 2017-T1/BIO-5435), Ministerio de Economía, Industria y Competitividad (CTQ 2015-71955-REDT (ELECTROBIONET), CTQ2014-53334-C2-1-R. and MAT 2015-71879-P). EMP acknowledges the European Research Council (ERC-PoC-842606), MINECO (CTQ 2017- 86060-P), Comunidad de Madrid (MAD2D-CM S2013/MIT-3007). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, Grant SEV2016–0686). RdC acknowledges support from UAM, Banco Santander, Fundacion ´ IMDEA (convocatoria CRUE–CSIC–SANTANDER, fondo supera 2020, project with reference 10.01.03.02.41). Authors also acknowledge BAT unit of CIA

Fabrication of devices featuring covalently linked MoS2–graphene heterostructures

The most widespread method for the synthesis of 2D–2D heterostructures is the direct growth of one material on top of the other. Alternatively, flakes of different materials can be manually stacked on top of each other. Both methods typically involve stacking 2D layers through van der Waals forces—such that these materials are often referred to as van der Waals heterostructures—and are stacked one crystal or one device at a time. Here we describe the covalent grafting of 2H-MoS2 flakes onto graphene monolayers embedded in field-effect transistors. A bifunctional molecule featuring a maleimide and a diazonium functional group was used, known to connect to sulfide- and carbon-based materials, respectively. MoS2 flakes were exfoliated, functionalized by reaction with the maleimide moieties and then anchored to graphene by the diazonium groups. This approach enabled the simultaneous functionalization of several devices. The electronic properties of the resulting heterostructure are shown to be dominated by the MoS2–graphene interface.The authors acknowledge European Research Council (ERC-PoC- 842606 (E.M.P.); ERC-AdG-742684 (J. S.) and the MSCA program MSCA-IF-2019-892667 (N.M.S.), MINECO (CTQ2017-86060-P (E.M.P.) and CTQ2016-79419-R), Ministerio de Ciencia e Innovación (RTI2018-096075-A-C22 (E.B.), RYC2019-028429-I (E.B.)) the Comunidad de Madrid (MAD2D-CM S2013/ MIT-3007 (E.M.P.), Y2018/NMT-4783 (A.D.)) and the Programa de Atracción del Talento Investigador 2017-T1/IND-5562 (E.B.)). CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110) are gratefully acknowledged. IMDEA Nanociencia acknowledges support from the Severo Ochoa Programme for Centres of Excellence in R&D (MINECO, grant no. SEV-2016-0686).Peer reviewe

Mild Covalent Functionalization of Transition Metal Dichalcogenides with Maleimides: A “Click” Reaction for TMDCs

The physical properties of ultrathin transition metal dichalcogenides (2D-TMDCs) make them promising candidates as active nanomaterials for catalysis, optoelectronics, and biomedical applications. Chemical modification of TMDCs is expected to be key in modifying/adding new functions that will help make such promise a reality. We present a mild method for the modification of the basal planes of 2H-MoS2 and WS2. We exploit the soft nucleophilicity of sulfur to react it with maleimide derivatives, achieving covalent functionalization of 2H-TMDCs under very mild conditions. Extensive characterization proves that the reaction occurs through Michael addition. Our results adapt one of the most popular “click” reactions in polymer chemistry and biochemistry to obtain a powerful tool for the chemical manipulation of TMDCs

Controlled covalent functionalization of 2 H‐MoS2 with molecular or polymeric adlayers

Special Issue: Chemical Functionalization of 2D Materials. This article also appears in: Chemical Functionalization of 2D Materials Society Volumes: Czech Republic.Most air‐stable 2D materials are relatively inert, which makes their chemical modification difficult. In particular, in the case of MoS2, the semiconducting 2 H‐MoS2 is much less reactive than its metallic counterpart, 1T‐MoS2. As a consequence, there are hardly any reliable methods for the covalent modification of 2 H‐MoS2. An ideal method for the chemical functionalization of such materials should be both mild, not requiring the introduction of a large number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, a comprehensive study on the covalent functionalization of 2 H‐MoS2 with maleimides is presented. The use of a base (Et3N) leads to the in situ formation of a succinimide polymer layer, covalently connected to MoS2. In contrast, in the absence of base, functionalization stops at the molecular level. Moreover, the functionalization protocol is mild (occurs at room temperature), fast (nearly complete in 1 h), and very flexible (11 different solvents and 10 different maleimides tested). In practical terms, the procedures described here allow for the chemist to manipulate 2 H‐MoS2 in a very flexible way, decorating it with polymers or molecules, and with a wide range of functional groups for subsequent modification. Conceptually, the spurious formation of an organic polymer might be general to other methods of functionalization of 2D materials, where a large excess of molecular reagents is typically used.The European Research Council (ERC‐StG‐307609; ERC‐PoC‐ ERC‐AdG‐742684), MINECO (CTQ2017‐86060‐P and CTQ2016‐79419‐R) the Comunidad de Madrid (MAD2D‐CM S2013/ MIT‐3007) are gratefully acknowledged. IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant SEV‐ 2016‐0686). Part of the work was carried out with the support of CEITEC Nano Research Infrastructure (ID LM2015041, MEYS CR, 2016–2019), CEITEC Brno University of Technology.Peer reviewe

A Chemical Approach to 2D-2D Heterostructures Beyond Van Der Waals: High-Throughput On-Device Covalent Connection of MoS2 and Graphene

The most widespread method for the synthesis of 2D-2D heterostructures is the direct growth of one material on top of the other. Alternatively, one can manually stack flakes of different materials. Both methods are limited to one crystal/device at a time and involve interfacing the 2D materials through van der Waals forces, to the point that all these materials are known as van der Waals heterostructures. Synthetic chemistry is the paradigm of atomic-scale control, yet its toolbox remains unexplored for the construction of 2D-2D heterostructures. Here, we describe how to covalently connect 2H-MoS2 flakes to several single-layer graphene field-effect transistors simultaneously, and show that the final electronic properties of the MoS2-graphene heterostructure are dominated by the molecular interface. We use a bifunctional molecule with two chemically orthogonal anchor points, selective for sulphides and carbon-based materials. Our experiments highlight the potential of the chemical approach to build 2D-2D heterostructures beyond van der Waals. </p