Molecular Devices and Materials (Mayor)Head of Research Unit Prof. Dr.Marcel MayorOverviewMembersPublicationsProjects & CollaborationsProjects & Collaborations OverviewMembersPublicationsProjects & Collaborations Projects & Collaborations 28 foundShow per page10 10 20 50 ELUQUINT: Exploring the Limits of Universal Quantum Interferometry Research Project | 2 Project MembersNo Description available Synthetische Nanoskalige Objekte: Bausteine für funktionale Materialien und Funktionseinheiten Research Project | 10 Project MembersThe proposal follows the SNF advice of a single project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. In spite of the different research targets, they have enough overlap enabling the fruitful exchange of knowledge and mutual developments required to build up a joint group identity. All five projects focus on current challenges in nanotechnology, molecular devices, and supramolecular materials, which are addressed by novel strategies and innovative molecular designs of functional structures. The five subprojects are briefly described in the following: (I) «Geländer»-molecules and helical architectures: «Geländer»-molecules consist of two periodically interlinked oligomers which compensate their length mismatch by wrapping the longer one helically around the shorter one, resembling the shape of the banister (Geländer in German) of a spiral staircase. The here promoted new designs profit from right-angled connections resulting in a simplified symmetry of the building blocks which should make longer oligomers synthetically accessible. A second strategy based on o-tetraphenylene building blocks is geared towards helical «plait»-type oligomers. (II) mechanosensitive model compounds for molecular junctions are based on cyclophane-type architectures enabling to tune the extent of the coupling between their subunits mechanically. With small [2.2]paracyclonaphthane derivatives the effect of torque motion shall be explored, while a polycyclic porphyrin hexamer will be assembled with two stacked states with large difference in their expansion. Based on a «upended» porphyrin type structure, even the coupling of the single electrons of two parallel radical planes might be investigated. (III) B-field sensitive macrocyclic model compounds are loop-shaped macrocycles consisting of a conjugated periphery decorated with terminal anchor groups enabling their integration in single molecule junction experiments. The intention is to detect the contribution of the Lorentz force to the molecules transport current. With a compact and twisted OPE type macrocycle, the axial chirality of the immobilized structure might become specifiable in the transport experiment. (IV) synthesis of an armchair carbon nanotube (CNT) is an interesting synthetic strategy for the controlled wet chemical assembly of an armchair CNT. A belt fragment of a CNT shall be obtained from a macrocycle by a reaction sequence, which can subsequently be repeatedly applied to control the length of the CNT. (V) approaches towards molecular textiles are based on the development of a cross-type junction acting a covalent template arranging the precursors at the water/air interface. Upon interlinking within the LB-film and cleavage of the template, textile-type interwoven molecular films should be obtained. The potential of the cross-type junction for superstructures will be investigated as well. Molecular Carbon Nanoscrolls Research Project | 2 Project MembersBending a planar sheet of graphene into a seamless three-dimensional cylindrical carbon nanotube requires the curved nanostructure to pass through a stage where the two-dimensional graphene sheet can, instead of making the carbon-carbon bonds between its edges, roll further into a nanoscroll. The edges of such a carbon nanoscroll are not fused and the structure, which is held only due to collective action of van der Waals forces, displays different properties than a nanotube as a result of its unique spiral topology. Small circular fragments of single-wall carbon nanotubes that retain information regarding chirality and diameter of carbon nanotubes have been designed and synthesized in the past decade as precursors for their uniform bottom-up synthesis. To this date, however, no molecular precursors for carbon nanoscrolls exist.This research project aims at the design and synthesis of such molecular fragments of carbon nanoscrolls and develops solutions to stabilize the structure of a molecular nanoscroll. Synthesis of a series of molecular nanoscrolls with a complete first turn will be accomplished and their optoelectronic properties of the prepared molecules will be studied in detail. Successful completion of this research project will represent a major achievement that will open a new line of research in the field of carbon allotropes and deliver topologically new carbon-rich molecules, molecular analogues of carbon nanoscrolls that are obtained by rolling-up graphene sheets. Toblerone-Shaped Polymers: Bridging the Gap between Conjugated Polymers and Carbon Nanotubes Research Project | 1 Project MembersElectronic devices fabricated from conjugated polymers are expected to be competitive with those based on inorganic materials because of their low production costs due to high-throughput processing methods. These linear polymers possess tunable optoelectronic and mechanical properties and can be highly soluble. Although, conjugated polymers can be found in prototypes of electronic devices, only a handful of applications found their way to the commercial use. One of the reasons is their relatively low charge carrier mobility. An alternative to conjugated polymers are cylindrical single-walled carbon nanotubes (SWCNTs). Despite their excellent charge transport properties, SWCNTs, however, suffer from low solubility, sample purity, limited tunability of their properties, and, overall, high production costs. Other approaches that would successfully combine the properties of linear polymers and the cylindrical SWCNTs preserving the typical advantages of former and displaying high charge carrier mobility are largely missing.In this research proposal, the synthesis and experimental investigation of nanoprismatic, i.e., toblerone-shaped, polymers and nanoprisms are described for the first time. These ladder structures built by combination of triangular electron acceptor and linear electron donor monomers possess aromatic p-electron surfaces exposed to the exterior of the polymer or nanoprism such that it allows for p-electron communication with adjacent polymer segments or nanoprisms. Such spatial arrangement will result in an improved charge carrier mobility, similar to SWCNT. The choice of the individual monomers allows for tailoring their optoelectronic and material properties. Therefore, successful completion of the proposed research will introduce a new unconventional approach to bridge the conceptual gap between the scientific field of conjugated polymers and SWCNTs unprecedented in the scientific literature. SuperMaMa / Superconducting Mass Spectrometry and Molecule Analysis Research Project | 2 Project MembersSuperMaMa is an EU-FET OPEN Research & Innovation project working on new technologies for mass spectrometry and analysis of lowly charged and neutral high-mass proteins. It comprises the development of neutral and lowly-charged biomolecular beam generation and detection. To this end arrays of superconducting detectors for molecular ions and neutrals will be designed and installed in a converted mass spectrometer, and methods for charge reduction of biomolecular ions in high vacuum devised. The team includes three academic research groups (M. Arndt, U. Vienna; E. Charbon, EPFL; M. Mayor, U. Basel) and two industrial partner (Single Quantum, Delft; MS Vision, Almere). The contribution from UNIBAS is primarily concerned with the development of suitable tags for biomolecules to enable charge manipulation in the gas phase by photochemical methods. Molecular Nanoprisms as Efficient Electron-Transporting Materials Research Project | 1 Project MembersThe global warming threats leave us no choice but to rely on the production of clean energy, where the solar energy will become our most important source to produce electricity due to its abundance from the sun. This, however, requires implementation of inexpensive and environmentally friendly materials into solar cells. In this regard, organic materials offer the solution because they can be produced cheaply on a large scale. The problem with organic photovoltaic devices is, however, their low power conversion efficiency, which is a consequence of the short exciton-diffusion lengths and imbalanced charge transport in organic materials with lower mobility of electrons than that of holes. Simultaneously, the best performing electron-transporting materials in organic solar cells, namely, fullerenes, absorb visible light poorly, are hard to modify, and expensive to produce. In this research proposal, the synthesis and experimental investigation of molecular nanoprisms with built-in visible-light absorbing molecular electron acceptors as their triangular base is described. The symmetric spatial arrangement of the molecular electron acceptor units, their mutual distance and orientation in these nanoprisms will allow for extensive radial electron delocalization and, consequently, for efficient charge separation in an active layer of a solar cell. The possibility of the controlled growth of the nanoprisms by well-defined synthetic methods permits to incorporate various combinations of donor-acceptor motifs into the nanoprisms to tune their photophysical and redox properties. The unique three-dimensional shape and the aspect ratio of these nanoprisms will allow them to efficiently transport electrons in the materials incorporating them. Such favorable properties of these molecules will, one day, allow to make efficient organic solar cells competitive with other photovoltaic technologies. Synthetic Nanoscale Objects: Building Blocks for Functional Materials and Devices Research Project | 10 Project MembersThe proposal follows the SNF rules of one project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. Even though these five PhD projects are very different in their aims, they have in common that they address current challenges in nano-technology, supramolecular chemistry, and material science, which are addressed by molecular approaches with tailor-made functional structures. The five subprojects are: (I) "Geländer-type" helical structures and (II) macrocyclic model compounds for molecular junctions, (III) giant conjugated graphene belts geared towards molecule based magnetization experiments. Pre-organized reactants for the assembly of (IV) 2D polymers and molecular fabrics and of (V) optically active nanoscale hybrid architectures.(I) "Geländer-type" helical structures consist of an oligophenylene-axis around which a longer oligomer is helically wrapped, resembling the shape of the banister (Geländer in German) of a helical staircase. The next generation of this appealing molecular design concept is geared towards derivatives with conjugated helical "Geländer", which not only is expected to improve their optical features, but also should enable the assembly of model compounds acting as coil-like molecular wires. (II) macrocyclic model compounds for molecular junctions is focused on model compounds for transport experiments in magnetic fields. A molecular loop of considerable dimension shall increase the influence of the magnetic field on the charge carriers and a variety of rod-like metal complexes shall provide insight into the interplay of the magnetic field with the electronic configuration of the central metal ion. (III) giant conjugated graphene belts are expected to have interesting magnetic properties. These molecular analogues of lithographically fabricated nano-scaled metallic structures shall be assembled by combining macrocyclization approaches from acetylene scaffolding strategies with current chemistry geared towards graphen ribbons. The approach might even make Möbius-shaped graphene belts accessible.(IV) 2D polymers and molecular fabrics shall be obtained by profiting from the perfectly pre-organized arrangement of the molecular building blocks in MOF layers. In a second, alternative approach the organization and intermolecular coupling chemistry at the air/water interface of tailor-made heteroleptic Fe(tpy)2 complexes shall make molecular fabrics available.(V) optically active nanoscale hybrid architectures based on our preliminary findings providing mono-functionalized gold nanoparticles in good yields but of too small dimensions to interact with visible light, a new strategy enabling larger particles by the chemically controlled merging shall be developed. QuIET / Quantum Interference Enhanced Thermoelectricity Research Project | 1 Project MembersOur vision is to demonstrate that room-temperature quantum interference effects, measured recently in single molecules, can be exploited in massively-parallel arrays of molecules and used to design ultra-thin-film thermoelectric devices with unprecedented ability to convert waste heat to electricity using the Seebeck effect and to cool at the nanoscale via the Peltier effect. Although the dream of high-performance thermoelectric devices has been discussed for many years, evidence of the room-temperature quantum interference effects needed to realise this dream was achieved experimentally only recently. Building on these indirect demonstrations of quantum interference in single molecules using non-scalable set ups, we anticipate that the next breakthrough will be the implementation of QI functionality these intechnologically-relevant platforms. We shall design molecules with built-in quantum interference functionality, which can be used to engineer the properties of ultra-thin molecular films. Molecules will be designed with robust anchors to metallic and carbon-based nano-gap electrodes, which enhance electron transport and eliminate unwanted phonons.This contacting strategy is scalable from a single junction, with the potential to be replicated billions of times on a single substrate. The ability to exploit quantum interference at room temperature will enable new thermoelectric materials and devices with the ability to scavenge energy with unprecedented efficiency. QuIET is a highly interdisciplinary project that brings together internationally leading scientists from four different countries with proven expertise on synthesis, transport measurements and theoretical modelling. Switching optical antennas via supramolecular translation Research Project | 2 Project MembersOptical antennas are able to efficiently link propagating light fields and nanolocalized excitations and are therefore ideally suited to bridge the gap between the macroscopic world and nanoscopic entities such as individual molecules placed inside the antenna feed gap. Recently, the toolbox of optical antennas has been enriched by the possibility to apply voltages to the antenna via electrical connectors which allows to generate enormous DC electric fields across the antenna gap. Here we propose to realize two-color switchable optical antennas representing reconfigurable functional nanodevices by making use of electric-field induced supramolecular translations, i.e. the nanomechanical motion of ring-like moieties on rod-like molecules (Rotaxanes) placed in the antenna feedgap. Electrically-induced supramolecular translation of the ring moiety will cause selective quenching of one of up to two chromophores whereby its coupling to the antenna resonance will be suppressed. In the final configuration light emission shall even be electrically excited via inelastic electron tunneling and switched via the polarity of the applied voltage. Encapsulation and Covalent Assembly of Nanoparticles Research Project | 1 Project MembersMetal nanoparticles (NPs) are three-dimensional structurally well-defined nanoclusters of around 10-100 atoms, which are best known for their unique size-dependent properties. It has been shown that the properties of a covalent ensemble of a number of NPs are greatly enhanced compared to those of the same number of single components. This, so-called collective, behavior can be useful, once controlled, for constructing NP nanocircuits of electronic devices. To build and study long chains of covalently linked NPs, their encapsulation by two shape- and size-complementary ligands is proposed. A series of bowl-shaped ligands, capable of (1) recognition and (2) covalent encapsulation of spherical NPs, is designed and the synthesis of these ligands is outlined. The ultimate goal is to connect the NP(ligand) 2 building blocks to generate long linear [(ligand)NP(ligand)] n chains and investigate their collective-behavior effect. In addition to standard analytical methods to characterize NPs, high-resolution transmission electron microscopy will be used to provide insight into this unusual phenomenon displayed by covalent NP ensembles. This project is geared towards (1) control over the organization of NPs through their covalent interconnection by chemical means to (2) enhance their electronic properties. The knowledge gained through this investigation can lead to a set of design principles, which can be used in future for making NP-based functional materials. This work can also result in an unprecedented methodology to separate NPs into fractions of extremely low size-distribution. 123 123 OverviewMembersPublicationsProjects & Collaborations
Projects & Collaborations 28 foundShow per page10 10 20 50 ELUQUINT: Exploring the Limits of Universal Quantum Interferometry Research Project | 2 Project MembersNo Description available Synthetische Nanoskalige Objekte: Bausteine für funktionale Materialien und Funktionseinheiten Research Project | 10 Project MembersThe proposal follows the SNF advice of a single project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. In spite of the different research targets, they have enough overlap enabling the fruitful exchange of knowledge and mutual developments required to build up a joint group identity. All five projects focus on current challenges in nanotechnology, molecular devices, and supramolecular materials, which are addressed by novel strategies and innovative molecular designs of functional structures. The five subprojects are briefly described in the following: (I) «Geländer»-molecules and helical architectures: «Geländer»-molecules consist of two periodically interlinked oligomers which compensate their length mismatch by wrapping the longer one helically around the shorter one, resembling the shape of the banister (Geländer in German) of a spiral staircase. The here promoted new designs profit from right-angled connections resulting in a simplified symmetry of the building blocks which should make longer oligomers synthetically accessible. A second strategy based on o-tetraphenylene building blocks is geared towards helical «plait»-type oligomers. (II) mechanosensitive model compounds for molecular junctions are based on cyclophane-type architectures enabling to tune the extent of the coupling between their subunits mechanically. With small [2.2]paracyclonaphthane derivatives the effect of torque motion shall be explored, while a polycyclic porphyrin hexamer will be assembled with two stacked states with large difference in their expansion. Based on a «upended» porphyrin type structure, even the coupling of the single electrons of two parallel radical planes might be investigated. (III) B-field sensitive macrocyclic model compounds are loop-shaped macrocycles consisting of a conjugated periphery decorated with terminal anchor groups enabling their integration in single molecule junction experiments. The intention is to detect the contribution of the Lorentz force to the molecules transport current. With a compact and twisted OPE type macrocycle, the axial chirality of the immobilized structure might become specifiable in the transport experiment. (IV) synthesis of an armchair carbon nanotube (CNT) is an interesting synthetic strategy for the controlled wet chemical assembly of an armchair CNT. A belt fragment of a CNT shall be obtained from a macrocycle by a reaction sequence, which can subsequently be repeatedly applied to control the length of the CNT. (V) approaches towards molecular textiles are based on the development of a cross-type junction acting a covalent template arranging the precursors at the water/air interface. Upon interlinking within the LB-film and cleavage of the template, textile-type interwoven molecular films should be obtained. The potential of the cross-type junction for superstructures will be investigated as well. Molecular Carbon Nanoscrolls Research Project | 2 Project MembersBending a planar sheet of graphene into a seamless three-dimensional cylindrical carbon nanotube requires the curved nanostructure to pass through a stage where the two-dimensional graphene sheet can, instead of making the carbon-carbon bonds between its edges, roll further into a nanoscroll. The edges of such a carbon nanoscroll are not fused and the structure, which is held only due to collective action of van der Waals forces, displays different properties than a nanotube as a result of its unique spiral topology. Small circular fragments of single-wall carbon nanotubes that retain information regarding chirality and diameter of carbon nanotubes have been designed and synthesized in the past decade as precursors for their uniform bottom-up synthesis. To this date, however, no molecular precursors for carbon nanoscrolls exist.This research project aims at the design and synthesis of such molecular fragments of carbon nanoscrolls and develops solutions to stabilize the structure of a molecular nanoscroll. Synthesis of a series of molecular nanoscrolls with a complete first turn will be accomplished and their optoelectronic properties of the prepared molecules will be studied in detail. Successful completion of this research project will represent a major achievement that will open a new line of research in the field of carbon allotropes and deliver topologically new carbon-rich molecules, molecular analogues of carbon nanoscrolls that are obtained by rolling-up graphene sheets. Toblerone-Shaped Polymers: Bridging the Gap between Conjugated Polymers and Carbon Nanotubes Research Project | 1 Project MembersElectronic devices fabricated from conjugated polymers are expected to be competitive with those based on inorganic materials because of their low production costs due to high-throughput processing methods. These linear polymers possess tunable optoelectronic and mechanical properties and can be highly soluble. Although, conjugated polymers can be found in prototypes of electronic devices, only a handful of applications found their way to the commercial use. One of the reasons is their relatively low charge carrier mobility. An alternative to conjugated polymers are cylindrical single-walled carbon nanotubes (SWCNTs). Despite their excellent charge transport properties, SWCNTs, however, suffer from low solubility, sample purity, limited tunability of their properties, and, overall, high production costs. Other approaches that would successfully combine the properties of linear polymers and the cylindrical SWCNTs preserving the typical advantages of former and displaying high charge carrier mobility are largely missing.In this research proposal, the synthesis and experimental investigation of nanoprismatic, i.e., toblerone-shaped, polymers and nanoprisms are described for the first time. These ladder structures built by combination of triangular electron acceptor and linear electron donor monomers possess aromatic p-electron surfaces exposed to the exterior of the polymer or nanoprism such that it allows for p-electron communication with adjacent polymer segments or nanoprisms. Such spatial arrangement will result in an improved charge carrier mobility, similar to SWCNT. The choice of the individual monomers allows for tailoring their optoelectronic and material properties. Therefore, successful completion of the proposed research will introduce a new unconventional approach to bridge the conceptual gap between the scientific field of conjugated polymers and SWCNTs unprecedented in the scientific literature. SuperMaMa / Superconducting Mass Spectrometry and Molecule Analysis Research Project | 2 Project MembersSuperMaMa is an EU-FET OPEN Research & Innovation project working on new technologies for mass spectrometry and analysis of lowly charged and neutral high-mass proteins. It comprises the development of neutral and lowly-charged biomolecular beam generation and detection. To this end arrays of superconducting detectors for molecular ions and neutrals will be designed and installed in a converted mass spectrometer, and methods for charge reduction of biomolecular ions in high vacuum devised. The team includes three academic research groups (M. Arndt, U. Vienna; E. Charbon, EPFL; M. Mayor, U. Basel) and two industrial partner (Single Quantum, Delft; MS Vision, Almere). The contribution from UNIBAS is primarily concerned with the development of suitable tags for biomolecules to enable charge manipulation in the gas phase by photochemical methods. Molecular Nanoprisms as Efficient Electron-Transporting Materials Research Project | 1 Project MembersThe global warming threats leave us no choice but to rely on the production of clean energy, where the solar energy will become our most important source to produce electricity due to its abundance from the sun. This, however, requires implementation of inexpensive and environmentally friendly materials into solar cells. In this regard, organic materials offer the solution because they can be produced cheaply on a large scale. The problem with organic photovoltaic devices is, however, their low power conversion efficiency, which is a consequence of the short exciton-diffusion lengths and imbalanced charge transport in organic materials with lower mobility of electrons than that of holes. Simultaneously, the best performing electron-transporting materials in organic solar cells, namely, fullerenes, absorb visible light poorly, are hard to modify, and expensive to produce. In this research proposal, the synthesis and experimental investigation of molecular nanoprisms with built-in visible-light absorbing molecular electron acceptors as their triangular base is described. The symmetric spatial arrangement of the molecular electron acceptor units, their mutual distance and orientation in these nanoprisms will allow for extensive radial electron delocalization and, consequently, for efficient charge separation in an active layer of a solar cell. The possibility of the controlled growth of the nanoprisms by well-defined synthetic methods permits to incorporate various combinations of donor-acceptor motifs into the nanoprisms to tune their photophysical and redox properties. The unique three-dimensional shape and the aspect ratio of these nanoprisms will allow them to efficiently transport electrons in the materials incorporating them. Such favorable properties of these molecules will, one day, allow to make efficient organic solar cells competitive with other photovoltaic technologies. Synthetic Nanoscale Objects: Building Blocks for Functional Materials and Devices Research Project | 10 Project MembersThe proposal follows the SNF rules of one project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. Even though these five PhD projects are very different in their aims, they have in common that they address current challenges in nano-technology, supramolecular chemistry, and material science, which are addressed by molecular approaches with tailor-made functional structures. The five subprojects are: (I) "Geländer-type" helical structures and (II) macrocyclic model compounds for molecular junctions, (III) giant conjugated graphene belts geared towards molecule based magnetization experiments. Pre-organized reactants for the assembly of (IV) 2D polymers and molecular fabrics and of (V) optically active nanoscale hybrid architectures.(I) "Geländer-type" helical structures consist of an oligophenylene-axis around which a longer oligomer is helically wrapped, resembling the shape of the banister (Geländer in German) of a helical staircase. The next generation of this appealing molecular design concept is geared towards derivatives with conjugated helical "Geländer", which not only is expected to improve their optical features, but also should enable the assembly of model compounds acting as coil-like molecular wires. (II) macrocyclic model compounds for molecular junctions is focused on model compounds for transport experiments in magnetic fields. A molecular loop of considerable dimension shall increase the influence of the magnetic field on the charge carriers and a variety of rod-like metal complexes shall provide insight into the interplay of the magnetic field with the electronic configuration of the central metal ion. (III) giant conjugated graphene belts are expected to have interesting magnetic properties. These molecular analogues of lithographically fabricated nano-scaled metallic structures shall be assembled by combining macrocyclization approaches from acetylene scaffolding strategies with current chemistry geared towards graphen ribbons. The approach might even make Möbius-shaped graphene belts accessible.(IV) 2D polymers and molecular fabrics shall be obtained by profiting from the perfectly pre-organized arrangement of the molecular building blocks in MOF layers. In a second, alternative approach the organization and intermolecular coupling chemistry at the air/water interface of tailor-made heteroleptic Fe(tpy)2 complexes shall make molecular fabrics available.(V) optically active nanoscale hybrid architectures based on our preliminary findings providing mono-functionalized gold nanoparticles in good yields but of too small dimensions to interact with visible light, a new strategy enabling larger particles by the chemically controlled merging shall be developed. QuIET / Quantum Interference Enhanced Thermoelectricity Research Project | 1 Project MembersOur vision is to demonstrate that room-temperature quantum interference effects, measured recently in single molecules, can be exploited in massively-parallel arrays of molecules and used to design ultra-thin-film thermoelectric devices with unprecedented ability to convert waste heat to electricity using the Seebeck effect and to cool at the nanoscale via the Peltier effect. Although the dream of high-performance thermoelectric devices has been discussed for many years, evidence of the room-temperature quantum interference effects needed to realise this dream was achieved experimentally only recently. Building on these indirect demonstrations of quantum interference in single molecules using non-scalable set ups, we anticipate that the next breakthrough will be the implementation of QI functionality these intechnologically-relevant platforms. We shall design molecules with built-in quantum interference functionality, which can be used to engineer the properties of ultra-thin molecular films. Molecules will be designed with robust anchors to metallic and carbon-based nano-gap electrodes, which enhance electron transport and eliminate unwanted phonons.This contacting strategy is scalable from a single junction, with the potential to be replicated billions of times on a single substrate. The ability to exploit quantum interference at room temperature will enable new thermoelectric materials and devices with the ability to scavenge energy with unprecedented efficiency. QuIET is a highly interdisciplinary project that brings together internationally leading scientists from four different countries with proven expertise on synthesis, transport measurements and theoretical modelling. Switching optical antennas via supramolecular translation Research Project | 2 Project MembersOptical antennas are able to efficiently link propagating light fields and nanolocalized excitations and are therefore ideally suited to bridge the gap between the macroscopic world and nanoscopic entities such as individual molecules placed inside the antenna feed gap. Recently, the toolbox of optical antennas has been enriched by the possibility to apply voltages to the antenna via electrical connectors which allows to generate enormous DC electric fields across the antenna gap. Here we propose to realize two-color switchable optical antennas representing reconfigurable functional nanodevices by making use of electric-field induced supramolecular translations, i.e. the nanomechanical motion of ring-like moieties on rod-like molecules (Rotaxanes) placed in the antenna feedgap. Electrically-induced supramolecular translation of the ring moiety will cause selective quenching of one of up to two chromophores whereby its coupling to the antenna resonance will be suppressed. In the final configuration light emission shall even be electrically excited via inelastic electron tunneling and switched via the polarity of the applied voltage. Encapsulation and Covalent Assembly of Nanoparticles Research Project | 1 Project MembersMetal nanoparticles (NPs) are three-dimensional structurally well-defined nanoclusters of around 10-100 atoms, which are best known for their unique size-dependent properties. It has been shown that the properties of a covalent ensemble of a number of NPs are greatly enhanced compared to those of the same number of single components. This, so-called collective, behavior can be useful, once controlled, for constructing NP nanocircuits of electronic devices. To build and study long chains of covalently linked NPs, their encapsulation by two shape- and size-complementary ligands is proposed. A series of bowl-shaped ligands, capable of (1) recognition and (2) covalent encapsulation of spherical NPs, is designed and the synthesis of these ligands is outlined. The ultimate goal is to connect the NP(ligand) 2 building blocks to generate long linear [(ligand)NP(ligand)] n chains and investigate their collective-behavior effect. In addition to standard analytical methods to characterize NPs, high-resolution transmission electron microscopy will be used to provide insight into this unusual phenomenon displayed by covalent NP ensembles. This project is geared towards (1) control over the organization of NPs through their covalent interconnection by chemical means to (2) enhance their electronic properties. The knowledge gained through this investigation can lead to a set of design principles, which can be used in future for making NP-based functional materials. This work can also result in an unprecedented methodology to separate NPs into fractions of extremely low size-distribution. 123 123
ELUQUINT: Exploring the Limits of Universal Quantum Interferometry Research Project | 2 Project MembersNo Description available
Synthetische Nanoskalige Objekte: Bausteine für funktionale Materialien und Funktionseinheiten Research Project | 10 Project MembersThe proposal follows the SNF advice of a single project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. In spite of the different research targets, they have enough overlap enabling the fruitful exchange of knowledge and mutual developments required to build up a joint group identity. All five projects focus on current challenges in nanotechnology, molecular devices, and supramolecular materials, which are addressed by novel strategies and innovative molecular designs of functional structures. The five subprojects are briefly described in the following: (I) «Geländer»-molecules and helical architectures: «Geländer»-molecules consist of two periodically interlinked oligomers which compensate their length mismatch by wrapping the longer one helically around the shorter one, resembling the shape of the banister (Geländer in German) of a spiral staircase. The here promoted new designs profit from right-angled connections resulting in a simplified symmetry of the building blocks which should make longer oligomers synthetically accessible. A second strategy based on o-tetraphenylene building blocks is geared towards helical «plait»-type oligomers. (II) mechanosensitive model compounds for molecular junctions are based on cyclophane-type architectures enabling to tune the extent of the coupling between their subunits mechanically. With small [2.2]paracyclonaphthane derivatives the effect of torque motion shall be explored, while a polycyclic porphyrin hexamer will be assembled with two stacked states with large difference in their expansion. Based on a «upended» porphyrin type structure, even the coupling of the single electrons of two parallel radical planes might be investigated. (III) B-field sensitive macrocyclic model compounds are loop-shaped macrocycles consisting of a conjugated periphery decorated with terminal anchor groups enabling their integration in single molecule junction experiments. The intention is to detect the contribution of the Lorentz force to the molecules transport current. With a compact and twisted OPE type macrocycle, the axial chirality of the immobilized structure might become specifiable in the transport experiment. (IV) synthesis of an armchair carbon nanotube (CNT) is an interesting synthetic strategy for the controlled wet chemical assembly of an armchair CNT. A belt fragment of a CNT shall be obtained from a macrocycle by a reaction sequence, which can subsequently be repeatedly applied to control the length of the CNT. (V) approaches towards molecular textiles are based on the development of a cross-type junction acting a covalent template arranging the precursors at the water/air interface. Upon interlinking within the LB-film and cleavage of the template, textile-type interwoven molecular films should be obtained. The potential of the cross-type junction for superstructures will be investigated as well.
Molecular Carbon Nanoscrolls Research Project | 2 Project MembersBending a planar sheet of graphene into a seamless three-dimensional cylindrical carbon nanotube requires the curved nanostructure to pass through a stage where the two-dimensional graphene sheet can, instead of making the carbon-carbon bonds between its edges, roll further into a nanoscroll. The edges of such a carbon nanoscroll are not fused and the structure, which is held only due to collective action of van der Waals forces, displays different properties than a nanotube as a result of its unique spiral topology. Small circular fragments of single-wall carbon nanotubes that retain information regarding chirality and diameter of carbon nanotubes have been designed and synthesized in the past decade as precursors for their uniform bottom-up synthesis. To this date, however, no molecular precursors for carbon nanoscrolls exist.This research project aims at the design and synthesis of such molecular fragments of carbon nanoscrolls and develops solutions to stabilize the structure of a molecular nanoscroll. Synthesis of a series of molecular nanoscrolls with a complete first turn will be accomplished and their optoelectronic properties of the prepared molecules will be studied in detail. Successful completion of this research project will represent a major achievement that will open a new line of research in the field of carbon allotropes and deliver topologically new carbon-rich molecules, molecular analogues of carbon nanoscrolls that are obtained by rolling-up graphene sheets.
Toblerone-Shaped Polymers: Bridging the Gap between Conjugated Polymers and Carbon Nanotubes Research Project | 1 Project MembersElectronic devices fabricated from conjugated polymers are expected to be competitive with those based on inorganic materials because of their low production costs due to high-throughput processing methods. These linear polymers possess tunable optoelectronic and mechanical properties and can be highly soluble. Although, conjugated polymers can be found in prototypes of electronic devices, only a handful of applications found their way to the commercial use. One of the reasons is their relatively low charge carrier mobility. An alternative to conjugated polymers are cylindrical single-walled carbon nanotubes (SWCNTs). Despite their excellent charge transport properties, SWCNTs, however, suffer from low solubility, sample purity, limited tunability of their properties, and, overall, high production costs. Other approaches that would successfully combine the properties of linear polymers and the cylindrical SWCNTs preserving the typical advantages of former and displaying high charge carrier mobility are largely missing.In this research proposal, the synthesis and experimental investigation of nanoprismatic, i.e., toblerone-shaped, polymers and nanoprisms are described for the first time. These ladder structures built by combination of triangular electron acceptor and linear electron donor monomers possess aromatic p-electron surfaces exposed to the exterior of the polymer or nanoprism such that it allows for p-electron communication with adjacent polymer segments or nanoprisms. Such spatial arrangement will result in an improved charge carrier mobility, similar to SWCNT. The choice of the individual monomers allows for tailoring their optoelectronic and material properties. Therefore, successful completion of the proposed research will introduce a new unconventional approach to bridge the conceptual gap between the scientific field of conjugated polymers and SWCNTs unprecedented in the scientific literature.
SuperMaMa / Superconducting Mass Spectrometry and Molecule Analysis Research Project | 2 Project MembersSuperMaMa is an EU-FET OPEN Research & Innovation project working on new technologies for mass spectrometry and analysis of lowly charged and neutral high-mass proteins. It comprises the development of neutral and lowly-charged biomolecular beam generation and detection. To this end arrays of superconducting detectors for molecular ions and neutrals will be designed and installed in a converted mass spectrometer, and methods for charge reduction of biomolecular ions in high vacuum devised. The team includes three academic research groups (M. Arndt, U. Vienna; E. Charbon, EPFL; M. Mayor, U. Basel) and two industrial partner (Single Quantum, Delft; MS Vision, Almere). The contribution from UNIBAS is primarily concerned with the development of suitable tags for biomolecules to enable charge manipulation in the gas phase by photochemical methods.
Molecular Nanoprisms as Efficient Electron-Transporting Materials Research Project | 1 Project MembersThe global warming threats leave us no choice but to rely on the production of clean energy, where the solar energy will become our most important source to produce electricity due to its abundance from the sun. This, however, requires implementation of inexpensive and environmentally friendly materials into solar cells. In this regard, organic materials offer the solution because they can be produced cheaply on a large scale. The problem with organic photovoltaic devices is, however, their low power conversion efficiency, which is a consequence of the short exciton-diffusion lengths and imbalanced charge transport in organic materials with lower mobility of electrons than that of holes. Simultaneously, the best performing electron-transporting materials in organic solar cells, namely, fullerenes, absorb visible light poorly, are hard to modify, and expensive to produce. In this research proposal, the synthesis and experimental investigation of molecular nanoprisms with built-in visible-light absorbing molecular electron acceptors as their triangular base is described. The symmetric spatial arrangement of the molecular electron acceptor units, their mutual distance and orientation in these nanoprisms will allow for extensive radial electron delocalization and, consequently, for efficient charge separation in an active layer of a solar cell. The possibility of the controlled growth of the nanoprisms by well-defined synthetic methods permits to incorporate various combinations of donor-acceptor motifs into the nanoprisms to tune their photophysical and redox properties. The unique three-dimensional shape and the aspect ratio of these nanoprisms will allow them to efficiently transport electrons in the materials incorporating them. Such favorable properties of these molecules will, one day, allow to make efficient organic solar cells competitive with other photovoltaic technologies.
Synthetic Nanoscale Objects: Building Blocks for Functional Materials and Devices Research Project | 10 Project MembersThe proposal follows the SNF rules of one project per applicant in division II. It is divided in five subprojects, each being the subject of a PhD thesis. Even though these five PhD projects are very different in their aims, they have in common that they address current challenges in nano-technology, supramolecular chemistry, and material science, which are addressed by molecular approaches with tailor-made functional structures. The five subprojects are: (I) "Geländer-type" helical structures and (II) macrocyclic model compounds for molecular junctions, (III) giant conjugated graphene belts geared towards molecule based magnetization experiments. Pre-organized reactants for the assembly of (IV) 2D polymers and molecular fabrics and of (V) optically active nanoscale hybrid architectures.(I) "Geländer-type" helical structures consist of an oligophenylene-axis around which a longer oligomer is helically wrapped, resembling the shape of the banister (Geländer in German) of a helical staircase. The next generation of this appealing molecular design concept is geared towards derivatives with conjugated helical "Geländer", which not only is expected to improve their optical features, but also should enable the assembly of model compounds acting as coil-like molecular wires. (II) macrocyclic model compounds for molecular junctions is focused on model compounds for transport experiments in magnetic fields. A molecular loop of considerable dimension shall increase the influence of the magnetic field on the charge carriers and a variety of rod-like metal complexes shall provide insight into the interplay of the magnetic field with the electronic configuration of the central metal ion. (III) giant conjugated graphene belts are expected to have interesting magnetic properties. These molecular analogues of lithographically fabricated nano-scaled metallic structures shall be assembled by combining macrocyclization approaches from acetylene scaffolding strategies with current chemistry geared towards graphen ribbons. The approach might even make Möbius-shaped graphene belts accessible.(IV) 2D polymers and molecular fabrics shall be obtained by profiting from the perfectly pre-organized arrangement of the molecular building blocks in MOF layers. In a second, alternative approach the organization and intermolecular coupling chemistry at the air/water interface of tailor-made heteroleptic Fe(tpy)2 complexes shall make molecular fabrics available.(V) optically active nanoscale hybrid architectures based on our preliminary findings providing mono-functionalized gold nanoparticles in good yields but of too small dimensions to interact with visible light, a new strategy enabling larger particles by the chemically controlled merging shall be developed.
QuIET / Quantum Interference Enhanced Thermoelectricity Research Project | 1 Project MembersOur vision is to demonstrate that room-temperature quantum interference effects, measured recently in single molecules, can be exploited in massively-parallel arrays of molecules and used to design ultra-thin-film thermoelectric devices with unprecedented ability to convert waste heat to electricity using the Seebeck effect and to cool at the nanoscale via the Peltier effect. Although the dream of high-performance thermoelectric devices has been discussed for many years, evidence of the room-temperature quantum interference effects needed to realise this dream was achieved experimentally only recently. Building on these indirect demonstrations of quantum interference in single molecules using non-scalable set ups, we anticipate that the next breakthrough will be the implementation of QI functionality these intechnologically-relevant platforms. We shall design molecules with built-in quantum interference functionality, which can be used to engineer the properties of ultra-thin molecular films. Molecules will be designed with robust anchors to metallic and carbon-based nano-gap electrodes, which enhance electron transport and eliminate unwanted phonons.This contacting strategy is scalable from a single junction, with the potential to be replicated billions of times on a single substrate. The ability to exploit quantum interference at room temperature will enable new thermoelectric materials and devices with the ability to scavenge energy with unprecedented efficiency. QuIET is a highly interdisciplinary project that brings together internationally leading scientists from four different countries with proven expertise on synthesis, transport measurements and theoretical modelling.
Switching optical antennas via supramolecular translation Research Project | 2 Project MembersOptical antennas are able to efficiently link propagating light fields and nanolocalized excitations and are therefore ideally suited to bridge the gap between the macroscopic world and nanoscopic entities such as individual molecules placed inside the antenna feed gap. Recently, the toolbox of optical antennas has been enriched by the possibility to apply voltages to the antenna via electrical connectors which allows to generate enormous DC electric fields across the antenna gap. Here we propose to realize two-color switchable optical antennas representing reconfigurable functional nanodevices by making use of electric-field induced supramolecular translations, i.e. the nanomechanical motion of ring-like moieties on rod-like molecules (Rotaxanes) placed in the antenna feedgap. Electrically-induced supramolecular translation of the ring moiety will cause selective quenching of one of up to two chromophores whereby its coupling to the antenna resonance will be suppressed. In the final configuration light emission shall even be electrically excited via inelastic electron tunneling and switched via the polarity of the applied voltage.
Encapsulation and Covalent Assembly of Nanoparticles Research Project | 1 Project MembersMetal nanoparticles (NPs) are three-dimensional structurally well-defined nanoclusters of around 10-100 atoms, which are best known for their unique size-dependent properties. It has been shown that the properties of a covalent ensemble of a number of NPs are greatly enhanced compared to those of the same number of single components. This, so-called collective, behavior can be useful, once controlled, for constructing NP nanocircuits of electronic devices. To build and study long chains of covalently linked NPs, their encapsulation by two shape- and size-complementary ligands is proposed. A series of bowl-shaped ligands, capable of (1) recognition and (2) covalent encapsulation of spherical NPs, is designed and the synthesis of these ligands is outlined. The ultimate goal is to connect the NP(ligand) 2 building blocks to generate long linear [(ligand)NP(ligand)] n chains and investigate their collective-behavior effect. In addition to standard analytical methods to characterize NPs, high-resolution transmission electron microscopy will be used to provide insight into this unusual phenomenon displayed by covalent NP ensembles. This project is geared towards (1) control over the organization of NPs through their covalent interconnection by chemical means to (2) enhance their electronic properties. The knowledge gained through this investigation can lead to a set of design principles, which can be used in future for making NP-based functional materials. This work can also result in an unprecedented methodology to separate NPs into fractions of extremely low size-distribution.
