Massimo Tormen

Molecule‐based functional devices may take advantage of surface‐mediated spin state bistability. Whereas different spin states in conventional spin crossover complexes are only accessible at temperatures well below room temperature, and the lifetimes of the high‐spin state are relatively short, a different behavior exhibited by prototypical nickel phthalocyanine is shown here. Direct interaction of the organometallic complex with a copper metal electrode mediates the coexistence of a high spin and a low spin state within the 2D molecular array. The spin state bistability is extremely non‐volatile, since no external stimuli are required to preserve it. It originates from the surface‐induced axial displacement of the functional nickel cores, which generates two stable local minima. Spin state unlocking and the full conversion to the low spin state are only possible by a high temperature stimulus. This spin state transition is accompanied by distinct changes in the molecular electronic structure that might facilitate the state readout at room temperature, as evidenced by valence spectroscopy. The non‐volatility of the high spin state up to elevated temperatures and the controllable spin bistability render the system extremely intriguing for applications in molecule‐based information storage devices.

On‐surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building‐blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On‐surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π‐extended two‐dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single‐active site character of their single‐molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom‐up constructed covalent nanomeshes.

On‐surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building‐blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On‐surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π‐extended two‐dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single‐active site character of their single‐molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom‐up constructed covalent nanomeshes.

The response time of state‐of‐the‐art humidity sensors is ≈8 s. A faster tracking of humidity change is especially required for health care devices. This research is focused on the direct nanostructuring of a humidity‐sensitive polymer thin film and it is combined with an optical read‐out method. The goal is to improve the response time by changing the surface‐to‐volume ratio of the thin film and to test a different measurement method compared to state‐of‐the‐art sensors. Large and homogeneous nanostructured areas are fabricated by nanoimprint lithography on poly(2‐hydroxyethyl methacrylate) thin films. Those thin films are made by initiated chemical vapor deposition (iCVD). To the author's knowledge, this is the first time nanoimprint lithography is applied on iCVD polymer thin films. With the imprinting process, a diffraction grating is developed in the visible wavelength regime. The optical and physicochemical behavior of the nanostructures is modeled with multi‐physic simulations. After successful modeling and fabrication a first proof of concept shows that humidity dependency by using an optical detection of the first diffraction order peak is observable. The response time of the structured thin film results to be at least three times faster compared to commercial sensors.

The surface chemistry of C₆₀F₄₈ deposited on Ag(111) at room temperature involves de-fluorination of the molecules and the formation of silver fluoride.

Guidance molecules, such as Sema3A or Netrin-1, can induce growth cone (GC) repulsion or attraction in the presence of a flat surface, but very little is known of the action of guidance molecules in the presence of obstacles. Therefore we combined chemical and mechanical cues by applying a steady Netrin-1 stream to the GCs of dissociated hippocampal neurons plated on polydimethylsiloxane (PDMS) surfaces patterned with lines 2 µm wide, with 4 µm period and with a height varying from 100 to 600 nm. GC turning experiments performed 24 hours after plating showed that filopodia crawl over these lines within minutes. These filopodia do not show staining for the adhesion marker Paxillin. GCs and neurites crawl over lines 100 nm high, but less frequently and on a longer time scale over lines higher than 300 nm; neurites never crawl over lines 600 nm high. When neurons are grown for 3 days over patterned surfaces, also neurites can cross lines 300 nm and 600 nm high, grow parallel to and on top of these lines and express Paxillin. Axons - selectively stained with SMI 312 – do not differ from dendrites in their ability to cross these lines. Our results show that highly motile structures such as filopodia climb over high obstacle in response to chemical cues, but larger neuronal structures are less prompt and require hours or days to climb similar obstacles.

A new spin-on alumina-based resist exhibits excellent performance in terms of both achievable lateral resolution and etch resistance in fluorine-based non-cryo-cooled dry etching processes. The resist has selectivity greater than 100:1 with respect to the underlying silicon during the etching process, patternability with various lithographic tools (UV, X-rays, electron beam, and nanoimprint lithography), and positive and negative tone behavior depending only on the developer chemistry.