Petr Henke

Optimization of deposition, surface passivation and functionalization of tin dioxide thin layers provided a versatile, selective and active semiconductor for liquid-gated field effect transistors that electrically detect proteins in solution.

The fascinating feature of metal-organic frameworks is that they can respond to external stimuli, unlike other inorganic materials. This feature corresponds to the framework's flexibility, which originates with the long-range crystalline order of the framework accompanied by cooperative structural transformability. We have synthesized a novel metal-organic framework comprised of Cu(I) nodes with pyrazine linkers and benzene-1,3,5-tricarboxylate acting as template anions, named CUCAM-1 [Cu(Py)₂(BTC)]_n. In the presence of polar solvent systems, CUCAM-1 undergoes an irreversible structural transformation to yield a mixed phase that consists of HKUST-1 [Cu₃(BTC)₂(H₂O)₃]_n and another CUCAM-2 [Cu(Py)(BTC)]_n MOFs, whose novel structure is successfully revealed by continuous rotation electron diffraction from the mixture. In this structural transformation, a new ligand exchange occurs where template anions become ligands, confirmed by single crystal X-ray analysis. Further, structural transformation and the mechanism are explained by ab initio molecular dynamics (AIMD) simulations. Interestingly, different halides (F^-, Cl^-, and Br^-) can be accompanied to affect/control the composition of the second phase by favoring the formation of the HKUST-1 phase over CUCAM-2, which was evident by the powder X-ray diffraction studies. Furthermore, the structural transformation induced by I^- resulted in a colorimetric response due to the formation of a new MOF CUCAM-3, paving the way for use as an iodide detector.

A series of [7]helical quinolizinium salts were prepared by using Rh-catalyzed cyclotrimerization and C–H activation processes. The prepared compounds exhibit high fluorescence in solution and in the solid phase in the orange-red light region.

Full photophysical picture and thermally activated ISC was revealed for rhodacyclopentadienes by fs-spectroscopy and Marcus analysis, while potential application on ¹O₂ sensitizing was explored.

Herein, we performed a simple virus capture and photoinactivation procedure using visible light on phosphatidylcholine vesicles. l-alpha-Phosphatidylcholine vesicles were enriched by viral receptors, GT1b gangliosides, and the nonpolar photosensitizer 5,10,15,20-tetraphenylporphyrin. These vesicles absorb in the blue region of visible light with a high quantum yield of antiviral singlet oxygen, O-2 ((1)Delta(g)). Through the successful incorporation of gangliosides into the structure of vesicles and the encapsulation of photosensitizers in their photoactive and monomeric state, the photogeneration of O-2((1)Delta(g)) was achieved with high efficiency on demand; this process was triggered by light, and specifically targeting/inactivating viruses were captured on ganglioside receptors due to the short lifetime (3.3 mu s) and diffusion pathway (approximately 100 nm) of O-2((1)Delta(g)). Time-resolved and steady-state luminescence as well as absorption spectroscopy were used to monitor the photoactivity of the photosensitizer and the photogeneration of O-2((1)Delta(g)) on the surface of the vesicles. The capture of model mouse polyomavirus and its inactivation were achieved using immunofluorescence methods, and loss of infectivity toward mouse fibroblast 3T6 cells was detected.

In this work, the overarching goal of improving the photooxidative stability of organic components used in photovoltaic devices is addressed, focusing on the common problem of degradation mediated by singlet molecular oxygen. Through a systematic exploration of boron subphthalocyanines (SubPcs), the influence of donor and acceptor substituents on the SubPc's redox properties has been examined, including the SubPc's ability to (1) act as a photosensitizer for singlet oxygen generation and (2) deactivate singlet oxygen are examined. How singlet oxygen formation and removal are influenced by linking together three SubPcs in a compact structure and by linking a SubPc to another molecular unit of relevance for organic photovoltaics (indenofluorene‐extended tetrathiafulvalene) is also examined. Synthetic protocols rooted in acetylenic scaffolding, experimental and computational structure–property relationships (optical and redox properties, singlet oxygen quantum yields, and removal kinetics), and characteristics of a functional photovoltaic device using a SubPc molecule are presented, demonstrating that cyano functionalization results in remarkably enhanced organic photovoltaic device stability.

One key challenge in the development of viable organic photovoltaic devices is to design component molecules that do not degrade during combined exposure to oxygen and light. Such molecules should thus remain comparatively unreactive towards singlet molecular oxygen and not act as photosensitizers for the generation of this undesirable species. Here, novel redox‐active chromophores that combine these two properties are presented. By functionalizing indenofluorene‐extended tetrathiafulvalenes (IF‐TTFs) with cyano groups at the indenofluorene core using Pd‐catalyzed cyanation reactions, we find that the reactivity of the exocyclic fulvene carbon‐carbon double bonds towards singlet oxygen is considerably reduced. The new cyano‐functionalized IF‐TTFs were tested in non‐fullerene acceptor based organic photovoltaic proof‐of‐principle devices, revealing enhanced device stability.

A three-step postprocessing functionalization of pristine electrospun polystyrene nanofiber membranes was used for the preparation of nanostructured biotinylated materials with an externally bonded porphyrin photosensitizer. Subsequently, the material was able to strongly bind biologically active streptavidin derivatives while keeping its photosensitizing and antibacterial properties due to the generation of singlet oxygen under the exclusive control of visible light. The resulting multifunctional materials functionalized by a streptavidin-horseradish peroxidase conjugate as a model bioactive compound preserved its enzymatic activity even in the presence of a porphyrin photosensitizer with some quenching effect on the activity of the photosensitizer. Prolonged kinetics of both singlet oxygen luminescence and singlet oxygen-sensitized delayed fluorescence (SODF) were found after irradiation by visible light. The above results reflected less effective quenching of the porphyrin photosensitizer triplet state by ground state oxygen and indicated hindered oxygen transport (diffusion) due to surface functionalization. We found that SODF could be used as a valuable tool for optimizing photosensitizing efficiency as well as a tool for confirming surface functionalization. Full photosensitizing and enzyme activity could be achieved by a space separation of photosensitizers and enzyme/biomolecules in the nanofiber composites consisting of two layers. The upper layer contained a photosensitizer that generated antibacterial singlet oxygen upon irradiation by light, and the bottom layer retained enzymatic activity for biochemical reactions.

The transport of a photosensitizer to target biological structures followed by the release of singlet oxygen is a critical step in photodynamic therapy. We compared the (photo)physical properties of polystyrene nanoparticles ([email protected]) of different sizes and self-assembled poly(ethylene glycol)-b-poly(ε-caprolactone) core/shell nanoparticles ([email protected]) with different lengths of copolymer blocks, both suitable for the transport of the tetraphenylporphyrin photosensitizer (TPP). The singlet oxygen was formed inside both nanoparticles after irradiation with visible light. Its kinetics was controlled by the size of [email protected]; its lifetime (τΔ) increased with increasing nanoparticle size (from 6.5 to 16 μs) due to hindered diffusion into the external aqueous environment, where it was quickly deactivated. Accordingly, the prolongation of the singlet oxygen-sensitized delayed fluorescence kinetics was found for [email protected] of high size. The [email protected] self-assemblies allowed for enhanced oxygen diffusion, the estimated low values of τΔ ~ 3.7 μs were independent of the size of building blocks. The delayed fluorescence in oxygen-free conditions originating from triplet-triplet annihilation indicated a high mobility of TPP in the PCL core in comparison with fixed molecules in the PS matrix. Photooxidation of uric acid revealed the highest efficacy for [email protected] of small sizes, whereas the largest [email protected] exhibited the lowest activity, and the efficacy of [email protected] remained independent of the sizes of the building blocks.