Twisting of Porphyrin by Assembly in a Metal-Organic Framework yielding Chiral Photoconducting Films for Circularly-Polarized-Light Detection.

While materials based on organic molecules usually have either superior optoelectronic or superior chiral properties, the combination of both is scarce. Here, a crystalline chiroptical film based on porphyrin with homochiral side groups is presented. While the dissolved molecule has a planar, thus, achiral porphyrin core, upon assembly in a metal-organic framework (MOF) film, the porphyrin core is twisted and chiral. The close packing and the crystalline order of the porphyrin cores in the MOF film also results in excellent optoelectronic properties. By exciting the Soret band of porphyrin, efficient photoconduction with a high On-Off-ratio is realized. More important, handedness-dependent circularly-polarized-light photoconduction with a dissymmetry factor g of 4.3×10-4 is obtained. We foresee the combination of such assembly-induced chirality with the rich porphyrin chemistry will enable a plethora of organic materials with exceptional chiral and optoelectronic properties.

Photoinduced Delamination of Metal-Organic Framework Thin Films by Spatioselective Generation of Reactive Oxygen Species.

Metal-organic frameworks (MOFs) built from different building units offer functionalities going far beyond gas storage and separation. In connection with advanced applications, e.g., in optoelectronics, hierarchical MOF-on-MOF structures fabricated using sophisticated methodologies have recently become particularly attractive. Here, we demonstrate that the structural complexity of MOF-based architectures can be further increased by employing highly spatioselective photochemistry. Using a layer-by-layer, quasi-epitaxial synthesis method, we realized a photoactive MOF-on-MOF hetero-bilayer consisting of a porphyrinic bottom layer and a tetraphenylethylene (TPE)-based top layer. Illumination of the monolithic thin film with visible light in the presence of oxygen gas results in the generation of reactive oxygen species (1O2) in the porphyrinic bottom layer, which lead to a photocleavage of the TPE units at the internal interface. We demonstrate that this spatioselective photochemistry can be utilized to delaminate the top layers, yielding two-dimensional (2D) MOF sheets with well-defined thickness. Experiments using atomic force microscopy (AFM) demonstrate that these platelets can be transferred onto other substrates, thus opening up the possibility of fabricating planar MOF structures using photolithography.

Modular Synthesis of trans-A2 B2 -Porphyrins with Terminal Esters: Systematically Extending the Scope of Linear Linkers for Porphyrin-Based MOFs.

Differently functionalized porphyrin linkers represent the key compounds for the syntheses of new porphyrin-based metal-organic frameworks (MOFs), which have gathered great interest within the last two decades. Herein we report the synthesis of a large range of 5,15-bis(4-ethoxycarbonylphenyl)porphyrin derivatives, through Suzuki and Sonogashira cross-coupling reactions of an easily accessible corresponding meso-dibrominated trans-A2 B2 -porphyrin with commercially available boronic acids or terminal alkynes. The resulting porphyrins were fully characterized through NMR, MS, and IR spectroscopy and systematically investigated through UV/Vis absorption. Finally, selected structures were saponified to the corresponding carboxylic acids and subsequently proven to be suitable for the synthesis of surface-anchored MOF thin films.

Bridging the Green Gap: Metal-Organic Framework Heteromultilayers Assembled from Porphyrinic Linkers Identified by Using Computational Screening.

In organic photovoltaics, porphyrins (PPs) are among the most promising compounds owing to their large absorption cross-section, wide spectral range, and stability. Nevertheless, a precise adjustment of absorption band positions to reach a full coverage of the so-called green gap has not been achieved yet. We demonstrate that a tuning of the PP Q- and Soret bands can be carried out by using a computational approach for which substitution patterns are optimized in silico. The most promising candidate structures were then synthesized. The experimental UV/Vis data for the solvated compounds were in excellent agreement with the theoretical predictions. By attaching further functionalities, which allow the use of PP chromophores as linkers for the assembly of metal-organic frameworks (MOFs), we were able to exploit packing effects resulting in pronounced redshifts, which allowed further optimization of the photophysical properties of PP assemblies. Finally, we use a layer-by-layer method to assemble the PP linkers into surface-mounted MOFs (SURMOFs), thus obtaining high optical quality, homogeneous and crystalline multilayer films. Experimental results are in full accord with the calculations, demonstrating the huge potential of computational screening methods in tailoring MOF and SURMOF photophysical properties.

Photoconductivity in Metal-Organic Framework (MOF) Thin Films.

Photoconductivity is a characteristic property of semi-conductors. Herein, we present a photo-conducting crystalline metal-organic framework (MOF) thin film with an on-off photocurrent ratio of two orders of magnitude. These oriented, surface-mounted MOF thin films (SURMOFs), contain porphyrin in the framework backbone and C60 guests, loaded in the pores using a layer-by-layer process. By comparison with results obtained for reference MOF structures and based on DFT calculations, we conclude that donor-acceptor interactions between the porphyrin of the host MOF and the C60 guests give rise to a rapid charge separation. Subsequently, holes and electrons are transported through separate channels formed by porphyrin and by C60 , respectively. The ability to tune the properties and energy levels of the porphyrin and fullerene, along with the controlled organization of donor-acceptor pairs in this regular framework offers potential to increase the photoconduction on-off ratio.

Synthesis and characterization of rigid [2.2]paracyclophane-porphyrin conjugates as scaffolds for fixed-distance bimetallic complexes.

This work presents a new approach to prepare mono- and disubstituted linear rigid bimetallic [2.2]paracyclophane-porphyrin conjugates via palladium-mediated Stille cross-coupling reaction. The metalated porphyrin moiety can be varied allowing convenient access to modular metal-metal fixed-distance Cu/Zn complexes.

Effects of a 15-Month Supervised Exercise Program on Physical and Psychological Outcomes in Prostate Cancer Patients Following Prostatectomy: The ProRehab Study.

PURPOSE: Despite advanced medical treatment options, many prostate cancer patients are still confronted with unfavorable physical and psychological burdens. Physical exercise has proven to be beneficial for prostate cancer patients, yet specific exercise offers are rare. The ProRehab Study aimed to evaluate the exercise program offered in rehabilitative prostate cancer sports groups in Germany and determine whether it is beneficial for patients following prostatectomy. METHODS: Eighty-five prostate cancer patients were recruited for a multicenter, 2-armed, nonrandomized controlled trial 6 to 12 weeks after prostatectomy. The intervention group (n = 56) took part in a 15-month supervised multimodal exercise program. Exercise sessions took place once a week for 60 minutes at a moderate intensity (3.84-4.84 MET-hour). The control group (n = 29) received no intervention. Outcomes included aerobic fitness, activity levels, quality of life, disease- and treatment-related adverse effects, such as urinary incontinence and erectile dysfunction, and relapse-relevant blood values. Intention-to-treat analysis was performed. RESULTS: A significant between-group difference was observed in the urinary symptom score (P = .027). Physical fitness, urinary incontinence, physical, role, emotional, and social functioning, as well as further disease- and treatment-related side effects (dyspnea, urinary, and bowel symptoms) significantly improved within the intervention group. Erectile dysfunction and physical activity levels improved similarly in both groups. CONCLUSIONS: The presented data hint at the potential of rehabilitative sports groups for prostate cancer patients. However, according to the current state of the art, exercise intensity and volume may need to be increased to enhance the effects. A number of shorter studies (8-24 weeks) have proven significant between-group differences in quality of life, incontinence, and fitness outcomes when patients exercised 2 to 3 times per week. This is the first exercise intervention study with prostate cancer patients that was conducted over 15 months. Further studies are necessary to investigate whether prostate cancer patients recover sooner when receiving a supervised exercise program.