Adaptable Overhanging Carboxylic Acid Porphyrins Towards Molecular Assemblies through Unusual Coordination Modes

International audienceA new family of strap porphyrins exhibiting out/in overhanging carboxylic acid stereoisomerism, has been synthesized and investigated for its coordination properties. Their 5,10 linkage allows a significant flexibility of the strap which exhibits various degrees of angulation relatively to the mean porphyrin plane, making the ligand adjustable to the metal it binds. Notably, in the case of Bi(III), a second sphere of coordination plays a crucial role for the side selective insertion of the large metal ion. As a result, inward and outward orientation of the overhanging carboxylic acid function can be tuned, which is of interest for supramolecular coordination assemblies

Effects of metformin, letrozole and atorvastatin on inflammation and apoptosis in experimental peritoneal and ovarian endometriosis in the rat

Endometriosis is a common gynecological hurting disorder in which tissue is similar to the tissue that normally lines the inner layer of the uterus. It often causes fertility problems. Unfortunately, effective treatments are limited. Therefore it's important to explore an imperative and easily accessible treatment to alleviate the probable pathologies and preserve fertility in endometriosis. Consequently, we aimed to investigate the effects of metformin, letrozole, and atorvastatin on inflammation and apoptosis in experimentally induced ovarian and peritoneal endometriosis in rat models. In the present study, 35 rats were randomly divided into five groups. Group 1: sham-operated control group. Group 2: untreated endometriosis group. Group 3: given 100 mg/kg/day of oral metformin. Group 4: given 0.1 mg/kg/day of oral letrozole. Group 5: given 2.5 mg/kg/day of oral atorvastatin. At the end of the 28 days, we examined Ki67, Bax and Bcl-2 immunoexpressions in ovarian and peritoneal tissues, and IL-6, IL-8, and TNF-alpha levels were evaluated from the peritoneal fluid. All medical treatment groups showed a significant decrease in Ki67 expression. A significant increase in Bax expression was also observed in all samples from all medical treatment groups (other than the untreated endometriosis groups). Further, a significant decrease in Bcl-2 expression was found in all medical treatment groups. IL-6, IL-8, and TNF alpha levels were significantly lower in all medical treatment groups than in the endometriosis groups. In conclusion; Metformin, letrozole, and atorvastatin showed apoptosis induction and anti-inflammatory effects on both ovarian and peritoneal endometriosis in experimental models.Scientific Research Projects Grants Unit, University of Health Sciences, Istanbul, Turkey [2017/050]This study was supported by the Scientific Research Projects Grants Unit, University of Health Sciences, Istanbul, Turkey [Grant Number: 2017/050]

Bio-Inspired Polydopamine Mimic Noble Metal Electrocatalysts in Hydrogen Evolution Reaction

The main electrocatalysts for the electrochemical hydrogen evolution reaction (HER) rely on platinum due to high efficiencies, low binding energy for hydrogen and high electroactive-site density, however the cost of platinum is a crucial limitation for the production of hydrogen by this rare metal.[1] Here, we establish a metal-free and bio-organic electrocatalyst platform that resembles the platinum surface by incorporating hydrogen-affine hydrogen bonds. We introduce keto-amine functional motifs, which act as selective reaction centres.[2, 3] The keto-amine-functionalized biopolymer shown in this work evolve hydrogen at the lowest overpotential in a non-metallic system. With excellent electrochemical stability and chemical robustness, we are able to present a scale-up continuous-flow electrolysis and produce 1 L net molecular hydrogen within less than 9 hours using 2.3 mg of biopolymer electrocatalyst. [1] Y. Zheng, Y. Jiao, Y. Zhu, L.H. Li, Y. Han, Y. Chen, A. Du, M. Jaroniec, S.Z. Qiao, Hydrogen evolution by a metal-free electrocatalyst, Nature Communications, 5 (2014) 3783. [2] H. Coskun, A. Aljabour, P. De Luna, D. Farka, T. Greunz, D. Stifter, M. Kus, X.L. Zheng, M. Liu, A.W. Hassel, W. Schofberger, E.H. Sargent, N.S. Sariciftci, P. Stadler, Biofunctionalized conductive polymers enable efficient CO2 electroreduction, Science Advances, 3 (2017). [3] H. Coskun, A. Aljabour, L. Uiberlacker, M. Strobel, S. Hild, C. Cobet, D. Farka, P. Stadler, N.S. Sariciftci, Chemical vapor deposition - based synthesis of conductive polydopamine thin-films, Thin Solid Films, 645 (2018) 320-325. </jats:p

Conducting, functional polymers from bio-organic molecules for catalysis

The utilization of bio-inspired, polymer-based materials in the field of catalysis can help to resolve relevant energy questions in the 21th century. This work is dedicated to the design and engineering of electrocatalysts for carbon dioxide reduction reaction (CO2RR) and hydrogen evolution reaction (HER) using bio-derived, hydrogen-bonded systems, that exhibit heterogenous catalytic activity. These will be important as sustainable systems, which are shown here to exhibit tremendous performance. In light of todays dependence on expensive and rare noble metals, it is of outmost interest to develop alternative polymeric and non-metallic contenders, which will replace metals and thus increase the catalyst material pool and the catalyst versatility. The here demonstrated electrocatalytic polymers are low-cost and bio-inspired, have low environmental impact and at the same time offer similar stability as noble metals but also tunable physical-electronic properties. Combined with their bio-compatibility they will be a future emerging material class in the field of electrocatalysis. The focus of this thesis has been to generate polymers with superior catalytic activity and therefore their electronic properties have been improved, in particular their intrinsically low capability to transport electrons. In their initial state, most biopolymers are insulators. In this work, a novel synthesis path is shown to create doped conductive biopolymers with excellent catalytic activity and long-term stability. The synthesis of two conductive and electrocatalytic biopolymers is presented: these are first polydopamine (PDA) as a derivative of the naturally occurring pigment eumelanin, and, second, polyguanine (PG), a purine base and component of the desoxyribonucleic acid (DNA), which adopted an emeraldine-related structure. Both biopolymers have been applied as electrocatalysts for CO2RR and/or HER. The synthesis pathway from the monomers to the conductive and functional biopolymers is described using a facile one-step oxidative chemical vapor deposition (o-CVD) technique. This has been the crucial effort to unit polymerization and doping leading to the desired electrically conductive biopolymers in a single step reaction without compromising on the organic functionality remaining unchanged on the polymer backbone. Besides replacing the metal catalysts by organic units, the main motivation in this work was to mimic natural phenomena by using artificial biopolymers. Therefore, polydopamine was firstly applied as an electrocatalyst for CO2RR to convert the anthropogenic carbon dioxide emissions into useful chemical feedstock. The catalytic effect driven by hydrogen-bonded functional motifs resulted in significant electrocatalytic performance with almost > 90 % Faraday efficiency and a geometric current density of 18 mA cm-2 at 210 mV overpotential. Besides the CO2 reduction productions leading to CO and formate, hydrogen was also produced as a side-product at neutral pH. This result gave the hint, that hydrogen could be evolved by the PDA catalyst, when the polymer is further re-designed. In the next approach, such structurally modified PDA was applied in HER in an acidic medium showing excellent HER performance with a Tafel slope of 80 mV dec-1 and an overpotential of -190 mV vs. reversible hydrogen electrode (RHE) at 10 mA cm-2 and stable catalytic activity demonstrated by an initial 168 hours electrolysis. More important, scaled continuous-flow electrolysis was exhibited, producing 1 L of molecular hydrogen within less than 9 hours using 2.3 mg of biopolymer electrocatalyst. In order to confirm the proof-of-principle of catalytic activity in biopolymers containing organic themes, an alternative concept was sought: polyguanine (PG) is synthesized similarly to PDA and utilized it as HER electrocatalyst. Its ability to bind protons similar to the emeraldine form of polyaniline led to a signficiant HER activity with a Tafel slope as low as 80 mV dec-1 at an overpotential of -290 mV vs. RHE at 10 mA cm-2 and 80 hours of continuous electrolysis. The idea of employing biopolymers in various heterogenous electrocatalytic applications reveals that these emerging materials will be promising candidates for future sustainable energy conversion catalysts.submitted by DI. Halime Coskun AljabourIn Zusammenarbeit mit dem Institut f\ufcr Physikalische ChemieDissertation Universit\ue4t Linz 201

(Invited) Conductive Biopolymers for Selective Metal-Devoid Electrocatalysis

Electrocatalysis can be useful in energy conversion, in particular for the production of synthetic fuels from renewable energy. However, this requires catalytic conductors, which sustain the reaction conditions that foremost occur in aqueous solution. Conducting polymers represent a chemically robust but conductive materials class that could be harnessed for aqueous electrocatalytic processes in order to facilitate the important reactions steps to electrosynthesize fuels. In terms of CO2 reduction this has been demonstrated by using a conducting form of polydopamine.(1–3) This system no than other incorporates a richly functionalized backbone able to attach CO2 and electro-reduce to formate efficiently. We shed light on the relevant electro-activation of the incorporated functional themes in the biopolymer and compare this mechanisms to similarly efficient inorganic catalysts. We find that it is the actual nature of the incorporated theme that significantly influences its final selectivity. Such tunability enables the tailoring of selective and highly active catalytic surfaces from organic-functional matter. The functionalzed organic catalysts rely on different reaction mechanisms than state-of-the-art metal-based systems and possibly can be optimized as future sustainable contenders for metal-based electrocatalysts. H. Coskun et al., Chemical vapor deposition - based synthesis of conductive polydopamine thin-films. Thin Solid Films. 645, 320–325 (2018). X. Zheng et al., Sulfur-Modulated Tin Sites Enable Highly Selective Electrochemical Reduction of CO2 to Formate. Joule (2017), doi:10.1016/j.joule.2017.09.014. H. Coskun et al., Biofunctionalized conductive polymers enable efficient CO2 electroreduction. Sci. Adv. 3, e1700686 (2017). </jats:p

Comparison of Ultrasound-Guided Erector Spinae Plane Block and Subcostal Transversus Abdominis Plane Block for Postoperative Analgesia after Laparoscopic Cholecystectomy: A Randomized, Controlled Trial

Purpose Laparoscopic cholecystectomy causes moderate to severe pain despite its minimally invasive nature. This study was performed to compare the efficacy of the bilateral erector spinae plane block (ESPB) and the subcostal transversus abdominis plane block (STAPB) under ultrasound guidance. Methods 64 patients were included in this prospective, randomized study. The patients were allocated into two groups as those receiving ESPB (n = 32) and those receiving STAPB (n = 32). Pain scores at rest and during movement, fentanyl requirement, postoperative walking time, and duration of hospital stay were compared. The complications which related to block were also recorded. Results In the ESPB group, the Numeric Rating Scale (NRS) scores at rest were lower at hour 0 [at the time of post-anesthetic care unit (PACU) admission] and postoperative hours 2, 4, 6, and 12 (p < 0.05). In the same group, the NRS scores at movement were lower at hours 0, 2, 4, 6, 12, and 24 (p < 0.05). In the ESPB group, the time to first analgesic need was longer (p < 0.05), intraoperative and postoperative Fentanyl requirement (p < 0.0001 for both) and PACU rescue analgesic requirement were lower (p < 0.05), the lengths of PACU and hospital stay were shorter (p < 0.0001), and unassisted walking time was shorter (p < 0.0001). There were no complications related to the block in either group. Conclusion Bilateral ultrasound-guided ESPB provides superior analgesia after laparoscopic cholecystectomy surgery compared to STAPB and further reduces unaided walking time and hospital stay

Mimicking Noble Metals Using Hydrogen-Bonded Conducting Polymers for Electrocatalysis

The most active and efficient catalysts for the electrochemical hydrogen evolution reaction rely on noble metals, a fact that increases the cost of producing hydrogen and thereby limits the widespread adoption of this fuel. Here we present metal-free polydopamine and polyguanine as selective organic hydrogen electrocatalysts1–3. The conducting functional polymers incorporate selective hydrogen-affine hydrogen bonds that possess a similar hydrogen binding energies and work function as e.g. platinum. We report the synthesis of hydrogen-selective electrocatalytic polyguanine and polydopamine and demonstrate the enhancement of the rate-determining step in the proton reduction. We further present mechanistic spectral IR-operando studies on the catalytic hydrogen bonded motifs as well as the continuous electrolysis to molecular hydrogen using polyguanine and polydopamine electrodes for several 100 hours without notable degradation. (1) Coskun, H.; Aljabour, A.; Schöfberger, W.; Hinterreiter, A.; Stifter, D.; Sariciftci, N. S.; Stadler, P. Cofunction of Protons as Dopant and Reactant Activate the Electrocatalytic Hydrogen Evolution in Emeraldine‐Polyguanine. Adv. Mater. Interfaces 2019, 1901364 DOI: 10.1002/admi.201901364. (2) Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S. Chemical Vapor Deposition - Based Synthesis of Conductive Polydopamine Thin-Films. Thin Solid Films 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063. (3) Coskun, H.; Aljabour, A.; Luna, P. De; Sun, H.; Nishiumi, N.; Yoshida, T.; Koller, G.; Ramsey, M. G.; Greunz, T.; Stifter, D.; Hassel, A. W.; Sariciftci, N. S.; Sargent, E. H.; Stadler, P. Hydrogen-Bonded Polymers Mimic Noble Metal Electrocatalysts. Adv. Mater., submitted. </jats:p

Catalytic Motifs in Bio-Inspired Materials As New Generation Electrocatalysts

Bio-inspired and bioorganic materials gain outmost of interest due to a wide application area. In the past years, hydrogen-bonded organic semiconductors relying on indigoid pigment family are applied in various device geometries e.g. organic solar cells, organic field effect transistors but also as thin film electrodes in catalysis [1,2]. Currently, the integration of the bio-inspired materials in sustainable catalysis is powerful. Especially, organic functionalities present in the chemical structure of this new material class provide these compounds outstanding properties in terms of using these functional themes as catalytic active centers to substitute state-of-the-art metallic catalysts. Herein, we report on the suitability of a bio-originated polymer – Polydopamine (PDA) - as an effective electrocatalyst [3]. Polydopamine is a major pigment of the eumelanin family. Due to its hydrogen-bonded sequences in the conjugated structure, stabilized over hydroxyl, amine and carbonyl groups, PDA is a prominent competitor for the new generation of sustainable catalysis. We engineered a new synthetic pathway for the polydopamine electrode prepraration [4]. We apply the chemical vapor deposition technique in the presence of the monomer dopaminhydrochlorid together with sulfuric acid as an oxidant in order to form polydopamine films directly on 3D, sponge-like carbon felt electrodes, creating an increased catalytically active surface area. Electrochemical investigations exhibit the interaction and interplay of the functionalities in catalytic processes resulting in high yields and current densities and thus reducing energy losses. [1] Glowacki E. D.; Irimia-Vladu M.; Kaltenbrunner M.; Gasiorowski J.; White M. S.; Monkowius U.; G. Romanazzi G.; Suranna G. P.; Mastrorilli P.; Sekitani T.; Bauer S.; Someya T.; Torsi L.; Sariciftci N. S.; Adv. Mater., 2013, 25, 1563–1569. [2] Glowacki E. D.; Romanazzi G.; Yumusak C.; Coskun, H.; Monkowius U.; Voss G.; Burian M.; Lechner R. T.; Demitri N.; Redhammer G. J.; Sünger N.; Suranna G. P.; Sariciftci N. S.; Adv. Funct. Mater.; 2014, DOI: 10.1002/adfm.201402539. [3] Coskun, H.; Aljabour, A.; De Luna, P.; Farka, D.; Greunz, T.; Stifter, D.; Kus, M.; Zheng, X.; Liu, M.; Hassel, A. W.; Schöfberger, W.; Sargent, E. H.; Sariciftci, N. S.; Stadler, P.; Sci. Adv. 2017, 3 (8), e1700686 DOI: 10.1126/sciadv.1700686. [4] Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S.; 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063. </jats:p