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The present study aimed to reveal intergenerational differences in the nutritional habits of the baby boomer, X, Y, and Z generations at a private college in Muğla, Türkiye. The study population included the students of the TED Bodrum College in Muğla province in the 2021-2022 academic year, including 311 participants: baby boomers (74), X (66), Y (43), and Z (128) generations. An online questionnaire was used to compare the eating habits among the generations. The data were evaluated using SPSS software. Most of the generations believed in healthy eating. Physical image and social media mainly influence the healthy eating habits of the Z generation. The baby boomers and X generations mostly skipped lunch, while the Y and Z generations skipped breakfast. Baby boomers, X, and Y generations mostly prefer healthy foods; however, the Z generation attaches importance to tasty foods. Z generation's interest in nutrition mostly concerns their physical appearance, not their health. Nutritional knowledge must be strengthened, particularly among young generations, and nutrition education programs need to be better supported by the government and educational sectors.

Introduction: Sodium-glucose cotransporter-2 (SGLT2) inhibitors are a new diabetes treatment. Considering the prescription of these medicines for kidney transplant patients, this systematic review and meta-analysis aimed to investigate the impact of SGLT2 inhibitors on kidney transplant patients. Material and Methods: This meta-analysis study was performed based on the PRISMA guideline. The necessary data were collected by searching the databases of Scopus, PubMed, Cochrane, Google Scholar search engine, and Web of Science without a time limit until March 1, 2023. The data were analyzed in STATA 14. A P value less than 0.05 was considered significant. Results: The authors assessed eight articles with a sample size of 960 patients. The SGLT2 inhibitors showed no significant impact on levels of estimated glomerular filtration rate [SMD: -0.21 (95% CI: -0.65, 0.25)], serum creatinine [SMD: -0.02 (95% CI: -0.19, 0.15)], plasma hemoglobin A1c (HbA1c) [SMD: -0.62 (95% CI: -1.43, 0.18)], systolic blood pressure [SMD: -0.64 (95% CI: -1.80, 0.52)], and diastolic blood pressure [SMD: -0.64 (95% CI: -1.41, 0.14)], and on the patient’s weight [SMD:-0.31 (95% CI: -0.80, 0.18)]. Patient age did not influence the impact of SGLT2 inhibitors on estimated glomerular filtration rate (50–59 years-old age group: [SMD: 0.13 (95% CI: -0.04, 0.30)], 60–69 years-old age group: [SMD: -0.56 (95 % CI: -1.38, 0.26]). Duration of medicine use did not affect the impact of SGLT2 inhibitors on estimated glomerular filtration rate [6 months after medicine use: SMD: -0.56 (95% CI: -1.38, 0.26)], 12 months after medicine use: [SMD: 0.10 (95% CI: -0.05, 0.26)]. Conclusion: SGLT2 inhibitors were not effective in lowering blood pressure, estimated glomerular filtration rate, serum creatinine, and hemoglobin A1c levels, or weight in kidney transplant patients. Although SGLT2 inhibitors were ineffective in improving kidney transplant patients’ renal function, there were no side effects, and the administration of this drug in kidney transplant patients can continue. Further research is required to ensure safety and determine the appropriate dosage and duration of drug use. Registration: The study was compiled according to the PRISMA checklist and its protocol was registered on the PROSPERO (ID: CRD42023407501) and Research Registry (UIN: reviewregistry1666) websites.

Objectives Marriage in old age is recommended as a way to improve the quality of life and reduce the loneliness of elders; however, studies disregarded measuring the satisfaction of elders who married in old age. Therefore, the present study aimed to determine the marital satisfaction among elders who were married during old ages. Methods & Materials This was a cross-sectional study conducted in Sanandaj City, Iran, in 2015. The convenience sampling method was used. The research participants were 190 people aged ≥60 years who were married in old ages. The required data were collected by Evaluation and Nurturing Relationship Issues, Communication, and Happiness (Enrich) Marital Satisfaction Scale. The obtained data were analyzed using SPSS, descriptive and analytical statistics, and Independent Samples t-test. Results The Mean±SD age of study participants was 67.37±11.24 years. The Mean±SD marital satisfaction score was 36.95±3.70. More than 60% of the elders who got married in old age reported high and very high marital satisfaction; only 3.7% of them reported low marital satisfaction. The obtained data revealed no significant gender difference in marital satisfaction. Conclusion A high marital satisfaction was reported by the studied elders. These results can be beneficial to encourage single elders to get married in old age.

Türkiye ile İran Orta Doğu’nun iki büyük devletlerindendir. Bu iki devlet geçmişten beri süre gelen dostluk ilişkilerine sahiptir. Bu dostluk Atatürk zamanında pekişmiş olsa da zaman zaman ilerlemiş ve gerilemiştir. İlerlediği süre zarfında karşılıklı anlaşmalar ve jestlerin arttığı ilişkiler gerildiği zaman bile tamamıyla kopmamıştır. Zira gerginken bile iki ülke ilişkisi sürmüştür. Belirtilen zaman aralığı olan 1950-1960 dönemi her iki ülke içinde sosyal ve siyasal şekilde değişimlerin yaşandığı bir dönemdir. Zira bahsi geçen zaman Orta Doğu’da yeni bir düzenin oluşturulmaya çalışıldığı bir dönemdi. Karşılıklı ilişki Demokrat Parti döneminde dış politikada benzer amaç ve hedefler belirlendiği zaman artmış ve yakınlaşmıştır. Bu yakınlaşmalardan biri her iki ülke içinde bir zaman Şah döneminde dış politika hedefi olan batılılaşma idi. Bu ortak amaç sayesinde iki ülke çıkarları doğrultusunda hareket etmiş ve ortak paktlar ve anlaşmalarda bir araya gelmiştir. Bunların yanı sıra ülke güvenliği amacıyla ekonomik, kültürel ve siyasal anlaşmalar yapmışlardır. Benzer bir diğer yaklaşım olan milliyetçi politika sayesinde iki ülke birbirleri ile işbirliğine yanaşmış ve yıllardan beri süre gelen bazı anlaşmaları sonuca bağlamıştır. Her ne kadar yabancıların da dâhil olduğu hatta başrol oynadığı Demokrat Parti’nin iktidarda kaldığı bu on yıllık süreç içerisinde iki devlet ortak paydada ve dostluk ilişkileri yürütme tutumunda bulunup çatışmadan kaçınmışlardır. Ancak buna rağmen Sovyet tehdidi olan komünizm sebebiyle Türkiye bir müddet İran ile olan ilişkisinde oldukça dikkatli olmuştur. Zira bir süre İran Başbakanlığı yapan Musaddık’ın Sovyet yanlısı olduğunu düşünmekteydi. Bu ve bunun gibi birçok iç ve dış sebepler dolayısıyla iki ülke ilişkilerinde dikkatli olmuş ve ortak çaba göstermişlerdir.

To efficiently capture, activate, and transform small molecules, metalloenzymes have evolved to integrate a well-organized pocket around the active metal center. Within this cavity, second coordination sphere functionalities are precisely positioned to optimize the rate, selectivity, and energy cost of catalytic reactions. Inspired by this strategy, an artificial distal pocket defined by a preorganized 3D strap is introduced on an iron-porphyrin catalyst (sc-Fe) for the CO 2 -to-CO electrocatalytic reduction. Combined electrochemical, kinetic, and computational studies demonstrate that the adequate positioning of a carboxylate/carboxylic group acting in synergy with a trapped water molecule within this distal pocket remarkably enhances the reaction turnover frequency (TOF) by four orders of magnitude compared to the perfluorinated iron-tetraphenylporphyrin catalyst (F 20 Fe) operating at a similar low overpotential. A proton-coupled electron transfer (PCET) is found to be the key process responsible for the unexpected protonation of the coordinating carboxylate, which, upon CO 2 insertion, shifts from the first to the second coordination sphere to play a possible secondary role as a proton relay., (© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Molecular catalysts offer a unique opportunity to implement different chemical functionalities to steer the efficiency and selectivity for the CO 2 reduction for instance. Metalloporphyrins and metallophthalocyanines are under high scrutiny since their most classic derivatives the tetraphenylporphyrin (TPP) and parent phthalocyanine (Pc), have been used as the molecular platform to install, hydrogen bonds donors, proton relays, cationic fragments, incorporation in MOFs and COFs, to enhance the catalytic power of these catalysts. Herein, we examine the electrocatalytic properties of the tetramethyl cobalt (II) tetrapyridinoporphyrazine (CoTmTPyPz) for the reduction of CO 2 in heterogeneous medium when adsorbed on carbon nanotubes (CNT) at a carbon paper (CP) electrode. Unlike reported electrocatalysis with cobalt based phthalocyanine where CO was advocated as the two electron and two protons reduced intermediate on the way to the formation of methanol, we found here that CoTmTPyPz does not reduce CO to methanol. Henceforth, ruling out a mechanistic pathway where CO is a reaction intermediate., (© 2024 Wiley-VCH GmbH.)

The development of functional artificial photosynthetic devices relies on the understanding of mechanistic aspects involved in specialized photocatalysts. Modified iron porphyrins have long been explored as efficient catalysts for the light-induced reduction of carbon dioxide (CO 2 ) towards solar fuels. In spite of the advancements in homogeneous catalysis, the development of the next generation of catalysts requires a complete understanding of the fundamental photoinduced processes taking place prior to and after activation of the substrate by the catalyst. In this work, we employ a state-of-the-art nanosecond optical transient absorption spectroscopic setup with a double excitation capability to induce charge accumulation and trigger the reduction of CO 2 to carbon monoxide (CO). Our biomimetic system is composed of a urea-modified iron(III) tetraphenylporphyrin (UrFe III ) catalyst, the prototypical [Ru(bpy) 3 ] 2+ (bpy=2,2'-bipyridine) used as a photosensitizer, and sodium ascorbate as an electron donor. Under inert atmosphere, we show that two electrons can be successively accumulated on the catalyst as the fates of the photogenerated UrFe II and UrFe I reduced species are tracked. In the presence of CO 2 , the catalytic cycle is kick-started providing further evidence on CO 2 activation by the UrFe catalyst in its formal Fe I oxidation state., (© 2024 Wiley-VCH GmbH.)

Iron porphyrins are among the most studied molecular catalysts for carbon dioxide (CO 2 ) reduction and their reactivity is constantly being enhanced through the implementation of chemical functionalities in the second coordination sphere inspired by the active sites of enzymes. In this study, we were intrigued to observe that a multipoint hydrogen bonding scheme provided by embarked urea groups could also shift the redox activation step of CO 2 from the well-admitted Fe(0) to the Fe(I) state. Using EPR, resonance Raman, IR and UV-Visible spectroscopies, we underpinned a two-electron activation step of CO 2 starting from the Fe(I) oxidation state to form, after protonation, an Fe(III)-COOH species. The addition of another electron and a proton to the latter species converged to the cleavage of a C-O bond with the loss of water molecule resulting in an Fe(II)-CO species. DFT analyses of these postulated intermediates are in good agreement with our collected spectroscopic data, allowing us to propose an alternative pathway in the catalytic CO 2 reduction with iron porphyrin catalyst. Such a remarkable shift opens new lines of research in the design of molecular catalysts to reach low overpotentials in performing multi-electronic CO 2 reduction catalysis., (© 2023 Wiley-VCH GmbH.)

The core challenge in developing cost-efficient catalysts for carbon dioxide (CO 2 ) conversion mainly lies in controlling its complex reaction pathways. One such strategy exploits bimetallic cooperativity, which relies on the synergistic interaction between two metal centers to activate and convert the CO 2 substrate. While this approach has seen an important trend in heterogeneous catalysis as a handle to control stabilities of surface intermediates, it has not often been utilized in molecular and heterogenized molecular catalytic systems. In this review, we gather general principles on how natural CO 2 activating enzymes take advantage of bimetallic strategy and how phosphines, cyclams, polypyridyls, porphyrins, and cryptates-based homo- and hetero-bimetallic molecular catalysts can help understand the synergistic effect of two metal centers., (© 2023 Wiley-VCH Verlag GmbH.)

Harvesting sunlight to drive carbon dioxide (CO 2 ) valorisation represents an ideal concept to support a sustainable and carbon-neutral economy. While the photochemical reduction of CO 2 to carbon monoxide (CO) has emerged as a hot research topic, the full CO 2 -to-CO conversion remains an often-overlooked criterion that prevents a productive and direct valorisation of CO into high-value-added chemicals. Herein, we report a photocatalytic process that unlocks full and fast CO 2 -to-CO conversion (<10 min) and its straightforward valorisation into human health related field of radiochemistry with carbon isotopes. Guided by reaction-model-based kinetic simulations to rationalize reaction optimisations, this manifold opens new opportunities for the direct access to 11 C- and 14 C-labeled pharmaceuticals from their primary isotopic sources [ 11 C]CO 2 and [ 14 C]CO 2 ., (© 2023. The Author(s).)

At the core of carbon monoxide dehydrogenase (CODH) active site two metal ions together with hydrogen bonding scheme from amino acids orchestrate the interconversion between CO 2 and CO. We have designed a molecular catalyst implementing a bimetallic iron complex with an embarked second coordination sphere with multi-point hydrogen-bonding interactions. We found that, when immobilized on carbon paper electrode, the dinuclear catalyst enhances up to four fold the heterogeneous CO 2 reduction to CO in water with an improved selectivity and stability compared to the mononuclear analogue. Interestingly, quasi-identical catalytic performances are obtained when one of the two iron centers was replaced by a redox inactive Zn metal, questioning the cooperative action of the two metals. Snapshots of X-ray structures indicate that the two metalloporphyrin units tethered by a urea group is a good compromise between rigidity and flexibility to accommodate CO 2 capture, activation, and reduction., (© 2022 Wiley-VCH GmbH.)

The covalent insertion of a cobalt heme into the cavity of an artificial protein named alpha Rep (αRep) leads to an artificial cobalt hemoprotein that is active as a catalyst not only for the photo-induced production of H 2 , but also for the reduction of CO 2 in a neutral aqueous solution. This new artificial metalloenzyme has been purified and characterized by Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS), circular dichroism, and UltraViolet-Visible spectroscopy. Using theoretical experiments, the structure of this biohybrid and the positioning of the residues near the metal complex were examined, which made it possible to complete the coordination of the cobalt ion by an axial glutamine Gln283 ligand. While the Co(III)-porphyrin catalyst alone showed weak catalytic activity for both reactions, 10 times more H 2 and four times more CO 2 were produced when the Co(III)-porphyrin complex was buried in the hydrophobic cavity of the protein. This study thus provides a solid basis for further improvement of these biohybrids using well-designed modifications of the second and outer coordination sphere by site-directed mutagenesis of the host protein.

Coupling a photoredox module and a bio-inspired non-heme model to activate O 2 for the oxygen atom transfer (OAT) reaction requires a vigorous investigation to shed light on the multiple competing electron transfer steps, charge accumulation and annihilation processes, and the activation of O 2 at the catalytic unit. We found that the efficient oxidative quenching mechanism between a [Ru(bpy) 3 ] 2+ chromophore and a reversible electron mediator, methyl viologen (MV 2+ ), to form the reducing species methyl viologen radical (MV˙ + ) can convey an electron to O 2 to form the superoxide radical and reset an Fe(iii) species in a catalytic cycle to the Fe(ii) state in an aqueous solution. The formation of the Fe(iii)-hydroperoxo (Fe III -OOH) intermediate can evolve to a highly oxidized iron-oxo species to perform the OAT reaction to an alkene substrate. Such a strategy allows us to bypass the challenging task of charge accumulation at the molecular catalytic unit for the two-electron activation of O 2 . The Fe III -OOH catalytic precursor was trapped and characterized by EPR spectroscopy pertaining to a metal assisted catalysis. Importantly, we found that the substrate itself can act as an electron donor to reset the photooxidized chromophore in the initial state closing the photocatalytic loop and hence excluding the use of a sacrificial electron donor. Laser Flash Photolysis (LFP) studies and spectroscopic monitoring during photocatalysis lend credence to the proposed catalytic cycle., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Iron porphyrins are among the best molecular catalysts for the electrocatalytic CO 2 reduction reaction. Powering these catalysts with the help of photosensitizers comes along with a couple of unsolved challenges that need to be addressed with much vigor. We have designed an iron porphyrin catalyst decorated with urea functions (UrFe) acting as a multipoint hydrogen bonding scaffold towards the CO 2 substrate. We found a spectacular photocatalytic activity reaching unreported TONs and TOFs as high as 7270 and 3720 h -1 , respectively. While the Fe 0 redox state has been widely accepted as the catalytically active species, we show here that the Fe I species is already involved in the CO 2 activation, which represents the rate-determining step in the photocatalytic cycle. The urea functions help to dock the CO 2 upon photocatalysis. DFT calculations bring support to our experimental findings that constitute a new paradigm in the catalytic reduction of CO 2 ., (© 2022 Wiley-VCH GmbH.)

Electron relays play a crucial role for efficient light-induced activation by a photo-redox moiety of catalysts for multi-electronic transformations. Their insertion between the two units reduces detrimental energy transfer quenching while establishing at the same time unidirectional electron flow. This rectifying function allows charge accumulation necessary for catalysis. Mapping these events in photophysical studies is an important step towards the development of efficient molecular photocatalysts. Three modular complexes comprised of a Ru-chromophore, an imidazole electron relay function, and a terpyridine unit as coordination site for a metal ion were synthesized and the light-induced electron transfer events studied by laser flash photolysis. In all cases, formation of an imidazole radical by internal electron transfer to the oxidized chromophore was observed. The effect of added base evidenced that the reaction sequence depends strongly on the possibility for deprotonation of the imidazole function in a proton-coupled electron transfer process. In the complex with Mn II present as a proxy for a catalytic site, a strongly accelerated decay of the imidazole radical together with a decreased rate of back electron transfer from the external electron acceptor to the oxidized complex was observed. This transient formation of an imidazolyl radical is clear evidence for the function of the imidazole group as an electron relay. The implication of the imidazole proton and the external base for the kinetics and energetics of the electron trafficking is discussed., (© 2022. The Author(s), under exclusive licence to European Photochemistry Association, European Society for Photobiology.)

Understanding the reactivity landscape for the activation of water until the formation of the O-O bond and O 2 release in molecular chemistry is a decisive step in guiding the elaboration of cost-effective catalysts for the oxygen-evolving reaction (OER). Copper(II) complexes have recently caught the attention of chemists as catalysts for the 4e - /4H + water oxidation process. While a copper(IV) intermediate has been proposed as the reactive intermediate species, no spectroscopic signature has been reported so far. Copper(III) ligand radical species have also been formulated and supported by theoretical studies. We found, herein, that the reactivity sequence for the water oxidation with a family of Copper(II) o -phenylene bis-oxamidate complexes is a function of the substitution pattern on the periphery of the aromatic ring. In-situ EPR, FTIR, and rR spectroelectrochemical studies helped to sequence the elementary electrochemical and chemical events leading toward the O 2 formation selectively at the copper center. EPR and FTIR spectroelectrochemistry suggests that ligand-centered oxidations are preferred over metal-centered oxidations. rR spectroelectrochemical study revealed the accumulation of a bis-imine bound copper(II) superoxide species, as the reactive intermediate, under catalytic turnover, which provides the evidence for the O-O bond formation during OER.

In his pioneering work to unravel the catalytic power of enzymes, Warshel has pertinently validated that electrostatic interactions play a major role in the activation of substrates. Implementing such chemical artifice in molecular catalysts may help improve their catalytic properties. In this study, a series of tetra-, di-, and mono-substituted iron porphyrins with cationic imidazolium groups were designed. Their presence in the second coordination sphere helped stabilize the [Fe-CO 2 ] intermediate through electrostatic interactions. It was found herein that the electrocatalytic overpotential is a function of the number of embarked imidazolium. Importantly, a gain of six orders of magnitude in turnover frequencies was observed going from a tetra- to a mono-substituted catalyst. Furthermore, the comparative study showed that catalytic performances trend of through-space electrostatic interaction, a first topological effect reported for iron porphyrins, outperforms the classical through-structure electronic effect., (© 2021 Wiley-VCH GmbH.)

The manipulation of the second coordination sphere for improving the electrocatalytic CO 2 reduction has led to breakthroughs with hydrogen bonding, local proton source, or electrostatic effects. We have developed two atropisomers of an iron porphyrin complex with two urea functions acting as multiple hydrogen-bonding tweezers to lock the metal-bound CO 2 in a similar fashion found in the carbon monoxide dehydrogenase (CODH) enzyme. The αα topological isomer with the two urea groups on the same side of the porphyrin provides a stronger binding affinity to tether the incoming CO 2 in comparison to the αβ disposition. However, the electrocatalytic activity of the αβ atropisomer outperforms its congener with one of the highest reported turnover frequencies at low overpotential. The strong H/D kinetic isotope effect (KIE) observed for the αα system indicates the existence of a tight water hydrogen-bonding network for proton delivery which is disrupted by addition of an acid source. The small H/D KIE for the αβ isomer and the enhanced electrocatalytic performance on addition of stronger acid indicate the free access of protons to the bound CO 2 on the opposite side of the urea arm., (© 2020 Wiley-VCH GmbH.)

Inspired by the sulfur-rich environment found in active hydrogenase enzymes, a Ni-based proton reduction catalyst with pentadentate N 2 S 3 ligand was synthesised. When coupled with [Ru(bpy) 3 ] 2+ (bpy=2,2'-bipyridine) as photosensitiser and ascorbate as electron donor in a 1:1 mixture of dimethylacetamide and aqueous ascorbic acid/ascorbate buffer, the catalyst showed improved photocatalytic activity compared with a homologous counterpart bearing a tetradentate N 2 S 2 ligand. The mechanistic pathway of photoinduced hydrogen evolution was comprehensively analysed through optical transient absorption and time-resolved X-ray absorption spectroscopy, which revealed important electronic and structural changes in the catalytic system during photoirradiation. The Ni II catalyst undergoes a photoinduced metal-centred reduction to form a Ni I intermediate with distorted square-bipyramidal geometry. Further kinetic analyses revealed differences in charge-separation dynamics between the pentadentate and tetradentate forms., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Research in the development of new molecular catalysts for the selective transformation of CO2 to reduced forms of carbon is attracting enormous interest from chemists. Molecular catalyst design hinges on the elaboration of ligand scaffolds to manipulate the electronic and structural properties for the fine tuning of the reactivity pattern. A cornucopia of ligand sets have been designed along this line and more and more are being reported. In this quest, the porphyrin molecular platform has been under intensive focus due to the unmatched catalytic properties of metalloporphyrins. There have been rapid advances in this particular field during the last few years wherein both electronic and structural aspects in the second coordination spheres have been addressed to shift the overpotential and improve the catalytic rates and product selectivity. Metalloporphyrins have also attracted much attention in terms of the elaboration of hybrid materials for heterogeneous catalysis. Here too, some promising activities have made metalloporphyrin derivatives serious candidates for technological implementation. This review collects the recent advances centred around the chemistry of metalloporphyrins for the reduction of CO2.

Using light energy and O 2 for the direct chemical oxidation of organic substrates is a major challenge. A limitation is the use of sacrificial electron donors to activate O 2 by reductive quenching of the photosensitizer, generating undesirable side products. A reversible electron acceptor, methyl viologen, can act as electron shuttle to oxidatively quench the photosensitizer, [Ru(bpy) 3 ] 2+ , generating the highly oxidized chromophore and the powerful reductant methyl-viologen radical MV +. . MV +. can then reduce an iron(III) catalyst to the iron(II) form and concomitantly O 2 to O 2 .- in an aqueous medium to generate an active iron(III)-(hydro)peroxo species. The oxidized photosensitizer is reset to its ground state by oxidizing an alkene substrate to an alkenyl radical cation. Closing the loop, the reaction of the iron reactive intermediate with the substrate or its radical cation leads to the formation of two oxygenated compounds, the diol and the aldehyde following two different pathways., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrochemistry and electrocatalysis have been receiving increased attention recently due to their crucial contribution to electrical-to-chemical conversion systems. We describe here the development and operation of a new spectroelectrochemical transmission cell for time-resolved X-ray absorption spectroscopy of solutions. X-ray absorption spectra were recorded on the ROCK beamline of SOLEIL under constant and scanning potentials. Spectra were recorded at a frequency of 2 Hz during a cyclic voltammetry experiment performed on a 20 mM solution of Fe III Cl 3 ·6H 2 O at 20 mV s -1 scanning speed. Spectra with good signal-to-noise ratios were obtained when averaging ten spectra over 5 s, corresponding to a 100 mV potential range. A 90% conversion rate from Fe(III) to Fe(II) was spectroscopically demonstrated in cyclic voltammetry mode.

A trinuclear triphenylene trisemiquinone complex containing paramagnetic NiII is obtained under ambient conditions from the reaction of deprotonated tricatecholate hexahydroxytriphenylene (H6HHTP) with NiII capped with a trispyrazolyl borate tridentate ligand. The magnetic and EPR data are consistent with delocalization of the electronic spin over the three NiII species. The two-electron reduced complex shows an EPR spectrum corresponding to a S = 1/2 species due to a large antiferromagnetic coupling between the radical and only one of the NiII ions highlighting the localization of the electronic spin. No EPR signal is observed for the one- and three-electron reduced species consistent with the closed shell of the bridging ligand.

Inspired by nature's orchestra of chemical subtleties to activate and reduce CO 2 , we have developed a family of iron porphyrin derivatives in to which we have introduced urea groups functioning as multipoint hydrogen-bonding pillars on the periphery of the porphyrinic ring. This structure closely resembles the hydrogen-bond stabilization scheme of the carbon dioxide (CO 2 ) adduct in the carbon monoxide dehydrogenase (CODH). We found that such changes to the second coordination sphere significantly lowered the overpotential for CO 2 reduction in this family of molecular catalysts and importantly increased the CO 2 binding rate while maintaining high turnover frequency (TOF) and selectivity. Entrapped water molecules within the molecular clefts were found to be the source of protons for the CO 2 reduction., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, we report, for the first time, the synthesis of two original nanosystems, based on gold Au(III) and copper Cu(II): simple gold-copper nanoparticles (Cu 0 AuNPs) and enriched monopicolinate cyclam (L1)-Cu(II)-Au(III)-complex (L1@Cu 2+ AuNPs). The two nanomaterials differ substantially by the chelation or not of the Cu(II) ions during the NPs synthesis process. The two hybrid nanoparticles (Cu 0 AuNPs; L1@Cu 2+ AuNPs) were deeply studied from the chemical and physical point of view, using many different analytical techniques such as Raman and UV-vis spectroscopy, electron transmission microscopy, and dynamic light scattering. Both nanosystems show morphological and good chemical stability at pH 4 values and in physiological conditions during 98 h. Undifferentiated and neural differentiated murine embryonic stem cells were used as a model system for in vitro experiments to reveal the effects of NPs on these cells. The comparative study between Cu 0 AuNPs and L1@Cu 2+ AuNPs highlights that copper chelated in its +2 oxidation state in the NPs is more functional for biological application., Competing Interests: The authors declare no competing financial interest.

In this study we report a strategy to attach methylimidazolium fragments as ionic liquid units on an established iron porphyrin catalyst for the selective reduction of CO2 to CO. Importantly, we found that the tetra-methylimidazolium containing porphyrin exhibits an exalted electrocatalytic activity at low overpotential in water precluding the need for an external proton donor.

We investigate a biomimetic model of a Tyr Z /His 190 pair, a hydrogen-bonded phenol/imidazole covalently attached to a porphyrin sensitizer. Laser flash photolysis in the presence of an external electron acceptor reveals the need for water molecules to unlock the light-induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties. The first phase is related to a one-electron transfer from the phenol to the porphyrin radical cation coupled with a domino two-proton transfer leading to the ejection of a proton from the imidazole-phenol pair. The second phase concerns conveying the released proton to the porphyrin N 4 coordinating cavity. Our study provides an unprecedented example of a light-induced electron-transfer process in a Tyr Z /His 190 model of photosystem II, evidencing the movement of both the phenol and imidazole protons along an isoenergetic pathway., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purpose: Although recent data from the literature suggest that PET imaging with [18]-Fluorodeoxyglucose ( 18 F-FDG) is a promising technique in multiple myeloma (MM), the development of other radiopharmaceuticals seems relevant. CD138 is currently used as a standard marker in many laboratories for the identification and purification of myeloma cells, and could be used in phenotype tumor imaging. In this study, we evaluated a 64 Cu-labeled anti-CD138 murine antibody ( 64 Cu-TE2A-9E7.4) and a metabolic tracer ( 64 CuCl 2 ) for PET imaging in a MM syngeneic mouse model., Experimental Design and Results: 64 Cu-TE2A-9E7.4 antibody and 64 CuCl2 were evaluated via PET imaging and biodistribution studies in C57BL / KaLwRij mice bearing either 5T33-MM subcutaneous tumors or bone lesions. These results were compared to 18F-FDG-PET imaging. Autoradiography and histology of representative tumors were secondly conducted. In biodistribution and PET studies, 64 Cu-TE2A-9E7.4 displayed good tumor uptake of subcutaneous and intra-medullary lesions, greater than that demonstrated with 18 F-FDG-PET. In control experiments, only low-level, non-specific uptake of 64 Cu-labeled isotype IgG was observed in tumors. Similarly, low activity concentrations of 64 CuCl 2 were accumulated in MM lesions. Histopathologic analysis of the immuno-PET-positive lesions revealed the presence of plasma cell infiltrates within the bone marrow., Conclusions: 64 Cu-labeled anti-CD138 antibody can detect subcutaneous MM tumors and bone marrow lesions with high sensitivity, outperforming 18 F-FDG-PET and 64 CuCl 2 in this preclinical model. These data support 64 Cu-anti-CD138 antibody as a specific and promising new imaging radiopharmaceutical agent in MM., Competing Interests: CONFLICTS OF INTEREST The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflicts of interest.

Aiming to develop new copper chelates for application in nuclear medicine we report two new chelators, te1th and te2th, based on a cyclam backbone mono-N- or di-N1,N8-functionalized by methylthiazolyl arms. The acid-base properties of both ligands were investigated as well as their coordination chemistry, especially with Cu(2+), when possible in aqueous solution and in the solid state. Single-crystal X-ray diffraction structures of complexes were determined. Stability constants of the copper(II) and zinc(II) complexes showed that the complexes of both ligands with Cu(2+) are thermodynamically very stable, and they exhibit an important selectivity for Cu(2+) over Zn(2+). The kinetic inertness in acidic medium of both copper(II) complexes was evaluated revealing a quite good resistance to dissociation (the half-life times of complexes with te1th and te2th are 50.8 and 5.8 min, respectively, in 5 M HCl and 30 °C). The coordination geometry of the metal center in the complexes was established in aqueous solution based on UV-visible, electron paramagnetic resonance (EPR) spectroscopy, DFT studies, and NMR by using the zinc(II) complex analogues. The [Cu(te1th)](2+) and [Cu(te2th)](2+) complexes adopt trans-I and trans-III configurations both in the solid state and in solution, while the [Zn(te2th)](2+) complex crystallizes as the cis-V isomer but exists in solution as a mixture of trans-III and cis-V forms. Cyclic voltammetry experiments in acetonitrile point to a relatively easy reduction of [Cu(te2th)](2+) in acetonitrile solution (Epc = -0.41 V vs NHE), but the reduced complex does not undergo dissociation in the time scale of our electrochemical experiments. The results obtained in these studies revealed that despite the limited solubility of its copper(II) chelate, te2th is an attractive chelator for Cu(2+) that provides a fast complexation process while forming a complex with a rather high thermodynamic stability and kinetic inertness with respect to dissociation even upon electrochemical reduction.

Azamacrocyclic bifunctional chelating agents (BCAs) are essential for the development of radiopharmaceuticals in nuclear medicine and we wish to prove that their bioconjugation by a function present on a carbon atom of the macrocyclic skeleton is a solution of choice to maintain their in vivo inertness. Based on our very recent methodology using a bisaminal template and selective N-alkylation approach, a new synthesis of conjugable C-functionalised teta, te2a and cb-te2a has been developed. These chelators have indeed a growing interest in nuclear medicine for positron emission tomography (PET) and radioimmunotherapy (RIT) where they show in several cases better complexation properties than dota or dota-like macrocycles, especially with (64)Cu or (67)Cu radioisotopes. Chelators are bearing an isothiocyanate grafting function introduced by C-alkylation to avoid as much as possible a critical decrease of their chelating properties. The synthesis is very efficient and yields the targeted ligands, teta-Ph-NCS, te2a-Ph-NCS and cb-te2a-Ph-NCS without fastidious work-up and could be easily extended to other cyclam based-BCAs. The newly synthetised te2a-Ph-NCS has been conjugated to an anti mCD138 monoclonal antibody (mAb) to evaluate its in vivo behavior and potentiality as BCA and to explore a first attempt of PET-phenotypic imaging in multiple myeloma (MM). Mass spectrometry analysis of the immunoconjugate showed that up to 4 chelates were conjugated per 9E7.4 mAb. The radiolabeling yield and specific activity post-purification of the bioconjugate 9E7.4-CSN-Ph-te2a were 95 ± 2.8% and 188 ± 27 MBq mg(-1) respectively and the immunoreactivity of (64)Cu-9E7.4-CSN-Ph-te2a was 81 ± 7%. Animal experiments were carried out on 5T33-Luc(+) tumor bearing mice, either in subcutaneous or orthotopic. To achieve PET imaging, mice were injected with (64)Cu-9E7.4-CNS-Ph-te2a and acquisitions were conducted 2 and 20 h post-injection (PI). A millimetric bone uptake was localised in a sacroiliac of a MM orthotopic tumor. Nonspecific uptakes were observed at 2 h PI but, unlike for the tumor, a significant decrease was observed at 20 h PI which improves the contrast of the images.

The synthesis of a new cross-bridged 1,4,8,11-tetraazacyclotetradecane (cb-cyclam) derivative bearing a picolinate arm (Hcb-te1pa) was achieved by taking advantage of the proton sponge properties of the starting constrained macrocycle. The structure of the reinforced ligand as well as its acid-base properties and coordination properties with Cu(2+) and Zn(2+) was investigated. The X-ray structure of the free ligand showed a completely preorganized conformation that lead to very fast copper(II) complexation under mild conditions (instantaneous at pH 7.4) or even in acidic pH (3 min at pH 5) at room temperature and that demonstrated high thermodynamic stability, which was measured by potentiometry (at 25 °C and 0.10 M in KNO3). The results also revealed that the complex exists as a monopositive copper(II) species in the intermediate pH range. A comparative study highlighted the important selectivity for Cu(2+) over Zn(2+). The copper(II) complex was synthesized and investigated in solution using different spectroscopic techniques and DFT calculations. The kinetic inertness of the copper(II) complex in acidic medium was evaluated by spectrophotometry, revealing the very slow dissociation of the complex. The half-life of 96 days, in 5 M HClO4, and 465 min, in 5 M HCl at 25 °C, show the high kinetic stability of the copper(II) chelate compared to that of the corresponding complexes of other macrocyclic ligands. Additionally, cyclic voltammetry experiments underlined the perfect electrochemical inertness of the complex as well as the quasi-reversible Cu(2+)/Cu(+) redox system. The coordination geometry of the copper center in the complex was established in aqueous solution from UV-vis and EPR spectroscopies.

We describe an easy synthesis of original C-functionalized cyclam derivatives based on the efficient bisaminal template method. In the perspective of developing bifunctional chelating agents (BCAs), this new synthetic strategy offers the possibility of introducing various coupling functions on one carbon atom in the β-N position of the macrocycle, leaving the four nitrogen atoms available for the introduction of pendant coordinating arms. The methodology is based on a keystone C-functionalized oxo-cyclam bisaminal intermediate that is obtained by cyclization of a preorganized tetraamine using various methyl acrylate analogues. These compounds constitute valuable precursors for selective preparation of mono- and di-N-protected C-functionalized cyclams and C-functionalized cyclams, cross-bridged cyclams, and oxo-cyclam derivatives. This approach was successfully adapted to the synthesis of three BCAs with great interest especially for biomedical applications: TETA, TE2A, and CB-TE2A. The structures of different intermediates and Cu(II) complexes of C-functionalized cyclam derivatives were confirmed using single-crystal X-ray diffraction, while reactivity of the key intermediates was rationalized by the analysis of the electrostatic potentials calculated at the TPSSh/6-311G(d,p) level.

The investigation of iron oxide-based positron emission tomography/magnetic resonance (PET/MR) multimodal imaging agents is an expanding field in which a variety of nanoparticle sizes, shapes, surface coatings and radioisotopes are open for exploration. This study develops iron oxide nanorods which are coated with various mixtures of poly(ethylene glycol) (PEG) and macrocyclic ligand (DO3A) via the formation of a silica layer on the surface. Gallium-68 radiolabelling of the nanorods was carried out in high radiochemical yields (RCY) and their stability in human serum was demonstrated for all constructs, even in the absence of the macrocyclic chelating unit. Further studies were carried out in an attempt to determine the appropriate amount of PEG coating to give optimal properties for future in vivo studies.

This study details the electronic structure of the heme–peroxo–copper adduct {[(F8)Fe(DCHIm)]-O2-[Cu(AN)]}+ (LS(AN)) in which O2(2–) bridges the metals in a μ-1,2 or “end-on” configuration. LS(AN) is generated by addition of coordinating base to the parent complex {[(F8)Fe]-O2-[Cu(AN)]}+ (HS(AN)) in which the O2(2–) bridges the metals in an μ-η2:η2 or “side-on” mode. In addition to the structural change of the O2(2–) bridging geometry, coordination of the base changes the spin state of the heme fragment (from S = 5/2 in HS(AN) to S = 1/2 in LS(AN)) that results in an antiferromagnetically coupled diamagnetic ground state in LS(AN). The strong ligand field of the porphyrin modulates the high-spin to low-spin effect on Fe–peroxo bonding relative to nonheme complexes, which is important in the O–O bond cleavage process. On the basis of DFT calculations, the ground state of LS(AN) is dependent on the Fe–O–O–Cu dihedral angle, wherein acute angles (<~150°) yield an antiferromagnetically coupled electronic structure while more obtuse angles yield a ferromagnetic ground state. LS(AN) is diamagnetic and thus has an antiferromagnetically coupled ground state with a calculated Fe–O–O–Cu dihedral angle of 137°. The nature of the bonding in LS(AN) and the frontier molecular orbitals which lead to this magneto-structural correlation provide insight into possible spin topology contributions to O–O bond cleavage by cytochrome c oxidase.

An efficient and selective four-electron plus four-proton (4e(-)/4H(+)) reduction of O(2) to water by decamethylferrocene and trifluoroacetic acid can be catalyzed by a synthetic analog of the heme a(3)/Cu(B) site in cytochrome c oxidase ((6)LFeCu) or its Cu-free version ((6)LFe) in acetone. A detailed mechanistic-kinetic study on the homogeneous catalytic system reveals spectroscopically detectable intermediates and that the rate-determining step changes from the O(2)-binding process at 25 °C room temperature (RT) to the O-O bond cleavage of a newly observed Fe(III)-OOH species at lower temperature (-60 °C). At RT, the rate of O(2)-binding to (6)LFeCu is significantly faster than that for (6)LFe, whereas the rates of the O-O bond cleavage of the Fe(III)-OOH species observed (-60 °C) with either the (6)LFeCu or (6)LFe catalyst are nearly the same. Thus, the role of the Cu ion is to assist the heme and lead to faster O(2)-binding at RT. However, the proximate Cu ion has no effect on the O-O bond cleavage of the Fe(III)-OOH species at low temperature.

The nature of the ligand is an important aspect of controlling the structure and reactivity in coordination chemistry. In connection with our study of heme-copper-oxygen reactivity relevant to cytochrome c oxidase dioxygen-reduction chemistry, we compare the molecular and electronic structures of two high-spin heme-peroxo-copper [Fe(III)O(2)(2-)Cu(II)](+) complexes containing N(4) tetradentate (1) or N(3) tridentate (2) copper ligands. Combining previously reported and new resonance Raman and EXAFS data coupled to density functional theory calculations, we report a geometric structure and more complete electronic description of the high-spin heme-peroxo-copper complexes 1 and 2, which establish mu-(O(2)(2-)) side-on to the Fe(III) and end-on to Cu(II) (mu-eta(2):eta(1)) binding for the complex 1 but side-on/side-on (mu-eta(2):eta(2)) mu-peroxo coordination for the complex 2. We also compare and summarize the differences and similarities of these two complexes in their reactivity toward CO, PPh(3), acid, and phenols. The comparison of a new X-ray structure of mu-oxo complex 2a with the previously reported 1a X-ray structure, two thermal decomposition products respectively of 2 and 1, reveals a considerable difference in the Fe-O-Cu angle between the two mu-oxo complexes ( angleFe-O-Cu = 178.2 degrees in 1a and angleFe-O-Cu = 149.5 degrees in 2a). The reaction of 2 with 1 equiv of an exogenous nitrogen-donor axial base leads to the formation of a distinctive low-temperature-stable, low-spin heme-dioxygen-copper complex (2b), but under the same conditions, the addition of an axial base to 1 leads to the dissociation of the heme-peroxo-copper assembly and the release of O(2). 2b reacts with phenols performing H-atom (e(-) + H(+)) abstraction resulting in O-O bond cleavage and the formation of high-valent ferryl [Fe(IV)=O] complex (2c). The nature of 2c was confirmed by a comparison of its spectroscopic features and reactivity with those of an independently prepared ferryl complex. The phenoxyl radical generated by the H-atom abstraction was either (1) directly detected by electron paramagnetic resonance spectroscopy using phenols that produce stable radicals or (2) indirectly detected by the coupling product of two phenoxyl radicals.

In order to investigate the possible coordination of both bismuth(III) and lead(II) by porphyrins for an application in alpha-radioimmunotherapy, several series of functionalized bismuth porphyrins have been synthesized and their stabilities in acidic medium were compared. Where unfunctionalized porphyrins are not suitable for such a purpose, strapped hanging carboxylate porphyrins are stable and allow a rapid coordination of both bismuth and lead. This property could lead to the preparation of an in-situ generator of alpha particles by a pre-complexation of (212)lead, the radioactive parent of (212)bismuth, in the ligand.

Simple chelating agents have been synthesized using a porphyrin and a covalently linked crown-ether. Depending on the relative spatial arrangement of both motifs, the resulting ligands, either a macrotricycle or bis-macrocycles, differ one from another by their flexibility or their aptitude to chelate bivalent or trivalent cations. The coordination chemistry as well as the structural study of these ligands and complexes are reported. In the particular case of the macrotricycle, the crown-ether motif, perpendicular to the porphyrin induces a side selectivity for the coordination of lead(II) outside the cavity. Furthermore, the coordination of zinc(II) implies a change of conformation of the ligand in which the crown-ether is parallel to the porphyrin.

We report the coordination studies of porphyrins with pre-organized but yet flexible straps, each bearing over the center of the porphyrin either a 2,2-malonic acid diethyl ester residue or a 2,2-malonic acid residue. The straps are attached to the porphyrin via two adjacent meso positions, 5,10 and 15,20, respectively, and the 2,2-malonic acid diethyl ester groups are connected to the straps on benzylic carbon atoms. These two structural features allow a significant flexibility of the straps, as confirmed by the comparison of the X-ray structures of the zinc, nickel, and lead complexes of porphyrin 1. In the latter, the influence of the lone-electron pair of lead is clearly demonstrated. The coordination of bismuth is also reported.

New picket porphyrins delivering at least one carboxylic group around the coordination site of the macrocycle were synthesized for bismuth coordination. The influence of the number, the length, and the pre-organization of the carboxylic acid pickets on the stability of the bismuth complexes was explored. Their stabilities in acidic medium were compared with those of their precursors bearing ester pickets. The molecular structure of one of the bismuth complexes, which is the only monomeric bismuth porphyrin reported up to now, is discussed. At the opposite of what we initially reported, and in agreement with the theoretical calculations, the distortion of the macrocycle in this structure is mainly due to the number of water molecules in the first sphere of coordination of the bismuth.

A single carboxylate picket bismuth porphyrin has been characterised in the solid state as the first instance of a non-dimeric structure; the carboxylate picket, bent over the macrocycle, is coordinated to the bismuth, inducing a significant distortion of the porphyrin core.