| 1. |
- Ruggeri, Kai, et al.
(författare)
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The globalizability of temporal discounting
- 2022
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Ingår i: Nature Human Behaviour. - : Springer Nature. - 2397-3374. ; 6:10, s. 1386-1397
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Tidskriftsartikel (refereegranskat)abstract
- Economic inequality is associated with preferences for smaller, immediate gains over larger, delayed ones. Such temporal discounting may feed into rising global inequality, yet it is unclear whether it is a function of choice preferences or norms, or rather the absence of sufficient resources for immediate needs. It is also not clear whether these reflect true differences in choice patterns between income groups. We tested temporal discounting and five intertemporal choice anomalies using local currencies and value standards in 61 countries (N = 13,629). Across a diverse sample, we found consistent, robust rates of choice anomalies. Lower-income groups were not significantly different, but economic inequality and broader financial circumstances were clearly correlated with population choice patterns. Ruggeri et al. find in a study of 61 countries that temporal discounting patterns are globally generalizable. Worse financial environments, greater inequality and high inflation are associated with extreme or inconsistent long-term decisions.
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| 2. |
- de Groot, Lisa H.M., et al.
(författare)
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Iron Photoredox Catalysis-Past, Present, and Future
- 2023
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Ingår i: Journal of the American Chemical Society. - 0002-7863. ; 145:17, s. 9369-9388
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Forskningsöversikt (refereegranskat)abstract
- Photoredox catalysis of organic reactions driven by iron has attracted substantial attention throughout recent years, due to potential environmental and economic benefits. In this Perspective, three major strategies were identified that have been employed to date to achieve reactivities comparable to the successful noble metal photoredox catalysis: (1) Direct replacement of a noble metal center by iron in archetypal polypyridyl complexes, resulting in a metal-centered photofunctional state. (2) In situ generation of photoactive complexes by substrate coordination where the reactions are driven via intramolecular electron transfer involving charge-transfer states, for example, through visible-light-induced homolysis. (3) Improving the excited-state lifetimes and redox potentials of the charge-transfer states of iron complexes through new ligand design. We seek to give an overview and evaluation of recent developments in this rapidly growing field and, at the same time, provide an outlook on the future of iron-based photoredox catalysis.
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| 3. |
- Ilic, Aleksandra
(författare)
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Investigation of Iron-N-Heterocyclic Carbene Complexes for Photocatalytic Applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Humanity’s ever-growing energy demands require the implementation of more sustainable ways to harvest and store energy. At the same time, the reduction of greenhouse gas emission and thus global warming remains of paramount importance. To this end, solar energy harvesting presents an attractive route towards satisfying these requirements—be that by conversion to thermal energy, electricity or to chemical energy. Molecular systems based on iron could prove particularly interesting in this area, due to their advantageous properties such as appreciable visible light-absorption as well as the high availability and low cost of iron. As of yet, they have not been extensively studied though, which can be attributed to the inherently poor photophysical and -chemical properties associated with these systems. However, well thought-out structural design can be used to combat said issues.The ligand motif used in Fe-N-heterocyclic carbene (NHC) complexes aids in mitigating the formerly mentioned unfavourable properties, allowing for bimolecular quenching with electron donors and acceptors to occur, which is crucial for photocatalysis. In this thesis, the application of hexa-NHC complexes based on Earth-abundant iron as light-harvesters for solar-to-chemical energy conversion is demonstrated. The utility of Fe(III)-NHC complexes for sensitisation of artificial photosynthesis reactions as well as their performance as photoredox catalysts in organic transformations has been studied and the underlying mechanisms have been investigated, giving insight into the prospects and limitations associated with these systems. For the hydrogen evolution and aminomethylation reactions investigated here, conventional single-photon mechanisms were observed. Meanwhile, in the case of the atom transfer radical addition reactions, sequential photon absorption of two different oxidation states of the catalyst within the same catalytic turnover was shown to be operative. Furthermore, a study featuring the Fe(II)-congener of an Fe(III)-NHC complex with demonstrated photocatalytic activity revealed a less than favourable excited state lifetime compared to the Fe(III)-parent complex, showcasing that the preparation of Fe(II)-NHC complexes with synthetically useful photophysical and chemical properties is not necessarily facile. Early investigations of a photocatalytic reaction driven by heterogenisation of Fe(III)-NHC complexes are also shown. There the goal was to improve upon the sustainability of these catalysts by facilitating their recyclability. This thesis thus showcases the potential of Fe-NHC complexes for photocatalytic applications, whilst also revealing their shortcomings.
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| 4. |
- Ilic, Aleksandra, et al.
(författare)
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Photoredox catalysis via consecutive 2LMCT- and 3MLCT-excitation of an Fe(iii/ii)–N-heterocyclic carbene complex
- 2022
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Ingår i: Chemical Science. - : Royal Society of Chemistry. - 2041-6520 .- 2041-6539. ; 13:32, s. 9165-9175
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Tidskriftsartikel (refereegranskat)abstract
- Fe-N-heterocyclic carbene (NHC) complexes attract increasing attention as photosensitisers and photoredox catalysts. Such applications generally rely on sufficiently long excited state lifetimes and efficient bimolecular quenching, which leads to there being few examples of successful usage of Fe-NHC complexes to date. Here, we have employed [Fe(iii)(btz)(3)](3+) (btz = (3,3 '-dimethyl-1,1 '-bis(p-tolyl)-4,4 '-bis(1,2,3-triazol-5-ylidene))) in the addition of alkyl halides to alkenes and alkynes via visible light-mediated atom transfer radical addition (ATRA). Unlike other Fe-NHC complexes, [Fe(iii/ii)(btz)(3)](3+/2+) benefits from sizable charge transfer excited state lifetimes >= 0.1 ns in both oxidation states, and the Fe(iii) (LMCT)-L-2 and Fe(ii) (MLCT)-M-3 states are strong oxidants and reductants, respectively. The combined reactivity of both excited states enables efficient one-electron reduction of the alkyl halide substrate under green light irradiation. The two-photon mechanism proceeds via reductive quenching of the Fe(iii) (LMCT)-L-2 state by a sacrificial electron donor and subsequent excitation of the Fe(ii) product to its highly reducing (MLCT)-M-3 state. This route is shown to be more efficient than the alternative, where oxidative quenching of the less reducing Fe(iii) (LMCT)-L-2 state by the alkyl halide drives the reaction, in the absence of a sacrificial electron donor.
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| 5. |
- Prakash, Om, et al.
(författare)
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Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived 2LMCT Excited States
- 2022
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 61:44, s. 17515-17526
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Tidskriftsartikel (refereegranskat)abstract
- Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6 (brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]–, [Fe(meophtmeimb)2]PF6 (meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]–, and [Fe(coohphtmeimb)2]PF6 (coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]–. These were derived from the parent complex [Fe(phtmeimb)2]PF6 (phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]– by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (2LMCT) excited states feature nanosecond lifetimes (1.6–1.7 ns) and sizable emission quantum yields (1.7–1.9%) through spin-allowed transition to the doublet ground state (2GS), completely in line with the parent complex [Fe(phtmeimb)2]PF6 (2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.
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| 6. |
- Rosemann, Nils W., et al.
(författare)
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Competing dynamics of intramolecular deactivation and bimolecular charge transfer processes in luminescent Fe(iii) N-heterocyclic carbene complexes
- 2023
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 14:13, s. 3569-3579
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Tidskriftsartikel (refereegranskat)abstract
- Steady state and ultrafast spectroscopy on [FeIII(phtmeimb)2]PF6 (phtmeimb = phenyl(tris(3-methylimidazol-2-ylidene))borate) was performed over a broad range of temperatures. The intramolecular deactivation dynamics of the luminescent doublet ligand-to-metal charge-transfer (2LMCT) state was established based on Arrhenius analysis, indicating the direct deactivation of the 2LMCT state to the doublet ground state as a key limitation to the lifetime. In selected solvent environments photoinduced disproportionation generating short-lived Fe(iv) and Fe(ii) complex pairs that subsequently undergo bimolecular recombination was observed. The forward charge separation process is found to be temperature-independent with a rate of ∼1 ps−1. Subsequent charge recombination takes place in the inverted Marcus region with an effective barrier of 60 meV (483 cm−1). Overall, the photoinduced intermolecular charge separation efficiently outcompetes the intramolecular deactivation over a broad range of temperatures, highlighting the potential of [FeIII(phtmeimb)2]PF6 to perform photocatalytic bimolecular reactions.
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| 7. |
- Schwarz, Jesper, et al.
(författare)
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High turnover photocatalytic hydrogen formation with an Fe(iii) N-heterocyclic carbene photosensitiser
- 2022
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 58:35, s. 5351-5354
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Tidskriftsartikel (refereegranskat)abstract
- Herein we report the first high turnover photocatalytic hydrogen formation reaction based on an earth-abundant Fe-III-NHC photosensitiser. The reaction occurs via reductive quenching of the (LMCT)-L-2 excited state that can be directly excited with green light and employs either Pt-colloids or [Co(dmgH)(2)pyCl] as proton reduction catalysts and [HNEt3][BF4] and triethanolamine/triethylamine as proton and electron donors. The outstanding photostability of the Fe-III-NHC complex enables turnover numbers >1000 without degradation.
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| 8. |
- Schwarz, Jesper, et al.
(författare)
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Simultaneous non-invasive gas analysis in artificial photosynthesis reactions using rotational Raman spectroscopy
- 2022
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Ingår i: Sustainable Energy and Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 6:19, s. 4388-4392
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Tidskriftsartikel (refereegranskat)abstract
- Optimising reactions in artificial photosynthesis research requires screening of many reaction and operation parameters, which is often resource-intense and time-consuming. In this paper, we demonstrate the use of a rotational Raman-based spectrometer for non-invasive quantification of several gases (H2, O2, N2, CO, CO2) with short analysis times (15 s), enabling high throughput screening. Furthermore, with this device, reaction progress can be monitored in situ, by real-time simultaneous quantification of multiple gases. We have applied this instrument and developed a method to study the O2 dependency of a prototypic light-driven hydrogen evolution reaction, showcasing the value of this approach for the artificial photosynthesis community in general.
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| 9. |
- Vitabile, Salvatore, et al.
(författare)
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Medical Data Processing and Analysis for Remote Health and Activities Monitoring
- 2019
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Ingår i: High-Performance Modelling and Simulation for Big Data Applications. - Cham : Springer. - 9783030162719 - 9783030162726 ; , s. 186-220
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Bokkapitel (refereegranskat)abstract
- Recent developments in sensor technology, wearable computing, Internet of Things (IoT), and wireless communication have given rise to research in ubiquitous healthcare and remote monitoring of human’s health and activities. Health monitoring systems involve processing and analysis of data retrieved from smartphones, smart watches, smart bracelets, as well as various sensors and wearable devices. Such systems enable continuous monitoring of patients psychological and health conditions by sensing and transmitting measurements such as heart rate, electrocardiogram, body temperature, respiratory rate, chest sounds, or blood pressure. Pervasive healthcare, as a relevant application domain in this context, aims at revolutionizing the delivery of medical services through a medical assistive environment and facilitates the independent living of patients. In this chapter, we discuss (1) data collection, fusion, ownership and privacy issues; (2) models, technologies and solutions for medical data processing and analysis; (3) big medical data analytics for remote health monitoring; (4) research challenges and opportunities in medical data analytics; (5) examples of case studies and practical solutions.
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| 10. |
- Zhang, Minli, et al.
(författare)
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High-Efficiency Photoinduced Charge Separation in Fe(III)carbene Thin Films
- 2023
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 145:35, s. 19171-19176
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Tidskriftsartikel (refereegranskat)abstract
- Symmetry-breaking charge separation in molecular materials has attracted increasing attention for optoelectronics based on single-material active layers. To this end, Fe(III) complexes with particularly electron-donating N-heterocyclic carbene ligands offer interesting properties with a 2LMCT excited state capable of oxidizing or reducing the complex in its ground state. In this Communication, we show that the corresponding symmetry-breaking charge separation occurs in amorphous films of pristine [Fe(III)L2]PF6 (L = [phenyl(tris(3-methylimidazol-2-ylidene))borate]−). Excitation of the solid material with visible light leads to ultrafast electron transfer quenching of the 2LMCT excited state, generating Fe(II) and Fe(IV) products with high efficiency. Sub-picosecond charge separation followed by recombination in about 1 ns could be monitored by transient absorption spectroscopy. Photoconductivity measurements of films deposited on microelectrode arrays demonstrated that photogenerated charge carriers can be collected at external contacts.
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