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Introduction: Cognitive accessibility is part of the overall accessibility framework. Cognitive accessibility means that services are simple, coherent, clear, multimodal, error tolerant and focused, taking into account all users. Aims: to validate a questionnaire on cognitive accessibility to be applied to health professionals. Methods: The study has a quantitative approach, with a non-experimental and cross-sectional design, developed in the period between March and June 2022. The sample consisted of 130 health professionals in Argentina, selected by means of purposive sampling. Results: the validation process was carried out in three stages. The analysis of internal consistency (reliability) was performed through Cronbach's Alpha. The descriptive results with the 17 items showed a variance of each item of 4.445, a total variance of 13.049, with a total Cronbach's Alpha of 0.701, showing that the instrument presents internal consistency. Conclusions: It was possible to verify that the scores of both Cronbach's Alpha and the factorial analysis, allow affirming that the instrument has the necessary metric aspects to be used in future research, taking into account that the instrument had a previous evaluation by expert criteria. It can be considered that this article becomes the starting point for future studies, in which it is intended to continue the line of research, which allows the analysis of cognitive accessibility in the context of health professionals.

Extreme ultraviolet lithography (EUVL) is the current technology used in the semiconductor industry for the fabrication of integrated circuits (ICs), since it enables the further miniaturization of their components. For its optimal operation, photoresist materials that can efficiently use EUV photons (92 eV) to yield sub-10 nm patterns are required. However, there is a lack of understanding of the complex mechanisms induced by EUV radiation. In this work, we investigate the ability of a new Zn-based oxocluster to fulfil the state-of-the-art requirements for EUVL. This molecular material was conceived to provide high EUV absorptivity, owing to its contents of Zn, F, and O atoms, and high resolution, given its small molecular size. High sensitivity/reactivity towards EUV is achieved through its mixed-ligand organic shell composed of methacrylate and trifluoroacetate ligands. This new resist shows outstanding lithography performance yielding down to 22 nm half pitch line/space patterns at ∼20 mJ cm-2. Spectroscopy studies on EUV exposed samples revealed an unexpected reaction pathway where fluoride ions are formed. This is an unprecedented way of efficiently inducing a solubility switch in an inorganic resist upon EUV irradiation.

Metal-organic frameworks (MOFs) have attracted a lot of interest for their numerous properties. However they are usually obtained as a powder (bulk) or as single crystals, which complicates their i...

The absorption of extreme ultraviolet (EUV) radiation by a photoresist strongly depends on its atomic composition. Consequently, elements with a high EUV absorption cross section can assist in meeting the demand for higher photon absorbance by the photoresist to improve the sensitivity and reduce the photon shot noise induced roughness. In this work, we enhanced the EUV absorption of the methacrylic acid ligands of Zn oxoclusters by introducing fluorine atoms. We evaluated the lithography performance of this fluorine-rich material as a negative tone EUV photoresist along with extensive spectroscopic and microscopic studies, providing deep insights into the underlying mechanism. UV-vis spectroscopy studies demonstrate that the presence of fluorine in the oxocluster enhances its stability in the thin films to the ambient atmosphere. However, the EUV photoresist sensitivity (D50) of the fluorine-rich oxocluster is decreased compared to its previously studied methacrylic acid analogue. Scanning transmission X-ray microscopy and in situ X-ray photoelectron spectroscopy in combination with FTIR and UV-vis spectroscopy were used to gain insights into the chemical changes in the material responsible for the solubility switch. The results support decarboxylation of the ligands and subsequent radical-induced polymerization reactions in the thin film upon EUV irradiation. The rupture of carbon-fluorine bonds via dissociative electron attachment offers a parallel way of generating radicals. The mechanistic insights obtained here will be applicable to other hybrid materials and potentially pave the way for the development of EUV materials with better performance.

Extreme ultraviolet (EUV) lithography uses 13.5 nm light to reach the sub-20 nm resolution. However, the process of pattern formation induced by this high-energy light is not well-understood. In this work, we provide an inorganic EUV photoresist with fluorescence properties by introducing a carbazole derivative as a ligand, and we study its effect on the patterning process. Using the fluorescence properties, changes in the emission of the material after EUV exposure could be tracked by means of spectroscopy and microscopy. The resist sensitivity was substantially reduced by the incorporation of the carbazole benzoate ligands, which is attributed to hole trapping and steric hindrance. After EUV irradiation of the resist films, infrared, UV-visible absorption, and fluorescence spectroscopies showed that the carbazole units were still mostly intact, although their fluorescence intensity was lowered. Our work shows that fluorescent labeling can provide relevant mechanistic insights in the patterning process of resists, potentially with a molecular resolution.

The fabrication of integrated circuits with ever smaller (sub-10 nm) features poses fundamental challenges in chemistry and materials science. As smaller nanostructures are fabricated, thinner layers of materials are required, and surfaces and interfaces gain a more important role in the formation of nanopatterns. We present a new bottom-up approach in which we use the high optical resolution offered by extreme ultraviolet (EUV) lithography to print patterns on self-assembled monolayers (SAMs). Upon radiation, low-energy electrons induce chemical changes in the SAM so that the projected image is transferred to the substrate surface. We use the chemical differences between exposed and unexposed regions to promote a selective growth of hybrid structures that can act as an etch-resistant layer for further pattern transfer or can be used as functional nanostructures. The EUV doses required to promote selective growth on exposed areas are close to industrial requirements. Furthermore, this method allows for the independent tuning of different steps in the EUV lithography process (photo-induced chemistry, spatially resolved chemical contrast, and formation of nanopatterns), an advantage over current resists, in which the same material plays all roles.

Extreme ultraviolet (EUV) lithography (13.5 nm) is the newest technology that allows high-throughput fabrication of electronic circuitry in the sub-20 nm scale. It is commonly assumed that low-energy electrons (LEEs) generated in the resist materials by EUV photons are mostly responsible for the solubility switch that leads to nanopattern formation. Yet, reliable quantitative information on this electron-induced process is scarce. In this work, we combine LEE microscopy (LEEM), electron energy loss spectroscopy (EELS), and atomic force microscopy (AFM) to study changes induced by electrons in the 0–40 eV range in thin films of a state-of-the-art molecular organometallic EUV resist known as tin-oxo cage. LEEM–EELS uniquely allows to correct for surface charging and thus to accurately determine the electron landing energy. AFM postexposure analyses revealed that irradiation of the resist with LEEs leads to the densification of the resist layer because of carbon loss. Remarkably, electrons with energies as low as 1.2 eV can induce chemical reactions in the Sn-based resist. Electrons with higher energies are expected to cause electronic excitation or ionization, opening up more pathways to enhanced conversion. However, we do not observe a substantial increase of chemical conversion (densification) with the electron energy increase in the 2–40 eV range. Based on the dose-dependent thickness profiles, a simplified reaction model is proposed where the resist undergoes sequential chemical reactions, first yielding a sparsely cross-linked network and then a more densely cross-linked network. This model allows us to estimate a maximum reaction volume on the initial material of 0.15 nm3 per incident electron in the energy range studied, which means that about 10 LEEs per molecule on average are needed to turn the material insoluble and thus render a pattern. Our observations are consistent with the observed EUV sensitivity of tin-oxo cages.

Organic-inorganic hybrid compounds are arising as promising resist materials for extreme-ultraviolet (EUV) lithography, a new technique introduced in the semiconductor industry for the fabrication of integrated circuits of sub-10 nm feature size. In this work, we show that the sensitivity to EUV radiation of zirconium oxo clusters with methacrylate ligands is substantially enhanced when a small fraction of the ligands are replaced by trifluoromethylacrylates. We studied the details of the chemical changes that occur in thin films of the precursor and the partially fluorinated materials using scanning transmission X-ray microscopy (STXM) and X-ray photoelectron spectroscopy (XPS). Evidence is presented for radical chain polymerization as a mechanism for the solubility switch. Yet, XPS results also indicate that Zr-F bonds are formed during the exposure to EUV light in the fluorinated material, dissociative electron attachment being likely involved. Our observations show that, while fluorinated ligands enhance EUV absorption, their effect on the reactivity of the material might be more critical, thereby contributing to an increase in the sensitivity of the resist in both ways.

Metal‐containing molecular hybrid compounds, such as metal oxoclusters (MOCs), are promising materials for extreme ultraviolet (EUV) lithography. The solubility, processability, and reactivity towards EUV photons in these compounds are mostly determined by the composition of their organic shells. Therefore, gaining molecular control on the composition of the shell is crucial to tune their lithographic performance of sensitivity, resolution, and line‐edge roughness. In this work, a new method to prepare MOCs that feature two types of carboxylate ligands is presented. In this method, amine‐functionalized resins are used for the purification step. By using this protocol, Ti‐ and Zr‐based MOCs with mixed‐ligands organic shells were synthesized. The new compounds showed clear differences in the processability and sensitivity as EUV resists compared to their analogues featuring only one type of ligand. The results validate this new synthetic approach for the preparation of custom‐made EUV resists towards better lithographic performance.

Low-energy electrons are released whenever ionizing high-energy radiation interacts with matter. They drive chemical reactions in the irradiated material, enable state-of-the art nanofabrication technologies such as focused electron beam induced deposition (FEBID), and contribute to the reactions of resist materials in extreme ultraviolet lithography (EUVL). This contribution presents fundamental research on the role of low-energy electrons in FEBID and EUVL. We discuss how reactions initiated by low-energy electrons can be exploited in FEBID to obtain metal-containing deposits with optimal purity. Regarding EUVL, the role of low-energy electrons in the conversion of an inorganic resist by EUV absorption has been investigated.

Recently, imec has installed and commissioned an industrial, ultrafast EUV materials characterization and lithography lab, imec’s AttoLab, with a primary aim to explore limits of photoresist performance and their associated ultrafast chemistries. Here, we demonstrate, for the first time, the use of a table-top, high-harmonic EUV system (KM Labs, XUUS4) to perform interference lithography of sub-22-nm pitch patterns in an Inpria MOx resist via a Lloyd’s mirror interference lithography (IL) tool. Analysis of SEM images enables us to identify potential sources of image blur, which we attribute to out-of-sync vibrations, flare, spectral purity, and laser stability. Nevertheless, these results confirm the ability of table-top, high-harmonic EUV sources to print lithographic patterns below a 22-nm pitch. In future work, we plan to investigate sub-20-nm patterning in different resist formulations, as well as expand the lithographic capabilities in AttoLab to perform IL on full 300-mm wafers.

The electron-induced chemistry of a resist material for extreme ultraviolet lithography (EUVL) consisting of Zn oxoclusters with methacrylate (MA) and trifluoroacetate (TFA) ligands (Zn(MA)(TFA)) has been studied. Electron energies of 80 eV and 20 eV mimic the effect of photoelectrons released by the absorption of EUV photons and low-energy secondary electrons (LESEs) produced by those photoelectrons. The chemical conversion of the resist is studied by mass spectrometry to monitor the volatile species that desorb during electron irradiation, combined with reflection absorption infrared spectra (RAIRS) measured before and after irradiation. The observed reactions are closely related to those initiated upon EUV absorption. Also, the conversion of the Zn(MA)(TFA) resist layer that is required in EUVL is achieved by a similar energy input upon electron irradiation. The dominant component of the desorbing gas is CO2, but CO detection also suggests Zn oxide formation during electron irradiation. In contrast, species deriving from the ligand side chains predominantly remain within the resist layer. RAIRS gives direct evidence that, during electron irradiation, C Created by potrace 1.16, written by Peter Selinger 2001-2019 C bonds of the MA ligands are more rapidly consumed than the carboxylate groups. This supports that chain reactions occur and contribute to the solubility switch in the resist in EUVL. Remarkably, 20 eV electrons still evolve roughly 50% of the amount of the gas that is observed at 80 eV for the same electron dose. The present results thus provide complementary and new insight to the EUV-induced chemistry in the Zn(MA)(TFA) resist and point towards the important contribution of low-energy electrons therein., Electron-induced reactions make an important contribution to the solubility switch of a novel Zn oxocluster resist in extreme ultraviolet lithography (EUVL). The study also gives direct evidence that chain reactions are involved in this process.

Happiness at work requires a good working environment, which undoubtedly improves productivity. In this sphere, the concept is closely related to job satisfaction, which is one of the main factors determining individual happiness, along with home ownership, security, and a healthy environment. Innovative policies to improve corporate well-being&mdash, organizational ethics&mdash, improve the image of the company, and help transfer the concept of &lsquo, happy management&rsquo, to all stakeholders. In addition, remote working, which has become essential for many during the COVID-19 pandemic, poses a key issue in terms of human resource management that needs to be taken into account. Using a survey of working-age Spanish citizens, we established a measure of organizational ethics based on the possible discrepancy between citizens&rsquo, personal happiness and their happiness at work. The analysis focused on one of the essential economic sectors in the face of the pandemic, the financial sector. These workers demand organizational ethics with clear values in social responsibility and training, going beyond the achievement of a socially acceptable income. A comparative linear model is also used to test the relationships between a number of conditioning variables and organizational ethics. Citizens&rsquo, /workers&rsquo, priorities are found to shift towards quality of life with a healthy environment, rather than sustainability.

Colloidal quantum dots have found many applications and patterning them on micro- and nanoscale would open a new dimension of tunability for the creation of smaller scale (flexible) electronics or nanophotonic structures. Here we present a simple, general, one-step top-down patterning technique for colloidal quantum dots by means of direct optical or electron beam lithography. We find that both photons and electrons can induce a solubility switch of both PbS and CdSe quantum dot films. The solubility switch can be ascribed to cross-linking of the organic ligands, which we observe from exposure with deep-UV photons (5.5 eV) to extreme-UV photons (91.9 eV), and low-energy (3–70 eV) as well as highly energetic electrons (50 keV). The required doses for patterning are relatively low and feature sizes can be as small as tens of nanometers. The luminescence properties as well as carrier lifetimes remain similar after patterning.

The investigation of the photoionization processes of a series of titanium oxo clusters evidenced that doping their organic shell with extended aromatic structures decreases their ionization energy and stabilises the resulting radical cations. Such tunability of their photochemistry arising from ligand exchange gives these hybrid compounds great potential as EUV photoresists.

Inorganic molecular materials such as tin oxo cages are a promising generation of photoresists compatible with the demands of the recently developed Extreme UltraViolet (EUV) lithography technology. Therefore, a detailed understanding of the photon-induced reactions which occur in photoresists after exposure is important. We used XUV broadband laser pulses in the range of 25-40 eV from a table-top high-harmonic source to expose thin films of the tin oxo cage resist to shed light on some of the photo-induced chemistry via XUV absorption spectroscopy. During the exposure, the transmitted spectra were recorded and a noticeable absorbance decrease was observed in the resist. Dill parameters were extracted to quantify the XUV induced conversion and compared to EUV exposure results at 92 eV. Based on the absorption changes, we estimate that approximately 60% of tin-carbon bonds are cleaved at the end of the exposure., 8 pages, 8 figures

Advanced atomically resolved characterization methods unveil the mechanism of a promising photocatalytic Co@MOF(Ti) system for H2 production. The combination of X-ray absorption spectroscopy (XAS) and electron paramagnetic resonance (EPR) experiments allows for the characterization of atomic and electronic rearrangements in the photoinduced species. This information provides the basis for the optimization of photocatalyst design.

The semiconductor industry plans to keep fabricating integrated circuits, progressively decreasing there features size, by employing extreme ultraviolet lithography (EUVL). With this method, new designs and concepts for photoresist materials need to be conceived. In this work, we explore an alternative concept to the classic photoresist material by using an organic self-assembled monolayer (SAM) on a gold substrate. The monolayer, composed of a richly fluorinated thiol sensitive to low-energy electrons, is adsorbed on the Au substrate which acts as main EUV-absorber and as the source of photoelectrons and secondary electrons. We investigate the stability of the SAM adsorbed on gold towards EUV radiation by means of in-situ photoelectron spectroscopy. The photoelectron spectra indicate that the monolayer attenuates a significant amount of primary electrons generated in the gold layer. The spectral evolution upon EUV irradiation indicates that the SAM loses a significant amount of its initial fluorine content (ca. 40% at 200 mJ/cm2). We attribute these chemical changes mostly to the interaction with the electrons generated in the thiol/Au system.

International audience; To meet the requirements for EUV nanolithography, the semiconductor industry has drawn attention towards hybrid inorganic-organic based photoresists. However, the mechanisms responsible for the solubility switch in these materials are not well understood. In this work, UV/ VUV (4-14 eV) photon-induced fragmentations of Zn-based oxoclusters in the gas phase are investigated to study the fundamental reactivity of their cationic form. Irradiation of the parent cations results mainly in the ligand dissociation and fragmentation of the inorganic clusters at energies below the second ionization threshold (～12 eV). This ionization energy appears to be linked to the methacrylate ligand in the organic shell. We presume that this type of fragmentations can also occur when the oxoclusters are ionized in the thin film upon EUV irradiation.

The cost-effectiveness and future progress of EUV (13.5 nm) lithography will largely depend on the resist technology development. Hybrid inorganic-organic photoresists have emerged as promising materials of EUV and have gained increasing attention in recent years. A crucial aspect for hybrid materials is their stability and the preservation of their molecular integrity when deposited as thin films. In this work, we study novel zinc (Zn) oxoclusters as molecular hybrid photoresists. Our aim is to combine the reactivity of methacrylate organic ligands with an inorganic cluster with high EUV photon absorption cross-section arising from this metal. To gain understanding on the shelf life of this material, changes in their structure under different conditions were monitored employing a combination of different spectroscopic techniques. The sensitivity of these oxoclusters under EUV light was investigated and their patterning performance is evaluated using EUV interference lithography. Our results indicate that these novel Zn-based oxoclusters are promising candidates for EUV lithography owing to their high dose sensitivity. Nevertheless, the labile nature of the methacrylate ligands has an important impact in the development process which seems to hamper their reproducibility. This work contributes to the understanding of the pitfalls and advantages of hybrid molecular resists.

As EUV lithography is being introduced into the market, the need for resists that can satisfy the exigent requirements of sensitivity, resolution, and line-edge roughness requires the development of guidelines for new generations of materials. In this work, we aim for gaining more understanding on the contribution of the organic components in inorganic-organic hybrid molecular resists to their sensitivity. A method to investigate the effect of specific functionalities on the sensitivity of metal oxo clusters is presented, which consists in the "doping" of the methacrylate shell through the introduction of fluorinated, iodinated and extended aromatic ligands. By introducing each of these functionalities in small ratios to the methacrylate ligand (1:11 and 2:10) the main chemical properties of the materials (solubility and molecular packing in the thin film) are expected to be unaltered. Our investigations show that the sensitivity is enhanced in the presence of halogens and drastically decreased when extended aromatic compounds are introduced. The trends are uncorrelated with the absorptivity estimated for each material, which seems to indicate that the doping functionalities might interfere with the cross-linking of the methacrylate ligands or introduce new chemical pathways. Our results indicate that specific organic functionalities can be used to tune the reactivity of hybrid compounds for EUV light by introducing them in doping amounts, thus preserving the processability of the initial material.

Background: Inorganic resists show promising performances in extreme ultraviolet (EUV) lithography. Yet, there is a need for understanding the exact chemical mechanisms induced by EUV light on these materials. Aim: To gain knowledge on the EUV chemistry of inorganic resists, we investigate hybrid inorganic–organic molecular compounds, metal oxoclusters (MOCs). Their molecular nature allows for the monitoring of specific structural changes by means of spectroscopy and thus for the elucidation of the mechanisms behind pattern formation. Approach: We compare the sensitivity of MOCs based on Zr and Hf, and methacrylate ligands as EUV resists. The chemical and structural changes causing the solubility switch were investigated by ex situ x-ray spectroscopy, infrared spectroscopy, ultraviolet–visible spectroscopy, and grazing incidence x-ray scattering. Results: Higher sensitivity was detected for the Hf-based material, in line with its higher absorptivity. A small fraction of the carboxylate ligands is lost at doses that yield solubility contrast, whereas aggregation of the inorganic clusters was not observed. Conclusions: These results provide evidence that, although the mechanism of solubility switch in these materials starts with decarboxylation reactions, it mainly proceeds through cross linking of the organic shells instead of aggregation of the inorganic clusters.

Metal oxoclusters are hybrid inorganic-organic molecular compounds with a well-defined number of metal and oxygen atoms in their cores. This type of materials is a promising platform for extreme ultraviolet (EUV) photoresists: their inorganic cores provide them with tunable EUV absorptivity and their molecular nature might favour smaller resolution and roughness while it also renders specific spectroscopic fingerprints that allow to monitor the chemical changes induced by EUV light. In this work, we compare the EUV photochemistry of metal oxoclusters based on Ti, Zr, and Hf and methacrylate ligands (Mc) and their sensitivity as resist materials for EUV lithography. Decarboxylation processes upon EUV exposure are detected in all cases with ex-situ X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). However, the structural changes after film deposition and after exposure differed among the three compounds. Higher sensitivity was detected for the Hf-based material than for the Zr-based analogue, in line with its higher absorptivity. XPS analyses suggest that only a small fraction of the carboxylate ligands is lost at the dose-to-gel. This change in the chemical composition is accompanied by an increased structural disorder in the layer and a rather small degree of aggregation, according to grazing incidence X-ray scattering (GIXS). These results indicate that neither a drastic loss of organic shell nor a high degree of aggregation of the naked inorganic cores are required for this type of molecular thin film to reliably operate as a resist material.

During the last decade the number of publications related to the synthesis of new metal-organic frameworks or coordination polymers has grown almost exponentially. Many of them are devoted to the study of the correlation between the molecular components (linkers and metal nodes or clusters) and the final properties of the resulting structure. Withal, the field of metal-organic frameworks has also witnessed important advances in the development of synthetic tools to control the particle size and shape and to obtain secondary porosity by applying knowledge from three disciplines: crystallography, coordination chemistry and chemical engineering. These tools allow for crystal engineering beyond the molecular scale extending over the meso and macro scales, so that certain degree of multi-scale design is already possible. In this manner, MOFs’ performance have been improved in certain applications by choosing the optimal particle morphology and dimensions that enhance the materials’ properties and/or facilitate their implementation on functional devices. This review highlights the latest advances on MOF crystal engineering, with special emphasis on the meso and macro scales. After discussing some general considerations on the fundamentals of MOF crystallization, we examine different synthetic approaches developed in order to tune the MOF particle size, shape and textural properties and the impact this multi-scale MOF crystal engineering has shown so far in different applications. Finally, our view on possible future research directions is outlined.

The ability to control the interplay of materials with low-energy photons is important as visible light offers several appealing features compared to ultraviolet radiation (less damaging, more selective, predominant in the solar spectrum, possibility to increase the penetration depth). Two different metal-organic frameworks (MOFs) were synthesized from the same linker bearing all-visible ortho-fluoroazobenzene photoswitches as pendant groups. The MOFs exhibit different architectures that strongly influence the ability of the azobenzenes to isomerize inside the voids. The framework built with Al-based nodes has congested 1D channels that preclude efficient isomerization. As a result, local light-heat conversion can be used to alter the CO2 adsorption capacity of the material on exposure to green light. The second framework, built with Zr nodes, provides enough room for the photoswitches to isomerize, which leads to a unique bistable photochromic MOF that readily responds to blue and green light. The superiority of green over UV irradiation was additionally demonstrated by reflectance spectroscopy and analysis of digested samples. This material offers promising perspectives for liquid-phase applications such as light-controlled catalysis and adsorptive separation.

Tin-oxo cage materials are of interest for use as photoresists for EUV (Extreme­ Ultraviolet) lithography (13.5 run, 92 eV), owing to their large absorption cross section for EUV light. In this work we exposed an n-butyl tin-oxo cage dication in the gas phase to photons in the energy range 4-14 eV to explore its fundamental photoreactivity. At all energies above the onset of electronic absorption at 5 eV (250 run) cleavage of tin-carbon bonds was observed. With photon energies >12 eV (

We present a synthetic strategy for the efficient encapsulation of a derivative of a well-defined cobaloxime proton reduction catalyst within a photoresponsive metal–organic framework (NH2-MIL-125(Ti)). The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully recyclable noble metal-free catalyst system for light-driven hydrogen evolution from water under visible light illumination.

Background: Hybrid inorganic-organic materials have emerged as promising candidates for EUV resists. However, knowledge on their stability when deposited as thin films is essential for their performance in EUV lithography. Aim: We investigate whether the molecular structure of Zn-based metal oxoclusters is preserved upon thin film deposition and study aging processes of the thin film under different atmospheres, since these chemical changes affect the solubility properties of the material. Approach: A hybrid cluster that combines the high EUV photon absorption cross-sections of zinc and fluorine with the reactivity of methacrylate organic ligands was synthesized. The structural modifications upon thin film formation and after aging in air, nitrogen, and vacuum were studied using a combination of spectroscopic techniques. Preliminary studies on the lithographic performance of this material were performed by EUV interference lithography. Results: The Zn-based compound undergoes structural rearrangements upon thin film deposition as compared to the bulk material. The thin films degrade in air over 24 h, yet they are found to be stable for the duration and conditions of the lithography process and show high sensitivity. Conclusions: The easy dissociation of the ligands might facilitate hydrolysis and rearrangements after spin-coating, which could affect the reproducibility of EUV lithography.

Conversion of light into chemical energy is a process that nature has optimized over eons in photosynthetic organisms, such as bacteria, plants, and algae. However, the search for non-natural systems that mimic the complex overall process of photosynthesis has remained a challenge. In particular, the key step of the initial light-induced charge separation between electron donors and acceptors is hampered by its inherent microscopic reversibility, that is, competing charge recombination. Well-defined molecular model systems typically comprise a donor (D) and an acceptor (A) covalently linked by a bridge (B). In the resulting D–B–A structures, the role of the bridge is ideally to facilitate the desired initial photoinduced charge separation, yet, to slow down the undesired charge recombination. Among the many combinations of donors and acceptors that have been explored, those consisting of proaromatic tetrathiafulvalene (TTF) and fullerene derivatives, such as C60, have shown outstanding results. The exceptional electron donating and accepting properties originate from the aromatic stabilization of the formed TTF radical cation and from C60 s unique three dimensional delocalized p-electron system, respectively. This last feature leads to low reorganization energies upon the reduction to the C60 radical anion and allows for the uptake of up to six additional electrons. The photophysical properties of various TTF–C60 conjugates featuring different p-conjugated molecular bridges have been investigated and charge-separated states with lifetimes ranging from a few nanoseconds up to hundreds of microseconds have been realized. Of particular interest are conjugates with p-extended TTF derivatives, in which a conjugated p-quinoid anthracene moiety is placed between the TTF s two 1,3-dithiole rings. Nevertheless, the design of such D–B–A architectures features inherent drawbacks. For example, even with optimized donors and acceptors, the bridge needs to play two opposing roles. On the one hand, it should enhance the coupling between D and A to facilitate the initial charge separation. On the other hand, once the charge-separated state has been formed it should prevent charge recombination by decoupling DC and AC . Clearly, conventional, static bridges have to be a compromise of these two demands. However, if D and A are connected by a dynamic bridge, which can be switched between a coupled and a decoupled form, prolonged charge-separated state lifetimes could potentially be attained without compromising the initial charge separation. Such improved molecular design requires a switch entity that adopts two electronically distinct forms and allows for precise timing of the switching, that is, when the bridge is being coupled or decoupled. Dithienylethenes (DTE) are ideal candidates as switchable bridges as they reversibly interconvert between their ring-open (decoupled) and ring-closed (p-conjugated) forms upon irradiation with light of specific wavelengths. Adopting this new strategy, we prepared four novel D–DTE–A structures connecting either TTF or exTTF acting as D and with C60 functioning as A by photochromic dithienylperhydrocyclopentene or perfluorocyclopentene bridges (Scheme 1). Some researchers have used photochromic units as lightresponsive electronic traps that allow or prevent intramolecular electron transfer from D to A depending on the adopted isomeric form. There are also some examples, in which the electron transfer kinetics are clearly altered by the structural modification of the bridging units by chemical inputs (chelation) or, in mechanically interlocked D and A units, by topological changes. However, herein, we show for the first time that in (ex)TTF–DTE–C60 architectures, the lifetime of the charge-separated state can be significantly shortened or prolonged by performing light-induced structural changes in the bridging unit. [*] Dr. S. Castellanos, Dr. J. Moreno, Prof. Dr. S. Hecht Department of Chemistry Humboldt-Universit t zu Berlin Brook-Taylor-Strasse 2, 12489 Berlin (Germany) E-mail: sh@chemie.hu-berlin.de

This paper describes the synthesis of the novel bis[4-(N-carbazolyl)-2,6-dichlorophenyl](2,4,6-trichlorophenyl)methyl radical (2*) and tris[4-(N-carbazolyl)-2,6-dichlorophenyl]methyl radical (3*). A Friedel-Crafts reaction on [4-(N-carbazolyl)-2,6-dichlorophenyl)bis(2,4,6-trichlorophenyl]methyl radical (1*), 2*, and 3* leads to the introduction of acyl chains in the 3- and 6-positions of the carbazolyl moiety without impairment of the radical character of the molecule to give radicals 5*, 6*, and 7*. All of these novel radical adducts are thermally stable, 5* and 6* being amorphous solids by differential scanning calorimetry. Electron paramagnetic resonance spectra of them show a multiplet at low temperature due to the electron-coupling with six aromatic hydrogens. They show electrochemical amphotericity being reduced and oxidized to their corresponding stable anionic and cationic species, respectively. These radical adducts have luminescent properties covering the red spectral band of the emission with high intensities.

During the last decade the number of publications related to the synthesis of new metal-organic frameworks or coordination polymers has grown almost exponentially. Many of them are devoted to the study of the correlation between the molecular components (linkers and metal nodes or clusters) and the final properties of the resulting structure. Withal, the field of metal-organic frameworks has also witnessed important advances in the development of synthetic tools to control the particle size and shape and to obtain secondary porosity by applying knowledge from three disciplines: crystallography, coordination chemistry and chemical engineering. These tools allow for crystal engineering beyond the molecular scale extending over the meso and macro scales, so that certain degree of multi-scale design is already possible. In this manner, MOFs’ performance have been improved in certain applications by choosing the optimal particle morphology and dimensions that enhance the materials’ properties and/or facilitate their implementation on functional devices. This review highlights the latest advances on MOF crystal engineering, with special emphasis on the meso and macro scales. After discussing some general considerations on the fundamentals of MOF crystallization, we examine different synthetic approaches developed in order to tune the MOF particle size, shape and textural properties and the impact this multi-scale MOF crystal engineering has shown so far in different applications. Finally, our view on possible future research directions is outlined.

The ability of modulating the properties of metal–organic frameworks (MOF) on demand by external light-stimuli is a most appealing pathway to enhance their performance in storage and separation and to render novel advanced applications. Photoswitchable linkers of different nature have been inserted in several MOF structures either as integral parts of their scaffolds or as guests in the pores. In this highlight we analyse the different strategies and expose some aspects that should be considered in the design of new generations of photoswitchable MOFs.

Three supramolecular isomers of lutetium metal-organic framework, {Lu2(H2O)4(ATA)3·4H2O}n (Lu-ATA@RT), {Lu2(H2O)2(C3H7NO)2(ATA)3}n (Lu-ATA@100), and {Lu2(C3H7NO)(ATA)3}n (Lu-ATA@150), have been obtained from the reaction of Lu(NO3)3·6H2O with 2-aminoterephthalic acid (ATA) at different temperatures. The resulting structures of Lu-ATA metal-organic frameworks depend on the temperature applied during the synthesis, revealing a temperature-susceptible supramolecular isomerism. Single-crystal X-ray diffraction analyses suggest that new compounds with formula {Lu2(S)x(ATA)3}n (S = solvent: H2O, DMF) display different three-dimensional architectures which consist of dinuclear lutetium building units. The supramolecular isomer Lu-ATA@RT, formed at room temperature, has a pcu-net topology, while its double interpenetrated analogue Lu-ATA@100 assembles at 100 °C under hydrothermal conditions. Hydrothermal synthesis at 150 °C affords formation of the dense Lu-ATA@150 cage-like framework displaying a new hexagonal-packed net topology. All Lu-ATA isomeric phases are porous and display different gas-uptake behavior toward carbon dioxide as a function of polymeric network arrangement. The luminescent properties of Lu-ATA frameworks in the solid state as well as in suspension in the presence of different solvents reveal a solvent-dependent emission., The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007−2013)/ERC Grant Agreement n. 335746, CrystEng-MOF-MMM.

Recently, MIL-125(Ti) and NH2 -MIL-125(Ti), two titanium-based metal-organic frameworks, have attracted significant research attention in the field of photocatalysis for solar fuel generation. This work reveals that the differences between these structures are not only based on their light absorption range but also on the decay profile and topography of their excited states. In contrast to MIL-125(Ti), NH2 -MIL-125(Ti) shows markedly longer lifetimes of the charge-separated state, which improves photoconversion by the suppression of competing decay mechanisms. We used spectroelectrochemistry and ultrafast spectroscopy to demonstrate that upon photoexcitation in NH2 -MIL-125(Ti) the electron is located in the Ti-oxo clusters and the hole resides on the aminoterephthalate unit, specifically on the amino group. The results highlight the role of the amino group in NH2 -MIL-125(Ti), the electron donation of which extends the lifetime of the photoexcited state substantially.

El presente artículo informa acerca de los hallazgos de la tercera etapa de una amplia investigación sobre el fraude académico universitario que ha conducido el Centro de Investigación y Formación en Educación, CIFE, de la Universidad de los Andes en Bogotá, con el propósito de desarrollar intervenciones para combatirlo. Ante resultados preocupantes de las primeras etapas en términos de la frecuencia de fraude en la Universidad y de las razones que dan los estudiantes para cometerlo y evitarlo, emprendimos una detallada investigación cualitativa que analiza con profundidad estas razones. A partir de los resultados, proponemos una interpretación de tipo cultural para las decisiones de fraude de los alumnos, que se aleja de una que considere solamente factores relacionados con el desarrollo moral individual. Luego utilizamos principios constructivistas del aprendizaje y su posible aplicación, para sustentar la necesidad de combatir el fraude académico desde el cambio pedagógico. The present article gives information about the findings of the third stage of a research project on academic fraud that has been conducted by the Centro de Investigación y Formación en Educación, CIFE, from the Andes University, Bogotá, with the purpose of developing interventions to fight it. Facing upsetting findings in the first two stages about the frequency of fraudulent behaviors and the reasons given by the students to justify academic fraud, we conducted a detailed qualitative study that analyzes these reasons. From the results we propose a cultural explanation for students’ decisions on academic fraud, instead of one that only takes into account factors related to individual moral development. Then we use constructivist learning principles and their possible applications to support the need to fight against academic fraud from pedagogical change.

Incorporation of new functionalities into metal-organic frameworks (MOFs) by post-synthetic modification is a most attractive strategy for attaining the desired properties without risking destruction of the crystalline structure chosen for the aimed application. In this work the amine group in NH2-MIL-53(Al) was used as anchoring point for the diphenylphosphinyl (Ph2PO-) moiety. The success of the derivatization was confirmed by P-31 MAS NMR and DRIFT spectroscopic studies. A newly synthesized reference linker bearing the same phosphinic amide functional group was used to assist in the MOF characterization. The introduction of the bulky diphenylphosphinyl group stabilizes the large-pore form of the MOF and leads to changes in the optical properties as a consequence of the electronic influence of the PO group. The approach described here is relevant for the preparation of novel phosphorus-containing MOFs., A. P., A. D., and J. G. have received funding from the European Research Council under the Seventh Framework Programme of the European Union (FP/2007-2013/ERC) Grant Agreement no. 335746, CrystEng-MOF-MMM.

The modulation of the electron-donor properties of tetrathiafulvalene (TTF) with light is attempted by two molecular designs: the integration of the TTF core as aryl unit(s) into the hexatriene system of diarylethene (DAE) derivatives and the attachment of terminal TTF unit(s) to a conventional 1,2-dithienylcyclopentene chromophore via conjugated ethynylene spacers. While photochromism is inhibited in the first approach, presumably by a twisted intramolecular charge transfer mechanism, the second approach yields photoswitchable TTF derivatives. Remarkably, the extension of the conjugated π-system upon ring closure affects the first oxidation potential values of the TTF–DAEs only slightly. Nevertheless, the electronic changes in the photochromic core are foreseen to play a crucial role in the intramolecular electron transfer process in donor–DAE–acceptor architectures.

Stable radical adducts of the TTM series bearing carbazolyl or indolyl fragments show bipolar transport properties with mobility values among the highest detected in glassy small molecules. Bipolarity is attributed to the radical character, while the heterocyclic ring confers the adducts the glassy morphological states and the non-dispersive regimes for charge transport.

Synthesis and characterization of new carbazolyl derivatives with a pendant stable radical of the TTM (tris-2,4,6-trichlorophenylmethyl radical) series are reported. The EPR spectra, electrochemical properties, absorption spectra, and luminescent properties of these radical adducts have been studied. All of them show electrochemical amphotericity being reduced and oxidized to their corresponding stable charged species. The luminescence properties of them cover the red spectral band of the emission. The luminescence of the electron-rich carbazole adducts shows the donor-acceptor nature of the excited state. On the other hand, the EPR parameters of these radical adducts show an imperceptible variation with the substituents in the carbazole.

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