Synthetic routes toward MOF nanomorphologies.

As metal–organic frameworks (MOFs) are coming of age, their structural diversity, exceptional porosity and inherent functionality need to be transferred into useful applications. Fashioning MOFs into various shapes and at the same time controlling their size constitute an essential step toward MOF-based devices. Moreover, downsizing MOFs to the nanoscale triggers a whole new set of properties distinguishing nanoMOFs from their bulk counterparts. Therefore, dimensionality-controlled miniaturization of MOFs enables the customised use of nanoMOFs for specific applications where suitable size and shape are key prerequisites. In this feature article we survey the burgeoning field of nanoscale MOF synthesis, ranging from classical protocols such as microemulsion synthesis all the way to microfluidic-based techniques and template-directed epitaxial growth schemes. Along these lines, we will fathom the feasibility of rationally designing specific MOF nanomorphologies—zero-, one- and two-dimensional nanostructures—and we will explore more complex “second-generation” nanostructures typically evolving from a high level of interfacial control. As a recurring theme, we will review recent advances made toward the understanding of nucleation and growth processes at the nanoscale, as such insights are expected to further push the borders of nanoMOF science

Solving the COF trilemma: towards crystalline,stable and functional covalentorganic frameworks

Covalent organic frameworks (COFs) have entered the stage as a new generation of porous polymers which stand out by virtue of their crystallinity, diverse framework topologies and accessible pore systems. An important – but still underdeveloped – feature of COFs is their potentially superior stability in comparison to other porous materials. Achieving COFs which are simultaneously crystalline, stable, and functional is still challenging as reversible bond formation is one of the prime prerequisites for the crystallization of COFs. However, as the COF field matures new strategies have surfaced that bypass this crystallinity – stability dichotomy. Three major approaches for obtaining both stable and crystalline COFs have taken form in recent years: Tweaking the reaction conditions for reversible linkages, separating the order inducing step and the stability inducing step, and controlling the structural degrees of freedom during assembly and in the final COF. This review discusses rational approaches to stability and crystallinity engineering in COFs, which are apt at overcoming current challenges in COF design and open up new avenues to new real-world applications of COFs

Growing Together—Effects of a school‐based intervention promoting positive self‐beliefs and social integration in recently immigrated children

We present a school‐based intervention geared to foster the social integration of recently immigrated (RI) primary school children by creating repeated positive contact situations with classmates brought up in the receiving society. Coaches encouraged groups of tandems, consisting of one RI and one child brought up in Germany each, to engage in cooperative activities designed to strengthen positive self‐beliefs and perception of equal status. In a quasi‐experimental control‐group design (N = 318), we compared the 30 children (12 RI) who participated in our intervention between pre‐test and post‐test with a reference group. Self‐beliefs were measured via self‐reports, social integration via sociometric peer‐nominations. The reference group (n = 288 children) included all children who did not participate in the intervention between pre‐test and post‐test: (a) 12 children (7 RI) of a waiting control group and (b) all classmates of both the students of the intervention and the waiting control group. Post‐test self‐beliefs were more positive in children having participated in the intervention. The intervention did not affect social integration: Neither the number of classmates nominating a student nor the number of peers the respective student nominated increased. Possibly, the intervention initiated self‐reinforcing processes which support social integration over longer time periods

Entwicklungspolitisch engagierte Migrantenorganisationen: Potenziale für die Integration in Deutschland?

Migrantenorganisationen engagieren sich in vielfältiger Hinsicht: Sie unterstützen ihre Mitglieder im Alltag und setzen sich auf politischer Ebene für das Zusammenleben von Deutschen und Migranten ein. Sie treten aber häufig auch als entwicklungspolitische Akteure in Erscheinung, indem sie etwa Hilfs- und Spendenprojekte in ihren Herkunftsländern durchführen oder in Deutschland über die entwicklungspolitische Situation in ihren Herkunftsländern berichten.Migrants' organisations are committed in very many ways: They support their members in their everyday lives, and are active at political level to encourage co-existence between Germans and migrants. What is more, they frequently play a role in development policy through activities such as aid projects and by organising donations to their countries of origin, or they help create an awareness in Germany of the development policy situation in their countries of origin

Additive-mediated size control of MOF nanoparticles

A fast synthesis approach toward sub-60 nm sized MOF nanoparticles was developed by employing auxiliary additives. Control over the size of HKUST-1 and IRMOF-3 particles was gained by adjusting the concentration and type of stabilizers. Colloidal solutions of the MOFs were used for the formation of optically homogeneous thin films by spin-coating

How do others think about my group? Adolescents’ meta-stereotypes about Turkish- and German-origin students’ subject-related German and general school competence

In Germany, Turkish-origin students face negative competence-related stereotypes held by different groups in society, including teachers at school. While a large body of research has examined stereotypes (i.e., other-stereotypes) about immigrant students, little is known about their own competence-related meta-stereotypes, i.e., beliefs regarding the other-stereotypes that outgroup peers hold about them. The present study addresses this research gap by examining Turkish- and German-origin students’ meta-stereotypes about two dimensions of competencies not yet investigated, namely Turkish- and German-origin students’ subject-related German competence as well as their general school competence using a newly developed instrument combining verbal and non-verbal measures. These assessments are juxtaposed to the evaluations of a group of peers with other immigrant backgrounds (i.e., others’ meta-stereotypes). In line with previous evidence, we found positive meta-stereotypes (as well as other- and others’ meta-stereotypes) towards German-origin students reported by all three groups. However, our study is the first that supports the existence of negative meta-stereotypes (as well as other- and others’ meta-stereotypes) towards Turkish-origin adolescents, again, among all participants. This pattern was particularly pronounced regarding the dimension of subject-related German competence. We discuss the findings’ potential relevance for students’ self-concepts and intergroup interactions in classrooms

Ahnak1 abnormally localizes in muscular dystrophies and contributes to muscle vesicle release

Ahnak1 is a giant, ubiquitously expressed, plasma membrane support protein whose function in skeletal muscle is largely unknown. Therefore, we investigated whether ahnak would be influenced by alterations of the sarcolemma exemplified by dysferlin mutations known to render the sarcolemma vulnerable or by mutations in calpain3, a protease known to cleave ahnak. Human muscle biopsy specimens obtained from patients with limb girdle muscular dystrophy (LGMD) caused by mutations in dysferlin (LGMD2B) and calpain3 (LGMD2A) were investigated for ahnak expression and localization. We found that ahnak1 has lost its sarcolemmal localization in LGMD2B but not in LGMD2A. Instead ahnak1 appeared in muscle connective tissue surrounding the extracellular site of the muscle fiber in both muscular dystrophies. The entire giant ahnak1 molecule was present outside the muscle fiber and did only partially colocalize with CD45-positive immune cell infiltration and the extracelluar matrix proteins fibronectin and collagenVI. Further, vesicles shedded in response to Ca2+ by primary human myotubes were purified and their protein content was analysed. Ahnak1 was prominently present in these vesicles. Electron microscopy revealed a homogenous population of vesicles with a diameter of about 150 nm. This is the first study demonstrating vesicle release from human myotubes that may be one mechanism underlying abnormally localized ahnak1. Taken together, our results define ahnak1 in muscle connective tissue as a novel feature of two genetically distinct muscular dystrophies that might contribute to disease pathology

Ionothermal Synthesis of Imide‐Linked Covalent Organic Frameworks

Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF

Single-Site Photocatalytic H-2 Evolution from Covalent Organic Frameworks with Molecular Cobaloxime Co-Catalysts

We demonstrate photocatalytic hydrogen evolution using COF photosensitizers with molecular proton reduction catalysts for the first time. With azine-linked N2-COF photosensitizer, chloro(pyridine)cobaloxime co-catalyst, and TEOA donor, H-2 evolution rate of 782,mu mol h(-1) g(-1) and TON of 54.4 has been obtained in a water/acetonitrile mixture. PXRD, solid-state spectroscopy, EM analysis, and quantum-chemical calculations suggest an outer sphere electron transfer from the COF to the co-catalyst which subsequently follows a monometallic pathway of H-2 generation from the Co-III-hydride and/or Co-II-hydride species

Rational Strain Engineering in Delafossite Oxides for Highly Efficient Hydrogen Evolution Catalysis in Acidic Media

The rational design of hydrogen evolution reaction (HER) electrocatalysts which are competitive with platinum is an outstanding challenge to make power-to-gas technologies economically viable. Here, we introduce the delafossites PdCrO$_2$, PdCoO$_2$ and PtCoO$_2$ as a new family of electrocatalysts for the HER in acidic media. We show that in PdCoO$_2$ the inherently strained Pd metal sublattice acts as a pseudomorphic template for the growth of a strained (by +2.3%) Pd rich capping layer under reductive conditions. The surface modification continuously improves the electrocatalytic activity by simultaneously increasing the exchange current density j$_0$ from 2 to 5 mA/cm$^2_{geo}$ and by reducing the Tafel slope down to 38 mV/decade, leading to overpotentials $\eta_{10}$ < 15 mV for 10 mA/cm$^2_{geo}$, superior to bulk platinum. The greatly improved activity is attributed to the in-situ stabilization of a $\beta$-palladium hydride phase with drastically enhanced surface catalytic properties with respect to pure or nanostructured palladium. These findings illustrate how operando induced electrodissolution can be used as a top-down design concept for rational surface and property engineering through the strain-stabilized formation of catalytically active phases