Isoreticular two-dimensional magnetic coordination polymers prepared through pre-synthetic ligand functionalization

Chemical functionalization is a powerful approach to tailor the physical and chemical properties of two-dimensional materials, increase their processability and stability, tune their functionalities and, even, create new 2D materials. This is typically achieved through post-synthetic functionalization by anchoring molecules on the surface of an exfoliated 2D crystal, but it inevitably alters the long-range structural order of the material. Here we present a pre-synthetic approach that allows the isolation of crystalline, robust, and magnetic functionalized monolayers of coordination polymers. A series of five isoreticular layered magnetic coordination polymers based on Fe(II) centres and different benzimidazole derivatives (bearing a Cl, H, CH3, Br or NH2 side group) were first prepared. On mechanical exfoliation, 2D materials are obtained that retain their long-range structural order and exhibit good mechanical and magnetic properties. This combination, together with the possibility to functionalize their surface at will, makes them good candidates to explore magnetism in the 2D limit and to fabricate mechanical resonators for selective gas sensing

Towards optimal quality requirement documentation in agile software development:a multiple case study

Abstract Context: Agile software development (ASD) promotes minimal documentation and often prioritizes functional requirements over quality requirements (QRs). The minimal documentation emphasis may be beneficial in reducing time-to-market for software. However, it can also be a concern, especially with QRs, since they are challenging to specify and document and are crucial for software success. Therefore, understanding how practitioners perceive the importance of QR documentation is valuable because it can provide insight into how they approach this task. It also helps in developing models and guidelines that support the documentation of QRs in ASD, which is a research gap. Objective: We aim to understand practitioners’ perceptions of QR documentation and factors influencing this task to derive a model that supports optimal QR documentation in ASD. Method: We conducted a multiple case study involving 12 participants from three cases that apply ASD. Results: Practitioners identify QR documentation as important and perceive it as contributing to ensuring quality, clarifying QRs, and facilitating decision-making. Time constraints, QR awareness, and communication gaps affect QR documentation. Missing and outdated QR documentation may lead to technical debt and a lack of common understanding regarding QRs. We introduce a model to support optimal QR documentation in ASD by focusing on the factors: time constraints, QR awareness, and communication gaps. The model provides a representation and explanation of the factors affecting QR documentation in ASD and identifies mitigation strategies to overcome issues that may occur due to these factors. Conclusion: The study reveals the importance of documenting QRs in ASD. It introduces a model that is based on empirical knowledge of QR documentation practices in ASD. Both practitioners and researchers can potentially benefit from the model. For instance, practitioners can analyze how time constraints or QR awareness affect documentation, see potential issues that may arise from them, and utilize strategies suggested by the model to address these issues. Researchers can learn about QR documentation in ASD and utilize the model to understand the topic. They can also use the study as a baseline to investigate the topic with other cases

How agile software development practitioners perceive the need for documenting quality requirements:a multiple case study

Abstract Agile software development (ASD) promotes minimal documentation and often prioritizes functional requirements over quality requirements (QRs). This may be beneficial in reducing the time to market of software. When considering QRs in ASD, the minimal documentation practice may be seen as a concern since QRs determine the success of software projects and are as well not easy to specify and document. Nevertheless, what do practitioners think of the necessity of documenting QRs in ASD? How do they perceive factors that may affect documentation of QRs in ASD? We conducted a multiple case study of three cases applying ASD, involving 12 participants. ASD practitioners identify that it is important to document QRs, and perceive that it contributes to ensuring quality, clarifying QRs, and helping in decision making. Time constraint, QR awareness and communication gaps on QRs influence the documentation of QRs in ASD. ASD teams may align their documentation practices to fit the sprint duration. The influence of QR awareness on documentation was dependent on project context and roles. Communication gaps can create confusion on QRs. Missing and outdated QR documentation may result in accruing technical debt, and lack of common understanding on QRs. The study synthesizes empirical evidence on the significance of documenting QRs in ASD and provides an insight into factors affecting documentation of QRs in ASD

Unexpected Spin-Crossover and a Low-Pressure Phase Change in an Iron(II)/Dipyrazolylpyridine Complex Exhibiting a High-Spin Jahn-Teller Distortion.

The synthesis of 4-methyl-2,6-di(pyrazol-1-yl)pyridine (L) and four salts of [FeL2]X2 (X(-) = BF4(-), 1; X(-) = ClO4(-), 2; X(-) = PF6(-), 3; X(-) = CF3SO3(-), 4) are reported. Powder samples of 1 and 2 both exhibit abrupt, hysteretic spin-state transitions on cooling, with T1/2↓ = 204 and T1/2↑ = 209 K (1), and T1/2↓ = 175 and T1/2↑ = 193 K (2). The 18 K thermal hysteresis loop for 2 is unusually wide for a complex of this type. Single crystal structures of 2 show it to exhibit a Jahn-Teller-distorted six-coordinate geometry in its high-spin state, which would normally inhibit spin-crossover. Bulk samples of 1 and 2 are isostructural by X-ray powder diffraction, and undergo a crystallographic phase change during their spin-transitions. At temperatures below T1/2, exposing both compounds to 10(-5) Torr pressure inside the powder diffractometer causes a reversible transformation back to the high-temperature crystal phase. Consideration of thermodynamic data implies this cannot be accompanied by a low → high spin-state change, however. Both compounds also exhibit the LIESST effect, with 2 exhibiting an unusually high T(LIESST) of 112 K. The salts 3 and 4 are respectively high-spin and low-spin between 3 and 300 K, with crystalline 3 exhibiting a more pronounced version of the same Jahn-Teller distortion