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Abstract Despite exhaled human breath having enabled noninvasive diabetes diagnosis, selective acetone vapor detection by fluorescence approach in the diabetic range (1.8–3.5 ppm) remains a long‐standing challenge. A set of water‐resistant luminescent metal‐organic framework (MOF)‐based composites have been reported for detecting acetone vapor in the diabetic range with a limit of detection of 200 ppb. The luminescent materials possess the ability to selectively detect acetone vapor from a mixture comprising nitrogen, oxygen, carbon dioxide, water vapor, and alcohol vapor, which are prevalent in exhaled breath. It is noteworthy that this is the first luminescent MOF material capable of selectively detecting acetone vapor in the diabetic range via a turn‐on mechanism. The material can be reused within a matter of minutes under ambient conditions. Industrially pertinent electrospun luminescent fibers are likewise fabricated alongside various luminescent films for selective detection of ultratrace quantities of acetone vapor present in the air. Ab initio theoretical calculations combined with in situ synchrotron‐based dosing studies uncovered the material's remarkable hypersensitivity toward acetone vapor. Finally, a freshly designed prototype fluorescence‐based portable optical sensor is utilized as a proof‐of‐concept for the rapid detection of acetone vapor within the diabetic range.

Abstract Owing to their unique functionalities and tailorable properties that are unattainable in conventional materials, metal‐organic frameworks (MOFs) have emerged as candidate materials for next‐generation chemical sensors and optoelectronics. For instance, the ZnQ@OX‐1 composite material, comprising a light‐emitting guest encapsulated in the pores of the OX‐1 framework, affords excellent sensing performance: a visible color change upon exposure to volatile acetone. In this work, a multimodal study on the exceptional vapochromism of this composite material using high‐resolution spectroscopy techniques based on inelastic neutron scattering and synchrotron radiation is presented, supported by density functional theory calculations. While FTIR spectroscopy in the far‐IR and mid‐IR regions reveals the underlying interactions between ZnQ, OX‐1, and acetone, the limit of detection at 50 ppm is determined through in situ gas dosing experiments using fluorescence spectroscopy. In addition, in situ gas dosing on the single crystal level is achieved with near‐field infrared nanospectroscopy.

The identification of catalytically active sites with atomic-scale precision occupies a central place in the theory and practice of heterogeneous catalysis. Here the authors assess the nature of the copper-oxygen bond in a Cu-CHA zeolite and recover the microscopic structure of single-metal sites.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two innovative classes of porous coordination polymers. MOFs are three-dimensional materials made up of secondary building blocks comprised of metal ions/clusters and organic ligands whereas COFs are 2D or 3D highly porous organic solids made up by light elements (i.e., H, B, C, N, O). Both MOFs and COFs, being highly conjugated scaffolds, are very promising as photoactive materials for applications in photocatalysis and artificial photosynthesis because of their tunable electronic properties, high surface area, remarkable light and thermal stability, easy and relative low-cost synthesis, and structural versatility. These properties make them perfectly suitable for photovoltaic application: throughout this review, we summarize recent advances in the employment of both MOFs and COFs in emerging photovoltaics, namely dye-sensitized solar cells (DSSCs) organic photovoltaic (OPV) and perovskite solar cells (PSCs). MOFs are successfully implemented in DSSCs as photoanodic material or solid-state sensitizers and in PSCs mainly as hole or electron transporting materials. An innovative paradigm, in which the porous conductive polymer acts as standing-alone sensitized photoanode, is exploited too. Conversely, COFs are mostly implemented as photoactive material or as hole transporting material in PSCs.

Metal oxide nanoparticles (NPs) are regarded as good candidates for many technological applications, where their functional environment is often an aqueous solution. The correct description of metal oxide electronic structure is still a challenge for local and semilocal density functionals, whereas hybrid functional methods provide an improved description, and local atomic function-based codes such as CRYSTAL17 outperform plane wave codes when it comes to hybrid functional calculations. However, the computational cost of hybrids are still prohibitive for systems of real sizes, in a real environment. Therefore, we here present and critically assess the accuracy of our electrostatic embedding quantum mechanical/molecular mechanical (QM/MM) coupling between CRYSTAL17 and AMBER16, and demonstrate some of its capabilities via the case study of TiO2 NPs in water. First, we produced new Lennard⁻Jones (LJ) parameters that improve the accuracy of water⁻water interactions in the B3LYP/TIP3P coupling. We found that optimizing LJ parameters based on water tri- to deca-mer clusters provides a less overstructured QM/MM liquid water description than when fitting LJ parameters only based on the water dimer. Then, we applied our QM/MM coupling methodology to describe the interaction of a 1 nm wide multilayer of water surrounding a spherical TiO2 nanoparticle (NP). Optimizing the QM/MM water⁻water parameters was found to have little to no effect on the local NP properties, which provide insights into the range of influence that can be attributed to the LJ term in the QM/MM coupling. The effect of adding additional water in an MM fashion on the geometry optimized nanoparticle structure is small, but more evident effects are seen in its electronic properties. We also show that there is good transferability of existing QM/MM LJ parameters for organic molecules⁻water interactions to our QM/MM implementation, even though these parameters were obtained with a different QM code and QM/MM implementation, but with the same functional.

Benchmark calculations provide a large amount of information that can be very useful in assessing the performance of density functional approximations, and for choosing the one to use. In order to condense the information some indicators are provided. However, these indicators might be insufficient and a more careful analysis is needed, as shown by some examples from an existing data set for cubic crystals.

The potential of ZnO4(1,4-bencenodicarboxilato)3 [MOF-5] as media for adsorptive hy­drogen storage is studied by means of quantum-mechanical calculations of the binding energy of H2 molecules adsorbed on different sites of the MOF-5 crystalline structure. In a first stage of the study, the binding energy is computed in periodic models with the B3LYP functional as level of theory, together with a localized Gaussian type basis set for the wave- function expansion. Subsequently, the computed binding energies are refined by including the contribution of the dispersive forces, which are estimated at the MP2 level in molecular models cut off from the periodic structure as established within the P-ONIOM approach.