Series of Cadmium-Organic Frameworks Based on Mixed Flexible and Rigid Ligands: Single-Crystal-to-Single-Crystal Transformations, Sorption, and Luminescence Properties

Here, we present a series of Cd(II) coordination polymers containing two types of ligands: sterically rigid terephthalate derivatives (bdc-NO22- and bdc-Br2-) and flexible bis(2-methylimidazolyl)propane (bmip). The combination of two types of ligands is used to obtain and characterize compounds by single crystal and powder X-ray diffraction, FT-IR, elemental analysis, and TGA. Guest exchange results in structural transformations. 2-fold interpenetrated 1·DMF and 2·DMF rapidly undergo to 4-fold interpenetrated 1·Et2O, 1·EtOH, and 1·H2O, or 2·Et2O, respectively. Also, changes in the coordinating numbers and length of the N,N'-donor bmip ligand were observed according to single crystal X-ray analysis. Activated guest-free compounds [Cd(bdc-NO2)(bmip)] (1) and [Cd(bdc-Br)(bmip)] (2) are shown to be porous with a BET surface area of 103 and 283 m2·g-1, respectively. Moreover, both compounds demonstrate gate-opening behavior of ethylene adsorption isotherms at low pressures (<1 bar) and highly selective adsorption of benzene over cyclohexane or lower alcohols. Also, both compounds demonstrate a strong dependence of the maximum of the photoluminescence emission on an excitation wavelength. As a result, the photoluminescence color changes from white to red and from blue to red through green and yellow for compounds 1 and 2, respectively, with excitation wavelength changing from 360 to 540 nm.

Recent reports on vanadium based coordination polymers and MOFs

Coordination polymers (CP) and metal-organic frameworks (MOF) have become a topic of immense interest in this century primarily because of the structural diversity that they offer. This structural diversity results in their multifaceted utility in various fields of science and technology such as catalysis, medicine, gas storage or separation, conductivity and magnetism. Their utility inspires a large variety of scientists to engage with them in their scientific pursuit thus creating a buzz around them in the scientific community. Metals capable of forming CPs and MOFs are primarily transition metals. Among them vanadium-based CPs and MOFs demand detailed discussion because of the unique nature of vanadium which makes it stable in many oxidation states and coordination number. Vanadium’s versatility imparts additional structural marvel and usefulness to these CPs and MOFs.

Anisotropic nanomaterials for asymmetric synthesis

The production of enantiopure chemicals is an essential part of modern chemical industry. Hence, the emergence of asymmetric catalysis led to dramatic changes in the procedures of chemical synthesis, and now it provides the most advantageous and economically executable solution for large-scale production of chiral chemicals. In recent years, nanostructures have emerged as potential materials for asymmetric synthesis. Indeed, on the one hand, nanomaterials offer great opportunities as catalysts in asymmetric catalysis, due to their tunable absorption, chirality, and unique energy transfer properties; on the other hand, the advantages of the larger surface area, increased number of unsaturated coordination centres, and more accessible active sites open prospects for catalyst encapsulation, partial or complete, in a nanoscale cavity, pore, pocket, or channel leading to alteration of the chemical reactivity through spatial confinement. This review focuses on anisotropic nanomaterials and considers the state-of-the-art progress in asymmetric synthesis catalysed by 1D, 2D and 3D nanostructures. The discussion comprises three main sections according to the nanostructure dimensionality. We analyze recent advances in materials and structure development, discuss the functional role of the nanomaterials in asymmetric synthesis, chirality, confinement effects, and reported enantioselectivity. Finally, the new opportunities and challenges of anisotropic 1D, 2D, and 3D nanomaterials in asymmetric synthesis, as well as the future prospects and current trends of the design and applications of these materials are analyzed in the Conclusions and outlook section.

Symmetry Breaking and Autocatalytic Amplification in Soai Reaction Confined within UiO-MOFs under Heterogenous Conditions

Symmetry breaking is observed in the Soai reaction in a confinement environment provided by zirconium‐based UiO‐MOFs used as crystalline sponges. Subsequent reaction of encapsulated Soai aldehyde with Zn(i‐Pr)₂ vapour promoted absolute asymmetric synthesis of the corresponding alkanol. ATR‐IR and NMR confirm integration of aldehyde into the porous material, and a similar localization of newly formed chiral alkanol after reaction. Despite the confinement, the Soai reaction exhibits significant activity and autocatalytic amplification. Comparative catalytic studies with various UiO‐MOFs indicate different outcomes in terms of enantiomeric excess, handedness distribution of the product and reaction rate, when compared to pristine solid Soai aldehyde, while the crystalline MOF remains highly stable to action of Zn(iPr)₂ vapour. This is an unprecedented example of absolute asymmetric synthesis using MOFs.

Methods of Encapsulation of Biomacromolecules and Living Cells. Prospects of Using Metal–Organic Frameworks

The review discusses different methods of encapsulation and biomineralization of macromolecules and living cells. Main advantages and disadvantages of most commonly used carriers, matrices, and materials for immobilization of proteins, enzymes, nucleic acids, and living cells are briefly surveyed. Examples of delivery vehicles for multifunctional encapsulation of protein-like substances are presented. Particular attention is paid to prospects of using metal–organic frameworks in medicine and biotechnology.

Applications of Nanomaterials in Asymmetric Photocatalysis: Recent Progress, Challenges, and Opportunities

Asymmetric catalysis is one of the most attractive strategies to obtain important enantiomerically pure chemicals with high quality and production. In addition, thanks to the abundant and sustainable advantages of solar energy, photocatalysis possesses great potential in environmentally benign reactions. Undoubtedly, asymmetric photocatalysis meets the strict demand of modern chemistry: environmentally friendly and energy-sustainable alternatives. Compared with homogeneous asymmetric photocatalysis, heterogeneous catalysis has features of easy separation, recovery, and reuse merits, thus being cost- and time-effective. Herein, the state-of-the-art progress in asymmetric photocatalysis by heterogeneous nanomaterials is addressed. The discussion comprises two sections based on the type of nanomaterials: typical inorganic semiconductors like TiO₂ and quantum dots and emerging porous materials including metal-organic frameworks, porous organic polymers, and organic cages. Finally, the challenges and future developments of heterogeneous asymmetric photocatalysis are proposed.