Amine Functionalization of Channels of Metal-Organic Frameworks for Effective Chemical Fixation of Carbon Dioxide: A Comparative Study with Three Newly Designed Porous Networks.

Catalytic transformation of CO2 into value-added chemical products can provide an appropriate solution for the raising environmental issues. To date, various metal-organic frameworks (MOFs) with transition metal ions have been explored for CO2 capture and conversion, but alkaline earth metal-based MOFs are comparatively less studied. Metal ions like Sr(II) having relatively large radius give rise to a high coordination number resulting in higher stability of the MOFs. Moreover, the introduction of N-rich functional group in organic linker like -NH2, -CONH- and triazole into MOF backbone enhance their CO2 capture and conversion efficiency. Herein, the effect of amine group on the catalytic efficiency of MOFs for CO2 cycloaddition with epoxides under solvent free and ambient conditions are presented. The di-carboxylates, such as 5-aminoisophthalate (AmIP) and 5-bromoisophthalate (BrIP) were utilized to synthesize Sr(II) based MOFs. The Zn(II) MOF was synthesized using tetra-carboxylate containing amide spacer (OAT) and 4-amino-4H-1,2,4-triazole (AMT). All three MOFs exhibited porous networks with guest available volume ranging from 15 to 58 %. The catalytic efficiency of the MOFs towards carbon dioxide fixation reaction was explored. The catalytic performances revealed that the presence of amine group in the channels enhances the catalytic efficiency of the MOFs.

Halogen⋠⋠⋠Halogen and Halogen⋠⋠⋠π Interactions Enabled Reversible Photo-oligomerization of Conjugated Dienones: Visible Light Triggered Single-Crystal-to-Single-Crystal Transformation.

The synthesis of reversible oligomer/polymers is fascinating both from the perspective of the fundamental understanding as well as their applications, ranging from biomedical to self-healing smart materials. On the other hand, the reactions that occur in single-crystal-to-single-crystal (SCSC) fashion offer great details of the structure, geometry and stereochemistry of the product. However, SCSC [2+2] oligomerization is rather difficult and rare. Further, till date there are no reports for a reversible [2+2] oligomerization in SCSC fashion. In this work, four halogen-substituted acrylic dienone molecules were deliberately designed and their ability to participate in [2+2] cycloaddition reaction in solid state was studied under visible light. Despite of having the required alignment of double bonds of dienes in all four crystal structures, they were found to exhibit variable reactivities given the differences in their weak intermolecular interactions such as halogen⋅⋅⋅halogen, halogen⋅⋅⋅π and C-H⋅⋅⋅O interactions. Notably, one of these materials exhibits reversible oligomerization in a SCSC manner.

Metal-organic frameworks as proton conductors: strategies for improved proton conductivity.

Recent studies on proton conductivity using pristine MOFs and their composite materials have established an outstanding area of research owing to their potential applications for the development of high performance solid state proton conductors (SSPCs) and proton exchange membranes (PEMs) in fuel cells (FCs). MOFs, as crystalline organic and inorganic hybrid materials, provide a large number of degrees of freedom in their framework composition, coordination environment, and chemically functionalized pores for the targeted design of improved proton carriers, functioning over a wide range of temperature and humidity conditions. Herein, our efforts have been emphasized on fundamental principles and different design strategies to achieve enhanced proton conductivity with appropriate examples. We also have discussed the modification mechanism of MOF-composite materials and mixed matrix membranes for commercial applications in FCs. Thus, this review aims to direct readers' attention towards the design strategies and structure-property relationship for proton transport in MOFs.

Porous Li-MOF as a solid-state electrolyte: exploration of lithium ion conductivity through bio-inspired ionic channels.

A rarely porous Li-MOF (Li-AOIA) with surface area of 605 m2 g-1 was employed for the formation of an emerging class of solid-state lithium ion electrolytes. Infiltration of LiBF4 into Li-AOIA afforded Li-AOIA@BF4 with ionic conductivity of 1.09 × 10-5 S cm-1 at room temperature and an activation energy of 0.18 eV.

Coordination polymers as heterogeneous catalysts in hydrogen evolution and oxygen evolution reactions.

The efficiency of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the process of electrochemical water oxidation will determine the competence for mass distributions of sustainable energy conversion technologies in the future. Recently, coordination polymers (CPs)/metal-organic frameworks (MOFs) have emerged as desirable hybrid materials for catalysing electrochemical energy conversion processes due to their unique advantages, such as crystalline porous structure, high surface area, and diverse and tunable chemical components. This feature article briefly summarizes the recent part of the fast growing literature on electrocatalysis by pristine MOF/CPs, MOF composites, as well as post-synthetically modified materials for HER, OER and overall water splitting reactions. The article highlights the contributions of various authors in this area and aims to provide a consolidated idea regarding the engineering strategies and composition-structure-activity relationships of these pristine CP based materials for such electrocatalytic applications.

Tailoring Coordination Polymers by Substituent Effect: A Bifunctional CoII -Doped 1D-Coordination Network with Electrochemical Water Oxidation and Nitroaromatics Sensing.

Three CdII coordination polymers (CPs) were synthesized with a tripodal ligand N,N',N' '-tris(4-pyridinylmethyl)-1,3,5-benzenetricarboxamide in combination with three different substituted isophthalic acids with general formulas {[Cd2 (L)(NIP)2 (H2 O)2 ].4H2 O}n , (CP-1), {[Cd2 (L)(AIP)2 (H2 O)2 ].4H2 O}n , (CP-2) and {[Cd(L)(BIP) (H2 O)].4H2 O}n , (CP-3). The substituent groups on the co-ligand had profound effect on the network topologies of the corresponding CPs as well as their properties. Out of the three, CP-1 and 2 were found to form 3D networks whereas CP-3 was a 1D linear chain with uncoordinated pyridyl sites. Due to its structural features CP-3 was found to show interesting properties. The 1D CP containing uncoordinated pyridyl site exhibited an excellent ability for doping with CoII which in turn acts as an efficient water oxidation electrocatalyst with required overpotential of 380 mV for an anodic current density of 1 mA cm-2 . The CP also exhibited luminescence-based detection of nitroaromatics (LOD: 0.003 mm) without any significant interference in presence of other organic compounds.