A 1-D coordination polymer route to catalytically active Co@C nanoparticles

Pyrolysis of a 1-D polymeric cobalt(II) coordination complex ([Co(BDC)(Mim)2]n, H2BDC = benzenedicarboxylic acid; Mim = N-methylimidazole) results in the formation of carbon embedded fcc cobalt nanoparticle composites, Co@C. The as-prepared Co@C shows an agglomerated secondary structure with a highly embedded carbon shell comprising of cobalt nanoparticles of 20-100 nm. These Co@C particles show excellent catalytic activity in the reduction of nitrophenol to aminophenol, studied as a model reaction, and evolves as a promising candidate for the gas phase reduction process

A 1-D Coordination Polymer Route to Catalytically Active Co@C Nanoparticles

Pyrolysis of a 1-D polymeric cobalt(ii) coordination complex ([Co(BDC)(Mim)2]n, H2BDC = benzenedicarboxylic acid; Mim = N-methylimidazole) results in the formation of carbon embedded fcc cobalt nanoparticle composites, Co@C. The as-prepared Co@C shows an agglomerated secondary structure with a highly embedded carbon shell comprising of cobalt nanoparticles of 20-100 nm. These Co@C particles show excellent catalytic activity in the reduction of nitrophenol to aminophenol, studied as a model reaction, and evolves as a promising candidate for the gas phase reduction process

Long-term ambient air-stable cubic CsPbBr3 perovskite quantum dots using molecular bromine

We report unprecedented phase stability of cubic CsPbBr3 quantum dots in ambient air obtained by using Br2 as halide precursor. Mechanistic investigation reveals the decisive role of temperature-controlled in situ generated, oleylammonium halide species from molecular halogen and amine for the long term stability and emission tunability of CsPbX3 (X = Br, I) nanocrystals

Temperature-Induced Single-Crystal-to-Single-Crystal Transformations with Consequential Changes in the Magnetic Properties of Fe(III) Complexes

The present article deals with an one-to-one structure–property correspondence of a dinuclear iron complex, [Dipic(H2O)FeOH]2·H2O (1) (Dipic = pyridine-2,6-dicarboxylic acid). Variable-temperature X-ray single-crystal structural analysis confirms a phase transition of complex 1 to complex 2 ([Dipic(H2O)FeOH]2) at 120 °C. Further, single-crystal-to-single-crystal (SCSC) transformation was monitored by temperature-dependent single crystal X-ray diffraction, powder X-ray diffraction, time-dependent Fourier-transform infrared spectroscopy, and differential scanning calorimetry. SCSC transformation brings the change in space group of single crystal. Complex 1 crystallizes in the C2/c space group, whereas complex 2 crystallizes in the Pi̅ space group. SCSC transformation brings the change in packing diagram as well. Complex 1 shows two-dimensional network through H-bonding, whereas the packing diagram of complex 2 shows a zigzag-like arrangement. Phase transformation not only fetches structural changes but also in the magnetic properties. Difference in Fe–O–Fe bond angles of two complexes creates notable variation in their antiferromagnetic interactions with adjacent metal centers

Tetragonal versus Hexagonal: Structure-Dependent Catalytic Activity of Co/Zn Bimetallic Metal–Organic Frameworks

Tetragonal and hexagonal phases of monometallic Zn and bimetallic Co/Zn metal–organic frameworks (MOFs), with secondary building units (SBUs) containing a M₃O (M = metal) cluster, were synthesized from identical constituents using a benzenetricarboxylate (BTC^3–) linker that forms decorated 3,6- and 3,5-connected networks, respectively. There exist subtle differences between the SBUs; one of the metal atoms in the M₃O cluster in the tetragonal phase has one dissociable DMF solvent molecule while that in the hexagonal phase has three. Connectivities between the SBUs form one-dimensional channels in both MOFs. These MOFs catalyze the chemoselective addition of amines to epoxides, giving exclusively β-hydroxyamine under heterogeneous conditions. A ring-opening reaction of a symmetrical epoxide showed that the hexagonal phase diastereoselectively yields <i>trans</i>-alcohol, exhibiting an exquisite model for structure-dependent activity

The ubiquitous paddle-wheel building block in two-dimensional coordination polymers with square grid structure

<p>This work describes design of a series of new paddle-wheel binuclear clusters containing 2-D coordination polymers based on ditopic carboxylate linkers, 1,4-benzenedicarboxylate (BDC) or 2-amino,1,4-benzenedicarboxylate (Am-BDC). The strategic use of strongly coordinating base/solvent as blocking ligand to restrict the structure in 2-D space is explored, and the role of organic base on the overall structure formation is further elaborated. The isostructural [Zn(BDC)(Py)]_n (<b>1</b>) and [Co(BDC(Py)]_n (<b>2</b>) were formed by the use of strong base pyridine (Py) as a blocking ligand whereas reaction using N-methylimidazole (Mim) in place of pyridine gives [Co(BDC)(Mim)]_n (<b>3</b>) with similar topology and coordination environment. The use of weak/non-coordinating base such as 2-chloropyrimidine, pyrazine, and tetramethylammoniumhexafluorophosphate [(CH₃)₄ N(PF₆)] gives the DMF-coordinated 2-D frameworks, [Cu(BDC)(DMF)]_n (<b>4</b>), [Zn(BDC)(DMF)]_n (<b>5</b>), and [Zn(AmBDC)(DMF)]_n (<b>6</b>). All the structures crystallize in monoclinic crystal system yielding 2-D nets with square grid 4⁴ topology and solid state 3-D structure <i>via</i> extensive non-covalent supramolecular interactions. Surface area analysis <i>via</i> N₂ adsorption of three representative 2-D coordination polymers, <b>1</b>, <b>4</b>, and <b>6</b>, indicate that <b>4</b> has a surface area of 450 m² g⁻¹ which is a signature of microporosity, while <b>1</b> and <b>6</b> have moderate (161.6 m² g⁻¹) and negligible (33 m² g⁻¹) surface areas, respectively.</p

Switching Closed-Shell to Open-Shell Phenalenyl: Toward Designing Electroactive Materials

Open-shell phenalenyl chemistry started more than half a century back, and the first solid-state phenalenyl radical was realized only 15 years ago highlighting the synthetic challenges associated in stabilizing carbon-based radical chemistry, though it has great promise as building blocks for molecular electronics and multifunctional materials. Alternatively, stable closed-shell phenalenyl has tremendous potential as it can be utilized to create an in situ open-shell state by external spin injection. In the present study, we have designed a closed-shell phenalenyl-based iron­(III) complex, Fe^III(PLY)₃ (PLY-H = 9-hydroxyphenalenone) displaying an excellent electrocatalytic property as cathode material for one compartment membraneless H₂O₂ fuel cell. The power density output of Fe^III(PLY)₃ is nearly 15-fold higher than the structurally related model compound Fe^III(acac)₃ (acac = acetylacetonate) and nearly 140-fold higher than an earlier reported mononuclear Fe­(III) complex, Fe^III(Pc)Cl (Pc = pthalocyaninate), highlighting the role of switchable closed-shell phenalenyl moiety for electron-transfer process in designing electroactive materials