Synthesis, Structure, and Magnetic Properties of Bithiophene- and Terthiophene-Linked Manganese Metal–Organic Frameworks

Zirconium Metal-Organic Frameworks Containing a Biselenophene Linker: Synthesis, Characterization, and Luminescent Properties

The bicyclic ditopic linker 2,2'-biselenophene-5,5'-dicarboxylic acid (H₂SpSp), specifically designed for metal-organic framework (MOF) construction, has been synthesized in good yield and fully characterized. The corresponding zirconium MOF (Zr-MOF) [Zr₆O₄(OH)₄(SpSp)_3.8Cl_4.4] (1; where missing linkers are replaced by chloride anions as shown by X-ray fluorescence and elemental analysis) is isostructural with its bithiophene and bithiazole analogues. Starting from 1, an extension of the biselenophene-based Zr-MOF family has been successfully achieved, exploiting the structural analogy of the five-membered heterocycles selenophene, thiophene, and thiazole. Thus, three mixed-linker MOFs containing variable amounts of different bis(heterocyclic) dicarboxylic acids have been prepared and fully characterized: the two double-mixed [Zr₆O₄(OH)₄(SpSp)_2.6(TpTp)_1.3Cl_4.2] (2; H₂TpTp = 2,2'-bithiophene-5,5'-dicarboxylic acid) and [Zr₆O₄(OH)₄(SpSp)₂(TzTz)_1.8Cl_4.4] (3; H₂TzTz = 2,2'-bithiazole-5,5'-dicarboxylic acid) materials, as well as the triple-mixed [Zr₆O₄(OH)₄(SpSp)_1.6(TpTp)_1.2(TzTz)_1.4Cl_3.6] (4) compound. The four MOFs are luminescent under UV irradiation, exhibiting emission wavelengths falling in the blue-green visible region, as observed for their constitutive linkers. These materials open new horizons in the preparation of porous luminescent sensors or multicolor emitters for light-emitting diodes.

Quantification of the Nucleophilicities of 3-X-Thiophenes: Highlighting the Hyperortho Correlation

Kinetics studies for the coupling reactions of the 3-X-thiophene 1a-c (X = CH3, H and Br) with the electrophiles 2a and 3a-c have been investigated in acetonitrile at 20°C The second-order rate constants have been employed to determine the nucleophilicity parameters N and s of the thiophene 1 according the Mayr equation log k (20°C) = s (E + N). The nucleophilic-specific parameters N and s quantified in this work have been derived and compared with the reactivity of other C nucleophiles. Based on the linear correlations log k1 = f(E) and log k1 = f(σp+), we have shown that the mechanism of interactions occurs by a unique process: electrophilic heteroaromatic substitution of an α-carbon position of substituted 3-X-thiophenes 1 known hyperortho correlation.

Synthesis, structures and magnetic properties in 3d-electron-rich isostructural complexes based on chains with sole syn–anti carboxylate bridges

A series of isostructures based on 2,2′,4,4′-biphenyltetracarboxylic acid have been synthesized via solvothermal reaction, whereas magnetic studies reveal the polymers with sole syn–anti carboxylate bridges show different magnetic behaviors of uniform chains.

Self-assembly and magnetic properties of Ni(ii)/Co(ii) coordination polymers based on 1,4-bis(imidazol-1-yl)benzene and varying biphenyltetracarboxylates

Five complexes of 1,4-bis(imidazol-1-yl)benzene, H₄bptas and cobalt/nickel are synthesized via solvothermal reaction; both of them have intriguing interpenetrated architectures.