Light on the sustainable preparation of aryl-cored dibromides

Both aryl and benzyl polybromides have gained significant importance as reactive building blocks in polymer and materials chemistry. Their preparation primarily relies on established synthetic methods using molecular bromine or N-bromosuccinimide, known for their reliability and effectiveness. However, from a sustainability perspective, these methods suffer from the generation of stoichiometric amounts of byproducts and often encounter selectivity troubles. To mitigate these issues, we extended the greener peroxide-bromide halogenation method, initially developed for monobromides, to afford aryl-cored polybromides in high yields. The same method can be employed in two variants modulated by light irradiation. This external switch can be used to selectively trigger side-chain or core halogenation.

Interpenetration Phenomena via Anion Template Effects in Fe(II) and Co(II) Coordination Networks with a Bis-(1,2,4-triazole) Ligand

Seven new coordination networks, [Fe(tbbt)3](BF4)2 (1), [Co(tbbt)3](BF4)2 (2), [Fe(tbbt)3](ClO4)2 (3), [Co(tbbt)3](ClO4)2 (4), [Fe(NCS)2(tbbt)2] (5), [Co(NCS)2(tbbt)2] (6), and [Fe(H2O)2(tbbt)2]Br2·2H2O (7), were synthesized with the linker 1,1'-(trans-2-butene-1,4-diyl)bis-1,2,4-triazole (tbbt) and structurally investigated. The structure of complexes 1-4 is composed of three interpenetrating, symmetry-related 3D networks. Each individual 3D network forms a primitive, nearly cubic lattice (pcu) with BF4- or ClO4- anions present in the interstitial spaces. The structure of compounds 5 and 6 is composed of two-dimensional sql layers, which are parallel to each other in the AB stacking type. These layers are interpenetrated by one-dimensional chains, both having the same formula unit, [M(NCS)2(tbbt)2] (M = Fe, Co). The structure of compound 7 consists of parallel, two-dimensional sql layers in the ABCD stacking type. The interpenetration in 1-6 is not controlled by π-π-interactions between the triazole rings or C=C bonds, as could have been expected, but by (triazole)C-H⋯F4B, C-H⋯O4Cl, and C-H⋯SCN anion hydrogen bonds, which suggests a template effect of the respective non-coordinated or coordinated anion for the interpenetration. In 7, the (triazole)C-H⋯Br anion interactions are supplemented by O-H⋯O and O-H⋯Br hydrogen bonds involving the aqua ligand and crystal water molecules. It is evident that the coordinated and non-coordinated anions play an essential role in the formation of the networks and guide the interpenetration. All iron(II) coordination networks are colorless, off-white to yellow-orange, and have the metal ions in the high-spin state down to 77 K. Compound 5 stays in the high spin state even at temperatures down to 10 K.

Effect of sulfur doping of zinc-imidazole coordination polymer (ZnIm CP) as a novel photocatalyst for degradation of ionic dyes

Zinc-Imidazole coordination polymer (ZnImCP) was simply synthesized hydrothermally at relatively low temperature (70 °C) from zinc acetate and imidazole. ZnImCP was treated by sulfide solution to produce sulfur-doped samples (S-ZnImCPs). Structures of the synthesized ZnImCP and S-ZnImCPs were characterized through FTIR, PXRD, and, Raman, SEM/EDX, N2-BET, UV–VIS DRS, and pHpzc analyses. The photocatalytic performances of pristine CP and sulfur modified CPs under visible and ultra-violet irradiations for degrading the cationic methylene blue (MB) and the anionic methyl orange (MO) were investigated considering different initial pH values 4, 7 and 10. Under visible light, the results indicate that these CPs display considerable photocatalytic degradation towards the cationic MB for the initial pH 4 and 7 where degradation increases with sulfur content. While under ultra-violet, results indicate considerable photocatalytic degradation towards both dyes for the initial pH 7 and 10 where degradation increases with sulfur content which indicates the gainful of non-metal dopping. The buffering nature of CPs and the type of radiation considering determined band-gap values effectively influence the degradation mechanisms.

Activation of Cadmium–Imidazole Buffering Coordination Polymer by Sulfur-Doping for the Enhancement of Photocatalytic Degradation of Cationic and Anionic Dyes Under Visible Light

The buffering Cadmium–Imidazole Coordination Polymer (Cd–Im-CP) was synthesized hydrothermally from cadmium chloride and imidazole at 70 °C and then was subjected to doping- by the non-metal sulfur using Na2S solution as a novel modification strategy to produce S–Cd–Im CPs. To investigate doping nature and its effects, Cd–Im CP and S–Cd–Im CPs were characterized applying different analyses techniques, FTIR, Raman, PXRD, SEM/EDX, TGA, and UV–Vis DRS analyses. Characterizations showed the successful chemical doping of sulfur. The inclusion of sulfur within chemical CP structure caused narrowing of material’s bandgap from 4.55 and 3.4 eV to 4.25 and 2.35 eV for S–Cd–Im CPs allowing it for photoresponse towards Visible-light. Both Cd–Im CP and S–Cd–Im CPs were applied for photocatalytic degradation of the selected dyes methylene blue (MB),and methyl orange (MO) employing visible and UV irradiations considering three different initial pH levels to investigate the consequence of sulfur doping. After eliminating the photolysis effect, the best degradation by S–Cd–Im CPs was recorded for MB at initial pH 4 being 13 fold that is for Cd–Im CP. The highest apparent turnover frequencies are 1.2 × 10−3 h−1 for MB at initial pH 10 and 1.03 × 10−4 h−1 for MO at initial pH 4 are given by 10S–Cd–IM CP under Visible-light. Generally, S–Cd–Im CPs remarkably improved photocatalysis degradation of both the dyes for all initial pH levels under Visible-light.

Visible light-assisted photocatalytic degradation of methylene blue in water by highly chemically stable Cd-coordination polymers at room temperature

Mesoporous YAU-10 based on a binuclear 3D structure has been synthesized as a photocatalytic material exhibiting excellent visible light-assisted degradation of methylene blue.

Syntheses, design strategies, and photocatalytic charge dynamics of metal–organic frameworks (MOFs): a catalyzed photo-degradation approach towards organic dyes

The presented review focuses on design strategies to develop tailor-made MOFs/CPs of main group, transition and inner-transition elements and their photocatalytic properties to decompose dyes in wastewater discharge and their photocatalytic mechanism.

Structures and photocatalytic properties of two new Zn(ii) coordination polymers based on semi-rigid V-shaped multicarboxylate ligands

Two new metal-organic coordination polymers (CPs), aqua-2,2'-bipyridine-5-(4'-carboxylphenoxy)isophthalatezinc(ii) polymer [Zn(HL)(2,2'-bipy)(H₂O)] _n (1) and tris-4,4'-bipyridine-bis-5-(4'-carboxylphenoxy)isophthalatetrizinc(ii) polymer [Zn₃(L)2(4,4'-bipy)₃] _n (2) (H₃L = 5-(4'-carboxylphenoxy)isophthalic acid, 4,4'-bipy = 4,4'-bipyridine and 2,2'-bipy = 2,2'-bipyridine), were obtained under hydrothermal conditions and characterized by microanalysis, FTIR spectroscopy and single crystal X-ray diffraction. The single crystal X-ray diffraction indicated that in both the CPs the coordination networks exhibited varied topologies and coordination modes around the Zn(ii) centers. CP 1 exhibits a one-dimensional (1D) chain structure, which further forms a 3D supramolecular architecture via intermolecular π⋯π and hydrogen bonding interactions, while 2 possesses a 3D framework generated from a 2D layered motif comprising zinc and tripodal carboxylate subunits pillared by 4,4'-bpy ligands. Apart from the structural investigation, the photocatalytic performances of both the coordination polymers to photodecompose an aqueous solution of methyl violet (MV) were examined. The results indicated that both the CPs displayed the potential to photodecompose aromatic dyes and in particular 2 showed good photocatalytic activity for dye degradation under light irradiation. The photocatalytic mechanism through which these CPs executed degradation of dyes has been explained with the assistance of band gap calculations using density of states (DOS) and its decomposed partial DOS calculations.

Microwave induced transformation of metal organic frameworks into defect rich carbon nanofibers

We report a fast and facile microwave synthesis of defect rich, nitrogen doped carbon nanofibers from novel MOF precursors.