Deconstructive Cycloaromatization Strategy towards N,O-Bidentate Ligands and Their Four-Coordinate Organoboron Complexes

The innovative construction of novel N,O-bidentate ligands and N,O π-conjugated four-coordinate organoboron complexes represent a long-standing challenge for chemists. Here, we report an unprecedented and straightforward approach for the construction of N,O-bidentate ligands and their organoboron complexes via the merge of ring deconstruction with cycloaromatization of indolizines and cyclopropenones. Without any catalysts, our method is able to deliver a series of polyaryl 2-(pyridin-2-yl)phenol ligands, N,O π-conjugated organoboron (BF2 and BAr2) complexes with good functional-group compatibility which are difficult or even impossible to synthesize with previous methods. Importantly, the formed N,O-bidentate ligands were easy to scale up and derive with valuable drugs and active molecules. In addition, the photoluminescence measurements and the HOMO/LUMO gap have been investigated, the results have revealed that N,O π-conjugated tetracoordinate boron complexes display bright fluorescence, large Stokes shifts, and good quantum yields (Φlum = 0.15–0.45). The method proposed by the paper will inspire the development of various N,O-bidentate metal and boron complexes, which is expected to move the area of catalysis chemistry and material science forward.

Electrochromic behavior of fac-tricarbonyl rhenium complexes

This paper aims to investigate the electrochromic properties of tricarbonyl rhenium complexes. Using 4,7-diphenylphenanthroline (L1) and 4,7-di(4-substituted)-1,10-phenanthroline (L2-L5) as bidentate ligands, a series of tricarbonyl rhenium complexes, fac-Re(CO)3(Lx)Cl (x=1-5), were...

Spectrophotometric determination of trace amount of iron in water, food, and pharmaceutical samples

The present study aimed to determine the trace amount of iron by using highly selective and sensitive spectrophotometric reagents in water, food, and pharmaceutical samples. For this, as-triazine containing ferroin-yielding chromogens; 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) and 3-(2-pyridyl)-5,6-bis(p-methoxyphenyl)-1,2,4-triazine (PBMPT) have been synthesized. The absorptiometric characteristics of the iron(II) complexes with PDT and PBMPT such as complex formation, sensitivity determination, composition determination have also been studied. It has been observed that these highly sensitive and selective ferroin-yielding reagents act as bidentate ligands and form intensive colored tris-complexes with iron(II) ions. The application of these spectrophotometric reagents for the determination of iron in water, food, and pharmaceutical samples has been described. Bangladesh J. Sci. Ind. Res.56(4), 299-306, 2021

Mini-Review of the Importance of Hydrazides and Their Derivatives—Synthesis and Biological Activity

Organic acid hydrazides include a vast group of organic derivatives of hydrazines containing the active functional group (-C(=O)NHNH2). Acid hydrazones were important bidentate ligands and show keto-enol (amido-iminol) tautomerism. They usually exist in keto form in the solid-state while in equilibrium between keto and enol forms in solution state. Such hydrazones were synthesized in the laboratory by heating substituted hydrazides or hydrazines with corresponding aldehydes or ketones in different organic solvents such as ethanol, methanol, butanol, tetrahydrofuran, etc., and some cases with the ethanol-glacial acetic acid or acetic acid alone. Hydrozones are very important intermediates for the synthesis of heterocyclic compounds and also have different biological activities. The organic chemist would have more interest in the synthesis of acid hydrazides and their derivatives because of their properties. These derivatives having wide applications as chemical preservers for plants, drugs, for manufacturing polymers, glues, etc., in industry and many other purposes. These acid hydrazides and their derivatives were found to be useful synthons for various heterocyclic five, six or seven-membered rings with one or more heteroatoms that were exhibited great biological, pharmacological and industrial applications. This paper will present a review of the chemistry and pharmacological potentials of hydrazide-hydrazones. The various synthetic routes for hydrazone, as well as antibacterial, antifungal and antiviral potentials, have been elaborated in brief.

Copper(I) iodide-based organic–inorganic hybrid compounds as phosphor materials

Two photoluminescent copper(I) iodide inorganic-organic hybrid materials have been synthesized and structurally characterized as 1D-Cu2I2(bpoe)2 (1) and 1D-Cu2I2(bbtpe-m)2 (2) (bpoe = 1,2-bis(pyridin-3-yloxy)ethane, bbtpe-m = 1,1′-(3-methylpentane-1,5-diyl)bis(1H-benzo[1,2,3]triazole). Both are chain-like structures composed of Cu2I2 rhomboid dimers connected by bidentate ligands. Their emission colors range from cyan to yellow with relatively high internal quantum yields in the solid state. The tunable band gap and emission color is achieved by varying the LUMO energies of the ligands. The structures are robust and remain stable up to T = 260 °C, and coupled with their efficient and adjustable luminescence, facile synthesis, and non-toxic nature, these compounds demonstrate potential as rare earth element (REE)-free phosphors.

C,C- and C,N-Chelated Organocopper Compounds

Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono-carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize unstable organocopper compounds. Bidentate ligands can chelate to the same copper atom via η2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via η1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles. The anionic coordinating sites of the bidentate ligand can also bridge two metals via μ2-mode, forming organocopper aggregates with Cu-Cu interactions and organocuprates with contact ion pair structures. The reaction chemistry of some selected organocopper compounds is highlighted, showing their unique structure–reactivity relationships.