Recent Investigations on Thiocyanate-Free Ruthenium(II) 2,2′-Bipyridyl Complexes for Dye-Sensitized Solar Cells

Three decades ago, dye-sensitized solar cells (DSSCs) emerged as a method for harnessing the energy of the sun and for converting it into electricity. Since then, a lot of work has been devoted to create better global photovoltaic efficiencies and long term stability. Among photosensitizers for DSSCs, thiocyanate-free ruthenium(II) complexes have gained increasing interest due to their better stability compared to conventional thiocyanate-based complexes, such as benchmark dyes N719 and Z907. In this mini-review, two classes of thiocyanate-free Ru(II) complexes are presented: (a) bis-bipyridyl compounds bearing an ancillary cyclometalating bidentate ligand; (b) bipyridyl compounds bearing non-cyclometalating ancillary ligands. The coverage, mainly from 2014 up to now, is not exhaustive, but illustrates the most recent design strategies and photovoltaic properties of these two families of ruthenium(II) dyes.

Pharmacokinetics and drug-likeness of antidiabetic flavonoids: Molecular docking and DFT study

Computer aided toxicity and pharmacokinetic prediction studies attracted the attention of pharmaceutical industries as an alternative means to predict potential drug candidates. In the present study, in-silico pharmacokinetic properties (ADME), drug-likeness, toxicity profiles of sixteen antidiabetic flavonoids that have ideal bidentate chelating sites for metal ion coordination were examined using SwissADME, Pro Tox II, vNN and ADMETlab web tools. Density functional theory (DFT) calculations were also employed to calculate quantum chemical descriptors of the compounds. Molecular docking studies against human alpha amylase were also conducted. The results were compared with the control drugs, metformin and acarbose. The drug-likeness prediction results showed that all flavonoids, except myricetin, were found to obey Lipinski’s rule of five for their drug like molecular nature. Pharmacokinetically, chrysin, wogonin, genistein, baicalein, and apigenin showed best absorption profile with human intestinal absorption (HIA) value of ≥ 30%, compared to the other flavonoids. Baicalein, butein, ellagic acid, eriodyctiol, Fisetin and quercetin were predicted to show carcinogenicity. The flavonoid derivatives considered in this study are predicted to be suitable molecules for CYP3A probes, except eriodyctiol which interacts with P-glycoprotein (p-gp). The toxicological endpoints prediction analysis showed that the median lethal dose (LD50) values range from 159–3919 mg/Kg, of which baicalein and quercetin are found to be mutagenic whereas butein is found to be the only immunotoxin. Molecular docking studies showed that the significant interaction (-7.5 to -8.3 kcal/mol) of the studied molecules in the binding pocket of the α-amylase protein relative to the control metformin with the crucial amino acids Asp 197, Glu 233, Asp 197, Glu 233, Trp 59, Tyr 62, His 101, Leu 162, Arg 195, His 299 and Leu 165. Chrysin was predicted to be a ligand with high absorption and lipophilicity with 84.6% absorption compared to metformin (78.3%). Moreover, quantum chemical, ADMET, drug-likeness and molecular docking profiles predicted that chrysin is a good bidentate ligand.

Synthesis, designing, characterization and anti-microbial studies of N, N'- Bis (2 hydroxyacetophenone) Ethylenediamine metal (II) complexes

Tetra dentate Schiff base N, N’-bis [2-hydroxyacetophenone] ethylendiamine (OAcPh-en) were formed by the 2:1 molar condensation of 2-hydroxyacetophenone with ethylenediamine. Their Ni(II), Cu(II), Co(II), Mn(II), Fe(II) and Zn(II) diaquo complexes (I) were synthesized. The neutral bidentate ligand derived from benzaldehyde and ethylenediamine or o-phenylenediamine in 1:1 molar ratio in alcoholic solution yield bis[benzylidene] ethylenediamine (Ben-en) or bis [benzylidene] o-phenylinediamine (Ben-opd) (II). Further reaction between (I) and (II) in alcohol yielded mixed ligand complexes. The characterization of these newly synthesized mixed-ligand complexes were done by elemental analysis, magnetic measurements, infrared spectra and uv-visible spectra, thermo gravimetric analysis, anti-microbial studies have also been under taken

Novel Lanthanide (III) Complexes Derived from an Imidazole–Biphenyl–Carboxylate Ligand: Synthesis, Structure and Luminescence Properties

A series of neutral mononuclear lanthanide complexes [Ln(HL)2(NO3)3] (Ln = La, Ce, Nd, Eu, Gd, Dy, Ho) with rigid bidentate ligand, HL (4′-(1H-imidazol-1-yl)biphenyl-4-carboxylic acid) were synthesized under solvothermal conditions. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. According to X-ray diffraction, all the complexes are a series of isostructural compounds crystallized in the P2/n monoclinic space group. Additionally, solid-state luminescence measurements of all complexes show that [Eu(HL)2(NO3)3] complex displays the characteristic emission peaks of Eu(III) ion at 593, 597, 615, and 651 nm.

Structural Requirements of 1-(2-Pyridinyl)-5-pyrazolones for Disproportionation of Boronic Acids

We observed an unusual formation of four-coordinate boron(III) complexes from the reaction of 1-(2-pyridinyl)-5-pyrazolone derivatives with arylboronic acids in the basic media. The exact mechanism is not clear; however, the use of unprotected boronic acid and the presence of a bidentate ligand appeared to be the key structural requirements for the transformation. The results suggest that base-promoted disproportionation of arylboronic acid with the assistance of the [N,O]-bidentate ligation of 1-(2-pyridinyl)-5-pyrazolone should take place and facilitate the formation of pyrazole diarylborinate. Experiments to obtain a deeper understanding of its mechanism are currently underway.

Synthesis, spectroscopic, and thermal studies of azo compounds from luminol and procaine with acetylacetone and their complexes

This The study entails the synthesis of two newly synthesized azo dyes luminol and procaine with acetylacetone (N1 and N2 correspondingly). Elementalanalysis, 1HNMR, T.G.A, and FTIR. have all been used to characterize dyes. These new dyes were reacted with Cpper and Nikel ionin 1:2 molar ratios to form of complexes of metals (II) with a general stoichiometry; CuL2, and NiL2 in complexes., FT IR, as well as the corresponding metal (II) complex, were used to characterize them. The dye acts as a bidentate ligand, according to elemental analysis and spectral results. The thermal properties of these compounds were investigated using thermogravimetric analysis (TGA). Thermal decomposition of these compounds is a process that occurs in stages.,

Highly Efficient Phosphorescent Blue-Emitting [3+2+1] Coordinated Iridium (III) Complex for OLED Application

Cyclometalated iridium (III) complexes are indispensable in the field of phosphorescent organic light-emitting diodes (PhOLEDs), while the improvement of blue iridium (III) complexes is as yet limited and challenging. More diversified blue emitters are needed to break through the bottleneck of the industry. Hence, a novel [3+2+1] coordinated iridium (III) complex (noted as Ir-dfpMepy-CN) bearing tridentate bis-N-heterocyclic carbene (NHC) chelate (2,6-bisimidazolylidene benzene), bidentate chelates 2-(2,4-difluorophenyl)-4-methylpyridine (dfpMepy), and monodentate ligand (-CN) has been designed and synthesized. The tridentate bis-NHC ligand enhances molecular stability by forming strong bonds with the center iridium atom. The electron-withdrawing groups in the bidentate ligand (dfpMepy) and monodentate ligand (-CN) ameliorate the stability of the HOMO levels. Ir-dfpMepy-CN shows photoluminescence peaks of 440 and 466 nm with a high quantum efficiency of 84 ± 5%. Additionally, the HATCN (10 nm)/TAPC (40 nm)/TcTa (10 nm)/10 wt% Ir-dfpMepy-CN in DPEPO (10 nm)/TmPyPB (40 nm)/Liq (2.5 nm)/Al (100 nm) OLED device employing the complex shows a CIE coordinate of (0.16, 0.17), reaching a deeper blue emission. The high quantum efficiency is attributed to rapid singlet to triplet charge transfer transition of 0.9–1.2 ps. The successful synthesis of Ir-dfpMepy-CN has opened a new window to develop advanced blue emitters and dopant alternatives for future efficient blue PhOLEDs.

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.

Synthesis, Characterization and Antibacterial Activity Study of Cobalt(II), Nickel(II), Copper(II), Palladium(II), Cadmium(II) and Platinum(IV) Complexes with 4-Amino-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole-3-thione

New transition metal complexes of cobalt(II), nickel(II), copper(II), palladium(II), cadmium(II), and platinum(IV) with bidentate ligand 4-amino-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole-3-thiol were synthesized and characterized by microelemental analyses (CHNS), Fourier-transform infrared (FT-IR), UV-Visible spectra, molar conductance, magnetic susceptibility and thermal analyses (TG-DSC). The ligand was synthesized by ring closure of potassium-2-(3,4,5-trimethoxybenzoyl) hydrazine carbodithioate with an excess amount of hydrazine, and then was acidified using hydrochloric acid. The ligand was used as Lewis bases to prepare metal complexes through the reaction of ratio (1:2) metal:ligand. The ligand was characterized by 1H-NMR and 13C-NMR and the previously described methods to identify the complexes. The results obtained from spectra and elemental analyses indicated the tetrahedral geometry around Cd(II) ion, square-planar for Cu(II) and Pd(II), and octahedral geometry around Co(II), Ni(II), and Pt(IV). All the metal complexes showed significant antibacterial activity in comparison with the free ligand. The antibacterial test of the platinum(IV) complex showed higher activity than other metal complexes against bacteria Staphylococcus aureus (G-positive) and Escherichia coli (G-negative).