Unusual fluorescent behavior of a heteroleptic Cu(I) complex featuring strong electron donating groups on the diimine ligand

A novel diimine ligand (N^Nb) and the corresponding heteroleptic diimine-diphosphine Cu(I) complex (Cu-N^Nb) have been synthesized and their structural properties characterized. The N^Nb ligand is the 2,9-bis-[4-(dimethylamino)phenyl]ethenyl]-4,7-diphenyl-1,10-phenanthroline, which has a...

Re(I) Complexes as Backbone Substituents and Cross-Linking Agents for Hybrid Luminescent Polysiloxanes and Silicone Rubbers

This study focuses on the synthesis of hybrid luminescent polysiloxanes and silicone rubbers grafted by organometallic rhenium(I) complexes using Cu(I)-catalyzed azido-alkyne cycloaddition (CuAAC). The design of the rhenium(I) complexes includes using a diimine ligand to create an MLCT luminescent center and the introduction of a triple C≡C bond on the periphery of the ligand environment to provide click-reaction capability. Poly(3-azidopropylmethylsiloxane-co-dimethylsiloxane) (N3-PDMS) was synthesized for incorporation of azide function in polysiloxane chain. [Re(CO)3(MeCN)(5-(4-ethynylphenyl)-2,2′-bipyridine)]OTf (Re1) luminescent complex was used to prepare a luminescent copolymer with N3-PDMS (Re1-PDMS), while [Re(CO)3Cl(5,5′-diethynyl-2,2′-bipyridine)] (Re2) was used as a luminescent cross-linking agent of N3-PDMS to obtain luminescent silicone rubber (Re2-PDMS). The examination of photophysical properties of the hybrid polymer materials obtained show that emission profile of Re(I) moiety remains unchanged and metallocenter allows to control the creation of polysiloxane-based materials with specified properties.

Novel Oxidovanadium Complexes with Redox-Active R-Mian and R-Bian Ligands: Synthesis, Structure, Redox and Catalytic Properties

A new monoiminoacenaphthenone 3,5-(CF3)2C6H3-mian (complex 2) was synthesized and further exploited, along with the already known monoiminoacenaphthenone dpp-mian, to obtain oxidovanadium(IV) complexes [VOCl2(dpp-mian)(CH3CN)] (3) and [VOCl(3,5-(CF3)2C6H3-bian)(H2O)][VOCl3(3,5-(CF3)2C6H3-bian)]·2.85DME (4) from [VOCl2(CH3CN)2(H2O)] (1) or [VCl3(THF)3]. The structure of all compounds was determined using X-ray structural analysis. The vanadium atom in these structures has an octahedral coordination environment. Complex 4 has an unexpected structure. Firstly, it contains 3,5-(CF3)2C6H3-bian instead of 3,5-(CF3)2C6H3-mian. Secondly, it has a binuclear structure, in contrast to 3, in which two oxovanadium parts are linked to each other through V=O···V interaction. This interaction is non-covalent in origin, according to DFT calculations. In structures 2 and 3, non-covalent π-π staking interactions between acenaphthene moieties of the neighboring molecules (distances are 3.36–3.40 Å) with an estimated energy of 3 kcal/mol were also found. The redox properties of the obtained compounds were studied using cyclic voltammetry in solution. In all cases, the reduction processes initiated by the redox-active nature of the mian or bian ligand were identified. The paramagnetic nature of complexes 3 and 4 has been proven by EPR spectroscopy. Complexes 3 and 4 exhibited high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The yields of products of cyclohexane oxidation were 43% (complex 3) and 27% (complex 4). Based on the data regarding the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play the most crucial role in the reaction. The initial products in the reactions with alkanes are alkyl hydroperoxides, which are easily reduced to their corresponding alcohols by the action of triphenylphosphine (PPh3). According to the DFT calculations, the difference in the catalytic activity of 3 and 4 is most likely associated with a different mechanism for the generation of ●OH radicals. For complex 4 with electron-withdrawing CF3 substituents at the diimine ligand, an alternative mechanism, different from Fenton’s and involving a redox-active ligand, is assumed.

Synthesis, Spectroscopic Characterization, and Biological Activities of New Binuclear Co(II), Ni(II), Cu(II), and Zn(II) Diimine Complexes

Metal-ligand complexes have attracted major interest due to their potential medical applications as anticancer agents. The work described in the current article aimed to synthesize, spectroscopic, thermal, and biological studies of some metal-diimine complexes. A diimine ligand, namely 2-{[2-(4-chlorophenyl)-2-hydroxyvinyl]-hydrazonomethyl}phenol (diim) was prepared via the reaction of p-chlorophenacyl bromide with hydrazine hydrate in ethanol, then condensation was completed with 2-hydroxybenzaldehyde in acetic acid. The Co(II), Ni(II), Cu(II), and Zn(II) complexes were prepared with a metal:ligand stoichiometric ratio of (2:1). 1H-NMR, UV-Vis, FTIR spectroscopic data, molar conductivity measurements, and microanalytical data (carbon, hydrogen, nitrogen, and halogen) were used for characterization of the formed ligand and its metal complexes. It was found that the diimine ligand act as tetradentate fashion. The non-electrolytic character for all the complexes was proved by molar conductivity. The first metal atom of the synthesized binuclear diimine complexes coordinates with the nitrogen of hydrazine group and oxygen of OH group. While, the second metal atom coordinates with the other nitrogen atom of the hydrazine group and oxygen of phenolic group. All the synthesized metal complexes have a six-coordinated except for Zn(II) has four-coordinated. Thermogravimetric analysis and its differential analysis were done to discuss the thermal degradation of the free ligand and its metal complexes. Molecular docking calculation showed that the diimine ligand is a good inhibitor for breast cancer 3hb5 and 4o1v kidney cancer proteins. Additionally, these compounds were evaluated as antibacterial and antifungal agents.

Impacts of Extending π-Conjugation of the 2,2′-Biquinoline Ligand on Photophysics and Reverse Saturable Absorption of the Heteroleptic Cationic Iridium(III) Complexes

Two heteroleptic monocationic Ir(III) complexes bearing 6,6′-bis(7-benzothiazolylfluoren-2-yl)-2,2′-biquinoline as the diimine ligand with different degrees of π-conjugation were synthesized and their photophysics were investigated by spectroscopic techniques and first principle calculations....

A series of luminescence Cu(I) complexes based on diphosphine ligand and diimine ligand: the weak intermolecular interactions, terahertz spectra and photoproperties

Five novel mononuclear [Cu(Bphen)(bdppmapy)]X complexes showing photoluminescence were synthesized. The same diphosphine ligand and diimine ligand and different Cu(I) salts were used in the one-pot synthesis of complexes 1-5. These...

Diversifying the luminescence of phenanthro-diimine ligands in zinc complexes

Strongly blue fluorescent 1-phenyl-2-(pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole (L1) is a facile block for the construction of multichromophore organic molecules, and simultaneously serves as a chelating diimine ligand.

Synthesis and crystal structures of manganese(I) carbonyl complexes bearing ester-substituted α-diimine ligands

The crystal structures of two manganese(I) complexes with ester-substituted bipyridine or biquinoline supporting ligands are reported, namely, fac-bromidotricarbonyl(diethyl 2,2′-bipyridine-4,4′-dicarboxylate-κ2 N,N′)manganese(I), [MnBr(C16H16N2O4)(CO)3], I, and fac-bromidotricarbonyl(diethyl 2,2′-biquinoline-4,4′-dicarboxylate-κ2 N,N′)manganese(I), [MnBr(C24H20N2O4)(CO)3], II. In both complexes, the manganese(I) atom adopts a distorted octahedral coordination sphere defined by three carbonyl C atoms, a Br− anion and two N atoms from the chelating α-diimine ligand. Both complexes show fac configurations of the carbonyl ligands. In I, the complex molecules are linked by C—H...Br hydrogen bonds and aromatic π–π contacts. In II, intramolecular C—H...O hydrogen bonds are present as well as intermolecular C—H...O and C—H...Br hydrogen bonds and π–π interactions.