Tricarbonyl rhenium(i) complexes with 8-hydroxyquinolines: structural, chemical, antibacterial, and anticancer characteristics

Twelve tricarbonyl rhenium(i) complexes in the '2 + 1' system with the anionic bidentate N,O-donor ligand (deprotonated 8-hydroxyquinoline (HQ) or its 2-methyl (MeHQ) or 5-chloro (ClHQ) derivative) and neutral N-donor diazoles (imidazole (Him), 2-methylimidazole (MeHim), 3,5-dimethylpyrazole (Hdmpz), and 3-phenylpyrazole (HPhpz)) were synthesized: [Re(CO)3(LN,O)LN] (LN,O = Q-, MeQ-, ClQ-; LN = Him, MeHim, Hdmpz, HPhpz). Their crystal structures were determined by the scXRD method, compared with the DFT-calculated ones, and characterized by analytical (EA) and spectroscopic techniques (FT-IR, NMR, and UV-Vis) interpreted with DFT and TD-DFT calculations. Most of the Re(i) complexes did not show relevant antibacterial activity against Gram-negative and Gram-positive bacterial strains. Only [Re(CO)3(MeQ)Him] demonstrated significant action 4-fold better against Gram-negative Pseudomonas aeruginosa than the free MeHQ ligand. The cytotoxicity of the compounds was estimated using human acute promyelocytic leukemia (HL-60), ovarian (SKOV-3), prostate (PC-3), and breast (MCF-7) cancer, and breast non-cancerous (MCF-10A) cell lines. Only HQ and ClHQ ligands and [Re(CO)3(Q)Hdmpz] complex had good selectivity toward MCF-7 cell line. HL-60 cells were sensitive to all complexes (IC50 = 1.5-14 μM). Still, pure HQ and ClHQ ligands were slightly more active than the complexes.

Exploration of intramolecular charge transfer in para-substituted nitrobenzofurazan: Experimental and theoretical analyses

The present work aims at exploring the high electrophilic character of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) toward the morpholine group by an S_NAr reaction in acetonitrile or water (thereafter referred to as NBD-Morph). The electron-donating ability of the morpholine causes intra-molecular charge transfer (ICT). In this report, we present a comprehensive study on the optical characteristics using UV-Vis, photoluminescence (cw-PL) and its time-resolved (TR-PL) to determine the properties of the emissive intramolecular charge transfer (ICT) in the NBD-Morph donor-acceptor system. An exhaustive theoretical investigation utilizing the density functional theory (DFT) and its extension TD-DFT methods is an essential complement of experiments to rationalize and understand the molecular structure and related properties. The findings from QTAIM, ELF, and RDG analyses establish that the bonding between morpholine and NBD moieties is of the electrostatic or hydrogen bond type. In addition, the Hirshfeld surfaces have been established to explore the types of interactions. Further, the non-linear optical (NLO) responses of the compound have been examined. The structure-property relationships obtained through the combined experimental and theoretical offer valuable insights for designing efficient NLO material.

Influence of methyl group in a quinoline moiety on optical and light-induced properties of side-chain azo-polymers

We present the optical and photochromic properties as well as surface quality of thin films of the methacrylic copolymers containing 2-methylquinoline and quinoline azo-dyes in side chain. The extinction coefficient and refractive index were determined using spectroscopic ellipsometry combined with transmittance measurements. Photo-responsive behavior was investigated by determination of trans–cis photoisomerization rates under irradiation with unpolarized 365 nm light. We found that optical properties as well as photoisomerization rates of investigated polymers are dependent on the presence of a methyl substituent in the 2nd position of the quinoline moiety. The quality of the thin films was examined using Atomic Force Microscopy measurements.

Physico-Chemical and Light-Induced Properties of Quinoline Azo-dyes Polymers

We present investigation of optical and photochromic properties as well as of surface quality of thin films of novel methacrylic polymers with 8-hydroxyquinoline azo-dyes in side-chain. Additionally, thermal stability of polymer powders was examined and their glass transition temperature was determined. Optical properties (extinction coefficient and refractive index) were determined by spectroscopic ellipsometry (SE) combined with absorbance measurements. Photoresponsive behavior was investigated by determination of photoisomerization rates under irradiation with unpolarized 365 nm light, as well as by conduction of holographic grating inscription experiment. Thin film quality was determined by atomic force microscopy (AFM) measurements. Thermal analysis was performed by thermogravimetric (TG), derivative thermogravimetric (DTG) and differential scanning calorimetry (DSC) measurements. We found that optical properties as well as photoisomerization rates of investigated polymers are dependent on the substituent in the para position of the phenyl ring. Surface relief grating inscription was successfully generated only for materials with chromophores containing dimethylamino (N(CH₃)₂) and methyl (CH₃) substituents, but all materials exhibited birefringence grating in the bulk. Surface of most thin films was very smooth, but its quality was impaired by neutral (H) as well as carboxyl (COOH) substituent. Thermal stability of copolymers with side-chain chromophores was improved compared to pure poly(methyl methacrylate) (PMMA).

Experimental and theoretical investigation of a metalloreceptor bearing a [Re(CO)3]+ core incorporating a multifunctional ligand: selective reactivity towards Zn2+ and CN− ions

Novel Re(i) complex containing multifunctional ligand HL shows selective reactivity towards Zn²⁺ and CN⁻.

Synthesis and luminescence properties of novel 8-hydroxyquinoline derivatives and their Eu(III) complexes

Six novel 8-hydroxyquinoline derivatives were synthesized using 2-methyl-8-hydroxyquinoline and para-substituted phenol as the main starting materials, and were characterized by ¹ H nuclear magnetic resonance (NMR), mass spectrometry (MS), ultraviolet (UV) light analysis and infra-red (IR) light analysis. Their complexes with Eu(III) were also prepared and characterized by elemental analysis, molar conductivity, UV light analysis, IR light analysis, and thermogravimetric-differential thermal analysis (TG-DTA). The results showed that the ligand coordinated well with Eu(III) ions and had excellent thermal stability. The structure of the target complex was EuY^1-6 (NO₃ )₃ .2H₂ O. The luminescence properties of the target complexes were investigated, the results indicated that all target complexes had favorable luminescence properties and that the introduction of an electron-donating group could enhance the luminescence intensity of the corresponding complexes, but the addition of an electron-withdrawing group had the opposite effect. Among all the target complexes, the methoxy-substituted complex (-OCH₃ ) had the highest fluorescence intensity and the nitro-substituted complex (-NO₂ ) had the weakest fluorescence intensity. The results showed that 8-hydroxyquinoline derivatives had good energy transfer efficiency for the Eu(III) ion. All the target complexes had a relatively high fluorescence quantum yield. The fluorescence quantum yield of the complex EuY³ (NO₃ )₃ .2H₂ O was highest among all target complexes and was up to 0.628. Because of excellent luminescence properties and thermal stabilities of the Eu(III) complexes, they could be used as promising candidate luminescent materials.

Heteroleptic iridium(iii) complexes bearing a coumarin moiety: an experimental and theoretical investigation

Three mononuclear heteroleptic Ir(iii) complexes have been synthesized. The electronic structure and the spectral properties of the complexes were calculated applying the DFT-TDDFT method. The chemical shift was also computed by the GIAO-DFT method.

Synthesis, characterization and DFT study of oxorhenium(v) complexes incorporating quinoline based tridentate ligands

Two mononuclear Re(v) complexes were synthesized using two different O, N, N coordinating Schiff base ligands. The X-ray structure and catalytic properties of the complexes are investigated and the electronic structure and absorption spectra were also calculated.