2,2'-Biquinoline

Conjugated, rigidified bibenzimidazole ancillary ligands for enhanced photoluminescence quantum yields of orange/red-emitting iridium(iii) complexes.[Pubmed:30874276]

Dalton Trans. 2019 Mar 15.

A series of six novel [Ir(C^N)2(N^N)](PF6) complexes (C^N is one of two cyclometalating ligands: 2-phenyl-4-(2,4,6-trimethylphenyl)pyridine, MesppyH, or 2-(napthalen-1-yl)-4-(2,4,6-trimethylphenyl)pyridine, MesnpyH; N^N denotes one of four neutral diamine ligands: 4,4'-di-tert-butyl-2,2'-bipyridine, dtbubpy, 1H,1'H-2,2'-bibenzimiazole, H2bibenz, 1,1'-(alpha,alpha'-o-xylylene)-2,2'-bibenzimidazole, o-xylbibenz or 2,2'-biquinoline, biq) were synthesised and their structural, electrochemical and photophysical properties comprehensively characterised. The more conjugated MesnpyH ligands confer a red-shift in the emission compared to MesppyH but maintain high photoluminescence quantum yields due to the steric bulk of the mesityl groups. The H2bibenz and o-xylbibenz ligands are shown to be electronically indistinct to dtbubpy but give complexes with higher quantum yields than analogous complexes bearing dtbubpy. In particular, the rigidity of the o-xylbibenz ligand, combined with the steric bulk of the MesnpyH C^N ligands, gives a red-emitting complex 4 (lambdaPL = 586, 623 nm) with a very high photoluminescence quantum yield (PhiPL = 44%) for an emitter in that region of the visible spectrum. These results suggest that employing these ligands is a viable strategy for designing more efficient orange-red emitters for use in a variety of photophysical applications.

Cationic Ir(III) Emitters with Near-Infrared Emission Beyond 800 nm and Their Use in Light-Emitting Electrochemical Cells.[Pubmed:30762257]

Chemistry. 2019 Apr 11;25(21):5489-5497.

Solid-state near-infrared (NIR) light-emitting devices have recently received considerable attention as NIR light sources that can penetrate deep into human tissue and are suitable for bioimaging and labeling. In addition, solid-state NIR light-emitting electrochemical cells (LECs) have shown several promising advantages over NIR organic light-emitting devices (OLEDs). However, among the reported NIR LECs based on ionic transition-metal complexes (iTMCs), there is currently no iridium-based LEC that displays NIR electroluminescence (EL) peaks near to or above 800 nm. In this report we demonstrate a simple method for adjusting the energy gap between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) of iridium-based iTMCs to generate NIR emission. We describe a series of novel ionic iridium complexes with very small energy gaps, namely NIR1-NIR6, in which 2,3-diphenylbenzo[g]quinoxaline moieties mainly take charge of the HOMO energy levels and 2,2'-biquinoline, 2-(quinolin-2-yl)quinazoline, and 2,2'-bibenzo[d]thiazole moieties mainly control the LUMO energy levels. All the complexes exhibited NIR phosphorescence, with emission maxima up to 850 nm, and have been applied as components in LECs, showing a maximum external quantum efficiency (EQE) of 0.05 % in the EL devices. By using a host-guest emissive system, with the iridium complex RED as the host and the complex NIR3 or NIR6 as guest, the highest EQE of the LECs can be further enhanced to above 0.1 %.

Novel Polyheteroarylene Membranes for Separation of MethanolHexane Mixture by Pervaporation.[Pubmed:30552355]

Sci Rep. 2018 Dec 14;8(1):17849.

Polymer membranes with improved transport properties are required for effective separation of organic mixtures (such as methanolhexane system) by combination of pervaporation and azeotropic distillation. The present work is devoted to comparative study of two types of membranes based on poly(amidoimide acid) with 2,2'-biquinoline-6,6' units in the backbone; the objects were prepared (i) from the initial polymer and (ii) from the polymer-metal complex (with Cu(I)). Thermo-mechanical and mass spectrometric investigations demonstrated good operational properties of the samples. Density measurements and SEM analysis revealed that the structure formed in polymer-metal complex is more compact as compared to that of the pure polymer membrane. Mass transfer processes of methanol and hexane through both kinds of membranes were studied by sorption, desorption and pervaporation tests. The values of equilibrium sorption degree, the Flory-Huggins parameter, and diffusion coefficient were determined for the obtained membranes. The pervaporation data allowed calculating permeability and selectivity of membranes in addition to the flux and the separation factor. The membrane based on polymer-Cu(I) complex allowed separating the methanolhexane azeotropic mixture with a separation factor of 980 and pervaporation separation index equal to 66.6; therefore, this process is significantly more effective than separation procedures involving other known membranes.

Low-dimensional compounds containing cyanido groups. Part XXXV. Structure, spectral, thermal and magnetic properties of a binuclear Cu(II)-biquinoline complex with bridging and terminal dicyanamide ligands.[Pubmed:30398203]

Acta Crystallogr C Struct Chem. 2018 Nov 1;74(Pt 11):1469-1476.

From the system CuCl2-biq-NaN(CN)2 (biq is 2,2'-biquinoline), the binuclear molecular complex bis(mu-dicyanamido-kappa(2)N(1):N(5))bis[(2,2'-biquinoline-kappa(2)N,N')(dicyanam ido-kappaN(1))copper(II)], [Cu2(C2N3)4(C18H12N2)2] or [Cu2(biq)2(dca)2(mu1,5-dca)2] (1) [dca is dicyanamide, N(CN)2(-)] was isolated and characterized by crystal structure analysis, and spectral, thermal and magnetic measurements. IR spectroscopy confirmed the presence of the biq and dca ligands in 1. Its solid-state structure consists of discrete centrosymmetric binuclear copper(II) units with double end-to-end dca bridges. Each Cu(II) atom is in a distorted square-pyramidal environment with the equatorial plane formed by two nitrile N atoms from bridging dca groups, one of the two N atoms of the chelate biq molecule and one nitrile N atom from a terminal dca ligand, whereas the second biq N atom occupies the axial position. Thermal decomposition of 1 in an air atmosphere proceeds gradually, with copper(I) cyanide being the final decomposition product. Magnetic measurements revealed the formation of alternating spin chains and a relatively strong exchange interaction within the binuclear units was also confirmed by Broken Symmetry DFT (density functional theory) calculations.

Luminescence Sensitization of Eu(III) Complexes with Aromatic Schiff Base and N,N'-Donor Heterocyclic Ligands: Synthesis, Luminescent Properties and Energy Transfer.[Pubmed:30368642]

J Fluoresc. 2019 Jan;29(1):111-120.

Five luminescent Eu(III)-4-fluoro-N-salicylideneaniline (Fsa) complexes with different N,N'- donor heterocyclic ligands (L) were synthesized (where L = 2,2'-bipyridine (bipy), 4,4'-dimethoxy-2,2'-bipyridine (dmbp), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neo) and 2,2'-biquinoline (biq)) and characterized by structural, thermal and spectroscopic analyses. The photophysical studies of the complexes viz. UV-Vis absorption spectra, emission spectra, lifetime decay curve, radiative, non-radiative transition rates and quantum yields were investigated. The photophysical properties indicated that fluorine substituted salicylideneaniline acts as a better sensitizer for Eu(3+) ion after involvement of ancillary ligands which leads to efficient energy transfer resulted in bright red emission due to (5)D0 --> (7)F2 transition. The highest overall quantum yield (32.78%) and sensitization efficiency (75.30%) of [Eu(Fsa)3neo] showed that it is a potential candidate in optical field. Graphical Abstract Sensitization of europium(III)-Schiff base complexes by antenna effect.

Effects of non-covalent interactions on the electronic and electrochemical properties of Cu(i) biquinoline complexes.[Pubmed:30177987]

Dalton Trans. 2018 Oct 7;47(37):13171-13179.

A Cu(i) complex {[Cu(I)(biq)2]ClO4-biq} with biq = 2,2'-biquinoline was prepared, fully characterized and its properties compared with those of the well-known [Cu(I)(biq)2]ClO4 complex. The crystal structures were obtained for both complexes (crystal structure for [Cu(I)(biq)2]ClO4 has not been previously reported). Complex [Cu(I)(biq)2]ClO4 crystallizes as a racemate where each enantiomer has a different tau4 value while compound {[Cu(I)(biq)2]ClO4-biq} crystallizes as a non-chiral supramolecular aggregate with an uncoordinated biq molecule forming a pi-pi stacking interaction with a coordinated biq. (1)H-NMR spectroscopy in non-coordinating solvents reveals that structures in solution are similar to those in the solid phase, confirming the presence of a supramolecular arrangement for compound {[Cu(I)(biq)2]ClO4-biq}. The stability of the non-covalent aggregate in solution of {[Cu(I)(biq)2]ClO4-biq} causes significant differences between the spectroscopic and electrochemical properties of {[Cu(I)(biq)2]ClO4-biq} and [Cu(I)(biq)2]ClO4.

A Cu(II) complex with an carbamoylcyanonitrosomethanide ligand formed in situ by the nucleophilic addition of water to dicyanonitrosomethanide: structure, spectral and magnetic properties.[Pubmed:29726467]

Acta Crystallogr C Struct Chem. 2018 May 1;74(Pt 5):584-589.

The complex (2,2'-biquinoline-kappa(2)N,N')(carbamoylcyanonitrosomethanide-kappa(2)N,O)chlori docopper(II) acetonitrile monosolvate, [Cu(C3H2N3O2)Cl(C18H12N2)].CH3CN or [Cu(ccnm)Cl(biq)].acn (acn is acetonitrile, biq is 2,2'-biquinoline and ccnm is carbamoylcyanonitrosomethanide), (I), was prepared as a result of nucleophilic addition of water to the dicyanonitrosomethanide ion in the presence of Cu(II) and biq. IR spectroscopy confirmed the presence of ccnm, biq and acn in (I). The solid-state structure consists of the neutral complex containing ccnm and biq ligands, coordinated to the Cu(II) atom in a bidendate chelating manner, and a chloride ligand, resulting in a distorted tetragonal pyramidal coordination of Cu(II). The asymmetric unit is supplemented by one molecule of solvated acn which, along with the nitrile group of ccnm, serves as an acceptor in intermolecular hydrogen bonding, creating infinite chains along the b axis. Magnetic measurements revealed a paramagnetic behaviour with a very small Weiss temperature Theta = -0.32 K and high anisotropy of the g tensor (gx = 2.036, gy = 2.120 and gz = 2.205).

Assessment of the reducing capacity of processed fruit juices with the copper(I)/4,4'-dicarboxy-2,2'-biquinoline complexes.[Pubmed:29606747]

J Food Sci Technol. 2018 Apr;55(4):1331-1338.

An alternative method for quantification of the total reducing capacity (TRC) of processed ready-to-drink fruit juices (orange, grape, peach, mango, cashew, strawberry, apple and guava) is suggested. The spectrophotometric procedure is based on the reduction of Cu(II) to Cu(I) by antioxidants (present in the samples) in aqueous buffered solution (pH 7.0), containing 4,4'-dicarboxy-2,2'-biquinoline acid (H2BCA), yielding the [Formula: see text] complexes. The absorbance values at 558 nm (A558 nm) of the [Formula: see text] complexes obtained with juice samples were compared with A558 nm values of the same complexes obtained with a standard ascorbic acid solution and used to quantify and express the reducing capacity of each sample. Regarding orange juices a positive relationship between the TRC values using the [Formula: see text] complexes and the labelled ascorbic acid (AA) content along with the total polyphenol content (TPC) was measured. Grape juices showed the best positive correlation was verified between the TRC (with the [Formula: see text] complexes) and the TPC. While other fruit juices showed good agreement of TRC values with [Formula: see text] complexes and DPPH reagent. The proposed method may be applied to measure the TRC of beers and wines and also for biological samples like serum and follicular fluid.

Metal transport capabilities of anticancer copper chelators.[Pubmed:29544811]

J Trace Elem Med Biol. 2018 May;47:79-88.

In the present study, several Cu chelators [2,2'-biquinoline, 8-hydroxiquinoline (oxine), ammonium pyrrolidinedithiocarbamate (APDTC), Dp44mT, dithizone, neocuproine] were used to study Cu uptake, depletion and localization in different cancer cell lines. To better understand the concentration dependent fluctuations in the Cu intracellular metal content and Cu-dependent in vitro antiproliferative data, the conditional stability constants of the Cu complex species of the investigated ligands were calculated. Each investigated chelator increased the intracellular Cu content on HT-29 cells causing Cu accumulation depending on the amount of the free Cu(II). Copper accumulation was 159 times higher for Dp44mT compared to the control. Investigating a number of other transition metals, intracellular accumulation of Cd was observed only for two chelators. Intracellular Zn content slightly decreased (cca. 10%) for MCF-7 cells, while a dramatic decrease was observed on MDA-MB-231 ones (cca. 50%). A similar decrease was observed for HCT-116, while Zn depletion for HT-29 corresponded to cca. 20%. The IC50 values were registered for the investigated four cell lines at increasing external Cu(II) concentration, namely, MDA-MB-231 cells had the lowest IC50 values for Dp44mT ranging between 7 and 35nM. Thus, Zn depletion could be associated with lower IC50 values. Copper depletion was observed for all ligands being less pronounced for Dp44mT and neocuproine. Copper localization and its colocalization with Zn were determined by mu-XRF imaging. Loose correlation (0.57) was observed for the MCF-7 cells independently of the applied chelator. Similarly, a weak correlation (0.47) was observed for HT-29 cells treated with Cu(II) and oxine. Colocalization of Cu and Zn in the nucleus of HT-29 cells was observed for Dp44mT (correlation coefficient of 0.85).

Visible-Light-Driven Photosystems Using Heteroleptic Cu(I) Photosensitizers and Rh(III) Catalysts To Produce H2.[Pubmed:29446925]

Inorg Chem. 2018 Mar 5;57(5):2865-2875.

The synthesis of two new heteroleptic Cu(I) photosensitizers (PS), [Cu(Xantphos)(NN)]PF6 (NN = biq = 2,2'-biquinoline, dmebiq = 2,2'-biquinoline-4,4'-dimethyl ester; Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene), along with the associated structural, photophysical, and electrochemical properties, are described. The biquinoline diimine ligand extends the PS light absorbing properties into the visible with a maximum absorption at 455 and 505 nm for NN = biq and dmebiq, respectively, in CH2Cl2 solvent. Following photoexcitation, both Cu(I) PS are emissive at low energy, albeit displaying stark differences in their excited state lifetimes (tauMLCT = 410 +/- 5 (biq) and 44 +/- 4 ns (dmebiq)). Cyclic voltammetry indicates a Cu-based HOMO and NN-based LUMO for both complexes, whereby the methyl ester substituents stabilize the LUMO within [Cu(Xantphos)(dmebiq)](+) by approximately 0.37 V compared to the unsubstituted analogue. When combined with H2O, N,N-dimethylaniline (DMA) electron donor, and cis-[Rh(NN)2Cl2]PF6 (NN = Me2bpy = 4,4'-dimethyl-2,2'-bipyridine, bpy = 2,2'-bipyridine, dmebpy = 2,2'-bipyridine-4,4'-dimethyl ester) water reduction catalysts (WRC), photocatalytic H2 evolution is only observed using the [Cu(Xantphos)(biq)](+) PS. Furthermore, the choice of cis-[Rh(NN)2Cl2](+) WRC strongly affects the catalytic activity with turnover numbers (TONRh = mol H2 per mol Rh catalyst) of 25 +/- 3, 22 +/- 1, and 43 +/- 3 for NN = Me2bpy, bpy, and dmebpy, respectively. This work illustrates how ligand modification to carefully tune the PS light absorbing, excited state, and redox-active properties, along with the WRC redox potentials, can have a profound impact on the photoinduced intermolecular electron transfer between components and the subsequent catalytic activity.

Synthesis and photoluminescence properties of europium(III) complexes sensitized with beta-diketonato and N, N-donors ancillary ligands.[Pubmed:29433041]

Spectrochim Acta A Mol Biomol Spectrosc. 2018 May 5;196:67-75.

Synthesis of three new europium(III) complexes with 1,3-[bis(4-methoxyphenyl)]propane-1,3-dionato (HBMPD) ligand and ancillary ligands such as 2,2'-biquinoline (biq) or neocuproine (neo) has been reported in this report. The synthesized complexes were characterized by IR (infrared), (1)H and (13)C NMR (nuclear magnetic resonance) spectroscopy, CHN (carbon, hydrogen and nitrogen) elemental analysis, XRD (X-ray diffraction), TGA (thermogravimetric analysis) and photoluminescence (PL) spectroscopy. The emission spectra of europium(III) complexes displayed both the low intensity (5)D1-3-->(7)F0-3 transitions in 410-560nm blue-green region and high intensity characteristic (5)D0-->(7)F0-3 transitions in 575-640nm orange-red region correspond to the emission of ancillary ligands and europium ion respectively, which can lead to white luminescence due to integration of blue, green and red color emissions. The photoluminescence investigations indicate that the absorbed energy of the HBMPD ligand transferred to the central europium(III) ion in an efficient manner, which clearly explained by antenna effect. The excellent results of thermal behavior and photophysical properties like luminescence spectra, CIE (Commission Internationale Eclairage) chromaticity coordinates, luminescence decay curves and high quantum efficiency of the complexes make them a promising component of the white light-emitting diodes in display devices.

Copper(i) complexes with phosphine derived from sparfloxacin. Part III: multifaceted cell death and preliminary study of liposomal formulation of selected copper(i) complexes.[Pubmed:29345262]

Dalton Trans. 2018 Feb 6;47(6):1981-1992.

The cytotoxic effect of iodide or thiocyanate copper(i) complexes (1-PSf, 2-PSf, 3-PSf, 4-PSf) with phosphine derived from sparfloxacin (HSf) and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2'-biquinoline (bq) as diimine auxiliary ligands was proved in vitro on somatic (MRC-5) and neoplastic (MCF7) human cell lines. Differences in mode of action were investigated in-depth for the selected dmp and bq complexes (1-PSf, 3-PSf, respectively) by elucidation of the following: (i) the efficiency to produce reactive oxygen species (ROS) in biological systems (cyclic voltammetry); (ii) their impact on mitochondrial membrane potential; (iii) potency for the activation of caspases 3 and 9; (iv) influence on the degree of DNA degradation (comet assay). It was concluded that the apoptosis of cancer cells is directly connected to the caspase-dependent mitochondrial pathway and supported by ROS production along with irreversible DNA fragmentation. Finally, it was demonstrated that the selected copper(i) complex encapsulated inside liposomes (1-PSf-L) exhibited enhanced accumulation inside cancer cells. This resulted in its higher cytotoxicity against cancer cells with therapeutic index of ca. 60. Increased selective accumulation in active neoplasm with simultaneous enhanced bioavailability and reduced systemic toxicity of liposomal formulation of copper(i) complexes can result in the development of new copper-based therapeutics and their successful implementation in anticancer chemotherapy.

A Lanthanide MOF Thin-Film Fixed with Co3 O4 Nano-Anchors as a Highly Efficient Luminescent Sensor for Nitrofuran Antibiotics.[Pubmed:28474416]

Chemistry. 2017 Aug 1;23(43):10293-10300.

Nitrofurans are a group of widely used veterinary antibiotics, which have been banned due to antibiotics pollution. Development of a rapid and effective method for the detection of nitrofuran antibiotics (NFAs) is an important challenge. Herein, we designed a chemical sensor based on a thin-film composed of the lanthanide metal-organic framework (Ln-MOF) {[Eu2 (BCA)3 (H2 O)(DMF)3 ]0.5DMFH2 O}n (Eu-BCA, in which BCA is 2,2'-biquinoline-4,4'-dicarboxylate) coated on a cost-effective stainless steel wire mesh (SSWM) by Co3 O4 nano-anchor fixation method. The MOF coatings were well adhered to the SSWM, resulting in a three-dimensional porous, flexible, and processable sensor. The structure of the as-prepared MOF thin-film was confirmed by powder X-ray diffraction (PXRD), and the surface morphology was examined by scanning electron microscopy (SEM). Significantly, the Eu-BCA thin-film was highly selective and sensitive to NFAs, and yet remained unaffected by other common antibiotics that may be present. The limits of detection for nitrofurantoin (NFT) and nitrofurazone (NFZ) are 0.21 and 0.16 mum, respectively. NFAs were also successfully detected in water from the Pearl River in Guangzhou, and from bovine serum samples. Hence, the reported Ln-MOF thin-film is a promising sensor for the detection of NFAs, thereby helping to protect human beings from all manner of hazards that arise from the abuse of antibiotics in livestock breeding.

Tuning the Photophysics and Reverse Saturable Absorption of Heteroleptic Cationic Iridium(III) Complexes via Substituents on the 6,6'-Bis(fluoren-2-yl)-2,2'-biquinoline Ligand.[Pubmed:27934300]

Inorg Chem. 2016 Nov 21;55(22):11908-11919.

To understand the effects of the terminal substituent at the diimine ligand on the photophysics of heteroleptic cationic Ir(III) complexes and to obtain Ir(III) complexes with extended ground-state absorption to the near-IR region while retaining the long-lived and broadly absorbing triplet excited state, we synthesized three heteroleptic cationic iridium(III) complexes bearing cyclometalating 1-phenylisoquinoline (C^N) ligands and substituted 6,6'-bis(7-R-fluoren-2-yl)-2,2'-biquinoline (N^N) ligand (R = H, NO2, or NPh2). The photophysics of these complexes was systematically investigated via spectroscopic methods and time-dependent density functional theory. All complexes possess strong ligand-localized (1)pi,pi* transitions mixed with ligand-to-ligand charge transfer ((1)LLCT)/metal-to-ligand charge transfer ((1)MLCT) transitions below 400 nm, and a broad and featureless absorption band above 400 nm that arises from the N^N ligand-localized (1)pi,pi*/(1)ILCT (intraligand charge transfer) transitions as well as the very weak (1,3)LLCT/(1,3)MLCT transitions at longer wavelengths. The electron-withdrawing NO2 substituent on the N^N ligand leads to a blue-shift of the (1)pi,pi*/(1)ILCT absorption band, while the electron-donating NPh2 substituent causes a pronounced red-shift of this band. The unsubstituted and NO2-substituted complexes (complexes 1 and 2, respectively) are moderately emissive at room temperature (RT) in solution as well as at 77 K in the glassy matrix, while the NPh2-substituted complex (3) is weakly emissive at RT, but the emission becomes much brighter at 77 K. Complexes 1 and 2 show very broad and strong triplet excited-state absorption from 460 to 800 nm with moderately long lifetimes, while complex 3 exhibits weak but broad absorption bands from 384 to 800 nm with a longer lifetime than those of 1 and 2. The nonlinear transmission experiment manifests that complexes 1 and 2 are strong reverse saturable absorbers (RSA) at 532 nm, while 3 shows weaker RSA at this wavelength. These results clearly demonstrate that it is feasible to tune the ground-state and excited-state properties of the Ir(III) complexes via the terminal substituents at the diimine ligand. By introducing the fluoren-2-yl groups to the 2,2'-biquinoline ligand to extend the diimine ligand pi-conjugation, we can obtain Ir(III) complexes with reasonably long-lived and strongly absorbing triplet excited state while red-shifting their (1,3)LLCT/(1,3)MLCT absorption band into the near-IR region. These features are critical in developing visible to near-IR broadband reverse saturable absorbers.

New copper(I) complexes bearing lomefloxacin motif: Spectroscopic properties, in vitro cytotoxicity and interactions with DNA and human serum albumin.[Pubmed:27764707]

J Inorg Biochem. 2016 Dec;165:25-35.

In this paper we present lomefloxacin's (HLm, 2nd generation fluoroquinolone antibiotic agent) organic and inorganic derivatives: aminomethyl(diphenyl)phosphine (PLm), its oxide as well as new copper(I) iodide or copper(I) thiocyanate complexes with PLm and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2'-biquinoline (bq) as the auxiliary ligands. The synthesized compounds were fully characterised by NMR, UV-Vis and luminescence spectroscopies. Selected structures were analysed by theoretical DFT (density functional theory) methods. High stability of the complexes in aqueous solutions in the presence of atmosferic oxygen was proven. Cytotoxic activity of all compounds was tested towards three cancer cell lines (CT26 - mouse colon carcinoma, A549 - human lung adenocarcinoma, and MCF7 - human breast adenocarcinoma). All complexes are characterised by cytotoxic activity higher than the activity of the parent drug and its organic derivatives as well as cisplatin. Studied derivatives as well as parent drug do not intercalate to DNA, except Cu(I) complexes with bq ligand. All studied complexes caused single-stranded cleavage of the sugar-phosphate backbone of plasmid DNA. The addition of H2O2 caused distinct changes in the plasmid structure and led to single- and/or double-strain plasmid cleavage. Studied compounds interact with human serum albumin without affecting its secondary structure.