Single-crystal X-ray Research Articles

A colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+ with 1,10-phenanthroline derivative

A colorimetric and ratiometric fluorescent probe 2-([1, 1′-biphenyl]-4-yl)-2, 3b,11a,11b-tetrahydro-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+. With the addition of Zn2+, the color of the solution changed from purple to green with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to cyan. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits of both Zn2+ and Cd2+ were 0.11 μM. The binding mode of probe 1 and Zn2+ was discussed according to the 1-Zn single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application prospect in environmental ion recognition.

Click Chemistry Inspired Synthesis of Hydroxyanthracene Triazolyl Glycoconjugates.

Novel hydroxyanthracene-based terminal alkynes 3 and 5a/b were synthesized by the acetylide addition reaction at the 9,10-position of anthraquinone 1 under mild conditions. The developed alkynes 3, 5a, and 5b on Huisgen azide-alkyne cycloaddition reaction with azido-sugars 6 in the presence of Cu(I) catalyst provided a series of triazole fasten hydroxyanthracene glycoconjugates 7, 8, and 9, respectively, in good yields. The representative compounds 9 and 7h were successfully deprotected under room-temperature conditions to liberate the corresponding free glycoconjugates 10 and 11, respectively. Further, structures of a few compounds were unmaliciously evidenced by their single-crystal X-ray.

Multiple strongly coupled antiferromagnetic spin S = 1/2 dimers in liroconite Cu2Al(As,P)O4(OH)4·4H2O

Abstract We report on the magneto-structural properties of the rare copper aluminum hydroxo-arsenate mineral liroconite with chemical composition Cu2AlAs1−x P x O4(OH)4·4H2O (x ≈ 0.2). In order to characterize the natural mineral sample chemical analyses, X-ray single crystal and powder diffraction, heat capacity and crystal water desorption, anisotropic thermal expansion and Raman scattering and magnetic susceptibility investigations have been carried out. The magnetic properties are well described by two discrete oxygen bridged Cu2+ spin S = 1/2 dimers with antiferromagnetic spin exchange ranging between −320 K and −136 K, depending on to which group-15 five-valent cation, As5+ or P5+, the dimer bridging oxygen atoms coordinate to. Accordingly the temperature dependence of the magnetic susceptibilities can be well fitted to a sum of two Bleaney–Bowers type spin S = 1/2 dimer susceptibilities suggesting that the dimers show negligible mixed coordination to (AsO4)3−/(PO4)3− tetrahedra. DFT + U calculation confirm the ratio of the spin exchange parameters of the (AsO4)3− or (PO4)3− coordinated Cu2+ – Cu2+ dimers. Inter dimer spin exchange is about two orders of magnitude smaller than intra dimer exchange.

Sesquiterpenes from Artemisia annua and Their Cytotoxic Activities.

Artemisia annua is a well-known traditional Chinese medicine. Due to its highest antimalarial efficacy, China has a long history of cultivating A. annua, and it is used for “clearing heat and detoxicating”. Several, studies have shown that the A. annua extract exerts cytotoxicity. In order to clarify the basis of the cytotoxic effect of A. annua, 18 sesquiterpenes were isolated from the herb, including 2 new sesquiterpenes and 16 known analogues. The structures of new compounds were elucidated by comprehensive spectroscopic analyses, including HR-ESI-MS, NMR experiments, single-crystal X-ray, and DP4+ and electronic circular dichroism (ECD) calculations. Cytotoxic activity screening revealed three compounds that exhibited cytotoxicity in a dose-dependent manner. Additional exploration showed that compound 5 significantly inhibited the proliferation of CT26 and HCT116 cells and induced apoptosis of HCT116 cells after 24 h. These chemical constituents contributed to elucidating the mechanism of action of the cytotoxic activity of A. annua.

Synthesis, Coordination Chemistry, and Mechanistic Studies of P,N-Type Phosphaalkene-Based Rh(I) Complexes.

The synthesis of P,N-phosphaalkene ligands, py-CH═PMes* (1, py = 2-pyridyl, Mes* = 2,4,6-tBu-C6H2) and the novel quin-CH═PMes* (2, quin = 2-quinolinyl) is described. The reaction with [Rh(μ-Cl)cod]2 produces Rh(I) bis(phosphaalkene) chlorido complexes 3 and 4 with distorted trigonal bipyramidal coordination environments. Complexes 3 and 4 show a pronounced metal-to-ligand charge transfer (MLCT) from Rh into the ligand P═C π* orbitals. Upon heating, quinoline-based complex 4 undergoes twofold C-H bond activation at the o-tBu groups of the Mes* substituents to yield the cationic bis(phosphaindane) Rh(I) complex 5, which could not be observed for the pyridine-based analogue 3. Using sub- or superstoichiometric amounts of AgOTf the C-H bond activation at an o-tBu group of one or at both Mes* was detected, respectively. Density functional theory (DFT) studies suggest an oxidative proton shift pathway as an alternative to a previously reported high-barrier oxidative addition at Rh(I). The Rh(I) mono- and bis(phosphaindane) triflate complexes 6 and 7, respectively, undergo deprotonation at the benzylic CH2 group of the phosphaindane unit in the presence of KOtBu to furnish neutral, distorted square-planar Rh(I) complexes 8 and 9, respectively, with one of the P,N ligands being dearomatized. All complexes were fully characterized, including multinuclear NMR, vibrational, and ultraviolet-visible (UV-vis) spectroscopy, as well as single-crystal X-ray and elemental analysis.

The High-Temperature Soft Ferromagnetic Molecular Materials Based on [W(CN)6(bpy)]2−/− System

The synthesis of molecular materials with magnetic properties, in particular ferromagnetic properties, has been the subject of interest in coordination chemistry for decades. In the last three decades, research has accelerated, as it has emerged that creating bridging systems based on cyanido ligands is a good and relatively simple way to create complex polymer structures exhibiting magnetic properties. Based on many years of personal experience in the field of the synthesis of polycyanido systems, supported by comprehensive structural analysis, a simple method of transforming cyanido complexes into soft ferromagnetic materials with a Curie temperature (TC) higher than the thermal decomposition temperature, usually above 150 °C has been developed. Two soft ferromagnetic materials based on zinc and cadmium hexacyanido salts in the system with [W(CN)6(bpy)]2−/− anions are presented. The crystal structures (X-ray single crystal as well as XRD) of the precursors and the properties of the ferromagnetic materials are discussed. Most importantly, a patented method of synthesizing this type of material, based on which we obtain more than 80 soft, high-temperature ferromagnetic compounds, which proves the wide spectrum of this method, is also presented.

Antiparallel π···π and C−H···H−C contacts in a novel Zn(II) coordination solid involving π-hole tetrel bonding interactions: A combined experimental and theoretical study, Hirshfeld surface analysis, molecular docking and potential drug property

A new Zn(II) coordination complex viz. [Zn(η2-Bz)(3-CNpy)(H2O)3]·Bz (1) [Bz = benzoate and 3-CNpy = 3-cyanopyridine] has been synthesized at room temperature and characterized by elemental analyses, electronic spectroscopy, FT-IR spectroscopy and single crystal X-ray diffraction.The molecules of 1 self-complimentarily assemble to form a 1D double-chain, stabilized by antiparallel π···π, C−H···H−C and π(nitrile)···π interactions along with other non-covalent interactions. These double-chains get interconnected through hydrogen bonding and π-hole tetrel bonding interactions to give a layered supramolecular architecture for 1. The interesting non-covalent interactions in 1 are studied by Hirshfeld surface analysis and different theoretical tools.The compound was docked with esterase as well as with glucosidase in order to check its biological potential. It was depicted from results that the compound 1 showed good docking score along interactions (2D and 3D) with amino acid residues located on the active sites of the selected enzymes. These in silico studies predicted that the synthesized compound may be effective against diseases related to these enzymes. To investigate the drug potential of 1, its pharmacokinetic and toxicokinetic properties were evaluated by ADMET calculations.

Synthesis, Characterization, X-Ray Single-Crystal Structure, Potentiometric Measurements, Molecular Modeling, and Bioactivity Screening of Some Thiosemicarbazones

A series of thiosemicarbazone (TSCN) compounds including ((E)-2-((E)-1-(2-(p-tolyl)hydrazono)propan-2-ylidene)hydrazine-1-carbothioamide (TSC1), (E)-N-ethyl-2-((E)-1-(2-(p-tolyl)hydrazono)propan-2-ylidene)hydrazine-1-carbothioamide (TSC2), and (E)-N-phenyl-2-((E)-1-(2-(p-tolyl)hydrazono)propan-2-ylidene)hydrazine-1-carbothioamide) (TSC3) were synthesized and fully characterized by diverse spectroscopies, such as X-ray single-crystal, infrared, mass, proton nuclear magnetic resonance, and ultraviolet-visible. Potentiometric measurements, molecular modeling, and biological and antitumor activity screening were studied. The thermodynamics and protonation constants of TSC1 as a representative of the synthesized TSCs were calculated and discussed. The solution speciation of different species was studied with pH. The molecular parameters of the optimized structures were calculated and discussed. The X-ray single crystals of TSC2 and TSC3 were established. Considering the antimicrobial activities and correlating structure-activity relationship of the synthesized compounds, the TSC1 molecule was considered a promising candidate as an antifungal agent against Candida albicans. Thus, it would be extremely helpful in the field of medicinal chemistry, particularly as an antimicrobial agent. The results are of significance to the chemistry of antimicrobial agents.

Synthesis, Single-Crystal XRD, Spectral and Computational Analysis of 2-(3,4-Dimethoxyphenyl)-1H-Phenanthro[9,10-d] Imidazole as Electron-Transport and NLO Material

A new Phenanthro-imidazole crystal, 2-(3,4-dimethoxyphenyl)-1H-phenanthro[9,10-d] was synthesized and characterized with spectral studies (IR, 1H-NMR, 13 C-NMR). Single Crystal X-ray and refinement studies reveals that the synthesized crystal system is monoclinic with P21/n space group and crystallographic data has been deposited in the Cambridge crystallographic data center with CCDC number: 2126693. RMSD values (Bond length = 0.035 Å and Bond angle=) and R-squared analysis (Bond length = 0.985 and bond angle = 0.990) reveals very good correlation between the experimental and theoretical structure. Analysis of frontier molecular orbitals and calculation of reorganization energy using DFT methods reveals that the crystals could be used as an electron transport material in OLED devices as the electron reorganization energy ( is comparatively low with a value of 0.373 eV. The computed value for the static first hyperpolarizability of the crystal was found to be 1.40023X10−of esu, which is four times higher than the standard value of urea and hence the crystal can be a potential candidate for future studies in non-linear optics.

Preparation of photonic molecular trains via soft-crystal polymerization of lanthanide complexes

Soft-crystals are defined as flexible molecular solids with highly ordered structures and have attracted attention in molecular sensing materials based on external triggers and environments. Here, we show the soft-crystal copolymerization of green-luminescent Tb(III) and yellow-luminescent Dy(III) coordination centers. Soft-crystal polymerization is achieved via transformation of monomeric dinuclear complexes and polymeric structures with respect to coordination number and geometry. The structural transformation is characterized using single-crystal and powder X-ray diffraction. The connected Tb(III) crystal-Dy(III) crystal show photon energy transfer from the Dy(III) centre to the Tb(III) centre under blue light excitation (selective Dy(III) centre excitation: 460 ± 10 nm). The activation energy of the energy transfer is estimated using the temperature-dependent emission lifetimes and emission quantum yields, and time-dependent density functional theory (B3LYP) calculations. Luminescence-conductive polymers, photonic molecular trains, are successfully prepared via soft-crystal polymerization on crystal media with remarkable long-range energy migration.

Epitaxial intergrowths and local oxide relaxations in natural bixbyite Fe2-x Mn x O3.

The scattering pattern of a crystal obeys the symmetry of the crystal structure through the corresponding Laue group. This is usually also true for the diffuse scattering, containing information about disorder, but here a case is reported where the diffuse scattering is of lower symmetry than the parent crystal structure. The mineral bixbyite has been studied by X-ray and neutron scattering techniques since 1928 with some of the most recent studies characterizing the low-temperature transition to a magnetically disordered spin-glass state. However, bixbyite also exhibits structural disorder, and here single-crystal X-ray and neutron scattering is used to characterize the different modes of disorder present. One-dimensional rods of diffuse scattering are observed in the cubic mineral bixbyite, which break the expected symmetry of the scattering pattern. It is shown that this scattering arises from epitaxial intergrowths of the related mineral, braunite. The presence of this disorder mode is found to be directly observable as well-defined residuals in the average structure refined against the Bragg diffraction. An additional three-dimensional diffuse scattering component is observed in neutron scattering data, which is shown to originate from the substitutional disorder on the Fe/Mn sites. This occupational disorder gives rise to local relaxations of the oxide sublattice, and the pattern of oxide displacements can be rationalized based on crystal-field theory. The combined use of neutron and X-ray single-crystal scattering techniques highlights their great complementarity. In particular, the large sample requirements for neutron scattering experiments prove to be an obstacle in solving the intergrowth disorder due to several growth orientations, whereas for X-ray scattering the one-dimensional nature of the intergrowth disorder renders solving this a more tractable task. On the other hand, the oxide relaxations cannot be resolved using X-rays due to the low Mn/Fe contrast. By combining the two approaches both types of disorder have been characterized.

L-Histidine with nitric acid: A comparison of crystal structures and Hirshfeld surfaces analysis

L-histidine crystallizes in three different crystal structure with nitric acid, i.e. L-histidinium nitrate, L-histidinium nitrate monohydrate and L-Histidinium dinitrate. Also there is DL-histidinium dinitrate. Though the structural aspects of histidinium nitrate monohydrate, L-Histidinium dinitrate and DL-histidinium nitrate are well studied, the structural studies on L-histidinium nitrate is not dealt in detail. Here we have tried to discuss in detail the crystal structure of L-histidinium nitrate using both single crystal X-ray and neutron diffraction. The crystal structure consists one L-histidine molecule which has the amino and imino groups protonated, but the carboxylic acid group is deprotonated. The nitrate ion is in anionic state ie NO3−. The conformation of histidine (N1-C2-C3-C4=64.99°) is gauche (-). Also a comparison of the structure of L-histidinium nitrate with other three available crystal structures retrieved using CSD have been carried out. It was found that L-histidine in L-histidinium nitrate monohydrate adopts gauche (+) conformation and in other three structure it is gauche (-), and L-histidinium nitrate has the lowest volume. Hirshfeld surface and interaction energies analysis of all the above structures were carried out using the x-ray data. L-histidinium nitrate monohydrate shows maximum globuarity. Interaction energy obtained from energy framework showed that L-histidinium nitrate monohydrate has maximum total energy of -41.5(kJ/Mole). The asphericity of our structure L-histidinium nitrate is 0.252 indicating prolate nature unlike the other three complexes. The percentage of H…H contacts is maximum in L-histidinium nitrate which is 27.3%. A comparison of various contacts of histidine between the x-ray and neutron structure of ours shows that the maximum change is reflected in the C…H and H…H contacts with C…H having a higher percentage and H…H having a lower percentage in the neutron structure indicating that the neutron diffraction maps shows the hydrogen bond interaction more accurately.The three complexes, except DL Histidinium dinitrate crystallizes in a non-centrosymmetric space group and hence could exhibit second-order optical non-linear properties, attempts were made to calculate heats of formation, dipole moments (D), polarizabilities (α) and first hyperpolarizabilities (β) using the semi empirical method at the PM6 level using MOPAC2009 and the packing energy as implemented in MERCURY. It was found that the average β of L-histidinium nitrate monohydrate was the highest amongst the three showing that it is more suitable for NLO material.

Synthesis, structural, photo-physical properties and DFT studies of some diarylheptanoids

In the present work, we have described the structures, photo-physical properties and DFT computations of some curcumin type diarylheptanoids (4a–c). These compounds were characterized by multi-spectroscopic techniques including X-ray single crystal of one of the intermediates (3a). The molecular geometries and structural features were configured by DFT -B3LYP/6-31G(d,p) calculations; however, combined 6-31G(d,p)/LANL2Dz basis sets (B3LYP/Gen) were employed in case of bromine and iodine derivatives. Compared to the native curcuminoids, these diarylheptanoids showed blue-shifted optical spectroscopic features in solution; aggregation enhanced emission properties were also noted. The incorporation of halogen atom enhanced thermal stability of the compounds. Aided by Cartesian coordinate displacement of the computed wavenumbers, we have suggested reliable vibrational assignments for the observed infrared fundamentals. The results of this study will be a valuable addition to the growing body of work on the properties of curcuminoids.

Concise Synthesis of BN-Dibenzo[f,k]tetraphenes with Different BN Substitution Positions and Direct Comparison with Their Carbonaceous Analogue.

Two types of "parental" BN-dibenzo[f,k]tetraphenes (BNDBT-1 and BNDBT-2) have been synthesized via a transition-metal-catalyzed tandem cross-coupling reaction as key steps. Both BNDBT-1 and BNDBT-2 are fully characterized; one of them is unambiguously confirmed by a single X-ray crystal structure. Compared to its all-carbon analogue DBT, BNDBT-1 and BNDBT-2 exhibit a higher highest occupied molecular orbital (HOMO) and lower lowest unoccupied molecular orbital (LUMO) energy, while the BN doping position slightly influences the HOMO and LUMO energies of BNDBT-1 and BNDBT-2. Both BNDBT-1 and BNDBT-2 exhibit red-shifted absorption and emission spectra and higher emission efficiencies, as compared to their carbonaceous analogue DBT. Moreover, organic light emitting diodes were fabricated using BNDBT-1 and BNDBT-2 as emitters, demonstrating their potential applications.

The spontaneous self-assembly of a molecular water pipe in 3D space.

The self-assembly and self-organization of water molecules are relevant in many fields of research. When water spontaneously reacts with 2,2,6,6-tetra-methyl-piperidine (TMP) to form colourless and crystalline discrete needles, only in the exact ratio of 2:1, it is important to understand the phenomenon. Single-crystal X-ray and neutron diffraction data have unveiled that TMP self-assembles around columns of water molecules, and as such, the resulting adduct may be described as a series of molecular water pipes.

4-[(Benzyl-amino)-carbon-yl]-1-methyl-pyridinium bromide hemihydrate: X-ray diffraction study and Hirshfeld surface analysis.

The hemihydrate of 4-[(benzyl-amino)-carbon-yl]-1-methyl-pyridinium bromide, C14H15N2O+·Br-·0.5H2O, was studied by single-crystal and powder X-ray diffraction methods. In the asymmetric unit, two organic cations of similar conformation, two bromide anions and one water mol-ecule are present. In the crystal, N-H⋯Br hydrogen bonds link the cations and anions. The formation of a set of inter-molecular C-H⋯Br and C-H⋯π inter-actions result in double chains extending parallel to [011]. A Hirshfeld surface analysis showed high contributions of H⋯H and C⋯H/H⋯C short contacts to the total Hirshfeld surfaces of the cations.

ROS -mediated anticancer response of potent copper(II) drug entities derived from S, O and N, N chelating donor scaffold: Single X-ray crystal diffraction and spectroscopic studies

New Cu(II) anticancer drug entities derived from S, O, and N, N donor chelating scaffolds were synthesized and thoroughly characterized by various spectroscopic and single X-ray diffraction studies. The single X-ray crystal structure of 1 and 2 revealed a monoclinic and triclinic crystal system with space group C 2 / c and P -1, respectively. The biomolecular interaction studies of 1 and 2 with ct-DNA were carried out by employing a battery of biophysical techniques, viz., absorption, emission, circular dichroic, and electrochemical (CV) and corroborative results of these experiments demonstrated avid electrostatic binding via surface groove. The synthesized Cu(II) complexes showed high efficacy as ROS generators involving Cu(II)/Cu(I) redox-active pair as evidenced by cleavage assay in the presence of radical scavengers. The ROS generation in the presence of copper-based complexes is considered one of the most favorable cell death mechanisms for the inhibition of cancers. In vitro anticancer activity of 1 and 2 was, therefore, evaluated against a panel of five human cancer cell lines, namely MCF-7, MDA-MB-231, Hop-62, AW1356, and SiHa, and results of cytotoxicity demonstrated good anticancer response against all tested cancerous strains with GI50 value <10 µM, except by 1 against MDA-MB-231, Hop-62 and AW1356 cell lines. Interestingly, 2 has displayed considerable cytotoxicity against MCF-7, Hop-62, and SiHa cancer cell lines even better than that of standard drug adriamycin. Furthermore, computational DFT studies validated the high binding efficacy and significant cytotoxicity of complex 2, which could be attributed to high positive charge density over the Cu(II) center.

Two novel pyrazine Zn(II)-porphyrins complexes: Synthesis, photophysical properties, structure study, DFT-Calculation and assessment of an azo dye removal from aqueous solution

In the current work, two new zinc-porphyrinic complexes bearing pyrazine as axial ligand, i.e. (pyrazine)(meso-tetrakis-(4-phenoxyphenyl)porphyrinato)zinc(II) [Zn(TBOPP)(pyz)] (1) and (aqua)(pyrazine)(meso-tetrakis(3,4,5-trimethoxyphenyl)porphyrinato)zinc(II) monohydrate [Zn(TTMP)(pyz)(H2O)].H2O (2) were successfully synthesized. New complexes were extensively characterized using elemental analysis, 1H NMR, UV–visible, single-crystal X-ray, and mass spectrometry (ESI) techniques. Single crystal X-ray studies revealed penta-coordinated environment around each Zn(II) metal in complexes with pyrazine as an axial ligand. The complexes were stabilized by weak C–H … Cg π intermolecular interactions involving pyridyl, phenyl and pyrrole centroid rings. Optical absorption studies confirmed the medium band gap and semiconducting nature of the compounds. Emission studies indicated that the axial ligand has no significant effect on the fluorescence quantum yields (ɸf) and the lifetime (τf) values. The ability of calmagite dye (an anionic dye) to remove the free bases and the Zn(II) complexes from aqueous solution has also been presented. Frontier molecular orbital (HOMO-LUMO) energies for H2TBOPP, H2TTMP, [Zn(TBOPP)] and [Zn(TTMP)] with calmagite were determined using density functional theory (DFT) calculation showing the charge transfer within the molecule.

Conjugation of triphenylantimony(V) with carvacrol against human breast cancer cells.

The organoantimony derivative of formula trans-O,O-[Ph3SbV(Carv)2] (TPAC) (CarvH = carvacrol) is obtained by the oxidation of triphenylstibine (Ph3SbIII) with hydrogen peroxide in the presence of carvacrol (CarvH). Physical methods such as X-ray Fluorescence (XRF) spectroscopy, single crystal and powder X-ray diffraction analysis (XRD and PXRD), Attenuated Total Reflection Fourier Transform Infra-red (ATR-FTIR) spectroscopy, Thermogravimetric Differential Thermal Analysis (TG-DTA) and Differential Scanning Calorimetry (DTG/DSC), confirm the retention of the formula of TPAC throughout the sample mass in solid state, while UV-Vis spectroscopy in the solution. TPAC is the first example of carvacrol (the main ingredient of oregano) covalently bonded to any metal ion. Only the trans-O,O-[Ph3Sb(Carv)2] isomer was isolated suggesting stereo-selectivity of the preparation route. TPAC inhibits in vitro both human breast adenocarcinoma cell lines: MCF-7 (positive to hormones receptor (HR +)), MDA-MB-231 (negative to hormones receptor (HR-)) stronger than normal human fetal lung fibroblast cells (MRC-5). The MCF-7 cells morphology, DNA fragmentation, Acridine Orange/Ethidium Bromide (AO/EB) Staining, cell cycle arrest and mitochondrial membrane permeabilization tests suggest an apoptotic pathway for cell death, especially, through the mitochondrion damage. The binding type of TPAC toward the calf thymus CT-DNA was initially deduced ex vivo from the differentiation of the DNA solution viscosity. Fluorescence spectroscopy confirms the interaction mode suggested. Spectroscopic evidence (FTIR, UV-Vis) suggest that glutathione (GSH) (a tripeptide over-expressed in tumor cells) induces conversion of non-active pentavalent antimony, which is contained in TPAC, to active trivalent one, providing a new strategy for the development of targeted chemotherapeutics.

Synthesis, X-ray Structure, Antimicrobial and Anticancer Activity of a Novel [Ag(ethyl-3-quinolate)2(citrate)] Complex

A novel Ag(I) citrate complex with ethyl-3-quinolate (Et3qu) was synthesized. Its structure was confirmed using X-ray single crystal to be [Ag(Et3qu)2(citrate)]. It crystallized in the Triclinic crystal system and P-1 space group with unit cell parameters of a = 8.6475(2) Å, b = 11.4426(3) Å, c = 15.2256(3) Å, α = 73.636(2)°, β = 79.692(2)° and γ = 86.832(2)°, while the unit cell volume was 1422.19(6) Å3. In the unit cell, there are two [Ag(Et3qu)2(citrate)] molecules and one unit as the asymmetric formula. The molecular structure comprised one Ag(I) coordinated with two Et3qu molecules via two almost equidistant Ag-N bonds and one citrate ion acting as a mono-negative monodentate ligand via a short Ag-O bond (2.5401(14) Å). Hence, Ag(I) is tri-coordinated and has a highly distorted triangular planar coordination geometry which is more like to be described as a slightly distorted T-shape. The supramolecular structure of the [Ag(Et3qu)2(citrate)] complex was analyzed using Hirshfeld calculations. The H···H (39.3–40.1%), O···H (33.2-34.0%), C···C (9.1–9.5%) and C···H (7.2–7.4%) contacts shared significantly in the packing of the studied Ag(I) complex. The antimicrobial and anticancer activities of the Ag(I) complex were investigated. The [Ag(Et3qu)2(citrate)] complex has broad-spectrum antimicrobial activity specifically against the fungus A. fumigatus. In addition, the IC50 values of 1.87 ± 0.09 µg/mL and 0.95 ± 0.06 µg/mL against the breast MCF-7 and lung A-549 cell lines, respectively, revealed the potent anticancer activity of the [Ag(Et3qu)2(citrate)] complex compared to the free Et3qu (IC50 = 30.64 ± 1.98 and 22.89 ± 1.48 µg/mL, respectively).