Mononuclear Molecules Research Articles

Palladium and platinum complexes based on pyridine bases induced anticancer effectiveness via apoptosis protein signaling in cancer cells.

Palladium and platinum complexes, especially those that include cisplatin, can be useful chemotherapeutic drugs. Alternatives that have less adverse effects and require lower dosages of treatment could be provided by complexes containing pyridine bases. The complexes [Pd(SCN)2(4-Acpy)2] (1), [Pd(N3)2(4-Acpy)2] (2) [Pd(paOH)2].2Cl (3) and [Pt(SCN)2(paO)2] (4) were prepared by self-assembly method at ambient temperature; (4-Acpy = 4-acetylpyridine and paOH = pyridine-2-carbaldehyde-oxime). The structure of complexes 1-4 was confirmed using spectroscopic and X-ray crystallography methods. Complexes1-4 have similar features in isomerism that include the trans coordination geometry of pyridine ligands with Pd or Pt ion. The 3D network structure of complexes 1-4 was constructed by an infinite number of discrete mononuclear molecules extending via H-bonds. The Pd and Pt complexes1-4with pyridine ligands were assessed on MCF-7, T47D breast cancer cells and HCT116 colon cancer cells. The study evaluated cell death through apoptosis and cell cycle phases in MCF-7 cells treated with palladium or platinum conjugated with pyridine base. Upon treatment of MCF-7 with these complexes, the expression of apoptotic signals (Bcl2, p53, Bax and c-Myc) and cell cycle signals (p16, CDK1A, CDK1B) were evaluated. Compared to other complexes and cisplatin, IC50 of complex 1 was lowest in MCF-7 cells and complex 2 in T47D cells. Complex 4 has the highest effectiveness on HCT116. The selective index (SI) of complexes 1-4 has a value of more than two for all cancer cell lines, indicating that the complexes were less toxic to normal cells when given the same dose. MCF-7 cells treated with complex 2 and platinum complex 4 exhibited the highest level of early apoptosis. p16 may be signal arrest cells in Sub G, which was observed in cells treated with palladium complexes that suppress excessive cell proliferation. High c-Myc expression of treated cells with four complexes 1-4 and cisplatin could induce p53. All complexes 1-4 elevated the expression of Bax and triggered by the tumor suppressor gene p53. p53 was downregulating the expression of Bcl2.

Hydrogen-bonded Complex-based Frameworks for Stable Lithium Storage.

Metal-complex-based materials for lithium storage have attracted great interest due to their highly designable structures with multiple active sites and well-defined lithium transport pathways. Their cycling and rate performances, however, are still constrained by structural stability and electrical conductivity. Herein, we present two hydrogen-bonded complex-based frameworks with excellent lithium storage capability. Multiple hydrogen bonds among the mononuclear molecules result in three-dimensional frameworks that are stable in electrolyte. The origin of the remarkable lithium storage performance of this family was revealed through kinetic analysis and DFT calculations.

Synthesis, Crystal Structure and Thermal decomposition of Copper(II) and Manganese(II) Complexes Based on Bipyridine Dicarboxylate and 1,10-Phenanthroline

Two novel transition metal complexes of the formulae [Cu(5,5′-bpdc)(phen)]n (1) and [Mn(6,6′-bpdc)(phen)(H2O)]·H2O (2) (where phen = 1,10-phenanthroline, 5,5′-H2bpdc = 2,2′-bipyridine-5,5′-dicarboxylic acid, 6,6′-H2bpdc = 2,2′-bipyridine-6,6′-dicarboxylic acid) were synthesized by hydrothermal reaction. The complexes were characterized by elemental analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetry and differential scanning calorimetry. The X-ray crystallographic investigation reveals that 1 is a coordination polymer, and its asymmetric structural units are connected by oxygen atoms in the carboxyl group of 5,5′-bpdc2– anion. 2 is a heptacoordination monomer complex with mono-capped trigonal prismatic configuration and its mononuclear molecules are connected by hydrogen bonds to form supramolecular structure. The result of fluorescence shows that 2 has fluorescent property.

Preparation of catechol boronate esters enabled by N → B dative bond as efficient, stable, and green catalysts for the transfer hydrogenation of various ketones

A series of new structurally related catechol boronate esters enabled by N → B dative bond of general composition (B1-B4) and (B1N-B4N) were designed and synthesized for the transfer hydrogenation of various ketones, as catalysts. The structures of the synthesized trigonal-planar and tetrahedral catechol boronate esters forming dative bonds with neutral base were well-elucidated by NMR (1H, 13C, and 11B), FT-IR, UV–Vis, fluorescence, and LC-MS/MS spectroscopy, melting point and microanalysis. With the development of a more active and stable catalytic system for transfer hydrogenation of ketones in mind, all catechol boronate esters were tested as catalysts for the transfer hydrogenation of aromatic ketones, showing good activity in this reaction. Particularly, it was proved that the mononuclear molecules can afford an efficient catalytic conversion compared to the corresponding dinuclear boronate esters in transfer hydrogenation catalytic studies. Among the catalysts, (B4) and (B4N) are the most active catalysts and catalytic activity of (B4) was generally much higher in the studied hydrogen transfer reactions than that of (B4N) under mild conditions in isoPrOH. This clearly suggests that catechol boronate esters are also one of the propitious catalyst candidates and are worthy of further investigations.

Luminescent lanthanide(III) complexes of DTPA-bis(amido-phenyl-terpyridine) for bioimaging and phototherapeutic applications

We report here a series of coordinatively-saturated and thermodynamically stable luminescent [Ln(dtntp)(H2O)] [Ln(III) = Eu (1), Tb (2), Gd (3), Sm (4) and Dy (5)] complexes using an aminophenyl-terpyridine appended-DTPA (dtntp) chelating ligand as cell imaging and photocytotoxic agents. The N,N″-bisamide derivative of H5DTPA named as dtntp is based on 4′-(4-aminophenyl)-2,2′:6′,2″-terpyridine conjugated to diethylenetriamine-N,N′,N″-pentaacetic acid. The structure, physicochemical properties, detailed photophysical aspects, interaction with DNA and serum proteins, and photocytotoxicity were studied. The intrinsic luminescence of Eu(III) and Tb(III) complexes due to f → f transitions used to evaluate their cellular uptake and distribution in cancer cells. The solid-state structure of [Eu(dtntp)(DMF)] (1·DMF) shows a discrete mononuclear molecule with nine-coordinated {EuN3O6} distorted tricapped-trigonal prism (TTP) coordination geometry around the Eu(III). The {EuN3O6} core results from three nitrogen atoms and three carboxylate oxygen atoms, and two carbonyl oxygen atoms of the amide groups of dtntp ligand. The ninth coordination site is occupied by an oxygen atom of DMF as a solvent from crystallization. The designed probes have two aromatic pendant phenyl-terpyridine (Ph-tpy) moieties as photo-sensitizing antennae to impart the desirable optical properties for cellular imaging and photocytotoxicity. The photostability, coordinative saturation, and energetically rightly poised triplet states of dtntp ligand allow the efficient energy transfer (ET) from Ph-tpy to the emissive excited states of the Eu(III)/Tb(III), makes them luminescent cellular imaging probes. The Ln(III) complexes show significant binding tendency to DNA (K ~ 104 M−1), and serum proteins (BSA and HSA) (K ~ 105 M−1). The luminescent Eu(III) (1) and Tb(III) (2) complexes were utilized for cellular internalization and cytotoxicity studies due to their optimal photophysical properties. The cellular uptake studies using fluorescence imaging displayed intracellular (cytosolic and nuclear) localization in cancer cells. The complexes 1 and 2 displayed significant photocytotoxicity in HeLa cells. These results offer a modular design strategy with further scope to utilize appended N,N,N-donor tpy moiety for developing light-responsive luminescent Ln(III) bioprobes for theranostic applications.

Magnetic slow relaxation of Tb(III) complex with a nitronyl nitroxide involving a brominated-pyridyl substituent

A new nitronyl nitroxide-Tb(III) complex, [Tb(hfac)3(NIT-3-Br-4Py)2] (1) (hfac = hexafluoroacetyl -acetonate, NIT-3-Br-4Py = 2-(3′-bromo-4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), has been synthesized and characterized. The single-crystal X-ray diffraction analysis shows it crystallizes in monoclinic C2/c space group, and is composed of mononuclear molecules. The central Tb(III) ion is eight-coordinated by three bidentate chelating hfac anions and two monodentate NITR ligands, with a dodecahedron environment. Ac magnetic susceptibility study shows that complex 1 exhibits slow magnetic relaxation, suggesting single-molecule magnet behavior.

SYNTHESIS, STRUCTURE, AND PHOTOLUMINESCENT PROPERTIES OF LANTHANIDE(III) COMPLEXES WITH A LIGAND BASED ON 1,10-PHENANTHROLINE AND BORNEOL

Chiral complexes [Ln((–)-L)2(NO3)3] (Ln = Sm (1), Eu (2), Tb (3)) with an optically active ligand (–)-L containing 1,10-phenanthroline and (–)-borneol moieties and also [Ln((±)-L)2(NO3)3]·1.5MeCN (Ln = Sm (4), Eu (5), Tb (6)) compounds with a racemic ligand (±)-L based on 1,10-phenanthroline and (+)-, (–)-borneol are synthesized. According to single crystal X-ray diffraction data, mononuclear complexes 1-3 are isostructural and crystallize in the non-centrosymmetric space group P43212. The crystal structures of isostructural complexes 4-6 crystallizing in the centrosymmetric space group C2/c contains (+)- and (–)-enantiomeric molecules of the mononuclear complex and MeCN molecules. In complexes 1-6, the (–)-L, (±)-L, and $$\text{NO}_{3}^{-}$$ ligands perform the bidentate chelate function (N4O6 coordination polyhedron of the Ln atom). Complexes 2 and 3 have high quantum yields (φ = 52% and 41%) and long-life luminescence (τ = 1.4 ms and 1.2 ms) in the solid state at 300 K. The luminescence quantum yields of chiral complexes 1-3 are found to several times exceed the quantum yields of racemic complexes 4-6.

STRUCTURE OF MIXED-LIGAND MAGNESIUM DIPIVALOYLMETHANATE COMPLEXES WITH PROPYLENEDIAMINE AND ITS DERIVATIVE

The structures of two mixed-ligand [Mg(Q)(thd)2] complexes (thd = 2,2,6,6-tetramethylheptane-3,5-dionate ion (dipivaloylmethanate ion), Q = propane-1,3-diamine (pda), N,N,N′,N′-tetramethylpropane-1,3-diamine (tmpda)) are determined by X-ray crystallography. The structure of the complex with tmpda is determined at 296 K, that of the complex with pda is determined at 296 K and 150 K. Crystallographic data (296 K) for [Mg(pda)(thd)2] I are: space group P $$\bar{1}$$ , a = 9.6363(3) A, b = 12.1063(4) A, c = 14.3401(5) A, α = 70.6430(10)°, β = 72.7680(10)°, γ = 89.376(2)°, V = 1500.41(9) A3, Z = 2. Crystallographic data for [Mg(tmpda)(thd)2] II are: space group С2/с, a = 10.3716(3) A, b = 17.3614(4) A, c = 19.1577(5) A, β = 90.8480(10)°, V = 3449.26(16) A3, Z = 6. Crystal packings are formed by mononuclear molecules that are organized in dimers by N–H…O hydrogen bonds in the structure of I. Magnesium atoms have a distorted octahedral coordination environment. In I and II molecules, Mg–O bond lengths are comparable and vary in ranges 2.027-2.062 A and 2.023-2.030 A respectively; OMgO chelate angles are close to 86°. In complex II, Mg–N bond lengths and the NMgN angle are remarkably larger than those in I: 2.331 vs. 2.193-2.229 A; 89.6 vs. 84.7°. A comparative analysis of molecular structures and crystal packings of related [Mg(Q)(thd)2] complexes with diamines of propylene and ethylene series is carried out.

Coordination Polymer and Monomer with the Cd(NO3)2 Fragment Containing 2-Amino-5-Bromopyridine: Synthesis, Structures, NMR Study, and Luminescence Properties

The reactions of Cd(NO3)2 ⋅ 4H2O with 2-amino-5-bromopyridine (Аbp) afford compounds [Cd(NO3)2(Аbp)(H2O)]n (I) and [Cd(NO3)2(Abp)2(H2O)2] (II). The structures of both complexes are determined by single-crystal X-ray structure analysis (CIF files CCDC nos. 1938624 (I) and 1959680 (II)). Compound I is a coordination 1D polymer in which two chelate-bonded $${\text{NO}}_{3}^{ - }$$ groups act as bridges. The coordination polyhedron of the octacoordinated central cadmium atom in compound I consists of seven oxygen atoms (one oxygen atom of water and six atoms of the $${\text{NO}}_{3}^{ - }$$ groups) and one nitrogen atom of Abp, being a triangular dodecahedron. Complex II is a mononuclear molecule in which the octahedral coordination polyhedron of Cd is formed by four oxygen atoms of two water molecules and two $${\text{NO}}_{3}^{ - }$$ groups and two oxygen atoms of two molecules of the Abp cycle. In both complexes, the amino group of Abp is not involved in coordination with the metal. Compound I is studied by 1H, 31C, and 15N NMR spectroscopy of a solution of the polymer complex in CD3CN, and the most substantial difference in the chemical shifts of the bound and free Abp ligands is observed in the 15N NMR spectra (37 ppm). According to the data of luminescence spectroscopy, compounds I and II exhibit an emission in a range of 430–690 nm.

Magnetic slow relaxation of pseudo-binuclear Ln(III)-nitronyl nitroxide radical complexes involving non-covalent O⋯O interactions

Five new nitronyl-nitroxide radical-Ln(III) complexes, [Ln(hfac)3(NITPh-2-OCH2Ph)(IMHPh-2–OCH2Ph)] (Ln = Tb(1), Dy(2)) and [Ln(hfac)3(NITPh-2-OCH2Ph)2] (Ln = Ho(3), Er(4), Yb(5)) (hfac = hexafluoroacetylacetonate, NITPh-2-OCH2Ph = 2-(2-benzyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, IMHPh-2-O-CH2Ph = the reduced derivative of NITPh-2-OCH2Ph), have been synthesized and characterized. The single-crystal X-ray diffraction analysis shows that all these complexes crystallize in triclinic P1−space group, and are composed of mononuclear molecules. The central Ln(III) ion is eight-coordinated by three bidentate chelating hfac anions and two monodentate NITR (or IMHR) molecules, with a dodecahedron environment. There arise a common interesting structural feature for these complexes that the mononuclear molecules form pseudo-binuclear structures through intermolecular non-covalent N–O⋯O–N contacts of nitroxide groups. All of them show intramolecular weak antiferromagnetic interactions between Ln(III) ion and radicals. Alternating current (ac) magnetic susceptibilities display a frequency-dependent characteristic for both Tb(1) and Dy(2), typical of magnetic slow relaxation of single-molecule magnet (SMM) behavior.

Bioinspired Mo, W and V complexes bearing a highly hydroxyl-functionalized Schiff base ligand

A series of bioinspired dioxidomolybdenum(vi), dioxidotungsten(vi) and oxidovanadium(v) complexes [MoO2(H2LSaltris)], [WO2(H2LSaltris)] and [VO(HLSaltris)]2 were prepared by the reaction of a hydroxyl-rich Schiff base proligand N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-3,5-di-tert-butylsalicylaldimine (H4LSaltris) with metal precursors in methanol solutions. Molybdenum and tungsten complexes crystallize as mononuclear molecules, whereas the vanadium complex forms dinuclear units. From the complexes, [VO(HLSaltris)]2 shows activity in the oxidation of 4-tert-butylcatechol and 3,5-di-tert-butylcatechol, mimicking the action of the dicopper enzyme catechol oxidase.

Catalysis of a Single Transition Metal Site for Water Oxidation: From Mononuclear Molecules to Single Atoms.

Low-cost, nonprecious transition metal (TM) catalysts toward efficient water oxidation are of critical importance to future sustainable energy technologies. The advances in structure engineering of water oxidation catalysts (WOCs) with single TM centers as active sites, for example, single metallic molecular complexes (SMMCs), supported SMMCs, and single-atom catalysts (SACs) in recent reports are examined. The efforts made on these configurations in terms of design principle, advanced characterization, performances and theoretical studies, are critically reviewed. A clear roadmap with the correlations between the single-TM-site-based structures (coordination and geometric structure, TM species, support), and the catalytic performances in water oxidation is provided. The insights bridging SMMCs with SACs are also given. Finally, the challenges and opportunities in the single-TM-site catalysis are proposed.

Molecular and Inner Complex Compounds of Dioxomolybdenum(VI) with Disubstituted Salicydenealcoholimines: Crystal Structure of 1 : 1 Dioxo(3,5-Dibromosalicylidenemonoethanoliminato)molybdenum(VI) Solvate with Methanol [MoO2(L1) · MeOH] (L1 = C9H7Br2NO2)

Complexes of dioxomolybdenum(VI) of the molecular (МоО2Сl2 · 2H2L) and inner complex ([MoO2L · Solv]) types are synthesized (H2L are azomethines, derivatives of disubstituted R1,R2-salicylaldehydes (R1, R2 = 3.5-Вr2; R1 = 3-МеО, R2 = 5-Вr) and monoethanolamine; Solv is a methanol, dimethylformamide, pyridine, or α-picoline molecule). The cis-octahedral structure of the complexes is concluded on the basis of the IR spectroscopic data. In the molecular compounds, the ligands are coordinated via the O atom of the carbonyl group of the H2L tautomeric form. In the inner complex compounds, the ligands are coordinated in the deprotonated benzoid form. The structure of [MoO2(L1) · МеОН] (I) (where L1 is C9H7Br2NO2) is determined by X-ray diffraction analysis (СIF file CCDC no. 1898088). In the mononuclear molecule of compound I, the Mo atom has the octahedral coordination by two oxo ligands, two oxygen atoms, the nitrogen atom of the tridentate bis(chelate) two-charge ligand (L1)2–, and the O atom of the methanol molecule. The neutral N(1) and O(1) atoms of the L1 and МеОН ligands, respectively, are arranged in the trans positions to the O(oxo) ligands. The Mo–N(1) (2.265 A) and Мо–О(1) (2.372 A) bonds are substantially elongated due to the structural manifestation of the trans effect of the multiply bonded oxo ligands. The intermolecular hydrogen bonds (МеОН)О–Н···О(oxo) join the molecules into supramolecular 1D chains.

Synthesis, structure, and cytotoxicity of complexes of zinc(II), palladium(II), and copper(I) chlorides with (−)-camphor thiosemicarbazone

Complexes [Zn(L2)2Cl2], [Pd2(L2)2Cl4], and CuL2Cl, where L2 is (−)-camphor thiosemicarbazone, were synthesized. The structures of complexes [Zn(L2)2Cl2] and [Pd2(L2)2Cl4] were determined by X-ray diffraction. The crystal structure of complex [Zn(L2)2Cl2] contains mononuclear molecules with distorted tetrahedral {ZnCl2S2} coordination units and monodentate L2 ligands. Complex [Pd2(L2)2Cl4] has binuclear structure with Pd metal centers linked by L2 ligands via μ2-S atoms. Complex CuL2Cl, according to IR and NMR spectra contains S and Cl atoms in the coordination sphere of ion Cu+. Complexes [Pd(tsc)Cl2] and Zn(tsc)2Cl2 (where tsc is thiosemicarbazide) were also obtained to determine the influence of the terpene moiety on cytotoxic properties of these compounds. Mononuclear complex [Pd(tsc)Cl2] contains an NSCl2 planar square coordination polyhedron, and tsc is a bidentate chelate ligand. The effects of tsc, L2, and the complexes with tsc and L2 on viability of the MCF-7 cell line were investigated next. The results showed that tsc and L2 are nontoxic at the tested concentrations (1–50 μM). All the complexes exerted a significant dose-dependent cytotoxic effect, whereas complex CuL2Cl was found to have the lowest half-maximal inhibitory concentration (IC50).

Rare earth complexes with 3,4-dimethylbenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

The combination of 3,4-dimethylbenzoic acid (3,4-DMHBA) and 5,5′-dimethyl-2,2′-bipyridine (5,5′-DM-2,2′-bipy) with rare earth nitrate under the room-temperature conditions results in two novel complex formulated as [Ho(3,4-DMBA)3(5,5′-DM-2,2′-bipy)(H2O)] (1) and [La(3,4-DMBA)3(3,4-DMHBA)(5,5′-DM-2,2′-bipy)]2(2), respectively. The structures were confirmed by single-crystal X-ray diffraction. Two complexes are all characterized with elemental analysis and PXRD. Interestingly enough, because of the lanthanide contraction phenomena, the complex 1 is a mononuclear molecule with the coordination number of eight, but the complex 2 is a binuclear molecule with the coordination number of nine. The thermal decomposition mechanism for two complexes was discussed by TG-DTG technology. In addition, the three-dimensional infrared accumulation spectra of the evolved gas during the thermal decomposition for title complexes were investigated via the simultaneous TG/DSC-FTIR techniques. Beyond that, the heat capacities of complexes were measured by DSC. And the smoothed value of heat capacities and thermodynamic functions (HT-H298.15) and (ST-S298.15) were calculated according to the fitted polynomial and thermodynamic equations.

Alkyl transfer reactions on solid acids. The disproportionation of ethylbenzene and toluene on H-mordenite and HY zeolites

ABSTRACTThe disproportionation of ethylbenzene and toluene have been compared on two zeolites, H-mordenite and HY. The online examination of products as a function of time on stream reflect the different processes occurring on the two zeolites. The relative activities expressed on a unit aluminium center basis, are in line with their relative cracking (n-heptane) activities reported by others, showing that no extraneous factors affect activity. The data set provides a baseline for the activity of these two zeolites for future use in comparing other more complex alkylation reactions involving mononuclear and binuclear aromatic molecules.

Copper(II) Complexes with Chiral Ligands Containing Fragments of Monoterpenoids and Amino Acid Esters

Complexes [CuL1Cl2] (I), [CuL2Cl2] · EtOH (II), and Cu2L3Cl4 (III) containing esters of the N-derivatives of optically active amino acids based on (+)-3-carene (L1, L2) and (‒)-α-pinene (L3) are synthesized. The crystal and molecular structures of compounds I and II are determined by X-ray diffraction analyses (CIF files CCDC nos. 1560071 (I), 1560072 (II)). The crystal structure of compound I consists of mononuclear complex molecules. In the structure of compound II, the unit cell contains two crystallographically independent molecules of mononuclear complex [CuL2Cl2] and two EtOH molecules. Ligands L1 and L2 perform the tridentate-chelating function by the N atoms of the NH and NOH groups and by the O atom of the C=O group. In compounds I and II, the coordination polyhedra Cl2N2O of the Cu atoms are trigonal bipyramid. According to the data of IR and electronic spectroscopy, binuclear complex III has similar coordination polyhedra. The experimental values of μeff for compounds I, II, and III at 300 K are 1.93, 1.88, and 2.71 μB. For complex III, the μeff(T) dependence in a range of 2–300 K indicates a weak ferromagnetic exchange interaction.

Four new rare-earth nitronyl nitroxide radical complexes: Magnetic and luminescent properties

Four new rare-earth nitronyl nitroxide radical complexes, [Ln(hfac)3(NITPh-Pa)2][0.5CH3(CH2)5CH3] (Ln = Gd(1), Tb(2), Dy(3), Ho(4), hfac = hexafluoroacetylacetonate, NITPh-Pa = 2-(3′,4′-dioxylmethylene-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), have been synthesized. The X-ray crystal structure analysis revealed that four compounds have similar mononuclear tri-spin structures, in which the Ln(III) ions are eight-coordinated by two nitronyl nitroxide radicals and three hexafluoroacetylacetonate ligands to form a slightly distorted dodecahedron. In complexes 1–4, isolated mononuclear molecules connect each other through intermolecular hydrogen bonds to form 3D supermolecular framework. Magnetic investigation indicates there are ferromagnetic interactions between Gd(III) ions and radicals in complex 1. Alternating current(ac) magnetic susceptibilities of complexes 2 and 3 show that there are no non-zero out-of-phase signal, which indicates the inexistence of slow magnetic relaxation. The luminescence properties of complex 2 exhibit the characteristic emission peaks of Tb3+ ions and the potential for recognition of Cr2O72− and Cr3+ ions. Furthermore, nearly linear at low concentration and the low detection limit (0.01 μM) indicate that complex 2 may potentially be acted as luminescence-based sensor for quantitative and highly sensitive detection of Cr2O72− ion.

Crystal structure, characterization and catalytic activities of Cu(II) coordination complexes with 8‐hydroxyquinoline and pyrazine‐2‐carboxylic acid

Green and blue crystals of the coordination complexes [Cu(8‐hquin)2(H2O)2], 1 and [Cu(pyzca)2(H2O)2], 2 were obtained by the reaction of copper chloride with 8‐hydroxyquinoline (8‐hquinH) or pyrazine‐2‐carboxylic acid (pyzcaH) as ligands. The structures of 1 and 2 were characterized by elemental analyses, electronic absorption, Infrared (IR) and thermal studies. The luminescent behavior complexes 1 and 2 was also discussed. The coordination environment of copper(II) center displays distorted octahedral coordination geometry. The structure of the complexes 1 and 2 is constructed by an infinite number of discrete mononuclear molecules extending along the a‐axis to form a 1D‐chain via H‐bonds. The extensive hydrogen bonds and short contacts develop the structures of 1 and 2 to 3D‐network. The catalytic behavior of the complexes 1 and 2 was utilized for degradation of methylene blue dye (MB). The kinetic data indicated that the complexes 1 and 2 are effective catalysts for degradation of MB dye. Photoluminescence probing technology was used as a sensitive probe for detecting •OH radicals.

Synthesis, Structure, and Magnetic Properties of a Copper(II) Metal‐Organic Framework with Biphenyl‐2,2′,4,4′‐tetracarboxylic Acid

The 2D CuII metal‐organic framework [Cu2(bptc)(H2O)4]n·4nH2O (1) (H4bptc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid) was hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction and magnetic measurements. In the structure, bptc4– serves as a twisted Π‐shaped organic building block to connect paddlewheel [Cu2(COO)4] dinuclear units and mononuclear units through 2‐/2′‐carboxylate and 4‐/4′‐carboxylate, respectively. According to the magnetic analysis using a dimer‐plus‐monomer model, strong antiferromagnetic coupling is operative within the dinuclear unit (J = –311 cm–1 based on H = –JS1S2), and the compound behaves like a mononuclear molecule at low temperature.