Luminescence Spectra Of Complexes Research Articles

Novel biologically active paddlewheel-like palladium thiocyanate complex catalyzed cyanation of alkyl bromide utilizing Q-tube system: A green perspective

A novel paddlewheel-like complex of [Pd(SCN)2(3-Acpy)2], (1) was produced at ambient temperature by adding an aqueous solution of palladium chloride to an aqueous acetonitrile solution of 3-acetylpyridine (3-Acpy) and potassium thiocyanate. Elemental analysis, Fourier-transform infrared (FT-IR), ultraviolet–visible (UV–vis), and nuclear magnetic resonance (NMR) spectroscopic methods were used to characterize complex 1 comprehensively. Single crystal X-ray diffraction was used to analyze the crystal structure of complex 1. The palladium atom is bonded to two 3-Acpy ligands and two thiocyanates groups in trans mode giving square planer geometry in complex 1. The discrete units of paddlewheel-like complex 1 through hydrogen bonding extend to form a 3D supramolecular network structure. The synthesized and characterized new palladium complex 1 was utilized as a precatalyst for the cyanation of alkyl bromide using potassium ferrocyanide as a benign cyanide source reagent. The suggested catalytic test reaction under high-pressure conditions via a Q-tube system in green solvent cyclopentyl methyl ether introduced high yields and a short reaction time. Moreover, the cytotoxic activity of complex 1 was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against HePG-2 of liver cancer and MCF7 of breast cancer cell lines. According to the findings, complex 1 has significant strong activity against the cancer cell lines HePG-2 and MCF-7. Additionally, the luminescence spectra of complex 1 were investigated.

Two unique M-MOFs (M:Zn, Mn) based on various metal-oxygen chains for good sensitivity sensing and magnetic properties

In this paper, two novel two-dimensional MOFs were synthesized by solvothermal reaction of 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid ligand and Zn(Ⅱ) and Mn(Ⅱ) metal ions: {[Zn2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (1), {[Mn2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (2). Complexes 1 and 2 are unique two-dimensional skeletons with particular metal-oxygen chains in their structures. The solid-state luminescence spectrum of complex 1 shows that its maximum emission peak is 448 nm. Further fluorescence studies of complex 1 show that it can efficiently detect Fe3+ and Cr2O72− in aqueous solution with a detection limit of 4.1 × 10−4 M and 2.7 × 10−4 M respectively, and has good recycling performance, so it is a potential bifunctional fluorescent probe material. The mechanism of fluorescence sensing quenching was also investigated in detail. Furthermore, magnetic studies have shown that there is an antiferromagnetic interaction between Mn(II) ions of complex 2.

Synthesis, structure characterization and antitumor activities of copper and cobalt thiocyanate complexes with 3-acetlpyridine ligand

Complexes of [Cu(SCN)2(3-Acpy)2], (1) and [Co(SCN)2(H2O)2(3-Acpy)2], (2) were synthesized at ambient temperature by adding an aqueous solution of copper(II) or cobalt(II) chloride to H2O/CH3CN solution of 3-acetlpyridine (3-Acpy) and potassium thiocyanate. Elemental analysis, FT-IR and UV–vis spectra were used to comprehensively characterize complexes 1 and 2. Single crystal X-ray diffraction was used to analyze the crystal structure of complexes 1 and 2. In complex 1, the copper is bonded to two 3-Acpy ligands and two thiocyanates groups in trans mode giving square planer geometry. While, in complex 2, the cobalt ion is coordinated to two water molecules, two 3-Acpy ligands and two thiocyanates ions in trans mode giving an octahedral structure. Through hydrogen bonding, the discrete units of complexes 1 and 2 extend to form a 3D supramolecular network. Additionally, the luminescence spectra of complexes 1 and 2 were investigated. Complexes 1 and 2 were evaluated to determine whether they were able to inhibit the growth of liver cancer (HepG2 cells) and breast cancer (MCF-7 cells). Complex 1 exhibits lower IC50 values than complex 2 against both of the two human cell lines. In HepG2 cells treated with complexes 1 and 2 at dosages roughly half of the IC50, apoptosis of complexes 1 and 2 is triggered by 18% and 22%, respectively. It was found that copper complex 1 has a greater cytotoxic effect on MCF-7 and influences on late apoptosis of HepG2.

Synthesis and structural characterization of a palladium complex as an anticancer agent, and a highly efficient and reusable catalyst for the Heck coupling reaction under ultrasound irradiation: A convenient sustainable green protocol

The complex [Pd(paOH)2].2Cl (1) was synthesized by the self-assembly method with palladium chloride and pyridine-2-carbaldehyde-oxime (paOH) in aqueous acetonitrile solution under ambient conditions. Complex 1 was fully characterized by FT-IR, UV–vis and NMR spectroscopic techniques, as well as elemental analysis. The single crystal X-ray structure of complex 1 indicates that the Pd(II) ion is bonded to four nitrogen atoms from two pyridine-2-carbaldehyde-oxime ligands. The molecular geometry of the Pd(II) ion in complex 1 is distorted square-planar with a trans geometry and with two free chloride ions. Using an MTT assay, the anticancer activities of the palladium complex 1 were studied with respect to human breast cancer (MCF-7) and hepatocellular carcinoma (HePG-2) cell lines. The data obtained show that complex 1 displays strong activity towards the viability and the growth of the cancer cell lines MCF-7 and HepG2. Additionally, complex 1 exhibits excellent catalytic activity for the Heck cross-coupling reaction with water as the solvent under ultrasound irradiation. Ultrasound irradiation not only enhanced the rate and the yield of the reaction, but also promoted the in situ generation of a well-dispersed zero-valent Pd-colloidal species as the active catalyst from complex 1. Finally, the luminescence spectrum of complex 1 is discussed.

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of NamMnUO2(CO3)3(4-m-2n)- (M = Mg, Ca; m, n = 0-2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies.

The luminescence spectra of triscarbonatouranyl complexes were determined by experimental and theoretical methods. Time-resolved laser-induced fluorescence spectroscopy was used to monitor spectra of uranyl and bicarbonate solutions at 0.1 mol kgw-1 ionic strength and pH ca. 8. The concentrations of Mg2+ and Ca2+ in the samples were chosen in order to vary the proportions of the alkaline earth ternary uranyl complexes MgUO2(CO3)32-, CaUO2(CO3)32-, and Ca2UO2(CO3)3. The luminescence spectrum of each complex was determined by decomposition in order to compare it with the simulated spectra of model structures NamMnUO2(CO3)3(4-m-2n)- (M = Mg, Ca; m, n = 0-2) obtained by quantum chemical methods. The density functional theory (DFT) and time-dependent (TD)-DFT methods were used with the PBE0 functional to optimize the structures in the ground and excited states, respectively, including relativistic effects at the spin-free level, and water solvent effects using a continuum polarizable conductor model. The changes in the structural parameters were quantified with respect to the nature and the amount of alkaline earth counterions to explain the luminescence spectra behavior. The first low-lying excited state was successfully computed, together with the vibrational harmonic frequencies. The DFT calculations confirmed that uranyl luminescence originates from electronic transitions from one of the four nonbonding 5f orbitals of uranium to an orbital that has a uranyl-σ (5f, 6d) character mixed with the 2p atomic orbitals of the carbonate oxygens. Additional single-point calculations using the more accurate TD-DFT/CAM-B3LYP allow one to determine the position of the luminescence "hot band" for each structure in the range 467-476 nm and compared fairly well with experimental reports at around 465 nm. The complete luminescence spectra were built from theoretical results with the corresponding assignment of the electronic transitions and vibronic modes involved, mainly the U-Oax stretching mode. The resulting calculated spectra showed a very good agreement with experimental band positions and band spacing attributed to MgUO2(CO3)32-, CaUO2(CO3)32-, and Ca2UO2(CO3)3. The evolution of luminescence intensities with the number of alkaline earth metal ions in the structure was also correctly reproduced.

Synthesis, luminescence studies and structural characterization of new Co(II) and Cu(II) complexes based on phenanthridine as a ligand

Four new complexes, [Co(phend)2Cl2] (1), [Co(phend)(ƞ2-NO3)2H2O].2phend (2), [Cu(phend)2Cl2] (3) and [Cu2(phend)2(μ-OAc)4] (4) have been synthesized by the reaction of two equivalent of phenanthridine (phend) ligand with one equivalent of CoCl2·6H2O (1), Co(NO3)2·6H2O (2), CuCl2·2H2O (3) and Cu(OAc)2·H2O (4), respectively. The complexes were fully characterized by elemental analysis, luminescence and IR spectroscopy, and their structures were studied by the single-crystal diffraction method. According to X-ray analysis, complex 1 (τ4 = 0.91) exhibits distorted tetrahedral geometry around Co(II) and complex 3 (τ4 = 0) presents a perfect square planar geometry around Cu(II). There is octahedrally distorted environment around the Co(II) center in complex 2 and the complex 4 consists of paddle-wheel binuclear Cu(II) tetracarboxylate units with Cu⋯Cu distance of 2.688 Å. There are intermolecular hydrogen bonding and π-π contacts (for complexes 1–4) and CH⋯π interactions (for complexes 1 and 2) which are effective in the stabilization of the crystal structure. The luminescence spectra of complexes 1 and 3 show that their emission bands are enhanced relative to the free phend ligand, while the emission spectrum of phend ligand is stronger than that of complexes 2 and 4. In addition, the luminescence spectra of all complexes in acetonitrile solution show that the intensity of their emission bands in complexes [Co(phend)2Cl2] (1) and [Cu(phend)2Cl2] (3) with chloride counterion ligands are stronger than that for free phend ligand, unlike the complexes 2 and 4, which have weaker emission than free ligand.

Lanthanide complexes with 3-methoxybenzoic acid and 5,5′-dimethyl-2,2′-bipyridine: Crystal structures, luminescence and magnetic property

Five dinuclear trivalent lanthanide complexes, [Ln(3-MOBA)3(5,5′-DM-2,2′-bipy)]2 (Ln = Er(1), Ho(2), Eu(3), Pr(4), Nd(5); 3-MOBA = 3-methoxybenzoate; 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine) have been successfully synthesized via conventional solution method at room temperature and structurally characterized by single crystal and powder X-ray diffraction. The molecular structures of complexes 1–5 are very novel-innovative. Complexes 1 and 2 were isomorphic, and the complex 1 was obtained with the coordination number of eight to form a distorted square-antiprism coordination geometry, while complexes 3–5 were nine-coordinated with a distorted monocapped square antiprismatic coordination geometry, but they can be all assembled into the same 1D, 2D supramolecular structure, which has rarely been reported previously. Over the temperature range of 300–1200 K, the thermal decomposition mechanism of complexes 1–5 were discussed by the technology of TG/DSC-FTIR. The luminescence spectra of complex 3 displayed the characteristic emission of Eu3+ ion (5D0 → 7F0-4), and it’s CIE coordinate was also calculated as (0.647, 0.341). In addition, the luminescence lifetime and intrinsic luminescence quantum yield were also investigated. Beyond that, the magnetic properties of complexes 1–2 were studied in detail.

Relative Study of Luminescent Properties with Judd-Ofelt Characterization in Trivalent Europium Complexes Comprising ethyl-(4-fluorobenzoyl) Acetate

Five new europium(III) complexes Eu(p-EFBA)3.(H2O)2 (C1), Eu(p-EFBA)3.neo (C2), Eu(p-EFBA)3.batho (C3), Eu(p-EFBA)3.phen (C4), Eu(p-EFBA)3.bipy (C5) have been synthesized by using ethyl-(4-fluorobenzoyl) acetate (p-EFBA) as β-ketoester ligand and neocuproine (neo), bathophenanthroline (batho), 1,10-phenanthroline (phen) and 2,2-bipyridyl (bipy) as ancillary ligands. The synthesized complexes C1-C5 were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (1H-NMR), infrared (IR) spectroscopy, thermogravimetric analysis (TG/DTG), UV-visible and photoluminescence (PL) spectroscopy. The relative study of luminescence spectra of complexes with the previously reported complexes of isomeric ligand (ortho and meta substituted ligand) indicate the higher luminescence properties of complexes as an effect of fluorine position on β-ketoester ligand. The para substituted ligand shows a remarkable effect on quantum efficiencies and Judd-Ofelt intensity parameters (Ω2, Ω4) of the complexes. The higher value of intensity parameter Ω2 associated with hypersensitive 5D0→7F2 transition of europium(III) ion revealing highly polarizable ligand field. The purposed energy transfer mechanism of complexes indicates the efficient energy transfer in complexes.

Substituent-dependent formation of Co(II) complexes based on phenyl-tetrazole acetic acid: from bis- to tristetrazole acetic acid

Tetrazole–carboxylates with both rigid tetrazole rings and flexible carboxylate groups provide excellent building blocks for the construction of diverse coordination architectures. We have selected a bistetrazole–carboxylate, H2btzphda [H2btzphda = 1,3-bis(tetrazol-5-yl)benzene-N2,N2′-biacetic acid] and a tristetrazole–carboxylate, H3ttzphta [H3ttzphta = 1,3,5-tris(tetrazol-5-yl)benzene-N2,N2′,N2′′-trisacetic acid] to construct new coordination compounds with CoCl2·6H2O, [Co(btzphda)(CH3OH)(H2O)2]·H2O (1), [Co3(ttzphta)2(H2O)12]·H2O (2). These coordination compounds were structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. Complex 1 has a two-dimensional layer structure with (4,4) grid topology, while complex 2 has a one-dimensional beaded chain structure. The luminescence spectra of complexes 1 and 2 at room temperature in the solid state show weaker emissions than those of the corresponding free ligands. The thermogravimetric properties of complexes 1 and 2 are presented and discussed.

Synthesis, crystal structures and thermodynamic properties of two novel lanthanide complexes based on 3,4-diethoxybenzoic acid and 2,2′-bipyridine

Two binuclear lanthanide complexes [Ln(3,4,-DEOBA)3DIPY]2 DIPY (Ln=Tb (1), Dy (2); 3,4,-DEOBA=3,4-diethoxybenzoate; DIPY=2,2′-bipyridine) have been synthesized and characterized. The single crystals of complexes 1 and 2 were obtained. And the two complexes are isostructural with a coordination number of eight to form a distorted square antiprism. Carboxylic groups adopt two modes coordinating with Ln(III) ions: bidentate chelate, and bridging bidentate. Binuclear complexes 1 and 2 are stitched together via π–π stacking interactions to form 1D chain and 2D layer supramolecular structures. The two complexes were characterized by elemental analysis, IR spectra, and powder X-ray diffraction. The luminescence spectra of complexes 1 and 2 show the characteristic emissions of Tb3+ (5D4→7F6-3) and Dy3+ (4F9/2→6H15/2, 6H13/2). The thermal decomposition mechanisms for title complexes were studied by the technology of TG-FTIR. And the heat capacities of two complexes were measured by DSC in the temperature range from 258.15 to 343.15K. The smoothed heat capacities and thermodynamic functions for complexes 1 and 2 were calculated by fitted polynomial and thermodynamic equations.

Structure, luminescent and thermal properties of two novel lanthanide complexes with 3,4-diethoxybenzoic acid and 5,5′-dimethy-2,2′-bipyridine

Two new lanthanide complexes [Tb(3,4,-DEOBA)3 5,5′-DME-2,2′-BIPY]2 (1), [Dy(3,4,-DEOBA)35,5′-DME-2,2′-BIPY]2 (2)(3,4,-DEOBA=3,4-diethoxybenzoate,5,5′-DME-2,2′-BIPY=5,5′-dimethy-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, IR spectra and powder X-ray diffraction. The single crystal of the complex 1 has been obtained. There are two kinds of coordination modes in complex, 1 and the Tb3+ ion is eight-coordinated. The luminescence spectra of complexes 1 and 2 show the characteristic emission of Tb3+ ion (5D4 → 7F6-3) and Dy3+ ion (4F9/2 → 6H15/2,6H13/2). The results of thermal decomposition mechanism of the title complexes show that two complexes are thermally stable. And the pathway of thermal decomposition has been investigated by the coupled TG-FTIR technique. In the thermal decomposition of the title complexes, neutral ligands lose firstly, and then 3,4-DEOBA decompose into gaseous molecules of H2O and CO2. The kinetics of the first decomposition stage for two complexes are investigated by using the integral isoconversional nonlinear (NL-INT) method, which suggests that the first decomposition step of two complexes is complex reactions. The heat capacities of title complexes were measured by DSC in the temperature range from 258.15 to 343.15 K. The smoothed heat capacities and thermodynamic functions of the complexes are calculated based on the fitted polynomial and thermodynamic equations. The antibacterial performance study of complexes shows that two complexes have good antibacterial activity against Candida albicans, Staphylococcus aureus and no bacteriostatic activity on Escherichia coli.

Synthesis, structural and photoluminescence studies of copper(I) complexes containing bis(azol-1-yl)methane derived bisphosphines

The synthesis and characterization of copper(I) complexes containing bisphosphines such as bis(2-diphenylphosphinoimidazol-1-yl)methane (1), bis(5-diphenylphosphinopyrazol-1-yl)methane (2) and bis(5-diphenylphosphino-1,2,4-triazol-1-yl)methane (3) is reported. Bisphosphines 1–3 exhibit bidentate (κ2P,P) chelating mode of coordination. The crystal structures of 4–6 have been established by single crystal X-ray crystallography. Luminescence spectra of complexes 7–9 recorded at room temperature in dichloromethane solution displayed single emission bands at 541, 542 and 519nm, respectively, with moderate quantum yields.

Synthesis, spectroscopic, thermochemical properties of lanthanide complexes with 3,4-Diethoxybenzoic acid and 1,10-phenanthroline

Three novel lanthanide complexes [Ln(3,4-DEOBA)3phen]2[Ln=Eu(1), Tb(2), Dy(3); 3,4-DEOBA=3,4- diethoxybenzoate; phen=1,10-phenanthroline] were synthesized and characterized by elemental analysis, molar conductance, X-ray diffraction and infrared spectrometry. The luminescence spectra of complexes 1 and 2 show the characteristic emission of Eu3+ ion(5 D 0→7 F 0—3) and Tb3+ ion(5 D 4→7 F 6—3). The thermal decomposition mechanism of the title complexes and the analysis of the evolved gases were investigated by thermogravimetry/differential scanning calorimetry-Fourier transform infrared(TG/DSC-FTIR) technology. The results indicate the complexes are thermally stable. In the thermal decomposition of the complexes, phen molecules lost firstly, and then 3,4-DEOBA ligand decomposed into H2O, CO2 and other gaseous molecules. Besides, several gaseous organic fragments were also detected. The heat capacities of complexes 1―3 were measured by DSC in a temperature range of 263.15―340.15 K. Based on the fitted polynomial and thermodynamic equations, the smoothed heat capacities and thermodynamic functions of the three complexes were calculated. The study on biological activity showed that the complexes exhibited good antibacterial activity against Candida albicans, Staphylococcus aureus and Escherichia coli.

Luminescent europium and terbium complexes of dipyridoquinoxaline and dipyridophenazine ligands as photosensitizing antennae: structures and biological perspectives.

The europium(III) and terbium(III) complexes, namely [Eu(dpq)(DMF)2(NO3)3] (1), [Eu(dppz)2(NO3)3] (2), [Tb(dpq)(DMF)2Cl3] (3), and [Tb(dppz)(DMF)2Cl3] (4), where dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 1 and 3), dipyrido[3,2-a:2',3'-c]phenazine (dppz in 2 and 4) and N,N'-dimethylformamide (DMF) have been isolated, characterized from their physicochemical data, luminescence studies and their interaction with DNA, serum albumin protein and photo-induced DNA cleavage activity are studied. The X-ray crystal structures of complexes 1-4 show discrete mononuclear Ln(3+)-based structures. The Eu(3+) in [Eu(dpq)(DMF)2(NO3)3] (1) and [Eu(dppz)2(NO3)3] (2) as [Eu(dppz)2(NO3)3]·dppz (2a) adopts a ten-coordinated bicapped dodecahedron structure with a bidentate N,N-donor dpq ligand, two DMF and three NO3(-) anions in 1 and two bidentate N,N-donor dppz ligands and three NO3(-) anions in 2. Complexes 3 and 4 show a seven-coordinated mono-capped octahedron structure where Tb(3+) contains bidentate dpq/dppz ligands, two DMF and three Cl(-) anions. The complexes are highly luminescent in nature indicating efficient photo-excited energy transfer from the dpq/dppz antenna to Ln(3+) to generate long-lived emissive excited states for characteristic f → f transitions. The time-resolved luminescence spectra of complexes 1-4 show typical narrow emission bands attributed to the (5)D0 → (7)F(J) and (5)D4 → (7)F(J) f-f transitions of Eu(3+) and Tb(3+) ions respectively. The number of inner-sphere water molecules (q) was determined from luminescence lifetime measurements in H2O and D2O confirming ligand-exchange reactions with water in solution. The complexes display significant binding propensity to the CT-DNA giving binding constant values in the range of 1.0 × 10(4)-6.1 × 10(4) M(-1) in the order 2, 4 (dppz) > 1, 3 (dpq). DNA binding data suggest DNA groove binding with the partial intercalation nature of the complexes. All the complexes also show binding propensity (K(BSA) ∼ 10(5) M(-1)) to the bovine serum albumin (BSA) protein. The intensity of the time-gated luminescence spectral bands enhances significantly with the increasing DNA concentration in aqueous buffer medium due to displacement of bound water upon interaction with DNA, thus reducing non-radiative quenching through the O-H oscillator. Complexes 1-4 efficiently cleave supercoiled (SC) ds-DNA to its nicked circular (NC) form on exposure to UV-A light of 365 nm via formation of singlet oxygen ((1)O2) and hydroxyl radicals (HO˙) as the reactive oxygen species at micromolar concentrations under physiological conditions.

Series of edge-sharing bi-triangle Ln4clusters with a μ4-NO3−bridge: syntheses, structures, luminescence, and the SMM behavior of the Dy4analogue

A series of Ln4 clusters, [Ln4L2(μ3-OH)2(μ4-NO3)(NO3)4(OCH3)(H2O)]·xMeCN·yMeOH (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5), Yb (6), L = 2-{[2-(2-hydroxy-ethoxy)-ethylimino]-methyl}-6-methoxyphenol), have been synthesized by the reaction of Ln(NO)3 and a Schiff-base ligand formed in situ. The six complexes display similar structures, with an overall metal core comprising two edge-sharing triangular Ln3 units linked by a μ4-NO3(-) bridge. The luminescence spectrum of complex 2 shows the characteristic emission of the Tb(III) ions. The magnetic susceptibility studies reveal that the Ln(III) ions are very weakly interacting in all six compounds. Frequency dependence of the ac-susceptibility was found for 3, suggesting a typical single-molecule magnet (SMM) behavior with an anisotropic barrier of 28 K.

Hydrothermal syntheses, crystal structures and properties of lanthanide complexes with 4-Hydroxy-6-methylnicotinic acid

Four isomorphous lanthanide complexes, [Ln2(L)6(H2O)2]·2H2O [Ln=Ce (1), Ln=Nd (2), Ln=Sm (3), Ln=Pr (4)] (HL=4-Hydroxy-6-methylnicotinic acid) were synthesized by the reaction of nitrate salts of LnIII and HL by hydrothermal method, which were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectra, UV–vis spectra, TG analyses and X-ray powder diffraction (XRPD). The crystal structures of 1–4 consist of homodinuclear species, which bridged by two oxygen atoms from two L ligands. The photoluminescence properties of compounds 3 and 4 in the solid state at room temperature were investigated. The complex 3 is demonstrated orange–red luminescence, while the luminescence spectrum of complex 4 is typical for the praseodymium complexes.

Photoluminescent nano-sized ternary and quaternary complexes of thorium(IV)

Abstract Some ternary and quaternary complexes of thorium(IV) with the general formula [Th(OOCCH3)2−n (SB) n (OOCC15H31)2] (HSB=Schiff bases and n=1 or 2) have been synthesized by the stepwise substitutions of acetate ions from thorium(IV) acetate, first with straight chain carboxylic acid and then with Schiff bases. The complexes are characterized by elemental analyses, spectral (electronic, infrared, 1H NMR, FAB mass, photoluminescence and powder XRD) and TEM studies. Conductance measurements indicated non-conducting behaviour of the complexes. Structural parameters from powder XRD data for complexes 5 and 6 which indicate poorly crystalline nano-sized triclinic particles. Electronic absorption spectra of the complexes showed π→π * and n→π * charge transfer transitions. All complexes displayed fluorescence and a correlation was sought between luminescence spectra of complexes in solution at room temperature. On the basis of physico-chemical studies, coordination number 8 was assigned for thorium(IV) in the complexes. The morphology and microstructure of the complexes were examined with transmission electron microscopy (TEM) and the selected area electron diffraction (SAED).

Self‐assembly and Properties of Three Novel Supramolecular Architectures: Dimensional Increase of Cd/Ag 4‐Formylbenzoate Complexes Controlled by Hexamethylenetetramine

AbstractThe reactions of Cd(NO3)2 or AgNO3 with hexamethylenetetramine (hmt) and 4‐formylbenzoic acid (4‐Hfba) yield three novel supramolecular architectures [Cd(4‐fba)2(μ2‐hmt)(H2O)]n (1), [Cd(4‐fba)2(μ2‐hmt)(H2O)2]n·nH2O (2), and [Ag(4‐fba)(μ3‐hmt)]n·2nH2O (3), which were characterized by elemental analysis, IR spectroscopy, luminescence spectroscopy, thermogravimetry, and powder as well as single‐crystal X‐ray diffraction. Structural analyses show that both complexes 1 and 2 have an one‐dimensional motif, except for a distinction arising from the coordination spheres and the bent angles of N–Cd–N. Both complexes are featuring three‐dimensional supramolecular frameworks through hydrogen bonding interactions, additional π–π interactions exist for complex 2. Complex 3 contains a classic undulating two‐dimensional Ag‐hmt layer, which is further axially connected by 4‐fba– linkers to give a 3D (3,5)‐connected gra net. The luminescence spectra of complexes 1 and 2 show a similar emission in the blue region at room temperature. Furthermore, efforts to further study the postsynthetic modification of these complexes are underway in our laboratory owing to the presence of the pendant formyl groups.

Synthesis, Structural Characterization and Luminescence Studies of Di‐ and Trinuclear Gold(I) Alkynyl‐phosphine Complexes

AbstractReactions of the polymer {AuIC2Ph}n with polyphosphine ligands [1,4‐bis(2‐diphenylphosphino‐1H‐imidazol‐1‐yl)‐benzene (dpib), 1,3,5‐tris(4‐diphenylphosphinophenyl)benzene (tppb), 2,2′‐bis(diphenylphosphanyl)‐4,4′‐bipyridine (dpbp), and 3,6‐bis(diphenylphosphanyl)pyridazine (dppz)] afforded four gold(I) alkynyl‐polyphosphine complexes [{AuC2Ph}2(μ‐dpib)] (1), [{AuC2Ph}3(μ3‐tppb)] (2), [{AuC2Ph}2(μ‐dpbp)] (3), and [{AuC2Ph}2(μ‐dppz)] (4) in nearly quantitative yield. The compounds obtained were characterized using elemental analysis, ESI‐MS, X‐ray crystallography, and polynuclear NMR spectroscopy. Intermolecular aurophilic interaction together with π–π and σ–π stacking build up the supramolecular 3D network of complex 3, whereas none of these intermolecular bondings were found in the crystal structures of compounds 1, 2, and 4. Complexes 1–4 are luminescent both in solution (CH2Cl2) and in solid state under laser irradiation (λex = 308 nm). In solution, the diphosphine complexes 1–4 display dual emission corresponding to ligand centered transitions (λem = 360–375 nm) along with weaker contribution from MLCT excited states at ca. 490 nm. The long wavelength component of the emission plays a dominant role in the solid state luminescence spectra of complexes 1, 3, and 4 (460, 544, 520 nm, respectively) whereas the triphosphine complex 2 shows dual luminescence (372 and 520 nm) with considerable contribution from ligand centered excited state.

Luminescence of metal complexes of chelate-substituted tetraphenylporphyrin

The luminescence and absorption spectra of some metal complexes of new tetraphenylporphyrin derivatives containing a chelating group with a heavy atom in the ligand structure were studied and compared with the properties of the zinc complex of unsubstituted tetraphenylporphyrin. The quantum yields of fluorescence and phosphorescence of liquid and frozen solutions of these compounds were measured. The life-times of delayed emission have been estimated, and the nature of bands in the absorption and luminescence spectra of the complexes and their relation with the structure are discussed.