Naphthalene and pyrrole substituted guanidine in selective sensing of Cu2+, Hg2+, Pb2+ and CN− ions under different conditions

Naphthalene and pyrrole substituted guanidine 1 has been designed and synthesised. Compound 1 efficiently distinguishes Cu²⁺, Hg²⁺ and Pb²⁺ ions by exhibiting different responses in fluorescence. While compound 1 exhibited turn-on emission selectively in the presence of Hg²⁺ and Pb²⁺ ions in CH₃CN and CH₃CN–H₂O (1:1, v/v), respectively, it showed decrease in emission upon interaction with Cu²⁺ ion in CH₃CN. Furthermore, the Cu-1 ensemble has been established as a potential probe for selective detection of CN^? ion over a series of other anions involving colour change (in ordinary light: colourless to light yellow and under UV light: colourless to sky blue). Theoretical insight has been invoked to understand the mode of metal–ligand interaction.     

Tris(dialkylamino)phosphine Chalcogenide Complexes of Tin(IV) Chloride: A Multinuclear (31P, 77Se,and 119Sn) NMR Characterization

Abstract

Four octahedral complexes of the type SnCl₄.2L [L = (R₂N)₃P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (³¹P, ⁷⁷Se, and ¹¹⁹Sn) NMR spectroscopy. ³¹P and ⁷⁷Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their ¹¹⁹Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes.

GRAPHICAL ABSTRACT      

Coumarin-based symmetrical bisamide as fluorescent and colorimetric probes for copper ions

Coumarin-based new symmetrical bisamide 1 has been designed and synthesised. The bisamide 1 fluorometrically recognises Cu²⁺ in CH₃CN containing 0.06% DMSO by exhibiting an increase in emission upon complexation. In comparison, the isomeric structure 2 also reports the selectivity for Cu²⁺ under identical condition by showing an opposite mode of emission. In addition, Cu²⁺ gives rise to a change in colour of the solution of 1, which is clearly visible to the naked eye.     

Tin(IV) Tetrachloride Complexes with Bis-(Dialkylamino)phosphoryl Fluoride: A Multinuclear (119Sn, 31P, 19F,and 1H) NMR Characterization in Solution

The two octahedral complexes SnCl₄·2(O)PF(NR₂)₂ (R = Me or Et) were prepared from reaction of SnCl₄ with the ligand (R₂N)₂P(O)F in anhydrous CHCl₃. The new adducts have been characterized by elemental analysis, IR, and multinuclear (¹¹⁹Sn, ³¹P, ¹⁹F, and ¹H) NMR spectroscopy. The NMR data show that the adducts exist in solution as a mixture of cis and trans isomers with markedly different proportions. When compared with previously described hexamethylphosphoramide (HMPA) and trimethylphosphate (TMPA) analogues, our results indicate that the cis isomer is the predominant species in solution. Low temperature ³¹P and ¹¹⁹Sn NMR spectra show that the compounds partially dissociate in dichloromethane.     

Synthesis, characterization and solution behaviour of phosphoryl complexes of tin tetrafluoride

The preparation and characterization of a series of octahedral complexes [SnF₄L₂] (L = (Me₂N)₃PO (1), L = (R₂N)₂P(O)F; R = Me (2); Et (3) or L = R₂NP(O)F₂; R = Me (4); Et (5)) are described. These new adducts have been characterised by multinuclear (¹⁹F, ³¹P and ¹¹⁹Sn) NMR, IR spectroscopy and elemental analysis. The NMR data particularly the ¹⁹F NMR spectra showed that the complexes exist in solution as mixtures of cis and trans isomers. The solution behaviour of the complexes studied by variable temperature NMR in the presence of excess ligand indicated that, unlike in the SnCl₄ analogues, the ligand exchange at room temperature is slow for 1–3 and fast only for 4 and 5. The metal–ligand exchange barriers in [SnF₄L₂] and [SnCl₄L₂] systems were estimated and compared. The results indicate that in addition to the difference in the Lewis acidity between SnF₄ and SnCl₄ the nature of the substituents (fluorine atoms) on the phosphorus atom of the ligand can contribute considerably to the lability of the complex obtained.     

Preparation and Characterization of Some Novel Diphenylphosphine Hydrazones and Semicarbazones and Their Metal Complex Derivatives

Interaction of hydrazones and semicarbazones derivatives I _{a ? t} with diphenylchlorophosphine II , gave new compounds III _a?t , and their complexation ability towards various divalent metal acetates Mn(OAc)₂. 4H₂O, Co(OAc)₂. 4H₂O, Ni(OAc)₂. 4H₂O, and Cu(OAc)₂. H₂O, in organic solvents are described. The metal/ phosphorsemi-carbazones ratios are measured and the results discussed. All these complexes are insoluble in organic solvents and in water. The structures of the isolated products were proposed on the basis of microanalyical data, TGA, IR, (UV/ VIS), (MS), and ¹H, ¹³C, and ³¹P-NMR spectroscopic analyses and magnetic susceptibility. The proposed structure of the complexes is based on a 1: 2 metal: ligand ratio. All of the complexes are found to have an octahedral geometry, with the exception of the square planar copper (II) complexes. The corrosion inhibition of aluminium and copper in 1 M HCl and chromium–nickel steel in crude oil using III_n have been studied by weight loss method.     

EXAFS studies on the methanol and ethanol solutions of cobalt(II) bromides

The results of an EXAFS investigation of methanol and ethanol solutions of CoBr₂ are reported. The curve fitting analysis gives the coordination numbers and the Co–Br and Co-solvent distances. The results for both 0.2M and 3.8M CoBr₂ in ethanol show the existence of [CoBr₂(C₂H₅OH)₂] as the dominant species, although a considerable amount of octahedral species also exists in the solutions. In 0.2 and 3.3M CoBr₂ methanol solutions, the dominant species are [Co(CH₃OH)₆]²⁺ and [CoBr(CH₃OH)₅]⁺, respectively.     

Complexes of unsymmetric bis-hydrazide ligands: crystal structures and properties

Two unsymmetric bis-aroyl-hydrazines, N′-(2-hydroxybenzoyl)isonicotinohydrazide (L1) and N′-(2-hydroxybenzoyl)nicotinohydrazide (L2), were synthesized through reactions of salicyl hydrazide with isonicotinoyl chloride and nicotinoyl chloride, respectively. Reactions of metal salts with L1 or L2 gave three new complexes, [Cd(L1)₂(SCN)₂] _n (1), [Zn(L1)₂Cl₂]?·?H₂O (2), and [Zn(L2)₂Cl₂] (3). Complex 1 features a 1-D double-chain structure built by SCN^– bridging six-coordinate Cd^II centers while 2 and 3 are mononuclear Zn^II complexes. In 1–3, isomeric ligands L1 and L2 coordinate with metal ions in a terminal coordination mode. Ligands L1 and L2 through O–H···N and N–H···O hydrogen-bonding interactions in 1–3 are crucial for the structure extension into 3-D supramolecular structures of 1 and 2, or 2-D sheet of 3. Complexes 1–3 emit interesting blue-green luminescence. Thermal behaviors of 1–3 as well as the specific rotation of 2 were also investigated.     

Melting and high-temperature solid state transitions in cobalt(II) halides

Melting and high temperature solid-state transitions in CoCl₂ and CoBr₂ are widely discussed. On the basis of DSC and conductometric measurements it was found that melting process of CoCl₂ is preceded by a solid-state transition appearing about 20 K below the melting point of CoCl₂. Due to deconvolution of the thermograms, the enthalpy of fusion and that of solid-state transition were found to be 36.4 and 9.6 kJ mol^–1, respectively. Melting points of CoCl₂ and CoBr₂ were established to be 999.0 and 949.7 K, respectively. Hitherto unknown enthalpy of fusion of CoBr₂ was determined to be 27.2 kJ mol^–1. A solid-state transition in CoBr₂ at 650 K has been confirmed.     

Syntheses and structures of two NiIICoIINiII complexes of macrocyclic ligands

Two new linear trinuclear complexes, [Co(NiL¹)₂(SCN)₂] (1) and [Co(NiL²)₂(H₂O)₂](ClO₄)₂?·?2C₂H₅OH (2), have been prepared by using Co(ClO₄)₂?·?6H₂O and two macrocyclic complex ligands NiL¹ and NiL². L¹ and L² are the doubly deprotonated forms of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazabicyclo[12.4.0^15,16]13,18-dicarboxylate and dimethyl 5,6,7,8,15,16-hexahydro-15-methyl-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate, respectively. X-ray single crystal analyses reveal the coordination geometries around Ni(II) in both 1 and 2 are identical and slightly distorted square planar with N₄ donors; all Ni–N bonds in the two complexes are very short. The Co(II) ions are at the centers of the trinuclear complexes and have distorted octahedral coordination geometries of O₄N₂ donors in 1 and an O₆ in 2. π?···?π interactions involving aromatic and non-aromatic π-systems join the trinuclear entities to form 2-D layers in the crystals of 1 and 2.     

Insights into the photophysics,protonation and Cu2+ ion coordination behaviour of anthracene-9,10-dione-based chemosensors

Carboxylic acid–diamine-based Cu²⁺ chromogenic sensors (3 and 4) exhibited colour switching from red to blue with good sensitivity and selectivity towards Cu²⁺ among other physiologically important alkali, alkaline earth and heavy metal ions. This colour-switching phenomenon arises due to selective deprotonation of aryl amine NH by Cu²⁺. Significantly, chemosensor 3 (λ_max 492 nm) shows multiple modes of complexation towards Cu²⁺. It is very much evident from the appearance of blue colour (λ_max 615 nm) at pH >7.0 and yellow colour (λ_max 465 nm) at pH < 4.0. In addition, chemosensor 3 exhibits a unique logic gate system that involves ‘INHIBIT’ and ‘TRANSFER’ logic gates.     

Bromokomplexe von Co(II) und Ni(II) in Acetonitril,Propandiol-1,2-carbonat und Trimethylphosphat

Zusammenfassung Die Bildung von Bromokomplexen von Co(II) und Ni(II) wird in Acetonitril (AN), Propandiol-1,2-carbonat (PDC) und Trimethylphosphat (TMP) auf spektrophotometrischem, potentiometrischem und konduktometrischem Wege untersucht. Folgende Koordinationsformen dürften vorliegen: [CoBr]⁺ (oktaedrisch inAN undTMP), CoBr₂ (tetraedrisch inAN, oktaedrisch inTMP), [CoBr₃]^– (tetraedrisch inAN, oktaedrisch inTMP), [CoBr₄]^2– (tetraedrisch inAN undPDC, oktaedrisch inTMP), [NiBr]⁺ (oktaedrisch inAN), NiBr₂ (tetraedrisch inAN, oktaedrisch inTMP), [NiBr₃]^– (tetraedrisch inAN), [NiBr₄]^2– (tetraedrisch inAN undPDC, oktaedrisch inTMP).

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The formation of bromo complexes of Co(II) and Ni(II) is investigated in acetonitrile (AN), propanediol-1,2-carbonate (PDC) and trimethylphosphate (TMP) by spectrophotometric, potentiometric and conductometric methods. The following coordination forms are reported: [CoBr]⁺ (octahedral inAN andTMP), CoBr₂ (tetrahedral inAN, octahedral inTMP), [CoBr₃]^– tetrahedral inAN, octahedral inTMP), [CoBr₄]^2– (tetrahedral inAN andPDC, octahedral inTMP), [NiBr]⁺ (octahedral inAN), NiBr₂ (tetrahedral inAN, octahedral inTMP), [NiBr₃]^– (tetrahedral inAN), [NiBr₄]^2– (tetrahedral inAN andPDC, octahedral inTMP).

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Mit 8 Abbildungen     

Indole-based distinctive chemosensors for ‘naked-eye’ detection of CN and HSO4−, associated with hydrogen-bonded complex and their DFT study

Colorimetric detection of anions (HSO₄^? and CN^?) was achieved via analyte triggered colour changing of the dipodal and tripodal sensors in CH₃CN–H₂O (1:1). The sensors exhibited very sharp visual colour changes and fluorescence quenching–enhancing effect upon addition of the HSO₄^? and CN^?. The large downfield shift of the NH proton signals in ¹H-NMR complexation studies and quantum chemical DFT calculations proved the formation of hydrogen-bonded complexes where no proton transfer mechanism was found.     

Perimedine-linked rhodamine dye in visual sensing of Al3+, Fe3+ and Fe2+ ions in aqueous organic medium under different experimental conditions

ABSTRACT

Perimedine labelled rhodamine dye 1 has been designed and synthesised. Metal ion binding studies of 1 have been performed in CH₃CN/H₂O (3:1, v/v, 10 mM Tris-HCl buffer, pH = 6.90). Compound 1 senses multiple metal ions such as Al³⁺, Fe³⁺ and Fe²⁺ by exhibiting turn on fluorescence and colour change (colourless to pink) under different experimental conditions. Concentration variation distinguishes Al³⁺ from Fe³⁺ ion. At low concentration (c = 1 x 10^?4 M), only Al³⁺ ion can exhibit turn on fluorescence with sharp colour change. Sensing of Fe²⁺ ion through turn on fluorescence and colour change has been possible via in situ oxidation by following Fenton’s reaction.     

Synthesis and structural characterization of mono- and dinuclear NiII and PdII complexes derived from tetradentate 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene

The reaction of Schiff base 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene (L) with either NiCl₂·6H₂O or [Pd^IICl₂(CH₃CN)₂]/Na[BF₄] in 1?:?1 stoichiometry yielded mononuclear ionic complexes, trans-[Ni^II(L)(H₂O)₂]Cl₂·3H₂O (1·3H₂O) and [Pd^II(L)][BF₄]₂ (2), respectively; the reaction of L with [Pd^IICl₂(CH₃CN)₂] in 1?:?2 ratio yielded dinuclear cis-[Pd^II ₂(μ-L)Cl₄] (3). Complexes 1–3 were characterized by vibrational spectroscopy and X-ray diffraction; diamagnetic 2 and 3 were also characterized by NMR in solution. The molecular structures of 1 and 2 displayed tetradentate coordination of L with formation of two five-membered and one six-membered chelate rings for both complexes. In 3, L showed bidentate coordination mode for each pyridylimine toward Pd^II. Complex 1 has distorted octahedral geometry around Ni^II and an extended hydrogen-bond network; distorted square planar geometry around Pd^II in 2 and 3 was observed.     

Synthesis and study of mixed oxide inorganic pigment from Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZnO–CeO<Subscript>2</Subscript> system

Novel environment-friendly yellow mixed oxide inorganic pigment from Bi₂O₃–ZnO–CeO₂ system with the composition 23 mol% Bi₂O₃, 15 mol% ZnO and 62 mol% CeO₂ was successfully synthesized by a conventional solid-state reaction method. Comprehensive analyses were carried out to characterize the develop pigment powder including simultaneous TG–DTA thermal analysis, colour properties and particle size distribution. The results demonstrated that the optimum calcination for pigment synthesis was located at a range 800–950 °C. The colour of the studied mixed oxide pigment is connected with the calcination condition. The substitution of Zn²⁺ changes the colour from orange to yellow. The colour of the obtained samples was dependent on the calcination condition and the particle size distribution. The most saturated yellow hue was obtained at the calcination temperature of 950 °C for 2 h in a furnace of pure air and after its application into organic binder in mass tone. The value C of this sample was approx. 65. The mixed oxide pigments were also evaluated from the standpoint of their particle size distribution. Bi₂Ce₂O₇ is considered to be a non-toxic compound, and the other component (Zn²⁺ ions) is also the safe element. Therefore, the present mixed oxide could be an attractive candidate as a novel environment-friendly inorganic yellow pigment.     

HgII-containing MOFs constructed from bis-benzimidazole-based ligand with highly selective anion-exchange capacity

Two Hg(II)-containing metal–organic frameworks (MOFs) based on 1,1′-(1,5-pentanediyl)bis-1H-benzimidazole (pbbm), {[HgBr₂(pbbm)]?·?DMF} _n (1) and [HgI₂(pbbm)]₂ (2), have been constructed to explore new and potent ion-exchange materials. Single-crystal X-ray diffraction shows that 1 features a 1-D zigzag chain framework, while 2 presents a dimeric structure in which two Hg(II) cations are bridged by two pbbm ligands. The significant differences of these MOFs indicate that the counteranions have impact on assembling and structures of the resultant MOFs. Remarkably, coordinated Br^? in 1 can be replaced completely when the solid polymer is treated with an aqueous solution containing I^?. Confirmation of retention of structure is provided by FT-IR spectra and the XRPD pattern. The thermal stabilities of 1 and 2 have also been investigated.     

A highly selective visual and fluorescent sensor for Pb2+ and Zn2+ and crystal structure of Cu2+ complex based-on a novel single-armed Salamo-type bisoxime

A novel single-armed Salamo-type bisoximes (H₄L) has been designed and synthesised. An obvious colour change from yellow (H₄L) to pale pink (HL-Pb²⁺) which can be visually observed by the naked eye in visible light. H₄L can act as a fluorescent sensor for ratiometric recognition of Zn²⁺ with high selectivity and sensitivity. Crystallographic data of the [Cu(HL)(μ-OAc)Cu] reveals that the two Cu²⁺ ions are both penta-coordinated with square pyramidal geometries, and forms a 2D supramolecular plane structure by hydrogen bonding interactions.     

Structure of iron (II) and cobalt (II) bromide complexes in aqueous solution by X-ray diffraction analysis

Structures of bromo-metal complexes in concentrated aqueous solutions of FeBr₂ and of CoBr₂ were investigated by X-ray diffraction analysis. The complexes possess an octahedral geometry coordinating Br^– along with H₂O ligands. The frequency factors of metal-Br contacts per one atom of metal were 0.325 for the 2.7M (mol-dm^–3) and 0.747 for the 4.5M FeBr₂ solutions, and 0.280 for the 2.8M and 0.595 for the 4.3M CoBr₂ solutions. The frequency factors suggested that the tendency of metal ions to forming monobromo complexes is in the order, Fe>Co>Ni相似文献