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1.
Inorg Chem ; 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32538622

RESUMO

A series of four isomorphous, 1:2 (complex/L) rare cocrystals of coordination compounds of Ln(III) ions as [Ln(L)(NO3)3(H2O)]2[L]2 (Ln(III) = Gd (1), Tb (2), Dy (3), and Ho (4)), were synthesized with N,N-diisobutylisonicotinamide (L) using a metal-to-ligand ratio of 1:1. All compounds are dimeric in nature with two cocrystallized L molecules centro-symmetrically interspersed between two dimeric units with H-bonded bridges between them to form interesting, self-assembled H-bonded tapes along the c-axis. Detailed Shape analysis and Hirshfeld analysis are done to demonstrate geometry around the metal centers and various noncovalent interactions present in the systems, respectively. Magnetic studies show that compound 3 is a field-induced single-molecule magnet (SMM) for which the magnetization relaxes through a combination of Orbach (Δ = 51 K and τ0 = 3.1 × 10-7 s) and Raman mechanisms. Solid-state luminescence studies reveal that compounds 1, 2, and 3 are photoluminescent in the visible range, while 4 exhibits luminescence in the NIR region. Compound 3 shows cold white-light emission with Commission Internationale de l'Eclairage (CIE) coordinates (0.31, 0.30) and correlated color temperature (CCT) value of 6942 K.

2.
ACS Omega ; 4(20): 18520-18529, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31737810

RESUMO

A hydrazone-based N'1,N'3-bis((E)-4-(diethylamino)-2 -hydroxybenzylidene)isophthalohydrazide (NDHIPH), has been synthesized, characterized, and assessed for its highly selective and sensitive (limit of detection, 2.53 nM) response toward Al(III) via fluorescence enhancement in 95% aqueous medium. All experimental results of analytical studies are in good consonance with the theoretical studies performed. Further, this NDHIPH-Al(III) ensemble is used for selective and sensitive (12.15 nM) detection of explosive picric acid (PA) via fluorescence quenching. This reversible behavior of NDHIPH toward Al(III) and PA is used for the creation of a molecular logic gate.

3.
Dalton Trans ; 48(12): 3922-3929, 2019 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-30816374

RESUMO

A centro-symmetric binuclear compound of formula [Dy(L)·(CH3COO)2·(H2O)2]2 (1) was isolated from the reaction between the 2,4-dinitrobenzoate anion (L) and the tris(acetate) of Dy(iii). Single crystal diffraction studies reveal a µ1-κ2,η1:η1 chelating binding mode of L while the binuclear compound is formed by the two bridging (µ2-κ3,η1:η2) acetate anions. The nona-coordinated sphere of each Dy(iii) ion is filled with a chelating (κ2,η1:η1) acetate anion and two terminal water molecules. Static magnetic measurements combined with ab initio SA-CASSCF/RASSI-SO calculations lead to two intramolecular competitive interactions i.e. ferromagnetic exchange interactions (0.04 cm-1) and antiferromagnetic dipolar interactions (-0.5 cm-1). Finally, dynamic magnetic measurements revealed a Single-Molecule Magnet behaviour in a zero-applied magnetic field with an effective energy barrier Δ = 21.5(2) cm-1 and τ0 = 7(3) × 10-6 s through Orbach and Quantum Tunnelling of the Magnetization relaxation mechanisms.

4.
Dalton Trans ; 47(13): 4722-4732, 2018 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-29537422

RESUMO

Single crystal diffraction studies reveal the formation of the following 10 new complexes of lighter Ln(iii) ions with general formulas {[Ln(µ2-L1)3·(H2O)2]·H2O}n (Ln = Nd (1) and Eu (2)), [Nd(µ2-L2)2·(CH3COO)·(H2O)2]n (3), [Ln2(µ2-L2)5·(L2)·(H2O)4]n (Ln = Sm (4), Ce (5), and Pr (6)), [La2(µ2-L2)6·(H2O)3·(DMF)]n (7) (DMF = dimethylformamide), [Ln(µ2-L2)2·(L2)·(H2O)3]2 (Ln = Eu (8) and Gd (9)) and [Gd(L2)·(CH3COO)2·(H2O)2]2 (10), where L1 and L2 are anions of 3,5- and 2,4-dinitrobenzoic acid, respectively. Complexes 1-7 are 1D coordination polymers, while 8-10 are dinuclear complexes. The luminescence properties of Nd(iii) and Eu(iii) analogues displayed metal-centred emission with L1 exhibiting weak but more efficient sensitization than L2. A study of the magnetic properties of the compounds clearly demonstrated the field-induced single ion magnet behaviour of the Nd(iii) compounds 1 and 3. Their behaviour has been compared to previously reported analogous Nd(iii) complexes and the role of the lattice solvent and polymorphism on the magnetic behaviour has been evaluated.

5.
Dalton Trans ; 46(43): 15138, 2017 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-29085926

RESUMO

Correction for 'Variable coordination and C-S bond cleavage activity of N-substituted imidazolidine-2-thiones towards copper: synthesis, spectroscopy, structures, ESI-mass and antimicrobial studies' by Jaspreet K. Aulakh, et al., Dalton Trans., 2017, 46, 1324-1339.

6.
Acta Chim Slov ; 64(3): 672-678, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28862293

RESUMO

This work presents four complexes with general formula [(ArO)2PS23Bi] (1-4), where Ar = 2,4-(CH3)2C6H3, 2,5-(CH3)2C6H3, 3,4-(CH3)2C6H3 and 3,5-(CH3)2C6H3, respectively. Reaction of [(ArO)2PS2Na] with Bi(NO3)3 · 5H2O in toluene in 3:1 molar stoichiometry afforded the complexes [(ArO)2PS23Bi]. These newly synthesized complexes have been characterized by elemental analysis, FT-IR and multinuclear NMR (1H, 13C and 31P) NMR. The crystal structure of [(3,5-CH3)2C6H3O2PS2]3Bi (4) has been determined by X-ray crystallography. The compound crystallizes in monoclinic P21/c space group and Bi(III) centre is surrounded by six sulfur atoms from three symmetrically chelating bidentate diphenyl dithiophosphate ligands in a distorted octahedron environment. Screening these complexes for their antifungal activity against Pencillium chrysogenum gave positive results.

7.
Dalton Trans ; 46(4): 1324-1339, 2017 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-28070570

RESUMO

An equimolar reaction of copper(i) iodide with N-ethyl-imidazolidine-2-thione (l-Et) in acetonitrile formed black prismatic crystals over a period of three weeks. The X-ray structure determination of black crystals revealed that the thio-ligand l-Et has transformed into a new thio-ligand, 1-ethyl-3-(1-ethyl-4,5-dihydro-1H-imidazol-2-yl)imidazolidine-2-thione (l-NEt), through C-S rupture/C-N bond formation which was coordinated in the unusual 2D polymer, {(CuII(κ2-N,S-l-NEt)2)·(CuI4)·(CuI2)}n1. An ESR spectrum supported the presence of divalent CuII in the polymer. In contrast, reaction of copper(i) iodide with N-phenyl-imidazolidine-2-thione (l-Ph) in 1 : 1 molar ratio yielded a polymer, [-Cu(µ-I)2Cu(µ-S-l-Ph)2Cu-]n2, with alternate Cu2I2 and Cu2S2 cores. Further, a series of reactions of copper(i) halides with N-substituted imidazolidine-2-thiones, namely, l-R in 1 : 2 metal to ligand molar ratio (M : L) in acetonitrile have yielded different type of complexes: trigonal planar {CuX(κ1-S-l-R)2, R, X : Et, I, 4; Me, I, 5; Bun, I,6; Me, Br,7; Bun, Br, 8; Me, Cl, 9; Prn, Cl, 10; Ph, Cl, 11}, dinuclear [Cu2Br2(µ-S-l-Ph)2(κ1-S-l-Ph)2] 12, tetranuclear, [Cu4I2(µ-I)2(µ-S-l-Ph)4(κ1-S-l-Ph)2] 3 and hexanuclear [Cu6Cl6(µ-S-l-Bun)6] 13. All these complexes have been characterized using analytical data, IR and proton NMR spectroscopy, ESI-mass studies and single crystal X-ray crystallography. The antimicrobial activity of these complexes has been investigated against Gram positive bacteria, namely, Staphylococcus aureus (MTCC740), methicillin resistant Staphylococcus aureus (MRSA), Gram negative bacteria, Klebsiella pneumoniae (MTCC109), Salmonella typhimurium (MTCC741) and Candida albicans (MTCC227)- a yeast. It is significant to add that among various complexes tested for cytotoxicity toward living cells, 4, 5, 8, 9 and 10 complexes were toxic, while complex 12 was non-toxic.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Cobre/química , Etilenotioureia/química , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Anti-Infecciosos/síntese química , Carbono/química , Técnicas de Química Sintética , Nitrogênio/química , Compostos Organometálicos/síntese química , Espectrometria de Massas por Ionização por Electrospray , Análise Espectral , Enxofre/química
8.
Org Biomol Chem ; 13(45): 11129-39, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26403695

RESUMO

Naphthimidazolium based monocationic chemodosimeters CD-1 and CD-2 undergo cyanide mediated catalytic transformation in the presence of cyanide ions (0.01% to 1% of CD-1/CD-2 concentrations) with a turnover number from 70 to 360. These chemodosimeters can detect as low as 0.5 nM and 1 nM cyanide ions under nearly physiological conditions (HEPES buffer-DMSO (5%), pH 7.4). The structures of CD-1 and its cyanide induced hydrolyzed product 4 have been confirmed by single crystal X-ray crystallography. CD-1 can also be used for the determination of 2 nM cyanide in the presence of blood serum. CD-1 and CD-2 also find applications in live cell imaging of 10 nM cyanide ions in rat brain C6 glioma cells. To the best of our knowledge, this is the first report where high sensitivity towards cyanide ions has been achieved through catalytic hydrolysis of the fluorescent chemodosimeter.


Assuntos
Cianetos/análise , Cianetos/sangue , Corantes Fluorescentes/química , Quinazolinas/química , Água/análise , Animais , Catálise , Linhagem Celular Tumoral , Cristalografia por Raios X , Hidrólise , Modelos Moleculares , Imagem Óptica , Ratos , Espectrometria de Fluorescência
9.
Dalton Trans ; 44(36): 15774-8, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26299199

RESUMO

Two non-isostructural homometallic 1D neodymium species displaying field-induced slow magnetization relaxations are presented together with theoretical studies. It is established that both systems are better described as organized 1D single molecule magnets (SMMs). Studies show great potential of Nd(III) ions to provide homometallic chains with slow magnetic relaxation.

10.
J Am Chem Soc ; 136(34): 12004-10, 2014 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-25093533

RESUMO

Stabilization of radical ions and highly electron-deficient systems under ambient conditions is of great significance. A new design concept is presented that applies the multifaceted features of the phosphonium group to achieve isolation of (a) the first naphthalenediimide (NDI) radical ion [(1a•+)BPh4(­)] as single crystals and (b) an ultra-electron-deficient NDI [(1a(2+))2BF4(­)] having the lowest LUMO level recorded for an NDI, overwhelming the formative tetracyanoquinodimethane (TCNQ) molecule. Both 1a•+ and 1a(2+) exhibit unprecedented stability to normal workup procedures, chromatography, and anion metathesis in open air. To our knowledge, this is the first instance where radical ions stable toward chromatography have been obtained, which is a noteworthy development in the field of synthetic radical chemistry. The crucial components of thermodynamic and kinetic stabilization, namely, the nonbonded P···O interaction, hypervalency, and propeller-like shape of the phosphonium groups in 1a(2+) and 1a•+, were substantiated by crystallography and theoretical studies. Natural bond orbital (NBO) calculations validated the P···O contact to be an nO → σP­C* orbital interaction. Spontaneous electron transfer reactions of 1a(2+) even in nonpolar solvents, anion−π interactions of 1a(2+) with the naphthalene core, and panchromism of 1a•+ are the other emergent properties. The high-yielding (∼90%) in situ synthesis of 1a•+ and the extraordinary stability fostered by the phosphonium group have the potential to turn hitherto unstable organic systems into a new genre of stable off-the-shelf systems.

11.
Artigo em Inglês | MEDLINE | ID: mdl-25080255

RESUMO

Donor-stabilized addition complexes of nickel(II) with disubstituted diphenyldithiophosphates, [{(ArO)2PS2}2NiL2] {Ar = 2,4-(CH3)2C6H3 [(1), (5)], 2,5-(CH3)2C6H3 [(2), (6)], 3,4-(CH3)2C6H3 [(3), (7)] and 3,5-(CH3)2C6H3 [(4), (8)]; L = C5H5N [(1)-(4)] and C7H9N [(5)-(8)]}, were successfully isolated and characterized by elemental analysis, magnetic moment, IR spectroscopy and single-crystal X-ray analysis. Compound (4) crystallizes in the monoclinic space group P2(1)/n whereas compounds (7) and (8) crystallize in the triclinic space group P1. The single-crystal X-ray diffraction analysis of (4), (7) and (8) reveals a six-coordinated octahedral geometry for the NiS4N2 chromophore. Two diphenyldithiophosphate ions act as bidentate ligands with their S atoms coordinated to the Ni centre. Each of them forms a four-membered chelate ring in the equatorial plane. The N atoms from two donor ligands are axially coordinated to the Ni atom.

12.
Dalton Trans ; 43(39): 14865-75, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25166631

RESUMO

Amide-based ligands H2L(1), H2L(2) and H2L(3) containing thiazole, thiazoline and benzothiazole appended groups have been used to synthesize Zn(2+) ( and ), Cd(2+) complexes ( and ), and a Mn(2+) complex (). In all cases, potentially multidentate ligands create a meridional N3 coordination environment around the M(ii) ion whereas additional sites are occupied by labile nitrate ions in and MeOH in . Interestingly, metal complexation caused the migration of protons from amidic N-H sites to the appended heterocyclic rings in complexes . Structural studies show that the protonated heterocyclic rings in these complexes create a hydrogen bond based cavity adjacent to the metal ion. Importantly, binding studies confirm that the substrates are bound within the complex cavity closer to the Lewis acidic metal in all complexes including the oxidation-sensitive Mn ion in complex . All complexes have been utilized as the reusable and heterogeneous catalysts for ring-opening reactions of assorted epoxides, cyanation reactions of various aldehydes, and epoxidation reactions of several olefins.

13.
Inorg Chem ; 53(14): 7770-9, 2014 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-24979501

RESUMO

The Cu(II)-catalyzed oxidative and reductive cleavage of the disulfide bond of N-(2-(2-(2-picolinamido)phenyl)disulfanyl)phenyl)picolinamide, L, is reported for the first time. Aerobic oxidation with Cu(II) gives complete oxidation of S-S bond to sulfonates, whereas Ag(I) gives only partial oxidation up to sulfinates, in the absence of any other oxidizing agent, in tetrahydrofuran/water solution. The in situ generated sulfonate product forms a thermally stable, two-dimensional H-bonded polymeric complex with Cu(II) ions in two polymorphic forms. L in the presence of Cu(II), in an inert atmosphere, results in a reductive cleavage of the disulfide bond and an in situ formation of a new C-S bond. The latter forms a unique tetranuclear complex with Cu(II) employing deprotonated amide groups and bridging thiol and chloride atoms. The disulfide precursor and the products were characterized by X-ray crystallography and spectroscopic techniques.


Assuntos
Cobre/química , Dissulfetos/química , Compostos de Sulfidrila/síntese química , Anaerobiose , Catálise , Oxirredução , Análise Espectral
14.
Org Biomol Chem ; 12(25): 4445-53, 2014 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-24849460

RESUMO

Three positional isomers of a Schiff base containing -OH as end groups have been synthesized and evaluated for selective Al(III) detection due to inhibition of ESIPT, PET and activation of CHEF in 70% aqueous medium. Devoid of any conventional fluorophore, these sensors have nanomolar detection limits with high quantum yields and naked eye sensing of Al(III). Moreover, these probes have been demonstrated to enable the Al(III) detection in live human HeLa cells and rat C6 glioma cells using a confocal microscope.


Assuntos
Alumínio/análise , Corantes Fluorescentes/química , Imagem Molecular/métodos , Bases de Schiff/química , Água/química , Animais , Sobrevivência Celular , Colorimetria , Cristalografia por Raios X , Células HeLa , Humanos , Conformação Molecular , Espectroscopia de Prótons por Ressonância Magnética , Ratos , Espectrometria de Fluorescência
15.
Chem Commun (Camb) ; 49(70): 7684-6, 2013 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-23752683

RESUMO

Herein we demonstrate the formation of the first tetrastable naphthalenediimide (NDI, 1a) molecule having multiple distinctly readable outputs. Differential response of 1a to fluoride anions induces intramolecular charge transfer (ICT), single/double electron transfer (SET/DET) leading to a set of combinational logic gates for the first time with a NDI moiety.


Assuntos
Imidas/química , Naftalenos/química , Ânions/química , Transporte de Elétrons , Elétrons , Fluoretos/química , Espectrofotometria Ultravioleta
16.
J Nanosci Nanotechnol ; 13(4): 2929-36, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23763181

RESUMO

Different phases in hybrid complexes of Co(II) with cis-4-cyclohexene-1-2-dicarboxylicacid (C6H8-1,2-CO2H=Cy-H2) have been generated depending on the reaction conditions. By microwave-irradiation of the same reaction mixtures at different temperatures we have obtained two new phases Co(C8H8O4) x H2O and [Co2(OH)2.8(Cy-H)1.2]. These phases have been established by XRD, UV-DRS, IR and thermo-gravimetric studies as well as by comparison with the reported phases. In these phases the Cy is found in a cis conformation. It has been seen that microwave synthesis proves to be a rapid and clean method of obtaining new high temperature phases in high purity which are obtained, in an impure state after a long time of hydrothermal synthesis.

17.
Chem Commun (Camb) ; 49(26): 2667-9, 2013 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-23435905

RESUMO

A highly selective and sensitive chemodosimeter for detection of cyanide ions in HEPES buffer and in the presence of blood serum using a ratiometric approach through dual UV-Vis and fluorescence channels with the lowest detection limit of 0.08 ppb has been synthesized.


Assuntos
Cianetos/análise , Corantes Fluorescentes/química , Humanos , Íons/análise , Modelos Moleculares , Estrutura Molecular , Espectrometria de Fluorescência , Água/química
18.
Org Biomol Chem ; 11(4): 654-61, 2013 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-23223944

RESUMO

Two mesitylene based probes, having catechol/phenol units in conjunction to the Schiff base have been synthesized. The probe with a catechol unit can be used to sense and discriminate between F(-) and CN(-) through different colorimetric and fluorimetric responses using DMSO as solvent. However in DMSO:water (2:1) solution it responds selectively to CN(-) ion. The probe with a phenol unit is highly selective and sensitive for CN(-) and can be used for naked eye, semiquantitative sensing of CN(-) ion in DMSO:water (2:1) solution. The chemodosimetry has been attributed to the acid catalyzed Strecker's reaction of an imine bond and is being reported for the first time in a Schiff's base.


Assuntos
Derivados de Benzeno/química , Técnicas de Química Analítica/instrumentação , Cianetos/análise , Cianetos/química , Corantes Fluorescentes/química , Fluoretos/análise , Fluoretos/química , Catálise , Colorimetria , Concentração de Íons de Hidrogênio , Iminas/química , Espectrometria de Fluorescência
19.
Analyst ; 137(21): 4913-6, 2012 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-22946086

RESUMO

1-(4-Biphenyl)benzimidazolium based dipodal system acts as a highly selective fluorescent chemosensor for determination of perchlorate ions in aqueous buffer and in drinking water at concentrations lower than that permissible by EPA. (1)H NMR titration studies, Job's plot, X-ray crystal structure and theoretical studies reveal cavity based recognition.


Assuntos
Técnicas de Química Analítica/instrumentação , Percloratos/análise , Água/química , Benzimidazóis/química , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Conformação Molecular , Percloratos/química , Espectrometria de Fluorescência
20.
Dalton Trans ; 40(46): 12560-9, 2011 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-21986896

RESUMO

Two similar synthetic pathways using the ligand N,N-diisobutylisonicotinamide (L) with anhydrous CoX(2) salts (being X = Cl(-), Br(-)) led to different species: a one-dimensional system, [CoLCl(2)](n), 1, and an ionic product [Co(L)(2)(H(2)O)(4)][CoLBr(3)](2)·2H(2)O, 2, respectively. Compound 1 is a polymer in which ligand L coordinates to tetrahedral Co(II) ions in a bidentate bridging fashion using the pyridine nitrogen and carbonyl oxygen atoms. Compound 2 consists of one octahedral cationic [Co(L)(2)(H(2)O)(4)](2+) entity and two tetrahedral anionic [CoLBr(3)](-) units. In this system, the ligand molecules coordinate only through the pyridine nitrogen atoms. The magnetic properties of 1 and 2 were investigated in the temperature range of 2.0 to 300.0 K and correlations between both (due to the existence of similar features) examined. The study of the magnetic properties of 1 was carried out by considering each Co(II) ion as a perfectly isolated system, hence, J = 0, but taking into account a significant zero-field splitting contribution due to distortions on the tetrahedral environment of the cobalt atoms. The fit of the magnetic susceptibility data together with reduced magnetization vs H/T measurements provided similar parameters (|D| = 10.8 cm(-1), g(⊥) = 1.92, g(‖) = 2.92 for the former and |D| = 11.04 cm(-1)and g = 2.05 for the latter, respectively). On the other hand, the magnetic response of compound 2 has been analyzed using a model which considers the presence of two tetrahedral and one octahedral Co(ii) ions (Co(Td) and Co(Oh)). The study was carried out in two separated blocks, above and below 80 K, where only the most significant effects at each interval of temperature were considered. As a result, the analysis of the magnetic data shows weak antiferromagnetic interactions between the Co(Oh)and the two Co(Td) ions (J = -0.41 cm(-1)) in 2. The best fit parameters were g(Co(Td)) = 2.89, g(Co(Oh)) = 3.50, |D(Co(Td))| = 10.62 cm(-1), |E(Co(Td))| = 2.95 cm(-1), Δ = 240.9 cm(-1) and J(L-S) = -107.1 cm(-1), from where λ was calculated with a final value of -144.8 cm(-1) (J(L-S) = Aκλ). The approximations performed to obtain these values provide reasonable results in agreement with compound 1 and also to other systems in the literature.

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