A ratiometric and exclusively selective Cu fluorescent probe based on internal charge transfer (ICT)

A new ratiometric and exclusively selective fluorescent probe N-butyl-4,5-di[N-(phenyl)-2-(amino)-acetamino]-1,8-naphthalimide (1) was designed and synthesized on the basis of the mechanism of internal charge transfer (ICT). The probe 1 showed exclusively selectivity for Cu^II in the presence of a variety of other metal ions in aqueous ethanol solutions and the binding mode of probe 1 with Cu^II was 1:1 metal-ligand complex. Fluorescent emission spectra of probe 1 in the presence of Cu^II showed a 50 nm blue shift, which is from 521 nm to 471 nm. Furthermore, probe 1 shows the same fluorescent change with the Cu^II in living cells.     

Novel colorimetric chemosensors containing pyridine moiety for detection of some cations in water and crops samples: Design,synthesis, and evaluation

This investigation deals with synthesis of some novel chemo sensors for identifying cations in drinking water and agricultural crops. This takes place via interaction of 2,5-dioxo-1,2,3,4-tertrahydropyridine-3-carbonitrile (3) and 2-thioxo-5-oxo-1,2,3,4-tertrahydropyridine-3-carbonitrile (4) with Cu^II and Co^II. The novel compounds' structures have been examined using spectrum data (IR, ¹H NMR, ¹³C NMR, and MS) as well as elemental and physical studies. Complexation behaviors of Compounds 3 and 4 as organic ligands were predicted, discussed, and calculated via Density-Functional Theory (DFT) and Colorimetric investigation. The newly synthesized receptors 3 and 4 showed selective colormetric sensing capability for some cations by color shifting from colorless to pale violet in a nearby ideal aqueous solution enabling naked eye identification and quantitative determination of cooper (Cu^II) and cobalt (Co^II) metal ion.     

Detection of cyanide (CN−) ion with high selectivity and sensitivity by using ‘Turn-ON’ fluorescence strategy of Rhodamine Schiff base

A Rhodamine based Schiff base, (E)-3′,6′-Bis(ethylamino)-2-(2-(((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methyl-ene)amino)ethyl)-2′,7′-dimethylspiro[isoindoline-1,9′-xanthen]-3-one (HL) has been synthesized and characterized by various spectroscopic data, viz. ¹H and ¹³C NMR, ESI-MS, FT-IR and elemental analysis. It shows very weak fluorescence emission (9:1 (v/v) DMSO/H₂O, HEPES buffer at pH 7.4) while it is enhanced considerably upon addition of CN⁻ ion selectively (λ_em, 456 ​nm) in presence of nineteen other biologically important anions. The Limit of Detection (LOD) is 24 ​nM which is significantly lower than literature reported data. The binding interaction of the probe to CN⁻ ion, 1:1 (HL:CN⁻) mole ratio has been confirmed by Job's plot, ESI-MS spectral data and ¹H NMR spectral titration measurement.     

Structural characterization and cytotoxicity studies of ruthenium(II)–dmso–chloro complexes of chalcone and flavone derivatives

A synthetic precursor cis-[Ru^IICl₂(dmso)₄] is complexed separately with 3-(4-benzyloxyphenyl)-1-(2-hydroxylphenyl)-prop-2-en-1-one (L¹H) and 2-(4-benzyloxyphenyl)-3hydroxy-chromen-4-one (L²H). The resulting complexes are assigned the composition fac-[RuCl(S-dmso)₃(L¹)] 1 and fac-[RuCl(S-dmso)₃(L²)] 2 using elemental analyses, FAB mass data and spectroscopic (IR, ¹H NMR, UV–Vis, emission) spectral properties. The X-ray diffraction analysis shows that complexes self-associate through non-covalent interactions and provide 1D and 2D supramolecular structures. These complexes are assayed for their cytotoxicity studies on Dalton Lymphoma cell lines.     

A chemosensor showing discriminating fluorescent response for highly selective and nanomolar detection of Cu and Zn and its application in molecular logic gate

A fluorescent based receptor (4Z)-4-(4-diethylamino)-2-hydroxybenzylidene amino)-1,2dihydro-1,5-dimethyl-2-phenylpyrazol-3-one (receptor 3) was developed for the highly selective and sensitive detection of Cu²⁺ and Zn²⁺ in semi-aqueous system. The fluorescence of receptor 3 was enhanced and quenched, respectively, with the addition of Zn²⁺ and Cu²⁺ ions over other surveyed cations. The receptor formed host-guest complexes in 1:1 stoichiometry with the detection limit of 5 nM and 15 nM for Cu²⁺ and Zn²⁺ ions, respectively. Further, we have effectively utilized the two metal ions (Cu²⁺ and Zn²⁺) as chemical inputs for the manufacture of INHIBIT type logic gate at molecular level using the fluorescence responses of receptor 3 at 450 nm.     

Synthesis,method optimization,anticancer activity of 2,3,7-trisubstituted Quinazoline derivatives and targeting EGFR-tyrosine kinase by rational approach: 1st Cancer Update

A novel 3-(substituted benzylideneamino)-7-chloro-2-phenyl quinazoline-4(3H)-one (7–27) has been synthesized and characterised by IR, ¹H NMR, ¹³C NMR spectroscopy, and elemental analysis. We changed the methodology for the synthesis of 3-amino 7-chloro-2-phenyl quinazolin-4(3H)-one 6 to fusion reaction at 250 °C, instead of using solvent, to avoid the problem of ring opening, which is commonly observed while synthesizing quinazolines from benzoxazinone. NCI selected, 7-chloro-3-{[(4-chlorophenyl) methylidene] amino}-2-phenylquinazolin-4(3H)-one 12, with GI₅₀ value of ?5.59 M, TGI value of ?5.12 M, and LC₅₀ value of ?4.40 M showed remarkable activity against CNS SNB-75 Cancer cell line. Rational approach and QSAR techniques enabled the understanding of the pharmacophoric requirement for 2,3,7-tri substituted quinazoline derivatives to inhibit EGFR-tyrosine kinase as antitumor agents and could be used as an excellent framework in this field that may lead to discovery of potent anti tumor agent.     

Microwave synthesis,characterization and antimicrobial study of new pyrazolyl-oxopropyl-quinazolin-4(3H)-one derivatives

Heterocyclic compounds containing pyrazolyl-oxopropyl-quinazolin-4(3H)-one are reported to possess significant biological activity. Syntheses of 6-bromo-2-(3-chloro-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 2 6-bromo-3-(4-fluorophenyl)-2-(3-hydrazinyl-2-oxopropyl)quinazolin-4(3H)-one 3 and 6-bromo-2-(3-(3-(4-(1-(2-chlorophenyl)-3-methyl-1H-pyrazol-5(4H)-ylideneamino)phenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 5a–j using microwave irradiation have been described. These compounds have been characterized on the basis of the UV, IR, ¹H NMR, ¹³C NMR, Mass and elemental analysis. Compounds have been evaluated for their antimicrobial activity.     

Design,synthesis and evaluate of imidazole,triazine and metastable oxazolone derivatives as chemosensor for detecting metals

In the current work, a novel series of substituted imidazole, triazine and metastable Oxazolone derivatives were synthesized. The performance of 4-arylideneoxazol-5(4H)-one (2a-c) towards amoniuma acetate, hydrazine hydrate, phenyhydrazine and primary amines has been discussed. DFT bases and calculations of HUMO, LUMO were used to predict the ability of binding between synthesized compound and cations. All the synthesized compounds were assessed as chemosensors for detection metals ions. Colorimetric investigation confirmed and showed high-selectivity and specificity of compounds 5b and 5c to detect cobalt ion, and copper ion respectively, so compounds 5b and 5c can be directed as a chemosensor for optical detection of Co²⁺and Cu²⁺ respectively. On the other hand, new organic chemosensor were established by, IR, ¹H NMR, ¹³C NMR ms spectroscopy and elemental analysis.     

Novel metallophthalocyanines bearing 3-(p-chlorophenyl)-5-p-tolyl-4H-1,2,4-triazole bulky substituents by microwave irradiation

The synthesis of metallophthalocyanines [6–9; M = Ni(II), Zn(II), Co(II) and Cu(II)] with four 1,2,4-triazole units obtained from 4-{(4-chloro-2-fluorobenzyl)[3-(4-chlorophenyl)-5-(4-methylphenyl)-4H-1,2,4-triazol-4-yl]amino}phthalonitrile (5) in the presence of dimethylaminoethanol and the corresponding anhydrous metal salts is described. The thermal stabilities of the Pc compounds were determined by thermogravimetric analysis. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis.     

Microwave-assisted and conventional synthesis of new phthalocyanines containing 4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one moieties

New metal-free and metal (Zn, Ni, Cu and Co) phthalocyanines containing 4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one moiety have been prepared from 1-(3,4-dicyanophenyl)-4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one by both conventional and microwave-assisted methods. All of these compounds are soluble in CHCl₃, DMF and DMSO. The new compounds have been characterized by elemental analysis, IR, NMR, UV-Vis spectroscopies. The crystal structures of compounds I and II were also determined by the single crystal diffraction technique.     

Synthesis,structure, photophysical properties and biological activity of a cobalt(II) coordination complex with 4,4′-bipyridine and porphyrin chelating ligands

A new bioactive material of cobalt(II) with 5,10,15,20-tetrakis[4 (benzoyloxy)phenyl] porphyrin (TPBP) and bpy ligands ([Co^II(TPBP)(bpy)₂] 1) has been synthesized and characterized by Single-crystal X-ray diffraction (SCXRD), spectroscopic methods and quantum-chemistry calculations. In the crystalline structures of six coordinated Co(II) [Co^II(TPBP)(bpy)₂] 1, linear 1D polymeric chains were observed in which all the porphyrin units are aligned parallel to each other. The crystal packing is stabilized by inter-and intramolecular C–H⋯O and C–H⋯N hydrogen bonds, and by weak C–H⋯Cg π interactions. Interestingly, NBO–Second-order perturbation theory analysis, carried out at the UB3LYP/6-31G(d)/SDD DFT level of theory, demonstrated that a two-center bond between the nitrogen atoms and the cobalt ions (Co) was not found, the Co–N_py/bp interactions are coming from an electronic delocalization between the N_py/N_bp filled orbitals to the anti-bonding LP*(4) and LP*(5) metal NBOs. Mass spectroscopy, and elemental analysis were also investigated to confirm the molecular structure. The downfield shift and the peak broadening of the axial ligand resonances observed in the ¹H NMR indicated the contiguity to the paramagnetic Co(II) center. Additionally, the photophysical properties have been evaluated by UV–visible absorption, and fluorescence emission spectroscopies. Finally, bioactivity investigations revealed that free porphyrin TPBP, Co^IITPBP and complex 1 could be used as potential antioxidant agents.     

A highly selective fluorescent probe for nanomolar detection of ferric ions in the living cells and aqueous media

A dipodal fluorescent probe 3, with imine and hydroxyl moieties as binding sites, has been synthesized and characterized with spectroscopic methods, single-crystal X-ray techniques, and DFT. The synthesized probe 3 (φ = 0.0028) showed highly sensitive and highly specific fluorescent ‘turn-on’ effect (λ_em = 453 nm) for the 1:1 binding with Fe³⁺ ions to form probe 3.Fe³⁺ complex (φ = 0.203) in semi-aqueous medium (acetonitrile:water (50:50; v/v)) and live cells. The 1:1 binding stoichiometry of probe 3 and Fe³⁺ ions was proposed by DFT calculations and confirmed by the NMR spectroscopy, crystal structures of probe 3 and 3.Fe³⁺ complex, and mass spectrum of probe 3.Fe³⁺ complex. The stability of probe 3.Fe³⁺ complex in a wide pH range (pH 2–12) and reversibility for binding with Fe³⁺ ions in the presence of EDTA indicates that it can be an effective chemosensor for the detection of Fe³⁺ ions in various samples, including living cells. Importantly, with the LOD of 21.5 nM for the detection of Fe³⁺ ions, probe 3 did not show any interference from potentially competing ions even at a 1:3 ratio, indicates its biocompatibility. The nanomolar limit of detection (21.5 nM), cell permeability, and low cytotoxicity allows the probe 3 to be an excellent tool for the live-cell imaging and detection of ferric ions in live cells.     

Chelate structures of 5-(H/Br)-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazones (H2L): Synthesis and structural characterizations of [Ni(L)(PPh3)] and [Ru(HL)2(PPh3)2]

The reactions of 5-R-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazone {R: H (L¹); Br (L²)} with [M^II(PPh₃)nCl₂] (M = Ni, n = 2 and M = Ru, n = 3) in a 1:1 molar ratio have given stable solid complexes corresponding to the general formula [Ni(L)(PPh₃)] and [Ru(HL)₂(PPh₃)₂]. While the 1:1 nickel complexes are formed from an ONS donor set of the thiosemicarbazone and the P atom of triphenylphosphine in a square planar structure, the 1:2 ruthenium complexes consist of a couple from each of N, S and P donor atoms in a distorted octahedral geometry. These mixed-ligand complexes have been characterized by elemental analysis, IR, UV–Vis, APCI-MS, ¹H and ³¹P NMR spectroscopies. The structures of [Ni(L²)(PPh₃)] (II) and [Ru(L¹H)₂(PPh₃)₂] (III) were determined by single crystal X-ray diffraction.     

New octahedral Zn<Superscript>II</Superscript> and Cd<Superscript>II</Superscript> complexes based on azo derivatives and azomethines of pyrazole-5-thione

New metal chelates of Zn^II and Cd^II (ML₂) based on (4Z)-3-methyl-1- phenyl-5-thioxo-1,5-dihydro-4-H-pyrazol-4-one quinolin-8-ylhydrazone (HL¹) and (4Z)-5- methyl-2-phenyl-4-[(quinolin-8-ylimino)methyl]-2,4-dihydro-3H-pyrazole-3-thione (HL²) were synthesized. The structures of the metal chelates were studied by EXAFS and NMR (¹H, ¹³C, and ¹¹¹Cd) spectroscopy. The structure of the Cd(L¹)₂ complex was established by X-ray diffraction analysis. The complexes have pseudooctahedral structures with the N₄S₂ ligand environment.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 623–629, March, 2005.     

Antifungal diastereomeric furanones from Mutisia friesiana: structural determination and conformational analysis

Two diastereomeric furanones, (4S,5S)-5-(4′-methyl-3′-pentenyl)-4-hydroxy-5-methyldihydrofuran-2-one 1 and (4S,5R)-5-(4′-methyl-3′-pentenyl)-4-hydroxy-5-methyldihydrofuran-2-one 2 were isolated for the first time from the shrub Mutisia friesiana. The relative stereochemistries of 1 and 2 were ascertained from NOESY NMR data and confirmed by a combination of molecular modeling (molecular mechanics and ab initio molecular orbital calculations) and NMR data. Comparison between experimental and calculated ¹H–¹H vicinal coupling constants revealed that both furanones exist in an equilibrium of two stable conformers of the five-membered ring. Application of Mosher's method suggests that both diastereomeric furanones have the same (S)-configuration at C-(4) and are epimers at C-(5). Furanones 1 and 2 showed antifungal activity against the pathogenic fungus Cladosporium cucumerinum.     

Ru(II) with chelating containing N4-type donor quadridentate Pd-oxime metal complexes: Syntheses, spectral characterization, thermal and catalytic properties

Five new metal complexes [Pd(LH)₂] (1), [Pd(L)₂Ru₂(bpy)₄](ClO₄)₂ (2), [Pd(L)₂Ru₂(phen)₄](ClO₄)₂ (3), [Pd(L)₂Ru₂(dafo)₄](ClO₄)₂ (4) and [Pd(L)₂Ru₂(dcbpy)₄](ClO₄)₂ (5), (where, L = ligand, bpy = 2,2′-bipyridine, phen = 1,10-phenantroline, dafo = 4,5-diazafluoren-9-one and dcbpy = 3,3′-dicarboxy-2,2′-bipyridine) have been isolated and characterized by UV-VIS, FT-IR, ¹H NMR, magnetic susceptibility measurements, elemental analysis, molar conductivity, X-ray powder techniques, thermal analyses and their morphology studied by SEM measurements. IR spectra show that the ligand acts in a tetradentate manner and coordinates N₄ donor groups of LH₂ to Pd^II ion. The disappereance of H-bonding (O−H···O) in the trinuclear Ru^II-Pd^II-Ru^II metal complexes, the Ru^II ion centered into the main oxime core by the coordination of the imino groups while the two Ru^II ions coordinate dianionic oxygen donors of the oxime groups and linked to the ligands of bpy, phen, dafo and dbpy. The X-powder results show that 1 metal complex is indicating crystalline nature, not amorphous nature. Whereas, the X-ray powder pattern of the ligand (LH₂) with 2, 3,4 and 5 exhibited only broad humps, indicating its amorphous nature. The catalytic activity of three different complexes were tested in the Suzuki coupling reaction. The 1, 4 and 5 metal complexes catalyse Suzuki coupling reaction between phenylboronic acid and arylbromides affording biphenyls. Also, the thermal results shown that the most stable complex is 1 compound while the less stable is 4 compound.     

A novel small molecule fluorescent sensor for Zn2+ based on pyridine-pyridone scaffold

The development of a water-soluble and small molecular weight fluorescent probe, 3-(4-methoxyphenyl)-4-(methylsulfanyl)-6-(pyridin-2-yl)pyridin-2(1H)-one (3), for detecting Zn²⁺ based on pyridine-pyridone skeleton is reported. We observed a clear chelation enhanced fluorescence effect of 3 in the presence of Zn²⁺. Other fluorescent properties of 3 are discussed.     

A ratiometric chemosensor for fluorescent determination of Hg based on a new porphyrin-quinoline dyad

Quinolin-8-ol p-[10′,15′,20′-triphenyl-5′-porphyrinyl]benzoate (1) was synthesized for the first time and developed as a ratiometric fluorescent chemosensor for recognition of Hg²⁺ ions in aqueous ethanol with high selectivity. The 1–Hg²⁺ complexation quenches the fluorescence of porphyrin at 646 nm and induces a new fluorescent enhancement at 603 nm. The fluorescent response of 1 towards Hg²⁺ seems to be caused by the binding of Hg²⁺ ion with the quinoline moiety, which was confirmed by the absorption spectra and ¹H NMR spectrum. The fluorescence response fits a Hill coefficient of 1 (1.0308), indicating the formation of a 1:1 stoichiometry for the 1–Hg²⁺ complex. The analytical performance characteristics of the chemosensor were investigated. The sensor shows a linear response toward Hg²⁺ in the concentration range of 3 × 10⁻⁷ to 2 × 10⁻⁵ M with a limit of detection of 2.2 × 10⁻⁸ M. Chemosensor 1 shows excellent selectivity to Hg²⁺ over transition metal cations except Cu²⁺, which quenches the fluorescence of 1 to some extent when it exists at equal molar concentration. Moreover, the chemosensor are pH-independent in 5.0–9.0 and show excellent selectivity for Hg²⁺ over transition metal cations.     

In vitro binding studies of organotin(IV) complexes of 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol with CT-DNA and nucleotides (5′-GMP and 5′-TMP): Effect of the ancillary ligand on the binding propensity

The chiral benzimidazole ligand, 1,2-Bis(1H-benzimidazol-2-yl)ethane-1,2-diol, L, exhibiting coordination mode with an oxygen atom of alcohol group directed towards the metal ion and another -OH group with different molecular axis directed away from the metal center was utilized as a building block for organotin complexes [C₁₈H₁₉N₄O₂SnCl], [C₂₈H₂₃N₄O₂SnCl] and [C₅₂H₄₂N₄O₂Sn₂] (1-3). Complexes 1 and 3 exhibit a pentacoordinate geometry while the complex 2 reveals hexacoordinated environment around the Sn(IV) metal ions as evidenced by ¹¹⁹Sn NMR studies. The DNA binding ability of benzimidazole ligand and their organotin(IV) complexes 1-3 were examined by employing different biophysical methods. The absorption titration of the complexes with CT-DNA reveal significant hyperchromic effect together with strong bathochromic shift of 4-5 nm which infer substantial binding of the complexes with CT-DNA. The intrinsic binding constant K_b values of the complexes 1-3 were found to be 2.16 ± 0.04 × 10⁴, 3.47 ± 0.04 × 10⁴ and 4.60 ± 0.04 × 10³ M⁻¹, respectively, suggesting pronounced binding of complex 2 with DNA double helix. The mechanism of binding of the complexes was further ascertained by the interaction studies of these complexes with nucleotides (5′-GMP and 5′-TMP) using absorption spectroscopy suggesting a clear preference for 5′-GMP binding which was further authenticated by NMR (¹H and ³¹P NMR) studies.     

An efficient multiple-mode molecular logic system for pH, solvent polarity, and Hg ions

A novel fluorophore 1,3-bis(1,1,3-trimethyl-1H-benzo[e]indol-2(3H)-ylidene)propan-2-one (L) was synthesized and fully characterized by ¹H NMR, ¹³C NMR, HRMS, and X-ray single-crystal structural analysis. Compound L is a pH-controlled molecular switch due to its protonation. The fluorescence change in protic polar solvents means that this compound also could be used as a protic solvent polarity sensor. Among the considered metal ions, the fluorescence of compound L could be quenched completely by Hg²⁺ ions with a high selectivity. Based on these fluorescence characters, this fluorescent dye L has promising applications as a multiple-mode molecular logic system.