A novel colorimetric and fluorometric anion sensor based on BODIPY-calix[4]pyrrole conjugate

A novel fluorescent anion sensor 1 based on boradiazaindacenes (BODIPY) derivative was synthesized and its absorption and fluorescence properties were investigated in various solvents. 1 exhibited a red shift of absorption spectrum and fluorescence quenching in varying degree in the presence of F^?, AcO^?, H₂PO₄ ^? and Cl^? due to multiple hydrogen bonding interactions between these anions and calix[4]pyrrole receptor. As an anion sensor in the visible region, 1 displayed the similar selectivity and sensitivity toward anions compared to the parent calix[4]pyrrole. However, 1 can be used as an effective dual responsive optical sensor for F^? via chromogenical and fluorogenical signals.     

Versatile acenaphtho[1,2-b]pyrrol-carbonitriles as a new family of heterocycles: diverse SNAr reactions, cytotoxicity and spectral behavior

The diverse reactivity of highly electron-deficient 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile 1 is attractive for the preparation of derivatives bearing different substituents via S_NAr^H reaction with N, O, S nucleophiles. These derivatives were versatile, possessing potential antitumor activities and displaying tunable fluorescence spectral behavior.     

A coumarin based highly selective fluorescent chemosensor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a new coumarin based fluorescent chemosensor 1, in which tren and quinolone are introduced as receptors for sequential recognition of Cu²⁺ and PPi. The structure of chemosensor 1 was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. Sensor 1 showed an obvious “on-off” fluorescence quenching response toward Cu²⁺, and the quenching efficiency reached a maximum of 99.6% with the addition of 20 equiv. of Cu²⁺. The 1-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions, especially HPO₄^2? and H₂PO₄^?. The detection limit of sensor 1 was 1.9?×?10^?6?M to Cu²⁺ and 5.96?×?10^?8?M to PPi. In addition, sensor 1 showed a 1:1 binding stoichiometry to Cu²⁺ and sensor 1-Cu²⁺ showed a 2: 1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.4). The stable pH range of sensor 1 to Cu²⁺ and 1-Cu²⁺ to PPi was from 4 to 8.     

A TCF-based colorimetric and fluorescent probe for palladium detection in an aqueous solution

A new fluorescent probe (TCF-AC) that contains 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) skeleton has been developed. Probe TCF-AC exhibits highly selective and sensitive detection toward Pd⁰ in EtOH/H₂O (1:1, v/v, PBS 20?mM, pH?=?7.4) solution with fluorescence “turn on” and colorimetric changes. The Pd⁰ detection by TCF-AC holds some advantages including good anti-interference ability, a relative large Stokes shift (>100?nm), and a low detection limit (7.05?×?10^?7?M). Cell imaging studies demonstrate that TCF-AC is applicable to detect Pd⁰ in living HeLa cells.     

A novel and synthetically facile coumarin-thiophene-derived Schiff base for selective fluorescent detection of cyanide anions in aqueous solution: Synthesis,anion interactions,theoretical study and DNA-binding properties

A colorimetric and fluorescent chemosensor (chemosensor 2) for the detection of cyanide anions in aqueous solution has been designed and synthesized in high yield. The sensing mechanism of the chemosensor was verified via UV–vis, fluorimetric, and NMR titrations, and was theoretically explained using DFT and TD-DFT calculations. The chemosensor could optically discriminate the presence of fluoride ions over other anions by a color change from yellow to red with an enhancement of pink fluorescence in DMSO. However, it showed strong green fluorescence when CN^? was added to a mixture of DMSO/water (6:4 v/v). Thus, the chemosensor can be employed in selective detecting of CN^? besides other interference anions (F^?, AcO^? and H₂PO₄^?) in aqueous solution. Moreover, 2 can be used to detect CN^? at a concentration as low as 0.32?μM, which is lower than the WHO guideline (2.7?μM) for cyanide. A low quantity of CN^? (1.08?μM) can be detected and quantified using the prepared chemosensor. Moreover, the UV–vis and fluorescence spectroscopy studies of the interactions between 2 and dublex DNA revealed intercalative binding of calf thymus DNA to the chemosensor.     

Structure and Composition of the 200 K‐Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH−)(H3S+)

At ultrahigh pressure (>110 GPa), H₂S is converted into a metallic phase that becomes superconducting with a record T_c of approximately 200 K. It has been proposed that the superconducting phase is body‐centered cubic H₃S (Im m, a=3.089 Å) resulting from the decomposition reaction 3 H₂S→2 H₃S+S. The analogy between H₂S and H₂O led us to a very different conclusion. The well‐known dissociation of water into H₃O⁺ and OH^? increases by orders of magnitude under pressure. H₂S is anticipated to behave similarly under pressure, with the dissociation process 2 H₂S→H₃S⁺+SH^? leading to the perovskite structure (SH^?)(H₃S⁺). This phase consists of corner‐sharing SH₆ octahedra with SH^? ions at each A site (the centers of the S₈ cubes). DFT calculations show that the perovskite (SH^?)(H₃S⁺) is thermodynamically more stable than the Im m structure of H₃S, and suggest that the A site hydrogen atoms are most likely fluxional even at T_c .     

General theoretical analysis of three-connected polyhedral molecules and their capped derivatives

The synthesis of the half-sandwich compound Na[(C₅H₅)Ni{P(S)(CH₃)₂}₂] is described. The anions [(C₅H₅)Ni{P(S)R₂}₂]^?, 1a (R = OCH₃) and 1b (R = CH₃) react as bidentate sulfur ligands with [Ni₂(C₅H₅)₃]⁺, giving nickelocene and weakly paramagnetic dinuclear complexes of the type [(C₅H₅)Ni{P(S)R₂}₂Ni(C₅H₅)] (2a,b). In these compounds, the P(S)R₂ units form NiPSNi bridges in such a fashion as to generate a (C₅H₅)NiP₂ and a (C₅H₅)NiS₂ unit. A temperature-dependent singlettriplet spin equilibrium is observed, which is essentially localized on the (C₅H₅)NiS₂ side. Accordingly, the position of the cyclopentadienyl peak of the (C₅H₅)Ni unit bound to the two sulfur donor centers displays a very large temperature dependence in the ¹H NMR spectra. MO model calculations (EHT) for P(S)H₂^?, [(C₅H₅)Ni{P(S)H₂}₂]^? (1c), [(C₅H₅)Ni{P(S)H₂}₂Ni(C₅H₅)] (2c) and its isomer 3c allow the observed spin crossover to be explained as a consequence of the pronounced π-donor properties of the sulfur centers and allow predictions for related complexes.The green complexes 2a,b isomerize completely and irreversibly in a first-order reaction to yield the diamagnetic red compounds [{(C₅H₅)NiP(S)R₂}₂] (3a,b), in which each (C₅H₅)Ni unit is coordinated to one P and one S donor atom. The rate constant of isomerization of 2a, k (7.6 ± 0.3) × 10^?4s^?1 at 306 K, and the energy of activation, E_a 76 kJ mol^?1, have been determined. The rate of isomerization is independent of the solvent, and crossover experiments verify that the isomerization is an intramolecular process without involvement of the monomeric units [(C₅H₅)NiP(S)R₂].     

Thiocarbonyl azide s-oxide—II: The decomposition of thiobenzoylazide s-oxide

The reaction between thiobenzoyl chloride S oxide 4, (R = C₆H₅) and the azide ion at -80° leads to the labile thiobenzoyl azide S-oxide 5, (R = C₆H₅) Raising the temperature to -40° initiates decomposition of the latter to benzomtrile, nitrogen, sulfur and sulfur dioxide The thermally induced process was monitored by differential thermal analysis (DTA) which yielded a maximum heat effect at -11° The derived reaction enthalpy is ΔH=?45.6 kcal mole^?1 and the activation parameters are ΔH^≠ = 20.2 kcal mol^?1 ΔS^≠ = 6.3 eu (at ?11°). The DTA shape index (S) and the reaction type index (M) are found to be in excellent agreement with a rate controlling first order reaction. Apart from the main peak at -11°, lack of a temperature difference signal throughout the range of measurement rules out an enthalpy-significant azide isomenzation and further suggests that decomposition takes place from a single isomer. Semi-empirical energy barrier calculations provide a rationale for the single conformer interpretation. The data are consistent either with a reaction in which N₂ and SO are expelled simultaneously or with the formation of a short-lived intermediate arising from N2 loss which rapidly eliminates sulfur monoxide. Intermediate formation of thiatriazole S-oxide cannot, however, be ruled out unambiguously.Since thioazides cyclize readily to thiatriazoles, whereas thioazide S oxides are not observed to cyclize, MO calculations have been carried out for the ring closures 2→3 and 5→6 (R= H) Orbital correlation diagrams for each potential energy surface show that ring formation is “allowed” in both cases. It is suggested that the variable chemical behavior of thioazides and their S-oxides is due to disruption of aromatic character in the hypothetical thiatriazole S-oxide product.     

Übergangsmetallkomplexe mit Schwefelliganden: XXXIV. [Fe11(CO)2]-Fragmente als Templatzentren und Schutzgruppen: Synthese makrozyklischer Thioether und Monoalkylierung von Dithiolen; Röntgenstrukturanalyse von Dibenzo-18-krone-S6, einem planaren “Kronen”-thioether

Using metal carbonyl fragments as templates, the directed, bridging alkylation of ligating dithiolates yields macrocyclic polythioethers. Treatment of cis-[Fe(CO)₂-(S₂C₆H₄)₂]²⁻ (1) with S(C₂H₄Br)₂, in THF at room temperature, gives [Fe(CO)-(dpttd)] (2) (dpttd²⁻ = 2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(2−)), which is alkylated by yet another S(C₂H₄Br)₂ under reflux to give dibenzo-18-crown-S6 (3) in 68% yield after hydrolysis and workup. Alkylation of [Fe(CO)₂dttd] (dttd² = 2,3,8,9-dibenzo-1,4,7,10-tetrathiadecane(2−)) by S(C₂H₄Br)₂ in THF under reflux gives analogously dibenzo-15-crown-S5 (4) in 20% yield. 4 is also obtained by alkylation of 2 with 1,2-C₂H₄Br₂, but in lower yield. Since each C₆H₄S₂²⁻ ligand in 1 is alkylated only once at room temperature the Fe(CO)₂ fragment acts as a protecting group for one thiolate function and permits the monoalkylation of o-benzenedithiol, a reaction which is not possible by conventional methods; with PhCH₂Br and CH₃Br the corresponding alkylthiobenzenethiols were obtained. An X-ray diffraction study of 3 shows it to have an unprecedented conformation viz. in the centrosymmetric molecule all six sulfur atoms and the C₂ (ethane) bridges form a plane (maximum deviation ± 8 pm) on which the benzo units stand nearly upright (83°). All sulfur atoms are exo and four of the twelve CS bonds show anti configuration. A comparison of the structures of 3 and the analogous oxo compound dibenzo-18-crown-6 are described.     

A study of gaseous 3-membered ring oxonium and sulphonium ions

The 1-methyl-1-thionia cyclopropane 3 and 1-phenyl-1-thionia cyclopropane 4 ions are stable, with lifetimes greater than 10^?5 sec, and can be identified from their collisional activation spectra. Their metastable counterparts (lifetime window 10^?6–10^?5 sec) have undergone ring opening to the isomeric structures CH₃S⁺CHCH₃9 and C₆H₅S⁺CHCH₃11 prior to decomposition. The 1-methyl-1-oxonia cyclopropane 1 and 1-phenyl-1-oxonia cyclopropane 2 ions could not be generated: instead acyclic structures CH₃O⁺CHCH₃5 and C₆H₅O⁺CHCH₃7 were found for both metastable and long living species. Loss of a phenoxy radical from C₆H₅OCH₂CH₂OCH₃ is shown to be preceded by a reciprocal hydrogen transfer and is not due to a SN_i-type reaction.     

Collisional ionization of fast K atoms by H2S and D2S

The process K + H₂S/D₂S → HS^?/DS^? + K⁺+ H/D has been investigated for K impact energies from near threshold to ≈100 eV. Positive and negative ion energy spectra have been obtained in the forward direction. The threshold for HS^? or DS^?production corresponds to the HS^?/DS^?+ H/D limit of the ²A₁ H₂S^?/D₂S^? state at 1.55 eV.     

A coumarin-based fluorescent and colorimetric chemosensor for rapid detection of fluoride ion

A novel coumarin-based compound 1 featuring thiosemicarbazone as binding unit, was reported as a colorimetric and fluorescent probe for the detection of fluoride anion. The addition of F^? to a solution of probe 1 in tetrahydrofuran resulted in evident naked-eye color change from green-yellow to orange-red under daylight and obvious fluorescence quenching within 3 s. And the detection limit toward F^? was calculated to be as low as 2.16 × 10^?7 mol/L. ¹H NMR titrations proved that the interaction between 1 and fluoride ion: hydrogen bond at low fluoride ion concentration, deprotonation at high fluoride ion concentration. Besides, it exhibited highly sensitivity and selectivity for F^? over other examined ions (Cl^?, Br^?, I^?, AcO^?, NO₃^?, HSO₄^?, H₂PO₄^?) in tetrahydrofuran solution.     

Novel coumarin-based containing denrons selective fluorescent chemosesor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a novel coumarin-based dendrons derivative CD and its chemical structure was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. The sensor CD showed an obvious “on-off” fluorescence quenching response toward Cu²⁺ with a maximum quenching efficiency of 99.8%. The CD-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions. The detection limit of the sensor CD was 0.29?×?10^?6?M to Cu²⁺ and 2.39?×?10^?9?M to PPi. In addition, the sensor CD showed a 1:1 binding stoichiometry to Cu²⁺ and the sensor CD-Cu²⁺ showed a 2:1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.2). The stable pH range of sensor CD to Cu²⁺ and CD-Cu²⁺ to PPi was from 3 to 8.     

A highly sensitive and selective fluorescent probe for Fe3+ containing two rhodamine B and thiocarbonyl moieties and its application to live cell imaging

A novel turn-on rhodamine B-based fluorescent chemosensor (RBCS) was designed and synthesized by reacting N-(rhodamine B)lactam-1,2-ethylenediamine and carbon disulfide. Upon addition of Fe³⁺ in EtOH/H₂O solution (2:1, v/v, HEPES buffer, 0.6?mM, pH 7.20), the RBCS displayed a significant fluorescence enhancement at 582?nm and a dramatic color change from colorless to pink, which can be detected by the naked eye. Significantly, the RBCS exhibited a highly selective and sensitive ability toward Fe³⁺. The detection limit of the probe was 2.05?×?10^?7?M. Job's plot indicated the formation of 1:1 complex between the RBCS and Fe³⁺. Moreover, the practical use of the RBCS is demonstrated by its application in the detection of Fe³⁺ in HeLa cells.     

Syntheses, characterization and ethylene polymerization of half-sandwich group IV metal complexes with tridentate [O,N,S] ligands

A series of half-sandwich group IV metal complexes with tridentate monoanionic phenoxy-imine arylsulfide [O NS] ligand [2-Bu t 4-Me-6-((2-(SC 6 H 5)C 6 H 4 N = CHC 6 H 2 O)](La) and dianionic phenoxy-amine arylsulfide [O N S] ligand [2-Bu t 4-Me-6-((2-(SC 6 H 5)C 6 H 4 N-CH 2 C 6 H 2 O)] 2(Lb) have been synthesized and characterized.Lb was obtained easily in high yield by reduction of ligand La with excess LiAlH 4 in cool diethyl ether.Half-sandwich Group IV metal complexes CpTi[O NS]Cl 2(1a),CpZr[O NS]Cl 2(1b),CpTi[O N S]Cl(2a),CpZr[O N S]Cl(2b) and Cp * Zr[O N S]Cl(2c) were synthesized by the reactions of La and Lb with CpTiCl 3,CpZrCl 3 and Cp * ZrCl 3,and characterized by IR,1 H-NMR,13 C-NMR and elemental analysis.In addition,an X-ray structure analysis was performed on ligand Lb.The title Group IV half-sandwich bearing tridentate [O,N,S] ligands show good catalytic activities for ethylene polymerization in the presence of methylaluminoxane(MAO) as co-catalyst up to 1.58 × 10 7 g-PE.mol-Zr 1.h 1.The good catalytic activities can be maintained even at high temperatures such as 100 ℃ exhibiting the excellent thermal stability for these half-sandwich metal pre-catalysts.     

Steric and electronic contributions to barriers of internal rotation in 1,8-dibenzoylnaphthalenes

Restricted rotation about the naphthalenylcarbonyl bonds in the title compounds resulted in mixtures of cis and trans rotamers, the equilibrium and the rotational barriers depending on the substituents. For 2,7-dimethyl-1,8-di-(p-toluoyl)-naphthalene (1) ΔH° = 3.66 ± 0.14 kJ mol^?1, ΔS° = 1.67 ± 0.63 J mol^?1 K^?1, ΔH^≠_ct = 55.5 ± 1.3 kJ mol^?1, ΔH^≠_ct = 51.9 ± 1.3 kJ mol^?1, ΔS^≠_ct = ?41.3±4.1 J mol^?1 K^?1 and ΔS^≠_ct = ?42.9±4.1 J mol^?1 K^?1. The rotation about the phenylcarbonyl bond requires ΔH^≠ = ?56.9±4.4 kJ mol^?1 and ΔS^≠ = ?20.5±15.3 J mol^?1 K^?1 for the cis rotamer, and ΔH^≠ = 43.5Δ0.4 kJ mol^?1 and ΔS^≠ =± ?22.4Δ1.3 J mol^?1 K^?1 for the trans rotamer. The role of electronic factors is likely to be virtually the same for both these rotamers but steric interaction between the two phenyl rings occurs in the cis rotamer only. Hence, the difference of the activation enthalpies obtained for the cis and trans rotamers, ΔΔH^?1 = 13.4 kJ mol^?1, provides a basis for the estimation of the role of steric factors in this rotation. For the tetracarboxylic acid 2 and its tetramethyl ester 3 the equilibrium is even more shifted towards the trans form because of enhanced steric and electrostatic interactions between the substituents in the cis form. The barriers for the rotation around the phenylcarbonyl bond and the cis-trans isomerization are lowered; an explanation for this result is presented.     

A colorimetric squaraine-based probe and test paper for rapid naked eyes detection of copper ion (II)

A colorimetric probe N,N’-bis(2-methoxy-ethyl)-2,3,3-trimethyl-3H-squaraine (MOESQ) with H₂O solubility was synthesized to detect Cu²⁺. MOESQ exhibits good selectivity, high sensitivity and fast UV-Vis response toward Cu²⁺ over other competing ions in CH₃CN. The detection limit of MOESQ for Cu²⁺ in CH₃CN can reach 1.88?×?10^?7?molL^?1. By adsorbing MOESQ on the chromatography paper, a colorimetric test paper for Cu²⁺ was prepared, which could detect Cu²⁺ with the color change from blue to faint yellow even in the limit of detection concentration of 10^?6?molL^?1.     

Heat capacity of polynuclear Fe(HTrz)3(B10H10)·H2O and trinuclear [Fe3(PrTrz)6(ReO4)4(H2O)2](ReO4)2 complexes (HTrz=1,2,4-triazole, PrTrz=4-propyl-1,2,4-triazole) manifesting 1A1⇔5T2 spin transition

Low-temperature heat capacity of polynuclear Fe(HTrz)₃(B₁₀H₁₀)·H₂O (I) and trinuclear [Fe₃(PrTrz)₆(ReO₄)₄(H₂O)₂](ReO₄)₂ (II) spin crossover coordination compounds was measured in 80–300 K temperature range using a vacuum adiabatic calorimeter. For I, an anomaly of heat capacity with a maximum at T _trs=234.5 K (heating mode) was observed, Δ_trs H=10.1±0.2 kJ mol^?1 Δ_trs S=43.0±0.8 J mol^? K^?1. For II, a smooth anomaly between 150 and 230 K was found, Δ_trs H=2.5±0.25 kJ mol^?1 Δ_trs S=13.6±1.4 J mol^? K^?1. Anomalies observed in both compounds correspond to ¹A₁?⁵T₂ spin transition.     

A simple and efficient anionic chromogenic chemosensor based on 2,4-dinitrodiphenylamine in dimethyl sulfoxide and in dimethyl sulfoxide–water mixtures

Solutions of 2,4-dinitrodiphenylamine (1) in dimethylsulfoxide (DMSO) are colorless but upon deprotonation they become red. Addition of various anionic species (HSO₄^?, H₂PO₄^?, NO₃^?, CN^?, CH₃COO^?, F^?, Cl^?, Br^?, and I^?) to solutions of 1 revealed that only CN^?, F^?, CH₃COO^?, and H₂PO₄^? led to the appearance of the red color in solution. The presence of increasing amounts of water in solutions containing 1 made it progressively selective toward CN^? and the system with the addition of 4.3% (v/v) of water was highly selective for CN^? among all anions studied. The experimental data collected indicated that proton transfer from 1 to the anion occurs, and a model was used to explain the experimental results, which considers two 1:anion stoichiometries, 1:1 and 1:2. For the latter, the data suggest that the anion forms firstly a hydrogen-bonded complex with a second anion equivalent necessary for the abstraction of the proton, with the formation of a [HA₂]^? complex. The study performed here demonstrates the important role of the environment of the anion and 1 for the efficiency of the chromogenic chemosensor. Besides the different affinities of each anion for water, the solvation of both the anion and 1 is responsible for reducing the interaction between these species. In small amounts, water or hydrogen-bonded DMSO–water complexes are able to stabilize the conjugated base of 1 through hydrogen bonding, making 1 more acidic, which explains the change from 1:1 and 1:2 toward 1:1 1:anion stoichiometry upon addition of water. In addition, water is able to solvate the anion and also 1, which hinders the formation of 1:1 hydrogen-bonded 1:anion complexes prior to the abstraction of the proton.     

‘Naked-eye’ detection of F− ions by two novel colorimetric receptors

Two novel colorimetric receptors, S1 and S2, linked to one or two nitrophenylurea groups were synthesized in good yields, characterized and their chromogenic properties investigated towards various anions (F^?, Cl^?, Br^?, I^?, NO₃^?, AcO^?, ClO₄^?, HSO₄^?, and H₂PO₄^?) by UV–vis and ¹H NMR techniques. The receptors, effectively and selectively, recognized and distinguished the biologically important F^? from other anions such as Cl^?, Br^?, I^? etc. in CH₃CN. This selectivity could be easily observed by the naked eye, indicating that receptors S1 and S2 are potential colorimetric sensors for fluoride ion.