Bis(naphthol)-based fluorescent chemoprobe for cesium cation and its immobilisation on silica nanoparticle as a high selective adsorbent

Abstract

A bis(naphthol)-based cation receptor 1 has been synthesised by three steps of synthetic procedure. The spectroscopic properties of 1 upon addition of various metal ions were investigated by UV–vis absorption and fluorescence spectroscopy. As a result, the absorption of 1 was linearly decreased as a function of concentration of added Cs⁺. Also, 1 exhibited dramatic fluorescence quenching effect upon exposure to caesium cation. Contrastively, no significant quenching effect was observed upon addition of other metal ions such as Na⁺, K⁺, Rb⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ni²⁺ and Zn²⁺. It was found that 1 formed a 1:1 complex with Cs⁺ by Job’s plot. Furthermore, we also prepared 1-functionalised silica nanoparticle (SiO₂-1) as an adsorbent for Cs⁺. SiO₂-1 showed a great capacity for selective removal of caesium ion from aqueous solution as well as from tap water. Thus, it is potentially useful for the detection and removal of caesium cation from environmental and biological fluids polluted by nuclear radiation and nuclear waste.     

Phenanthroline-based fluorescence sensors for Eu3+ ion and subsequent enantioselective discriminating of malate

A pair of novel chiral fluorescent and colorimetric sensors L1 and D1 had been designed and synthesized, which were based on phenanthroline as the fluorophore and mandelohydrazide as the binding site. They showed selective recognition toward Eu³⁺ ion as ‘turn-off’ mode in DMSO-H₂O solution (v/v = 1:5, 10 mM HEPES, pH = 7.4). The fluorescence discrimination towards chiral carboxylate anions had been studied for L1-Eu³⁺ and D1-Eu³⁺ complex and they showed good enantioselective recognition ability towards malate as ‘turn-on’ mode. The interaction of sensor L1, D1 with Eu³⁺ and L1-Eu³⁺, D1-Eu³⁺ towards malate caused different color changes in the naked eye.     

13C, 15N and 113Cd NMR and Molecular Orbital Studies of Novel Bile Acid N-(2-aminoethyl)amides and Their Cd2+-complexes

Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by¹H, ¹³C and ¹⁵N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd²⁺-complexes (1+Cd and 2+Cd) in CD₃OD solution have been detected by ¹H,¹³C, ¹⁵N and ¹¹³Cd NMR. The ¹³C NMR chemical shift assignments of 1 and 2 and their Cd²⁺-complexes are based on DEPT-135 and z-GS ¹H,¹³C HMQC experiments as well as comparison with the assignments of the related structures. The ¹⁵N NMR chemical shiftassignments of the ligands and theirCd²⁺-complexes are based on z-GS¹H,¹⁵N HMBC experiments. ¹³C NMR chemical shift differences between 1and its 1:1 Cd²⁺-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd²⁺-complexation.     

Can five-membered Te<Subscript>2</Subscript>N<Subscript>2</Subscript>S rings be considered aromatic?

The structures and molecular properties of three cyclic tellurium species [Te₂N₂S]²⁺ (1 ²⁺ ), [Te₂N₂SCl]⁺ (1 ⁺ ), and Te₂N₂SCl₂ (1) were studied using Density Functional Theory (DFT) with the aim of analyzing and quantifying the degree of electron delocalization in the rings. The structural data for the AsF₆⁻ salt of the cation 1 ⁺ , as well as the experimental vibrational frequencies of 1 and 1 ⁺ , were compared to calculated structures and vibrational modes. While only the five-membered ring of 1 ²⁺ obeys the classic Hückel aromaticity criteria, reflected in the nature of the π orbitals and natural resonance structures, all the three species are magnetic aromatic according to nucleus-independent chemical shift (NICS). However, the out-of-plane component of the NICS tensor (NICS_zz) is able to provide a reliable characterization of the π aromatic character, by showing that successive binding of two chlorine atoms to the same tellurium atom disrupts the π electron delocalization, and that total NICS cannot always be trusted as an aromaticity indicator.     

A highly selective fluorescent chemosensor for successive detection of Fe3+ and CN− in pure water

A water-soluble fluorescent chemosensor (D) based on 1, 8-naphthalimide derivative has been designed and synthesised as a new fluorescent sensor for successive detection of Fe³⁺ and CN^?. Fluorescence measurements show that chemosensor D has excellent fluorescent-specific selectivity and high sensitivity for Fe³⁺ over many other metal ions in pure water. Moreover, the complex of D and Fe³⁺ (D–Fe³⁺) displayed high sensitivity for CN^? over many other anions in the same medium. Even more important, the recognition of the sensor D for Fe³⁺ and D–Fe³⁺ complex for CN^- could be used successfully in pure water. The test strips based on D and D–Fe³⁺ exhibited good selectivity to Fe³⁺ and CN,^- respectively, we believe the test strips could serve as convenient and efficient Fe³⁺ and CN^? test kits.     

Supramolecular Influences on Metal Ion Coordination: Lead(II) under Eight-coordination

Crystal structure determinations on the “acid salt” of Pb(II) and dipicolinic acid (pyridine-2,6-dicarboxylic acid, dipicH²), regarded as composed of dimer entities, [Pb²(dipic)²(dipicH²)²(OH²)⁶], 1, infinitely cross-linked, and on the complex of 2,4-dinitrophenol (2,4-DNPH), a simpler coordination polymer, [Pb(2,4-DNP)²]n, 2, show both solid state structures to be influenced by π-stacking of the ligands. Although the Pb(II) coordination environment in 1 can be regarded as “hemidirected” and that in 2 as “holodirected”, it is argued that inter-dimer stacking interactions, rather than lone pair effects, are responsible for the distorted 9-coordination of Pb in 1. In 2, Pb adopts close-to-cubic 8-coordination.     

Two novel steroidal derivatives from chloroform-soluble extract of Hoya longifolia

The structures of two novel steroidal derivatives (1 and 4) were elucidated. Steroidal derivatives namely fologenin (1) and hoyagenin (4) have been isolated from chloroform-soluble extract of the whole plant of Hoya longifolia (family: Asclepiadaceae), and their structures were determined by using ¹H NMR, ¹³C NMR, ¹H–¹H COSY and FAB-MS techniques as well as chemical degradation and derivatisation.     

Syntheses and characterization of two new compounds based on versatile 1,2,3,5-benzenetetracarboxylic acid and 2,2′-bibenzimidazole

Two coordination complexes based on H₄btec and H₂bibzim (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, H₂bibzim = 2,2′-bibenzimidazole), [Ni(H₂bibzim)₃]₂(btec) (1) and [Zn(H₂bibzim)(btec)_0.5]_n (2), have been synthesized by hydrothermal methods and characterized by single-crystal X-ray diffraction. Complex 1 is composed of [Ni(H₂bibzim)₃]²⁺ with free btec^4? as counter anion. In 2, the btec^4? ligands bridge the Zn(II) ions into a 1-D chain with H₂bibzim as auxiliary chelating ligands. Interesting supramolecular structures were demonstrated due to the existence of hydrogen bonding as well as π?π interactions in the two different complexes. The H₂bibzim ligands act as a 2-connected spacer in both complexes. However, in 1, the [Ni(H₂bibzim)₃]²⁺ cations act as 3-connected nodes, hydrogen bonded with the 6-connected btec^4? ligands into a 3-D framework with (3,6)-connected topology Schläfli symbol as (4.6.8)(4².6)(4³.6⁴.8⁷.10). As for 2, Zn serves as a 3-connected node with btec^4? as a 6-connected node, leading to a 2D (3,6)-connected hydrogen bonding kgd topology sheet with Schläfli symbol of (4³)²(4⁶.6⁶.8³). Thermal stabilities and photoluminescent properties of 1 and 2 were also studied.     

Supramolecular dyad derived from a buckybowl series of O2N2-donor naphthodiaza-crowns coordinated to C60: photophysical,NMR and theoretical studies

Supramolecular complexation of C₆₀ with L¹-L⁵ were studied in toluene, chloroform and 1,2-dichlorobenzene solvents using UV–vis, fluorescence, ¹H, ¹³C NMR spectroscopy as well as density functional theory (DFT) calculations. The Job’s plot of continuous variation method established 1:1 stoichiometry for L¹-L⁵/C₆₀. Binding constants (K) calculated for L¹-L⁵/C₆₀ were also determined employing UV–vis and fluorescence spectroscopy. Both steady-state and time-resolved fluorescence spectroscopic surveys showed remarkable fluorescence quenching phenomenon for L¹-L⁵ in the presence of C₆₀ which was primarily attributed to involvement of a static process. The observed fluorescence quenching in L¹–L⁵ was described in terms of both π–π and n–π interactions of the naphthalene moieties and the nitrogen donor groups on the aza-crown macrocyclic ligands with C₆₀, respectively. Moreover, DFT calculations using B₃LYP/6-31G* basis set confirmed on the aforesaid π–π interaction of naphthalene groups on the aza-crowns with C₆₀. The DFT calculations also established significant distributions of charge between C₆₀ and L¹-L⁵ in according to the electronic structure and geometry of L¹-L⁵/C₆₀, very similar to phthalocycnine/C₆₀ systems.     

Excellent Ag+ selective receptors: Syntheses and complexation properties of novel biscalix[4]arene with benzalazine groups

By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, ¹H NMR and ¹H–¹H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag⁺. The Ag⁺/Na⁺ and Ag⁺/Hg²⁺ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag⁺ was 1.9 × 10⁵ M^? 1 and the 1:1 stoichiometry of receptor 7–Ag⁺ complex was formed. The ¹H NMR spectra complexation experiments suggested that Ag⁺ was bound in a cavity composed of two benzalazine groups on bridging chains.     

Synthesis and Characterization of a Novel Phosph(V)azane-Tin(IV) Complex

Abstract

The reaction of bis(anilino)phosphine oxide (C₆H₅NH)₂P(O)H, 1 with Bu₂ ⁿSnCl₂ in the presence of an excess of triethylamine (TEA) in dry tetrahydrofurane (THF) yields the novel N,O-bonded tin complex Bu₂ ⁿSn[NPh(O)P(H)NPh(HNEt₃)]₂, 2. TEA is used as a base to deprotonate the phosphazane ligand and is separated as Et₃NH⁺Cl^?, whereas HTEA⁺ exists in the final product 2 and act as a charge balancing and H-bond structure–directing agent. This new compound has been fully characterized by means of IR, MS, and multinuclear (¹H, ³¹P, and ¹¹⁹Sn NMR) spectroscopy.     

Synthesis of new bicarbazole-linked triazoles as non-cytotoxic reactive oxygen species (ROS) inhibitors

Abstract

Carbazole analogs 3 and 4 and a new library of bicarbazole-linked triazoles 6–11 were prepared via new synthetic methodology. Metal-catalyzed oxidative coupling reaction was utilized for the synthesis of bicarbazole acetylene 4 and different metals (Zn⁺², Co⁺², Fe⁺³, Ni⁺², Cu⁺², Mn⁺²) as catalyst were screened. Only Fe-catalyzed reaction was found to be excellent and gave homocoupled product 4. Cu-catalyzed 1,3-dipolar cycloaddition was also utilized to install triazole moiety for the synthesis of hybrid molecules 6–11. Based on reported anti-inflammatory activity of carbazole and triazole scaffolds, all compounds were screened for their reactive oxygen species (ROS) inhibitory potential. Results from these studies revealed triazole 9 as most active compound (IC₅₀ value of 7.6?±?0.1?µg/mL on human whole blood and 2.7?±?0.09?µg/mL on isolated neutrophils) using ibuprofen as a standard. Therefore, class described herein can serve as attractive structural element for further studies on ROS inhibition.     

Two 1-D and 2-D cobalt(II) complexes: synthesis,crystal structures,spectroscopic and electrochemical properties

Two new cobalt(II) complexes, [Co(L³)₂]·CH₃OH·CH₃COCH₃ (1) (HL³ = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L⁴)₂ (2) (HL⁴ = 1-(2-{[(E)-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL¹ and HL². HL¹, HL², and their corresponding Co(II) complexes were characterized by IR, ¹H NMR spectra, as well as by elemental analysis and UV–Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C–X···π bonding interactions construct the 1-D infinite chain [Co(L³)₂]·CH₃OH·CH₃COCH₃ and Co(L⁴)₂ into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.     

Synthesis and Structures of 3,5-disubstituted 1,2,4-triazole Head Units and Incorporation of 3,5-dibenzoyl-1,2,4-triazolate into New [2 + 2] Schiff-Base Macrocyclic Complexes

The synthesis and characterization of sodium 3,5-diacetyl-1,2,4-triazolate (4 ^Me ) and sodium 3,5-dibenzoyl-1,2,4-triazolate (4 ^Ph ), both of which can be used as head unit building blocks in Schiff-base reactions, are reported. The crystal structures of sodium 3,5-diacetyl-1,2,4-triazolate, as [4 ^Me (H₂O)]_∞, and sodium 3,5-dibenzoyl-1,2,4-triazolate, as [4 ^Ph (CH₃OH)₂]₂, have been determined. The former is a helical polymer whilst the latter is a methanol-bridged dimer. The lead(II) templated cyclization reaction of sodium 3,5-dibenzoyl-1,2,4-triazolate (4 ^Ph ) with 1,3-diaminopropane or 1,4-diaminobutane, respectively, leads to the formation of two new [2 + 2] Schiff-base macrocycles as their lead(II) complexes, [Pb₂ L ^3Ph (μ-OH)]ClO₄ (5) and [Pb₂ L ^4Ph (μ-OH)]ClO₄ (6), respectively. Transmetallation of 5 with nickel(II) ions yields a novel, structurally characterized, dinickel(II) macrocyclic complex, [Ni₂ L ^3Ph (NCS)₂] (7), which features double triazolate bridging of the two five-coordinate nickel(II) ions.     

The Superbulky Pn Ligand Complexes [CpBIGFe(η5−P5)] and [(CpBIGFe)2(μ,η4:4-P4)]—Synthesis and Characterization

Abstract

A new synthesis of [Cp^BIGFe(CO)₂]₂ 3 (Cp^BIG = C₅(4-ⁿBuC₆H₄)₅) was developed starting from Cp^BIGNa and FeCl₂ in the presence of CO. Reaction of this product with P₄ leads to the two new P_n ligand complexes [Cp^BIGFe(η⁵-P₅)] 1b and [(Cp^BIGFe)₂(μ,η^4:4-P₄)] (4) containing the highly sterically demanding Cp^BIG ligand. Depending on the solvent, different ratios of 1b:4 are obtained. The products 1b, 3, and 4 were characterized by spectroscopic methods as well as by X-ray diffraction.     

A new fluorescence chemosensor based on benzothiazole derivative for Zn2+ and its logic gate behavior

A novel benzothiazole derivative J as a fluorescent chemosensor for Zn²⁺ has been designed and synthesized. The chemosensor J exhibits high selectivity and sensitivity to Zn²⁺ as fluorescence “turn-on” behavior, which the other cations do not make sense. The detection limit calculated by fluorescence titration method was 1.64 × 10^?8 M. Furthermore, the generated J-Zn²⁺ ensemble could recover the enhanced fluorescence upon the addition of EDTA generating an “on-off-on” recycle. In addition, the test strip based on J was fabricated, which could act as a convenient and efficient Zn²⁺ test kit.     

Synthesis,structural characterization,and anion interactions of new triazole-linked urea derivative fully substituted cyclotriphosphazene compounds

Three novel fully substituted urea derivative cyclotriphosphazene compounds 5–7 were synthesized by alkyne-azide 1,3-dipolar cycloaddition reaction of propargyl substituted ureas 2–4 with hexaazide substituted cyclotriphosphazene 1 in the presence of Cu(I) catalyst. All compounds were characterized with spectroscopic techniques such as FT-IR, ¹H, ¹³C, and ³¹P nuclear magnetic resonance and mass spectroscopy. Also, the usefulness of compounds 5–7 as anion carriers was investigated by ¹H NMR spectroscopy. For this purpose, ¹H NMR spectra of compounds 5–7 were recorded in the presence of tetrabutylammonium fluoride in DMSO-d₆. It was determined, that the urea protons in the compounds interact with fluoride.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.     

A Simple Synthesis of Dimethylphosphinyl-Substituted Tetrahydropyrroles

Abstract

New dimethylphosphinyl-substituted tetrahydropyrroles 3, 5, 6 and 8 have been synthesized via 1,3-cycloaddition reaction of the N-(4-chlorophenylmethylene)aminomethyl-dimethylphosphinoxide (1) to benzylideneacetophenone, ethyl cinnamate and cinnamonitrile. The structure of the compounds was confirmed by elemental analysis, IR, ¹H-, and ³¹P¹H-NMR spectroscopy and in some cases by mass spectrometry, as well.     

Synthesis,characterization, and pharmacological evaluation of the proton transfer salts of 2-aminobenzothiazole derivatives with 5-sulfosalicylic acid and their Cu(II) complexes

Abstract

Two proton transfer compounds, formed between 2-aminobenzothiazole derivatives (2-aminobenzothiazole (abt) and 2-amino-6-ethoxybenzothiazole (EtOabt)) and 5-sulfosalicylic acid dihydrate (H₃ssa) as parent compounds, (Habt)⁺(H₂ssa)^? (1) and (HEtOabt)⁺(H₂ssa)^? (2) and their Cu(II) complexes (3 and 4, respectively) have been prepared and characterized using spectroscopic techniques. The single crystal X-ray diffraction method has been also applied to 3 and 4. Although 3 has a distorted octahedral form, 4 exhibits a distorted square pyramidal geometry. All compounds, including saline and diclofenac sodium as standards, have been evaluated pharmacologically for their anti-inflammatory and analgesic activities in rats and mice. Parent compounds (abt, EtOabt, and H₃ssa) 3 and 4 show significant anti-inflammatory and analgesic activities as compared with control compounds.