新型杯[4]芳烃氨基苯酚类衍生物的合成及对La3 的选择性识别

设计合成了下缘连有氨基苯氧基结构的杯[4]芳烃衍生物:5,11,17,23-四叔丁基-25-[2-(2-氨基苯氧基)乙氧基]-27-(2-羟基乙氧基)-26,28-二羟基杯[4]芳烃(化合物C),增加了与阳离子的结合位点,有利于通过配位作用对金属离子进行识别。化合物C的结构通过红外光谱、1H NMR、13C NMR和质谱进行了表征。通过紫外可见光谱和荧光发射光谱对化合物C与24种金属阳离子的络合作用进行了研究,结果发现,其对La3+有特殊的识别作用,化合物C与La3+的络合比为1∶1。     

The molecular recognition of tetra(p-t-butyl)tetrathiocalix[4]arene and its derivatives to heavy metal ions

The molecular recognition of tetra(p-t-butyl)tetrathiocalix[4]arene (I)and its three derivatives to heavy metal ions has been investigated by UV spectroscopy and solvent extraction. These derivatives include 5,11,17,23,-tetra-t-butyl-25,26,27,28-tetrakis(acetylmethoxy)tetrathiocalix[4]arene (II), 5,11,17,23-tetra-t-butyl-25,26,27,28-tetrakis(2'-hydroxypropyloxy) tetrathiocalix[4]arene (III), 5,11,17,23,-tetra-t-butyl-25,27-bis(3'-hydroxy propyloxy)tetrathiocalix[4]arene (IV). The UV spectra and solvent extraction of I show that it has an effective molecular recognition to heavy metal ions, especially to Cd(2+), while IV has a special molecular recognition to Ag(+) ion. These results confirmed the feasibilities for I to be applied in separation for toxic heavy metal ions Pb(2+), Cd(2+) and IV to be used as the sensor compound of Ag(+) ion-selective electrode.     

Calix[4]arene based molecular probe for sensing copper ions

A novel calix[4]arene based molecular probe for metal ions has been designed, synthesized and evaluated. Studies on its binding with different metal ions reveal a noticeable naked eye color change, bathochromic shift in absorption spectrum and remarkable enhancement in fluorescence emission in the presence of Cu²⁺ only. The role of calix[4]arene scaffold for selective recognition of Cu²⁺ has been demonstrated by repeat evaluation and analysis of an appropriate reference molecule. A rational explanation for fluorescence enhancement in 3 on interaction with copper has been suggested.     

Imino-phenolic-pyridyl conjugates of calix[4]arene (L1 and L2) as primary fluorescence switch-on sensors for Zn2+ in solution and in HeLa cells and the recognition of pyrophosphate and ATP by [ZnL2

Pyridyl-based triazole-linked calix[4]arene conjugates, viz. L(1) and L(2), were synthesized and characterized. These two conjugates were shown to be selective and sensitive for Zn(2+) among the 12 metal ions studied in HEPES buffer medium by fluorescence, absorption, and visual color change with the detection limit of ~31 and ~112 ppb, respectively, by L(1) and L(2). Moreover, the utility of the conjugates L(1) and L(2) in showing the zinc recognition in live cells has also been demonstrated using HeLa cells as monitored by fluorescence imaging. The zinc complexes of L(1) and L(2) were isolated, and the structure of [ZnL(1)] has been established by single-crystal XRD and that of [ZnL(2)] by DFT calculations. TDDFT calculations were performed in order to demonstrate the electronic properties of receptors and their zinc complexes. The isolated zinc complexes, viz. [ZnL(1)] and [ZnL(2)], have been used as molecular tools for the recognition of anions on the basis of their binding affinities toward Zn(2+). [ZnL(2)] was found to be sensitive and selective toward phosphate-bearing ions and molecules and in particular to pyrophosphate (PPi) and ATP among the other 18 anions studied; however, [ZnL(1)] was not sensitive toward any of the anions studied. The selectivity has been shown on the basis of the changes observed in the emission and absorption spectral studies through the removal of Zn(2+) from [ZnL(2)] by PPi. Thus, [ZnL(2)] has been shown to detect PPi up to 278 ± 10 ppb at pH 7.4 in aqueous methanolic (1/2 v/v) HEPES buffer.     

Fluorescent chemosensor for Cu2+ ion based on iminoanthryl appended calix[4]arene

Calix[4]arene based podands 1a of cone conformation and 1b of 1,3-alternate conformation possessing imine units and bearing anthracene moieties have been synthesized by a 1 + 2 Schiff base condensation in good yields and examined for their cation recognition abilities towards cations such as lithium, sodium, potassium, nickel, cadmium, copper, zinc, lead, silver and mercury ions by UV–vis and fluorescence spectroscopy. The calix[4]arene derivative 1b shows a selective fluorescence enhancement in presence of Cu²⁺ ions among the various metal ions tested (Li⁺, Na⁺, K⁺, Ni²⁺, Cd²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Ag⁺ and Hg²⁺ ions). The colour of the solution changes from colourless to light yellow in the presence of Cu²⁺ ions. The stoichiometry of the complex formed between 1b and Cu²⁺ was found to be 1:1 as established by Job’s plot.     

Cation- and anion-assisted binding of triethylenediamine by zinc bisporphyrinates

The complexation of zinc calix[4]arene or calix[4]pyrrole bisporphyrinates with alkali metal cations, halide anions, and triethylenediamine was studied by ¹H NMR spectroscopy. It was established that the binding of molecules and/or charged particles by various fragments of calix[4]arene and calix[4]pyrrole porphyrins are interrelated processes. This makes it possible to use one process (for example, complexation of the calix[4]arene fragment of the macrocycle with alkali metal cations or complexation of the calix[4]pyrrole fragment with halide ions) as a tool for controlling another process (complexation of the porphyrin fragments of the macrocycle with neutral molecules).     

Triazole-linked-thiophene conjugate of calix[4]arene: its selective recognition of Zn2+ and as biomimetic model in supporting the events of the metal detoxification and oxidative stress involving metallothionein

Supramolecular calix[4]arene conjugate (L) has been developed as a sensitive and selective sensor for Zn(2+) in HEPES buffer among the 12 metal ion by using fluorescence, absorption and ESI MS and also by visual fluorescent color. The structural, electronic, and emission properties of the calix[4]arene conjugates L and its zinc complex, [ZnL], have been demonstrated using ab initio density functional theory (DFT) combined with time-dependent density functional theory (TDDFT) calculations. The TDDFT calculations reveal the switch on fluorescence behavior of L is mainly due to the utilization of the lone pair of electrons on imine moiety by the Zn(2+). The resultant fluorescent complex, [ZnL], has been used as a secondary sensing chemo-ensemble for the detection of -SH containing molecules by removing Zn(2+) from [ZnL] and forming {Cys/DTT·Zn} adducts as equivalent to those present in metallothioneins. The displacement followed by the release of the coordinated zinc from its Cys/DTT complex by heavy metal ion (viz. Cd(2+) and Hg(2+)), as in the metal detoxification process or by ROS (such as H(2)O(2)) as in the oxidative stress, has been well demonstrated using the conjugate L through the fluorescence intensity retrieval wherein the fluorescence intensity is the same as that observed with [ZnL], which in turn mimics the zinc sensing element (MTF) in biology.     

Spectroscopic behavior on the formation complex of three double-armed calix[4]arene derivatives with lanthanoid nitrates in acetonitrile

The complexation spectroscopic behavior of three p-tert-butylcalix[4]arene Schiff bases i.e. 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(3-nitrobenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (1), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(2-hydroxybenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (2), and 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(2-hydroxy-3-methoxybenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (3) with lanthanoid nitrates (Tb3+ and Eu3+) has been investigated in anhydrous acetonitrile at 25 degrees C by using UV-vis and FT-IR as well as fluorescence spectra. The results obtained indicated that the spectroscopic behavior of compounds 1-2 upon complexation with lanthanoid ions did not show any significant larger difference in comparison with free compounds 1 and 2, which may be contributed to the poor binding ability. Contrary to compounds 1 and 2, the lower rim functional groups in compound 3 can form two large pi electron conjugate system with lanthanide ion and encapsulate lanthanide ions tightly, displaying the novel spectroscopic behavior upon complexation with lanthanide ions. As compared with compound 3, the formation complexes of compound 3 with Tb3+ and Eu3+ showed new broad intense absorption at 398 nm, respectively, and IR spectra showed that O-H stretching vibration at 3413.40 cm(-1) displayed a large drop. It is interestingly noted that the narrow emission line spectra were observed only for 3 complex with Tb3+, but did not for 3-Eu3+ complex. In the 3-Eu3+ complex, the broad-band emission at lambda(max) = 534 nm was obtained at the excitation of 398 nm. The spectroscopic behavior of three calix[4]arene derivatives upon complexation with lanthanoids was discussed from the relationship between the host structure and the properties of guest lanthanide ions.     

Novel calix[4]arene based metallo-supramolecular complex for recognition of cyanide ions in aqueous medium

A novel bis-naphthalimidocalix[4]arene-Cu(II) supramolecular complex has been observed to provide an efficient recognition system for CN^? ions in aqueous medium. The binding stoichiometry of bis-naphthalimidocalix[4]arene and copper ion has been found to be 1:1 while that for bis-naphthalimidocalix[4]arene-Cu(II) and cyanide ion it has been determined to be 1:2.     

Two novel fluorescent calix[4]arene derivatives with benzoazole units in 1,3-alternate conformation for selective recognition to Fe~(3+) and Cr~(3+)

Two novel fluorescent calix[4]arene derivatives 1a and 1b with benzoxazole or benzothiazole units in 1,3-alternate conformation have been synthesized and characterized by IR,~1H NMR,~(13)C NMR and MS.Their complexation properties to different heavy and transition metal ions have been studied by UV-vis spectroscopy and fluorescence spectrometer.Compounds 1a and 1b show selective recognition to Fe~(3+) and Cr~(3+).     

Role of the conformational changes brought in the arms of the 1,3-di-capped conjugate of calix[4]arene (L) in turning on the fluorescence of L by Hg2+

A new 1,3-di-capped calix[4]arene conjugate of salicylidene (L) has been synthesized, characterized and the structure has been established by single crystal XRD. L shows selectivity towards Hg(2+) in ethanol by turn-on fluorescence among the biologically important metal ions studied. The species of recognition has been modeled by DFT computational calculations to result in conformational changes in the arms that support the turn-on fluorescence behaviour.     

An electrospray ionization tandem mass spectrometric study of p-tert-butylcalix[6]arene complexation with ammonium hydroxide, and ammonium and sodium ions

The formation of complexes involving p-tert-butylcalix[6]arene with neutral and charged species has been investigated by tandem mass spectrometry combined with electrospray ionization. Complexes of p-tert-butylcalix[6]arene with NH4+ ions were observed in the ratios 1:1, 2:1, and 3:1, together with the complexes of p-tert-butylcalix[6]arene with NH4OH and Na+ ions in the ratios 1:1:1, 2:1:1, and 3:1:1. A single 1:1 complex of p-tert-butylcalix[6]arene with Na+ ions was observed. In addition, a doubly charged complex of p-tert-butylcalix[6]arene with NH4OH, Na+, and NH4+ ions in the ratio 6:1:1:1 was observed. The identity of each complex was determined by mass analysis of product ions formed by the application of a declustering potential over the range 20-220 V and by observation of product ion mass spectra wherein the collision energy was varied from 5 to 50 eV. Fragmentation of the complexes is characterized by the facile loss of the ammonia molecule, sodium and ammonium ions, loss of neutral p-tert-butylcalix[6]arene, and successive neutral losses of C4H8 from the six tert-butyl groups in each p-tert-butylcalix[6]arene molecule. Copyright     

Fluorescence switch-on sensor for Cu by an amide linked lower rim 1,3-bis(2-picolyl)amine derivative of calix[4]arene in aqueous methanol

A highly selective fluorescence switch on sensor, L for detecting Cu²⁺ has been synthesized by introducing a bis-(2-picolyl)amine moiety at the lower rim of a calix[4]arene platform via amide linkage. Binding properties of L toward ten different biologically relevant Mⁿ⁺ ions have been studied by fluorescence and absorption spectroscopy in methanol and aqueous methanol. L was found to detect Cu²⁺ selectively down to a concentration of 196 and 341 ppb, respectively, in methanol and 1:1 aqueous methanol even in the presence of other metal ions. The composition of the complex has been found to be 1:1 based on the Job plot and is further confirmed by ESI MS. The role of calix[4]arene platform as well as the pre-organized binding core in the selective recognition of Cu²⁺ has been demonstrated by studying appropriate reference molecules. The possible modes of binding of L with Cu²⁺ have been modeled by computational calculations. L and its Cu²⁺ complex could very well be differentiated based on the nano-structural features observed in SEM and AFM.     

Cytosine: para-sulphonato-calix[4]arene assemblies: in solution, in the solid-state and on the surface of hybrid silver nanoparticles

The molecular recognition by para-sulphonato-calix[4]arene of cytosine, occurs in solution, in the solid-state and by assembly on the surface of para-sulphonato-calix[4]arene capped silver nanoparticles. Each of these states shows different modes of assembly; in solution a 1:1 complex is formed; in the solid state a 4:1 assembly exists, however some of the cytosine molecules are present as space fillers and do not participate in the host (guest complexes, finally on the surface of the hybrid silver/para-sulphonato-calix[4]arene nanoparticles a 2:1 cytosine/para-sulphonato-calix[4]arene assembly is observed. The assembly processes have been studied by DOSY NMR, fluorescence spectroscopy, Dynamic Light Scattering (DLS), Single Crystal Solid State Diffraction, Visible Spectroscopy and Electron Microscopy. The results demonstrate how cytosine initiates the aggregation of the hybrid silver/para-sulphonato-calix[4]arene hybrid nanoparticles.     

Synthesis,crystal structure and complexation behaviour of a thiacalix[4]arene bearing 1,2,3-triazole groups

The structure and complexation behaviour of 1,3-alternate-1,2,3-triazole based on thiacalix[4]arene,1,3-alternate-1 and 2 have been determined by means of X-ray analysis, fluorescence and ¹H NMR spectroscopy. The X-ray results suggested that the nitrogen atom N3 on triazole ring can act as hydrogen bond acceptors in the self-assembly of a supramolecular structure. The fluorescence spectra changes indicated that the thiacalix[4]arene bearing 1,2,3-triazole groups were highly selective for Ag⁺ in comparison with other tested metal ions by enhancement of the monomer emission of pyrene. The ¹H NMR results suggested that Ag⁺ can be strongly bonded by the triazole groups with the cooperation of the ionophoric cavity formed by the two inverted benzene rings and the sulfur atoms of the thiacalix[4]arene.     

Comparison of pillar[5]arene and calix[4]arene anion receptor ability in aqueous media

Abstract

Recognition ability of both cationic pillar[5]arene and calix[4]arene has been studied in aqueous media. Anion complexation can be evaluated from their ability to complex their counterions as well as an added external organic anion. DOSY NMR experiments and fluorescence quenching show that pillararenes have a larger ability for including their own counterions than calixarenes irrespective of the anion (tetrafluoroborate or chloride or bromide) and the structure of the cationic moiety (trimethylammonium or methylimidazolium). Counterion complexation shows a picture where four to five positive charges of the pillar[5]arene are neutralised, meanwhile only one positive charge of the calixarene is neutralised for a 1 mM solution of the macrocycle. Irrespective of the smaller net positive charge in the pillar[5]arene, its binding ability for organic anions (toluenesulfonate or hydroxybenzoate) is larger than for calix[4]arene allowing a better accommodation of the guest in its cavity. The larger separation between the cationic groups of the receptor and its electron-rich aromatic region improves the anion recognition ability for pillar[5]arene.     

键合香豆素席夫碱基的杯[4]芳烃的合成及其对金属离子的荧光识别作用

通过5,17-二氨基杯[4]芳烃衍生物与7-羟基-8-甲酰基-4-甲基香豆素缩合,得到了一种以亚胺基团为离子载体、香豆素为荧光基团的新型杯芳烃荧光识别试剂。 采用IR、1H NMR、13C NMR和MS测试技术表征了合成化合物的结构。 通过紫外光谱和荧光光谱,研究了其对过渡金属和重金属离子的识别性能。 结果表明,该化合物对Fe3+和Cr3+离子具有选择识别能力,与Fe3+和Cr3+配合的化学计量比为1∶1,配合生成常数分别为4.1×105和1.07×105 L/mol。     

A Zn(2+) specific triazole based calix[4]arene conjugate (L) as a fluorescence sensor for histidine and cysteine in HEPES buffer milieu

A highly fluorescent Zn(2+) complex of the triazole linked salicyl-imino-thiophenyl conjugate of calix[4]arene, [ZnL] has been demonstrated to be a chemo-sensing ensemble for the recognition of His and Cys among the naturally occurring amino acids in HEPES buffer milieu. The recognition behaviour of the [ZnL] towards these amino acids has been shown on the basis of fluorescence, absorption and visual fluorescent colour changes. The species of recognition were shown by ESI MS titrations, AFM & TEM microscopy and cell studies.     

Design of a novel inherently chiral calix[4]arene for chiral molecular recognition

A newly designed inherently chiral calix[4]arene was synthesized and resolved to an optically pure form. Enantiomeric recognition ability of the chiral calix[4]arene was examined using 1H NMR experiments with mandelic acid. In addition, the chiral calix[4]arene was applied to asymmetric reactions, as an organocatalyst.     

新型吡啶-杯[4]芳烃荧光探针的合成及其对Fe3+的检测性能

合成了一种新型的高选择性检测Fe3+的上沿功能化吡啶-杯[4]芳烃荧光探针,其结构经1H NMR, 13C NMR和HR-MS表征。离子检测实验结果表明,该吡啶-杯[4]芳烃探针的最大吸收峰出现在295 nm处,并在371 nm处显示出一个强的荧光发射带。与其他金属离子相比,新型探针对Fe3+表现出高选择性和强抗干扰能力的荧光淬灭响应。通过荧光滴定法和Job曲线图研究了探针与Fe3+的结合性。结果表明,探针与Fe3+形成2:1的配合物,缔合常数为3.26×107 M-1,检出限为7.9×10-7 M。