Syntheses and Metal-ion Binding Properties of Calix[4]arene Derivatives Containing Soft Donor Atoms: Highly Selective Extraction Reagents for Ag+

A series of calix[4]arene derivatives containing N or S atoms atthe lower rim were synthesized by etherification of OH groups and their metal-ion extraction abilities were studied. The extraction selectivity for Ag⁺ over other ions with these novel receptors was outstanding. Among these ligands, calix[4]arene podand, which possessed two linear ligands, has shown better binding ability with Ag⁺ than calix[4]crowns.     

Sensitive Assay for the Lactonase Activity of Serum Paraoxonase 1 (PON1) by Harnessing the Fluorescence Turn-On Characteristics of Bioorthogonally Synthesized and Geometrically Controlled Chemical Probes

The lactonase activity of paraoxonase 1 (PON1) has a crucial antiatherogenic function, and also serves as an important biochemical marker in human blood because the aberrant lactonase activity of PON1 is a key indicator for a number of diverse human diseases. However, no sensitive fluorescence assays that detect PON1 lactonase activity are available. We report the synthesis of two fluorescence turn-on chemical probes 16a and 16b (16) able to quantify PON1 lactonase activity. The chemical probes were constructed utilizing a disulfide-containing bicyclononyne, derivatives of rhodamine B and carboxyfluorescein, and reactions including copper-free azide–alkyne cycloaddition. Fluorescence quenching in 16 was characterized by spectroscopic studies and was mainly attributed to the effect of contact quenching. Kinetic analysis of 16b confirmed the outstanding reactivity and specificity of 16b with thiols in the presence of general base catalysts. The 16b-based assay was employed to determine PON1 lactonase activity, with a linear range of 10.8–232.1 U L⁻¹ and detection limit (LOD) of 10.8 U L⁻¹, to quantify serum PON1 activity in human sera, and to determine the K_i of 20.9 μM for the 2-hydroxyquinoline inhibition of PON1 lactonase. We are employing 16b to develop high-throughput assays for PON1 lactonase activity.     

Interaction of Sulfonated Calix [n] arenes with Rhodamine B and Its Application to Determine Acetylcholine in a Real Neutral Aqueous Medium

Complexation between Rhodamine B (RB) and sulfonated calix [n] arenes (SCnA) were studied by means of UV‐vis spectroscopy and fluorescence spectroscopy. In the presence of sulfonated calix[n] arenes, the absorption band of Rhodamine B shifts to longer wavelength and its intensity decreases. The formation of a host‐guest type complex also results in the fluorescence quenching of Rhodamine B. The association constants for the RB/SCnA complexes increase in the order of SC4A < SC6A < SC8A and show dependence on the size of the cavities of the calixarenes. The fluorescence is selectively regenerated by adding acetylcholine. Based on this observation, a method to determine acetylcholine in a real neutral aqueous medium was developed.     

Tailored Synthesis of Various Nanomaterials by Using a Graphene‐Oxide‐Based Gel as a Nanoreactor and Nanohybrid‐Catalyzed CC Bond Formation

New graphene oxide (GO)‐based hydrogels that contain vitamin B₂/B₁₂ and vitamin C (ascorbic acid) have been synthesized in water (at neutral pH value). These gel‐based soft materials have been used to synthesize various metal nanoparticles, including Au, Ag, and Pd nanoparticles, as well as nanoparticle‐containing reduced graphene oxide (RGO)‐based nanohybrid systems. This result indicates that GO‐based gels can be used as versatile reactors for the synthesis of different nanomaterials and hybrid systems on the nanoscale. Moreover, the RGO‐based nanohybrid hydrogel with Pd nanoparticles was used as an efficient catalyst for C? C bond‐formation reactions with good yields and showed high recyclability in Suzuki–Miyaura coupling reactions.     

A New Fluorometric Method for the Detection of the Neurotransmitter Acetylcholine in Water Using a Dansylcholine Complex with p-Sulfonated Calix[8]arene

A new method for the fluorometric detection of the neurotransmitter acetylcholine (ACh) in water is presented. Use of the fluorescence of dansylcholine (DANCh) bound to p-sulfonated calix[8]arene affords a new fluorometric method for the detection of ACh (>10^-4 M) inaqueous solution (pH = 6.9). The fluorescence intensity of DANCh in aqueous solution was enhanced 1.8 fold after the complexation with p-sulfonated calix[8]arene. The addition of ACh to the aqueous solution of the DANCh-calix[8]arene complex significantly decreased the fluorescence intensity, which results from the replacement of DANCh in the complex with ACh. The effects of other synaptic neurotransmitters on the fluorescence of the DANCh complex were examined for dopamine, histamine, ATP, GABA, glycine, l-glutamic acid, and l-aspartic acid. Among the neurotransmitters studied, ACh was most effective in changing the fluorescence of the DANCh complex. Possible application of the DANCh complex dye for the detection of ACh in biological systems is discussed.     

A Facile Method of Synthesis of a Calix[4]arene Amide and the Crystal Structure of a Self-assembled Calix[4]arene Amide via van Der Waals Interaction

A new facile method of synthesis of calix[4]arene amide via the aminolysis of the calix[4]arene esters was reported. One ethyl ester of the compound (2) was aminolysized byn-butylamine. The crystal structure of compound (1)shows that one ethyl ester of compound (1) enters into thecavity of another compound (1) forming a long chainhost-guest supramolecule. From the 2D NMR data, the compound(1) does not assemble in THF or CHCl₃ solution. The CH- interaction and crystallization energy might be theimportant driving forces for forming the self-assembledcalix[4]arene.     

Large Calixarenes: Structure and Conformation of a Calix[16]arene Complexed with Neutral Molecules

A crystal of an inclusion compound between a calix[16]arene and molecules ofacetonitrile and dichloromethane, used as solvents, has been obtained and its X-raystructure studied. The cell is monoclinic, space group C2/c with a = 38.508(8) Å,b = 21.593(4) Å, c = 26.625(5) Å and = 121.34(3)°.The macrocycle is in the form of two superimposed celtic torcs connected by theirextremities.¹ Two acetonitrile molecules are situated in the middleof this double torc, two dichloromethane molecules are encapsulated in the pseudocalix[4]arenes obtained on both extremities of the torcs by the folding of the lastfour phenolic rings. A disorder is observed for the other acetonitrile and dichloromethanemolecules situated outside the macrocycle.     

Constructing a Nonfluorescent Conformation of AIEgen: A Tetraphenylethene Embedded in the Calix[4]arene's Skeleton

Two novel 1,1‐diphenylmethylidene decorated calix[4]arenes, ( Calix‐DPE(OCH₃)₄ and Calix‐DPE(OH)₄ ), were designed and prepared. The tetraphenylethene (TPE) unit is embedded in the calix[4]arenes skeleton, so the conformation of tetraphenylethene unit is significantly affected by the conformation of calix[4]arene. Unlike the Calix‐DPE(OCH₃)₄ , the Calix‐DPE(OH)₄ does not show the aggregation‐induced emission (AIE) phenomena in solution or the crystal state because of the presence of intramolecular hydrogen bonding, which leads to a cone conformation for the calix[4]arene skeleton in which the embedded phenyl rings of the TPE have to take an almost perpendicular configuration to the C=C bond. This result provides direct evidence that the maximal cross‐chromophore π‐conjugation within the tetraphenylethene is one of the prerequisites of switching on its AIE. This offers the possibility of switching the emission of TPE by conformation changes.     

A,C-Bridged Calix[6]arene： Relationship between the Length of Bridge and Conformation

Three new A,C-diamide bridged p-tert-butylcalix[6]arenes were synthesized from p-tert-butylcalix[6]arenes by bridging ClCH2CONH(CH2)nNHCOCH2Cl(n=3,4,6) in acetonitrile using K2CO3 as a base in 17%-25% yields.It was found that the bridged calix[6]arenes with shorter bridges (n=2,3,4 in N′,N′-bischloroacetodiamines) adopt cone conformation, but the last one (n=6) adopts alternate conformation, i.e., accompanying the lengthening of bridge, the conformation of A,C-bridged calix[6]arenes changes from cone to alternate.     

Nano CaCO3:An Unique Condensation Agent for the Preparation of Monosubstituted Calix[4] arene by Ring-opening Reaction

Nano CaCO3 was used as a condensation agent in the ring-opening reaction of p-tert-butylcalix[4] arene with epichlorohydrin to afford 5,11,17,23-tetra-tert-butyl1-26,27,28-trihydroxy-25-(1′-chloro-2′-hydroxy-3′-propyl)calix(4] arene regioselectively in 52% yield,The yield was less than 2% by using normal CaCO3 instead of nano one under the same conditions.     

The Synergistic Extraction of Lanthanide Ions by a Mixture of Calix[4]resorcinarene or its Dimethylamino-, Piperidyl- or Trimethylammoniummethylated Derivatives and 1,10-Phenanthroline in n-Heptanol

The alkylaminomethylatedcalix[4]resorcinarene derivatives, modified bydimethylamino-, piperidyl- and trimethylammoniummoieties, have been synthesised to investigate theirextractability towards lanthanide ions and to comparewith the extractability of calix[4]resorcinarene. Both calix[4]resorcinarene and its derivatives have beenshown to synergistically affect lanthanide ionextraction from neutral aqueous solutions by1,10-phenanthroline through outer-sphere interactionof lanthanide bis-phenanthrolinate cations withdeprotonated forms of calix[4]resorcinarene. Thederivatives with dimethylamino- andpiperidylmethylated moieties are shown to be moreeffective extractants in comparison with theunsubstituted one.     

Calix[4]arenes containing urea and crown/urea moieties: effects of the crown ether unit and Na towards anion binding ability

Calix[4]arenes containing urea and crown/urea moieties, 7 and 10, respectively have been synthesized. ¹H NMR titrations of 7 and 10 with anions in DMSO-d₆ showed that 7 and 10 formed complexes with Cl⁻, Br⁻, NO₃⁻ and H₂PO₄⁻ to a different extent. The association constants of 7 and 10 towards anions were calculated and found to vary as H₂PO₄⁻>Cl⁻>Br⁻>NO₃⁻. However, compared to 7 the presence of the crown unit in 10 resulted in a slightly higher affinity to Cl⁻ and Br⁻, but a lower affinity to H₂PO₄⁻. Upon addition of Na⁺, the binding ability of 10 towards H₂PO₄⁻ is increased due to ion-pair enhancement.     

杯[4]芳烃的表面化学组装及其在气态四氢呋喃荧光传感薄膜创制中的应用

挥发性有机化合物(Volatile Organic Compounds,VOCs)是重要的大气污染物,严重地危害着人类健康.本文设计合成了一种末端携带反应活性硅氧烷基团的杯[4]芳烃衍生物,通过自组装和表面化学反应将其共价结合于玻璃基质表面,获得了一种杯[4]芳烃修饰玻璃基质.以此基质物理担载荧光活性物质--芘封端三聚噻吩(Py-3T),得到了一种对气相四氢呋喃具有"turn-on"及快速灵敏(26.7 μg/mL)响应特性的荧光传感薄膜.实验表明:除苯和甲苯之外,其它常见有机溶剂和化学物质蒸汽对该薄膜荧光发射基本没有影响.苯和甲苯也因响应程度小、响应速度慢而难以干扰测定过程.据此,可以预期该荧光薄膜有可能在THF气体传感上获得应用.     

结构预测及分子对接方法研究几种水解产物对新阿魏酸酯酶的抑制作用

应用基于生物信息学的蛋白质结构预测方法, 探讨了来源于荷斯坦奶牛瘤胃宏基因组文库的一个新型阿魏酸酯酶(FAE-SH1)的结构及可能的催化机制. 同时通过对该酶的预测结构与4种模式底物的对接研究发现, 实验所测得酶促反应动力参数V_max与对接的亲和能存在线性关系, 底物与酶形成的氢键可能是影响催化效率的关键因素. 同时, 本研究发现D-木糖、 L-阿拉伯糖、 D-葡萄糖及阿魏酸能够对FAE-SH1的水解反应产生抑制作用, 并对其进行了验证.     

Electrolysis at the Interface between Two Immiscible Electrolyte Solutions: Determination of Acetylcholine by Differential Pulse Stripping Voltammetry

Abstract

A three-electrode system with the hanging electrolyte drop electrode (HEDE) was developed for the analytical exploitation of electrolysis at the interface between two immiscible electrolyte solutions (ITIES). The use of the differential pulse stripping voltammetry (DPSV) for the quantitative determination of the species which participates in a charge transfer reaction at ITIES was demonstrated with acetylcholine cation transfer across the water/nitrobenzene interface. Trace concentration of acetylcholine in water in the part per million level (ppm) can be determined. It was concluded that the electrolysis at ITIES represents the perspective method of chemical analysis.     

Synthesis and Properties of Double Calix[4]arene Derivatives Linked by Schiff-base in the Lower Rim

Calixarenesareregardedasthethirdgenerationofh0stmoleculesbecauseoftheirinclusionabilitytocati0ns,anionsandneutralmoleculesI'2.Duringthepastdecademosteff0rtshavebeentakenonthefunctionalizati0n0fcalixareness0thattheycanbeappliedn0tonlyastheionoph0resintheextractionprocess','andassensitivematerialsforionelectrodes"',butalsoastheenZymemimicscatalyzingthecleavageofphosphatediesters"'.Inordertoenablethemtoincludeandrecognizelargerchemicalspecies,manyappr0acheshavebeenusedtoc0nstructoIigo-calixarene…     

Synthesis of a Calix[4]arene Containing 'Hard' and 'Soft' Metal Ion Binding Sites

Co-receptor 1,3-calix[4]-di(aza-benzo)crown-crown-6 (1-H) designed with one calix[4]arene in a 1,3-alternate conformation and hard and soft metal ion binding sites has been prepared according to three pathways (A-C). Pathway B, consisting of two different 1 + 1 condensations with ditosylate derivatives, was shown to be the most efficient.     

Metal–Ligand Cooperativity of the Calix[4]pyrrolato Aluminate: Triggerable C−C Bond Formation and Rate Control in Catalysis

Metal‐ligand cooperativity (MLC) had a remarkable impact on transition metal chemistry and catalysis. By use of the calix[4]pyrrolato aluminate, [ 1 ]^?, which features a square‐planar Al^III, we transfer this concept into the p‐block and fully elucidate its mechanisms by experiment and theory. Complementary to transition metal‐based MLC (aromatization upon substrate binding), substrate binding in [ 1 ]^? occurs by dearomatization of the ligand. The aluminate trapps carbonyls by the formation of C?C and Al?O bonds, but the products maintain full reversibility and outstanding dynamic exchange rates. Remarkably, the C?C bonds can be formed or cleaved by the addition or removal of lithium cations, permitting unprecedented control over the system's constitutional state. Moreover, the metal‐ligand cooperative substrate interaction allows to twist the kinetics of catalytic hydroboration reactions in a unique sense. Ultimately, this work describes the evolution of an anti‐van't Hoff/Le Bel species from their being as a structural curiosity to their application as a reagent and catalyst.