Spectrophotometric study of the supramolecular complexes of [60]- and [70]Fullerenes with biscalix[6]arene and crown[4]calix[6]arene

[60]- and [70]Fullerenes have been shown to form 1:1 supramolecular complexes with bis[2-(5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41-pentahydroxycalix[6]arenyl-oxy ethyl ether) (1) and 5,11,17,23,29,35-hexa-tert-butyl-37,38,40,41-tetra hydroxyl-39,42-(crown-4)calix[6]arene (2) in CHCl3 medium by electronic absorption spectroscopy. Formation constants (K) of the complexes of [60]- and [70]fullerenes with 1 and 2 have been determined at room temperature from which free energy of formation values of the complexes have been estimated. The very high formation constant value of [60]fullerene/1 complex (5900 dm3 mol-1) in indicative of formation of inclusion complex. Moreover, PM3 calculations reveal that intermolecular interaction between [60]fullerene and 1 proceeds through quite deep energy molecular orbital.     

p-t-Butylcalix[4]arene tetra-acetamide: a new strong receptor for alkali cations [1]

From the reaction ofp-t-butylcalix[4]arene with -chloro-N,N-diethyl acetamide a new lipophilic ether-amide ligand (2) has been obtained in high yield. Solution studies show (2) to be a very strong cation receptor for alkali cations, especially sodium and potassium. The X-ray crystal structure determination of the free ligand (2) and two potassium complexes (KI and KSCN) shows the calix[4]arene in a fixed cone structure and the cation completely encapsulated in a polar cavity of eight oxygen atoms. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82059 (57 pages).Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

An inclusion complex between acetonitrile andp-tert-butylcalix[6]arene

p-tert-Butylcalix[6]arene forms a complex with 1.5 acetonitrile molecules, that are included in the macrocycle cavity. This complex crystallizes in the monoclinic system: space groupP2₁/m,a=14.043(4),b=16.916(11),c=14.199(11) Å,=98.27(6)°,V=3338(4) ų,Z=2 (formula units). Refinement led to a final conventionalR value of 0.113 for 1654 reflections. Thepinched cone conformation of the calixarene is the same as that of the neutral and freeR-calix[6]arene already described. The two acetonitrile molecules interact with some phenyl ring -clouds, a methylene bridge and sometert-butyl groups of the calixarene. Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters, selected geometrical parameters and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82188 (16 pages).     

杯[4]芳烃单取代1,3-二酮衍生物的合成及生物活性研究

以杯[4]芳烃为原料经醚化和克莱森缩合两步反应首次合成杯[4]芳烃单取代1,3-二酮衍生物,其结构经1H NMR、13C NMR及MS表征。初步的HIV-1整合酶链转移反应活性测试结果表明,该杯[4]芳烃单取代1,3-二酮衍生物在测试浓度为25μM时其抑制率为12.67%。     

含硫杯[4]芳烃衍生物修饰电极伏安行为的研究

杯芳烃具有与环糊精类似的洞穴结构,且具有可调节大小的洞穴,有卓越的络合识别能力,杯芳烃衍生物的研究引起了国内外众多化学工作者极大的兴趣,在识别-催化、识别-配合、识别-分析等领域取得了可喜的研究成果。Stuart等研究了亚铁氰化钾及铁氰化钾在杯[4]间苯二酚修饰金电极上的电化学行为。Gomez-Kaifer用循环伏安法研究了系列母体醌式功能化杯[4]衍生物的氧化还原特性,发现该特性对Na^＋、Ag^＋有选择性识别响应。     

Synthesis and structure of a novel molybdenum imido calix[6]arene

Treatment of p-tert-butylcalix[6]areneH₆ (H₆L) with [Mo(OBu^t)₂{[2,2′-(N)-C₆H₄]₂(CH₂CH₂)}] in refluxing toluene affords, after work-up, the complex [Mo(2-NC₆H₄CH₂CH₂C₆H₄NHC(Me)NH-2^/)LH₂]·4MeCN (1), which contains an 11-membered metallocyclic ring as characterised by Synchrotron X-radiation.     

A fluorescent probe for fluoride ion based on 2-aminopyridyl-bridged calix[6]arene

An 2-aminopyridyl-bridged calix[6]arene on the upper rim fixed in cone conformation (3) was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and ¹H NMR titration experiments.     

Selectively formylated and bridged calix[6]arene derivatives at the upper rim

The strategy of bridging the anisole units at the upper rim of calix[6]arene has been applied to strain the conformations of calix[6]arene. Based on the selective formylation of the 1,3,5-tri-p-tert-butylcalix[6]arene, several new calix[6]arene derivatives with different 1,3-bridged chains or a 1,3,5-tripod bridge at the upper rim have been prepared with moderate yields. The ¹H NMR spectra indicate that these calix[6]arene derivatives adopt a cone conformation, which has also been confirmed by the theoretical calculation at AM1 level. X-ray crystal structure of 1,3,5-tripod bridged compound 5 discloses that the calix[6]arene host stands in a cone conformation with approximate C_3v symmetry, and that a methanol molecule is enclosed in its hydrophobic cavity and stabilized by multi hydrogen bonds.     

Rare earth (Eu, Tb) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy-26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE³⁺ (Eu³⁺, Tb³⁺) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb³⁺ complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb³⁺ and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb³⁺ very well.     

Ab initio and density functional studies of cooperative hydrogen bonding in calix[4]-and calix[6]arenes

The cone conformation of C ₄ symmetry is shown by the Hartree-Fock method (3-21G basis) to be the predominant conformer of calix[4]arene; the compressed cone of C ₂ symmetry is the major conformer of calix[6]arene. Using quantum chemical methods we calculated hydrogen bond cleavage energies for calix[4]-(ab initio and density functional methods) and calix[6]arene (ab initio), and also for the complex of calix[4]arene with carbon disulfide. These energies along with structural data point to the cooperative effect of hydrogen bonds. The results of these studies provided an explanation to the greater conformational lability of calix[6]arene compared with calix[4]arene molecules. It is also predicted that the nucleophilic substitution reaction involving calix[6]arene in the presence of weak bases and in aprotic solvents, as well as in the gas phase, will occur via diastereomeric transition states.     

Synthesis and characterization of an inherently chiral calix[6]arene in the 1,4-alternate conformation

An inherently chiral calix[6]arene possessing a C₂-symmetric A-B-H substitution pattern was synthesized via a two step process starting from the parent hexa-t-butylcalix[6]arene. The racemic, inherently chiral compound exists as a single isomer with the 1,4-alternate conformation. The inherent chirality was confirmed by treatment of the racemic compound with Pirkle’s reagent to form diastereomeric complexes in solution.     

Synthesis of molybdenocene(IV) and tungstenocene(IV) tropolonato complexes: Its derivative containing calix[4]arene moiety

The cationic di-μ-hydroxo dinuclear complexes of molybdenocene and tungstenocene [Cp₂M(μ-OH)₂MCp₂]⁺ (Cp = η-C₅H₅; M = Mo or W) react with tropolone to afford corresponding tropolonato complexes [Cp₂M(trop)]⁺ (trop = C₇H₅O₂). The products were investigated by IR, ¹H NMR, and ¹³C NMR spectroscopy as well as by X-ray crystallography (M = W). The structure shows that the central metal is surrounded by a distorted tetrahedral array of the two centers of cyclopentadienyl ligands and the two oxygen atoms of tropolonato ligand. The reaction has been extended to the synthesis of calix[4]arene receptor functionalized at the 1,3-positions of the upper rim with two tropolonato-molybdenocene centers.     

新型杯[4]芳烃衍生物的合成及其氨基酸萃取性能

杯[4]-1,3-二乙酸乙酯衍生物(1)与水合肼反应生成杯[4]芳烃酰肼衍生物(2),化合物(2)与异硫氰酸苯酯反应得到含酰胺和硫脲单元的新型杯[4]芳烃衍生物(3).总产率达70%.系列氨基酸萃取实验表明化合物(3)对异亮氨酸有较好的选择性萃取能力.     

Materials design and sensing mechanism of novel calix[6]arene composite for sensitively detecting amine drugs

In order to improve the convenience and sensitivity of amphetamines drug testing and reduce the threat of drugs to humans, we have designed a QCM gas sensor to detect amine-containing drugs. The sensing material is designed based on the chemical nature of amine drugs. The sensing mechanism is derived from a reversible Schiff base interaction between the amino group of the drug and the carbonyl group of the novel calix[6]arene derivatives as well as the hydrogen bond interaction between amino group and hydroxyl. The new composite material was well characterized by different analytical techniques including ¹H nuclear magnetic resonance (¹H-NMR), fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), transmission electron microscope (TEM), Raman spectra, powder X-ray diffraction, etc. The sensing experiments were conducted by coating the composite onto quartz crystal microbalance (QCM) transducers. The experimental results indicated that the novel calixarene derivatives and their GO complexes based on the design have excellent selectivity, high sensitivity and repeatability to β-phenylethylamine.     

Lower Rim Substituted tert-Butyl calix[4]arene (part VII): Ionophoric Properties of Calix[4]arene-crown-6 Derivatives in Plasticized PVC-Membrane Electrodes and in Solution

The synthesis and characterization of p-tert-butylcalix[4]arene-crown-6 derivatives (compounds 2–9) are presented. Their ability to complex alkali, alkaline earth and some “softer” cations was investigated by using these compounds as ionophores in ion-selective membrane electrodes and determining the potentiometric selectivity coefficients and the complex stability constants in the membrane. The selectivities of these compounds depend on the size and nature of the substituents on the distal phenolic oxygens. The complexing properties of the two cone and partial cone conformers of compound 2 in the PVC membrane were compared with those in acetonitrile solution studied by UV absorption spectrophotometry and with alkali metal picrate liquid–liquid extraction.This revised version was published online in July 2005 with a corrected issue number.     

Selective functionalization of a resorcin[6]arene

The Mannich-type condensation of hexaethylresorcin[6]arene with achiral primary amines results in S₆-symmetrical hexadihydro-1,3-oxazine derivatives, which are mesoforms. The reaction with individual enantiomers of α-phenylethylamine leads to C₃-symmetrical enantiomeric hexaoxazines, which crystallize from reaction mixtures in an analytically pure form.     

Ratiometric chemosensing of Mg ions by a calix[4]arene diamide derivative

A new chemosensor with a phenanthroimidazole subunit based upon calix[4]arene-diamide has been synthesized, and its Mg²⁺-selective fluoroionophoric properties were investigated in an aqueous DMSO solution. The compound exhibited a pronounced Mg²⁺-selective fluoroionophoric behavior over other physiologically relevant metal ions. A significant red shift in fluorescence emission (Δλ = 86 nm) provided the ratiometric determination as well as naked-eye detection of Mg²⁺ ions.     

A Novel Type of Lower-Rim-Connected Double-Calix[6]arenes Composed of A 1,2,4-Triply Bridged and A Normal Calix[6]arene

Calixareneshavebeenprovedtobeusefulbuildingblockstoconstructmolecularreceptorsinsupramolecularchemistry.Chemicalmodificationsofcalixarenesattheupperrimorthelowerrimcanaffordpreorganizedligandsabletocomplexmetalionsandneutralmolecules,oftenwithspecialselectivitiesl.Inordertoimprovethebindingpropertiesofcalixarenes,double-calixareneshavebeenpreparedandattractedmuchmoreattentionduetothecombinationoftwobuildingblockswithenforcedcavitiesandspecialmolecularrecognitionabilitiesbyco-operationeffects2.…     

Highly selective fluorescent sensing of Pb by a new calix[4]arene derivative

A new chemosensor was synthesized by the alkylation of p-tert-butyl-calix[4]arene with three N,N-diethylacetamide groups and one methyl 3-ethoxy-naphthalene-2-carboxylate, which exhibited highly selective fluorescent response to Pb²⁺ over alkali, alkali earth metal ions and some transition metal ions in CH₃CN-H₂O.     

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。