Synthesis of （p-Formylphenyl）azo Calix[4]arenes

Five novel azo calix[4]arenes were reported. The p-aminobenzaldehyde was diazotized with sodium nitrite in aqueous hydrochloride solution. Mono-, bis-, tris- and tetrakis(p-formylphenyl)azo calix[4]arenes (including proximal and distal isomers) were obtained respectively by diazo-coupling in different molar ratio to calix[4]arene(1) under pH=7.5--8.5 at 0-5℃. All (p-formylphenyl)azo calix[4]arenes were characterized by ^1H NMR, ^13C NMR, IR, MS (ESIMS) spectroscopies and elemental analysis.     

Upper Rim Diester—bridged Calix[4] arenes and Oligocalix [4]—arenes：the Effects of the Length of Bridged Reagents on Their Distribution

A series of monobridged calix [4] arenes 3a-f,cyclic biscalix-[4] arenes 4a-f ,diametrically bridged at the upper rim with saturated aliphatic diester chians,have been synthesized,The results at diluted conditions show that the percentage of yields of mono-,bis- and oligo-calix[4] arenes are related to the legth of the chains ,With the shortening of the chains ,the percent-age of monocalix[4] arenes decreased ,All the calix [4] arene moieties are in a cone conformaiton according to the AB quar-tet pattern of the methylene protons between the phenolic rings in the ^1H NMR spectra.     

Synthesis and Characterization of Picolinamide Calix[6]arenes Derivatives

It is well known that calixarenes are extremely versatile classes of macrocyclic receptor able to complex various metal ions as well as to selectively recognize both neutral and charged inorganic or organic species in solution. It is unable to get a clear…     

Synthesis of Calix[4]resorcinarene Amide Derivatives

Three different synthetic routes were developed to introduce carbamoyloxy functional groups at the upper periphery of two calix[4]resorcinarenes. By treating activated esters 2a-b with excess corresponding amine such as 3-(dimethylamino)propylamine 3, ct-phenethylamine 4 and triethylenetetramine 5, six amide derivatives 6a-8b were obtained in high yield (Route 1). The pyridine-linked amide derivatives 9a-b were prepared by using acid chloride intermediate (Route 2).The amide derivatives 10a-b were obtained in moderate yields by direct alkylation of phenolic hydroxyl groups of la-b with N,N-dipropylchloroacetoamide in the presence of K2CO3/KI in acetone (Route 3).     

Synthesis and Chiral Recognition of a New Type of Chiral Calix[4]-arene Derivatives

Two new chiral calix[4] arenes bearing chiral pendants,which were from by-product of the antibiotic industry,were synthesized and characterized by ^1H NMR.MS-FAB and elemental analysis,Studies of ^1H NMR of the two calix[4] arene derivatives indicate that they exist in cone conformation in solution.Results of chiral recognition of the two chiral ligands 2a and 2b towards the tartaric acid derivative 3 show that ligand 2a exhibited good chiral recognition abilities compared to ligand 2b.     

Synthesis and Complexation Properties of Novel Biscalixarene Composed of Calix[4]arene and Thiacalix[4]arene Subunits

Biscalixarenes, as examples of higher order molecular architectures than normal calixarene derivatives, were studied extensively in the recent years due to they possess two calixarene cavities which have the potential for complexing with two guests in two…     

Synthesis of Calix [4] resorcinarene Core Dendrimers with Peripheral Salicylideneimine Functional Groups

IntroductionOver the past two decades, dendrimers have at-tracted considerable attention because of their inherentnovel structural features and their potential applicationsin various scientific and industrial fields such as cataly-sis or newmaterials, and…     

Studies on Properties of p—Nitrophenylazo Calix[4]arene Derivatives

The p-nitrophenylazo calix[4] arene derivatives la-ld with nonlinear optical(NLO)properties were prepared by the diazo-coupling reaction of calix[4]arene with p-nitrophenyl diazonium.The diazotization reaction of p-nltroaniline was caried out with isoamyl nitrite as a source of nitrous acid in EtONa/EtOH under refluxing conditon.X-Ray crystallographic analysis and ^1H NMR sptectra reveal that they exist as cone conformation in crystal state or in soution.HRS measurements at 1064 nm in THF indicate that p-nitrophenylazo calix[4]arenes have higher hyperpolarizability βz values than the corresponding reference compound 4-(4-nitrophenylazo)-2,6-dimethyl-phenol,without red shift of the charge transfer band.The tetrakis p-nitropheylazo calix[4]arene(2)with longer alkyl chains can form monolayer aht the air/water interface.     

Synthesis and characterization of a novel series of pyrimidinylthiaalkoxycalix[4]arenes

A novel series of pyrimidinylthiaalkoxycalix[4]arenes with the reaction between 4,6-dimethylpyrimidine-2-thiol and thedifferent dibromides calix[4]aryl groups have been synthesized and structurally characterized by IR,1H NMR and MS.From theiranalysis data,it was found that compounds 8,9,11 adopted a cone conformation,while compound 10 existed as a mixture ofconformations.     

Syntheses of Chiral Calix [4] arene Derivatives Bearing Amino Acid Residue

The syntheses of chirai calix[4]arene derivatives bearing amino acid residue at the lower rim or upper rim by three different methods were reported.     

Synthesis of Pyridylazo-substituted Chromogenic Calix[4]arenes

Calixarenes are a versatile class of macrocyclic compounds which have attracted extensive interest due to their ability to form host-guest complexes and act as enzyme mimic, especially when appropriately functionalized1. Introduction of azo group to calixarenes can make the later to be easily detected in the process of molecular recognition, azo groups have been introduced into calixarenes by the diazo-coupling reaction of calix[4]arene with BF4- or chloride salt of substituted benzene diazon…     

Synthesis of Ionizable Calix[4]arenes for Chelation of Selected Divalent Cations

Two sets of functionalised calix[4]arenes, either with a 1,3-crown ether bridge or with an open-chain oligo ether moiety in 1,3-position were prepared and further equipped with additional deprotonisable sulfonamide groups to establish chelating systems for selected cations Sr²⁺, Ba²⁺, and Pb²⁺ ions. To improve the complexation behaviour towards these cations, calix[4]arenes with oligo ether groups and modified crowns of different sizes were synthesized. Association constants were determined by UV/Vis titration in acetonitrile using the respective perchlorate salts and logK values between 3.2 and 8.0 were obtained. These findings were supported by the calculation of the binding energies exemplarily for selected complexes with Ba²⁺.     

Bridged Calix[6]arenes

Bridging including capping of calix[6]arene is not only an importantroute to synthesize new host molecules, but also an efficient route to reduce the mobility of conformationof calix[6]arene. This article reviews the syntheses, conformations and complexation behavior of this kindof host molecules.     

Synthesis of p-Formylphenylazo Calix [ 4 ]arenes

Calixarenes are a versatile class of macrocyclic compounds, which have attracted extensive interest due to their ability to form host-guest complexes and act as enzyme mimic. Moreover, a number of calixarenes with D-π-A units have been synthesized, and their second-order nonlinear optical (NLO) properties investigated.     

Calix[4]arenes as Molecular Platforms for Magnetic Resonance Imaging (MRI) Contrast Agents

The novel amphipilic conjugate of a calix[4]arene with four Gd–1,4,7,10‐ tetra(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane (DOTA) chelates has potential as a magnetic resonance imaging contrast agent, both in its monomeric and in its micellar form. The system, illustrated here with its nuclear magnetic relaxation profile, shows good relaxivities, thanks to its high rigidity.

     

Calix[4]arenes with 1,2- and 1,3-upper rim tetrathiafulvalene bridges

Herein we report the synthesis of several calix[4]arene derivatives with tetrathiafulvalene bridges at the upper rim. Calix[4]arene-tetrathiafulvalene (TTF) conjugates 4a–d, fixed in cone conformation and comprising two smaller 1,2-bridges, were prepared by cyclisation of tetrakis-chloromethylated calix[4]arene 1 with 2,3-dithiolates of TTFs. Larger calix[4]arene-TTF macrocycles 14 and 15, also in cone conformation, contain 1,3-bridges and were synthesised by cyclisation of 2,6- and 2,7-dithiolates of TTFs with bis-bromomethylated calix[4]arene 7. Redox properties of new calix[4]arene-TTF conjugates were characterised using cyclic voltammetry.     

Dimeric Capsules Formed by Tetra‐CMPO Derivatives of (Thia)Calix[4]arenes

Thiacalix[4]arene 2 , calix[4]arene 3 a and its tetraether fixed in the cone conformation 3 b form homo‐ and heterodimeric capsules in apolar solvents, which are held together by a seam of NH???O=P hydrogen bonds between carbamoylmethyl phospine oxide functions attached to their wide rim. Their internal volume of ～370 ų requires the inclusion of a suitable guest. Although neutral molecules such as adamantane (derivatives) or tetraethylammonium cations form kinetically stable complexes (¹H‐ and ³¹P‐time scale), the included solvent is rapidly exchanged. The internal mobility of the included tetraethylammonium cation is distinctly higher (ΔG=42.5 and 49.7 kJ mol^?1 for 3 a and 3 b ) than that for similar capsules of tetraurea calix[4]arenes 1 . Mixtures of 1 with 2 , 3 a , or 3 b contain only the two homodimers but the heterodimerization occurs with the tetraloop tetraurea 6 , which cannot form homodimers. Two dimers with cationic guests ( 2? (C₅H₅)₂Co⁺ ?2 and 3 a? Et₃NH⁺ ? H₂O ?3 a ) were confirmed by single‐crystal X‐ray analysis.