Synthesis of New Calix[4]arenes Functionalizated by Acetylhydrazide Groups

A series of new calix[4]phenols, calix[4]resorcinols and calix[4]pyrogallols with acetylhydrazide substitutes has been␣synthesized with high yields by hydrazinolysis of ester group containing calix[4]arenes. The synthesized calix[4]phenols adopt the cone conformation while the calix[4]resorcinol and calix[4]pyrogallol derivatives prefer the boat conformation. The amide fragment of the hydrazide groups predominantly exists in the trans-conformation. The binding ability of synthesized calix[4]arenes toward transition and alkali metals by solvent extraction has been investigated.     

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 with siloxanes bridging opposite rings

Several C-silylated (allyldimethylsilyl) calixarenes (1, 14, and 18) were treated with commercial TBAF in THF, giving the novel calixarenes 2, 15, and 19, in which the opposite rings were bridged by a Si-O-Si siloxane group. Compound 19 and the derived phenol 20 (as well as the dibromocalixarene precursor 17) were mixtures of cone and partial cone conformations according to NMR, while 2 and 15 (as well as 14 and the cone components of 17, 19, and 20) were in flattened cone conformations.     

Selective Upper-Rim Adamantylation of Calix[4]arenes

Lower-rim mono- and diacylated calix[4]arenes [acyl = C₆H₅CO, 3,5-(NO₂)₂C₆H₃CO] undergo selective adamantylation with 3-Y-1-adamantanols (Y = H, i-Pr, 4-MeC₆H₄) in trifluoroacetic acid at the free phenolic fragments of the macroring. The reaction provides a convenient preparative route to di-, tri-, and tetraadamantylated calix[4]arenes.     

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…     

上端含长链烷基的手性杯[4]芳烃合成

脱叔丁基的杯[4]芳烃与长链的叔醇或者叔氯代烷烃进行傅-克反应, 在其上端引入长链烷基. 然后在下端引入光学活性的1-苯基乙胺基团, 得到了一系列上端含长链烷基的手性杯[4]芳烃.     

Calix[4] crowns with Methoxynaphthoylmethyl Pendant Groups

The novel calix [4] crowns with two pendant groups were prepared by the alkylation of calix 141 crowns with 6-methoxy-2-bromoacetylnaphthalene. ^1H NMR titration and picrate extraction experiments indicated that they exhibit higher complexing efficiency than their parent compounds and possess obvious selectivity for Na^ or K^ , respetively, and that the cation is encapsulated inside the preorganized ionophoric cavity defined by carbonyl oxygens, the crown ether and the phenoxy oxygens.From UV and fluorescent spectra it is revealed that calix [4]crown-4 3a with 6-methoxy-2-naphthoylmethyl pedant groups exhibits remarkable cation-induced photophysical effects and it could be utilized as a selective fluorescent sensor for Ca^2 .     

Ultramacrocycle with Four Calix[4]arenes: Synthesis and X-Ray Crystal Structure of A Quadruple Calix[4]arene

A quadruple calix[4]arene has been synthesized efficiently from the known diaminocalix[4]arene and 4,4′-biphenyldisulfonyl chloride in just one step (38% yield). The compound has been fully characterized including the determination of the X-ray crystal structure.     

Preferred Conformations of Calix[4]- and Calix[6]arenes,Calculated ab initio

Ab initio STO-2G calculations showed that the preferred conformation of a series of calix[6]arenes substituted at the upper rim is a compressed cone stabilized by a pseudo-ring of six hydrogen bonds with close characteristics. The endocyclic dihedral angles between the benzene ring planes, characterizing the molecular shape of the above macrocyclic compounds in this conformation, were calculated. The calculation results are consistent with the conformational data obtained by other theoretical methods and describe the characteristics of hydrogen bonds more adequately, in agreement with the experimental data and with the existing concepts of the hydrogen bonding efficiency.     

新型偶氮杯[4]芳烃的合成与构象研究

使用相应的w-硫醚羧酸酰氯与杯[4]芳烃或者偶氮杯[4]芳烃酰化合成了一类新型的杯[4]芳烃衍生物。分离得到六个新化合物4a-4c和5a-5c，并使用MALDI, EA, ¹H和¹³C NMR进行了表征。NMR图谱表明偶氮杯[4]芳烃衍生物 5a-5c均为1,3-转换构型，而4a-4c则均为锥式构型。对偶氮杯[4]芳烃衍生物5a-5c的红外和紫外性质也进行了研究。     

Calix[4]arenes with two different chemical modifications at the bridges

Hexabromocalix[4]arene derivatives (3a and 3b) possessing pairs of dibromomethylene and bromomethylene groups located at distal or proximal positions of the calix scaffold were prepared via photochemical bromination of tetramethoxycalix[4]arene. The dibromomethylene groups undergo hydrolysis to afford calix[4]arenes possessing pairs of carbonyl groups and bromomethylene groups located at distal or proximal bridges (4a and 4b, respectively). The bromomethylene groups of 4 undergo reactions with nucleophiles under S(N)1 conditions to afford a wide array of derivatives possessing two different chemical modifications at the bridges.     

Rotaxanes and Catenanes Derived from Tetra-Urea Calix[4]arenes

Summary: Calix[4]arenes, substituted by four urea groups at their wide rim, form dimeric capsules in apolar solvents, which are held together by a seam of intermolecular hydrogen bonds. The heterodimerisation of tetra-aryl and tetratosyl ureas was used to synthesize various derivatives, in which adjacent urea residues are connected to form two, three or four loops. The aliphatic connections were tied by olefin metathesis between adjacent alkenyl residues followed by hydrogenation. Heterodimers of tetra-alkenyl substituted tetra-ureas and bis- or tetraloop derivatives were converted analogously to multiple catenanes. Tetra[2]rotaxanes were obtained in a similar manner. In addition to the spectroscopic evidence (NMR, MS) several compounds were confirmed by crystal structures.     

Analysis of Calix[4]arenes Using Nonaqueous Capillary Electrophoresis

In nonaqueous capillary electrophoresis (NACE), an organic solvent is used in place of an aqueous medium as the background solution to improve the solubility and selectivity for hydrophobic analytes. In this study, we employed NACE with UV detection for the analysis of eight calix[4]arenes. We examined the influence of several parameters—the buffer composition, the nonaqueous solvent‘s composition and proportion, and the concentration of the electrolyte of the nonaqueous buffer—on the efficiency of the electrophoretic separation. The separation was achieved through the analyte's different effective mobility via different degrees of deprotonation on the phenolic OH groups of the calix[4]arene. This deprotonation can further affect the analyte's ability to form a complex with the metal ion. The optimized background electrolyte (BGE), comprising a mixture of N‐methylformamide/acetonitrile (30:70, v/v) and 100 mM AcOH/20 mM NH₄OAc, provided rapid (<11 min) separation of the calix[4]arenes with good resolution. The relative standard deviations of the migration times for the eight analytes were all less than 1%. Within the calibration concentration range, the coefficients of determination (R²) were all greater than 0.9914. Thus, the present study demonstrated NACE can provide adequate separation for the analysis of calix[4]arenes.     

Lower Rim-Upper Rim Hydrogen-Bonded Adducts of Calix[4]arenes

An upper-rim-substituted calix[4]arene tetracarboxylic acid forms hydrogen-bonded duplexes with lower-rim-substituted tetra(4-pyridyl)- and tetra(3-pyridyl)calix[4]arenes in chloroform. The formation of these adducts was studied by extraction experiments. The association constants determined via (1)H NMR dilution experiments in CDCl(3) are 7.6 x 10(3) and 1.3 x 10(3) M(-1) for the 4-pyridyl and the 3-pyridyl derivative, respectively. IR studies in the solid state and in solution indicate that the interaction is based on hydrogen bonding and that the degree of proton transfer is negligible. VPO measurements support the formation of 1:1 adducts.     

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.     

Calix[4]arenes containing benzodiazepinone fragments at the lower rim

A series of p-tert-butylcalix[4]arene derivatives containing 1,4(1,5)-benzodiazepinone fragments as substituents were prepared. The biological activity of the compounds, namely, their antispasmodic activity in mice, was evaluated by antagonism with a spasmodic agent, Corazol, upon transdermal administration. According to the data obtained, benzodiazepine derivatives of calixarenes show higher antispasmodic activity compared to 3-hydroxyphenazepam, taking into account their considerably higher molecular weight.     

Crystallographic and Inclusion Properties of some Diacetylated Calix[4]arenes

Three 5,17-diacetylcalix[4]arene derivatives 3–5 have been prepared, evaluated for inclusion properties, and their single crystal X-ray structures determined. The diacetyl calixarenes 3 and 4 were obtained by acetylation of their parent dimethoxy 1 or dipropoxy 2 compounds, respectively, whereas 5,17-diacetyl-25,26,27,28-tetrapropoxycalix[4]arene 5 was prepared by alkylation of 4. Crystallisation of 3 resulted in no inclusion from chloroform, but yielded lattice inclusion compounds from acetonitrile or acetone. The calixarene 3 maintains its cone conformation in these crystals, but displays degrees of distortion depending upon the included solvent. Crystal structures of solvent-free 4 and 5 are also described. A new preparation of the monomethoxy derivative 6 is described, and its X-ray structure with chloroform guest is analysed.     

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.