Hard–Soft Receptors, Tetrakis[(N,N-diethylaminocarbonyl)methoxy] thiacalix[4]arene Derivatives with cone and 1,3-alternate Conformation

Direct O-alkylation of p-tert-butyltetrathiacalix[4]arene with N,N-diethylchloroacetamide afforded two conformational isomers (1,3-alternate and cone) of tetrakis[(N,N-diethylaminocarbonyl)methoxy]thiacalix[4]arene and 1,3-disubstituted bis[(N,N-diethylaminocarbonyl)methoxy]thiacalix[4]arene, depending on the base used. The complaxation behaviors of the tetrakis isomers were assessed by ¹H NMR titration experiments. Evidence of 1:2 (homo- and hetero-dinuclear) complexes formation of 1,3-alternate-tetrakis[(N,N-diethylaminocarbonyl)methoxy]thiacalix[4]arene with alkali (K⁺ and Na⁺) or transition (Ag⁺) metal ions was obtained. Interestingly, it was found that the cone-tetrakis[(N,N-diethylaminocarbonyl)methoxy]thiacalix[4]arene required a prior Ag⁺ complexation to form 1:2 heterodinuclear complex. Received in final form: 26 January 2005     

Synthesis and properties of mono-O-[(N-(aminoalkyl)aminocarbonyl)-methoxy]thiacalix[4]arenes and novel mono-O-bridged bisthiacalix[4]arene

A simple method for thiacalix[4]arene O-monoamide preparation with high yields using 5,11,17,23-tetra-tert-butyl-28-(ethoxycarbonyl)methoxy-2,8,14,20-tetrathiacalix[4]arene reaction with diaminoalkanes is reported. The solid state cyclization reaction of the acylethylenediamines function of 5,11,17,23-tetra-tert-butyl-28-O-[(N-(2-aminoethyl)aminocarbonyl)-methoxy]thiacalix[4]arene leading to the formation of the 5,11,17,23-tetra-tert-butyl-28-[2-methoxy-imdazoline]thiacalix[4]arene compound is described for the first time for the calixarene macrocycle family. Finally, preliminary results show that O-mono-amide-thiacalixarene derivatives are promising candidates for the production of self-assembled materials and efficient precursors for the synthesis of bisthiacalix[4] arenes.     

Synthesis and Properties of New Thiacalixarene Derivatives with Palladium Ion

Three new thiacalix[4]arene derivatives, 5,11,17,23-tetra-tert-butyl-25,27-di(2-hydroxyethoxy)-26,28-dihydroxythiacalix-{}[4]arene (2), 5,11,17,23-tetra-tert-25, 26,27,28-tetrakis[(methylcarboxyl)methoxy]thiacalix[4]arene (3),5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(2-hydroxy-1-propanoxy)thiacalix[4]arene (4), were synthesized for the first time. The coordination properties of thiacalix[4]arene(1) and its derivatives (2 and 4) were investigated by detecting the interactions betweenthese compounds and two palladium complexes, cis-[Pd(en)(H₂O)₂]²⁺ and cis-[Pd(dtco-3-OH)(H₂O)₂]²⁺, by means of electrospray ionization mass spectrometry (ESI-MS) technique.     

Synthesis and Inclusion Properties of a Novel Thiacalix[4]arene-Based Hard–Soft Receptor with 1,3-Alternate Conformation

A novel ditopic receptor possessing two complexation sites and bearing 1,3-alternate conformation based on thiacalix[4]arene was prepared. The binding behaviors with alkali metals and silver ion have been examined by ¹H NMR titration experiment. Although the formation of the heterogeneous dinuclear complexes was not observed, the exclusive formation of mononuclear complexes of 1,3-alternate-3 with metal cations is of particular interest in negative allosteric effect in the thiacalix[4]arene family. These findings demonstrate that preorganization, subtle conformational changes and affinity have a pronounced effect on the complexation process between the two different arms placed at the two edges of the thiacalix[4]arene cavity.     

Comparative study on the transition metal complexes of a novel thiacalix[4]arene derivative

A comparative study on Zn²⁺ and Cu²⁺ complexes of the novel compound 5,11,17,23-tetra-tert-butyl-25,27-bis{[4-(methoxycarbonyl)phenyl]methoxy}-2,8,14,20-tetrathiacalix[4]arene, that possesses potential as a core unit for the construction of molecular receptors, is presented using semiempirical AM1 calculation. The possible structures of each metal complex and their corresponding energetic data are compared with the parent 5,11,17,23-tetra-tert-butyl-2,8,14,20-tetrathiacalix[4]arene. The complexation ability of both thiacalix[4]arenes towards the two metal ions is discussed on the basis of binding energies. Both thiacalix[4]arene 1:1 complexes show higher complexation ability towards Cu²⁺. However, 5,11,17,23-tetra-tert-butyl-25,27-bis{[4-(methoxycarbonyl)phenyl]methoxy}-2,8,14,20-tetrathiacalix[4]arene presents lower complexation ability when compared with the 5,11,17,23-tetra-tert-butyl-2,8,14,20-tetrathiacalix[4]arene. The results of liquid–liquid extraction experiments of the thiacalix[4]arenes are in good agreement with the theoretical calculations.     

Synthesis of novel p-tert-butyl-calix[4]arene derivatives and their cation binding ability: chromogenic effect upon side arms binding

A series of novel double-armed calix[4]arene derivatives, i.e. 5,11,17,23-tetra-tert-butyl -25,27-bis[2-[(2-hydroxy-5-(4-nitroazo)benzylidene)amino]ethoxy]-26,28-dihydroxy-calix[4]-arene (4), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[(2-hydroxy-5-(2-nitroazo)benzylidene) amino]ethoxy]-26,28-dihydroxycalix[4]arene (5), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[(2-hydroxy-5-(4-chloroazo)benzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (6), have been synthesized as an selective chromoionophore for Na⁺. The complexation behavior of ligands 4-6 with alkali metal ions Na⁺, K⁺, Rb⁺and Cs⁺ has been evaluated by using UV-Vis spectrometry in CH₃CN-H₂O (99:1/V:V) solution at 25°C. The UV-Vis spectra show that the complexation of 4-6 with Na⁺exhibits obvious bathochromic shifts (λ_max 379→480 nm) and there is a unique color change in the solution from yellow to red upon complexation. The binding constants for Na⁺ are higher than that of other alkali metal ions, giving the highest cation selectivity up to 7 for Na⁺/K⁺. The binding ability and photophysical behavior of alkali cations by calix[4]arene derivatives 4-6 are discussed from the point of view of substituted effects at the lower rim of parent calix[4]arene and size-fit concept between host calix[4]arenes and guest cations.     

Synthesis and Structure of a 1,3-alternate-Thiacalix[4]arene diamide Derivative

A novel receptor possessing two complexation sites and bearing 1,3-alternate conformation based on thiacalix[4]arene, confirmed by single crystal X-ray analysis, was prepared. The tetrathiacalix[4]arene diamide shows strong intramolecular hydrogen bonding. The binding behavior towards K⁺ and halides has been examined by ¹H NMR titration experiments.     

Regioselective Synthesis and Inclusion Properties of distal-Bis[(2-pyridylmethyl) oxy]tetrathiacalix[4]arenes

Regioselective synthesis of bis[(2-pyridylmethyl)oxy]tetrathiacalix[4]arenes was accomplished by a protection–deprotection method using benzyl groups as a protecting group. The conformational studies of distal-bis[(2-pyridylmethyl)oxy]thiacalix[4]arenes in solution and solid state are described. The two-phase solvent extraction data indicated that bis[(2-pyridylmethyl)oxy]tetrathiacalix[4]arenes show strong Ag⁺ (E%, 97%) affinity. In contrast, no significant E% is observed for K⁺. A good Job plots proves 1:1 coordination of 1,3-alternate -3 with Ag⁺ cation. ¹H-NMR Titration of 1,3-alternate- 3 with AgSO₃CF₃ also clearly demonstrates that a 1:1 complex is formed with retention of the original symmetry. The conformational changes of pyridine moiety from the original outward orientation of the ring nitrogen to the inside orientation toward the thiacalixarene cavity were observed in the process of Ag⁺ complexation. The down-field shifts of the benzene protons of the benzyl group were also observed and attributed to the conformational deviation from the original face to face overlapping.     

Aminolysis of p‐tert‐Butyl‐tetrakis[(ethoxycarbonyl)methoxy]thiacalix[4]arene

A convenient method for preparation of thiacalix[4]arene tetraamides in high to good yields by reacting conic or 1,3‐alt‐p‐tert‐butyl‐tetrakis[(ethoxycarbonyl)methoxy]‐thiacalix[4]arene with excess monoamines or diamines is reported. In most cases, corresponding tetraamides with original conformation were obtained. However, when the cone one was reacted with ethylenediamine or propylenediamine, the obtained tetraamides possessed partial conic conformation, which meant that conversion of conformation occurred.     

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.     

Design, synthesis, characterization, and preliminary complexation studies of chromogenic vanadophiles: 1,3-alternate thiacalix[4]arene tetrahydroxamic acids

New chromogenic supramolecular vanadophiles were designed and synthesized by incorporating hydroxamic acid chains on a 1,3-alternate thiacalix[4]arene scaffold and were found to show high affinity toward vanadate ions. The article describes a comprehensive design process to devise a tailor-made co-ordination cavity for vanadate ions by pre-organization of hydroxamic acid chelating moieties on a 1,3-alternate thiacalix[4]arene scaffold. These receptors simultaneously co-ordinate two vanadate ions giving a highly ‘staggered’ geometry with almost D_2d symmetry. Proposed structures and complexation behavior of the receptors were explained by critical examination of FTIR, UV-visible, mass, and ¹H NMR data.     

Preparation and biological properties of inclusion compounds of calix[4]arene and 1,4-benzodiazepinone derivatives

The possibility of enhancing the oral bioavailability of certain 1,4-benzodiazepinones by using them as complexes with a series of calix[4]arene derivatives was examined. All the inclusion compounds prepared exhibit anticonvulsant activity by antagonism with Corazol spasmodic agent. Complexes with 25,27-bis[(hydrazinocarbonyl)methoxy]-26,28-dihydroxy-p-tert-butylcalix[4]arene exhibit higher pharmacological activity compared to the starting 7-bromo-5-(o-chloro)phenyl-and 1-hydrazinocarbonylmethyl-7-bromo-5-phenyl-1,2-dihydro-3H-1,4-benzodiazepin-2-ones.     

The influence of isomerism on the self-assembly behavior and complexation property of 1,3-alternate tetraaminopyridyl-thiacalix[4]arene derivatives

A series of 1,3-alternate conformation thiacalix[4]arenes containing different isomeric aminopyridyl pendent arms have been synthesized. It was found that their self-assembly behaviors and complexation properties strongly depended on the structures of aminopyridyl pendent arms. The crystal structures demonstrate that tetra(meta-aminopyridyl)-thiacalix[4]arene motif is capable of forming intramolecular hydrogen bondings between the sp² nitrogen donors in the meta position of the aminopyridyl groups and the facing amide N-H of the adjacent aminopyridyl groups, and self-assembles via C-H?O weak hydrogen bondings and C-H?π interaction to generate a double stranded rectilineal networks. By contrast, in the case of tetra(para-aminopyridyl)-thiacalix[4]arene, the presence of para-aminopyridyl units enables the formation of N-H?N strong hydrogen bondings between the individual molecules leading to the solid-state structure with water-bridged double strands. Their complexation properties had been also studied by measurement of the stability constants for their complexation in a range of metal cations and investigation of their binding models via ¹H NMR titration and ESI-MS experiments. It was found that the three ligands exhibited high and selective extractability toward Ag⁺, and their stoichiometry of ligand to Ag⁺ was 1:1, while the meta-aminopyridyl derivative showed the best extraction capacity and possessed the most efficient binding sites.     

Anion receptors based on ureido-substituted thiacalix[4]arenes and calix[4]arenes

The regioselective nitration of 25,27-dipropoxythiacalix[4]arene was carried out as a key step in the synthesis of thiacalix[4]arene derivative bearing two arylureido functions on the upper rim. The preorganisation of ureido units using the thiacalix[4]arene/calix[4]arene moieties as a molecular scaffold gave novel anion receptors. These compounds, albeit based on hydrogen bonding interactions, show good complexation ability even in highly HB-competitive solvent, such as DMSO. Direct comparison of otherwise identical structures 6a and 7a revealed remarkable dominance of the thiacalix[4]arene derivative over its classical analogue in anion binding.     

One- and two-dimensional NMR study of structure of 1,2-disubstituted p-tert-butylthiacalix[4]arene containing amide fragment

The structure of 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-bis[N-(4′-nitrophenyl)aminocarbonylmethoxy] thiacalix[4]arene I was examined by 1D and 2D (NOESY) ¹H and ¹³C NMR methods in a CDCl₃ solution using numerical simulation (semi-empirical quantum-chemical calculations, PM3 method). Compound I was found to exist in the 1,2-alternate conformation, where bulky substituents OCH₂C(O)· NHPhNO₂ are in the endo-position relative to the macrocycle cavity.     

含酰胺和席夫碱单元的杯[4]芳烃衍生物的合成与配合性能

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, 然后进一步与相应的芳醛反应, 高产率地合成了三个新型的含酰胺和席夫碱单元的杯[4]芳烃衍生物3a～3c和一例新型杯[4]冠醚4. 阳离子萃取实验表明新型杯芳烃衍生物比只含有酰胺基或席夫碱基的杯芳烃衍生物有更强的软金属离子配合性能, 杯[4]冠醚4还对Ag^＋有较好的选择性萃取能力.     

Thia- and Sulfonyl-Calix[4]Arene Methylphosphonous Acids: Synthesis,Structure, and Amino Acids Binding

Abstract

Thia- and sulfonyl-calix[4]arene methylphosphonous acids have been synthesized by hydrolysis of corresponding alkyl esters. Host-Guest complexation of the thiacalix[4]arene tetrakis-methylphosphonous acid with a series of 12 amino acids has been investigated by HPLC and molecular modeling methods. Stability constants of the complexes are within 530—10,140 M^?1 in water contained solution.     

Synthesis and Complexation properties of N,N’-bis(calix[4]Arenoxyacetyl)Hydrazine Derivative

Heating of p-tert-butylcalix[4]arene bearing acethydrazide moiety at the lower rim in MeCN or PrⁱOH (EtOH) affords the corresponding N,N’-bis(calix[4]arenoxyacetyl)hydrazine derivative. The hydrazinolysis of mono(methoxycarbonylmethoxy)-p-tert-butylcalix[4]-arene in benzene or refluxing biscalixarene hydrazide in benzene in the presence of hydrazine hydrate produces the mixture of 1,2- and 1,3-(N,N’-diacetylhydrazine)-p-tert-butylcalix[4]arenes.     

一种基于硫杂杯[4]芳烃的高效银离子载体

合成了基于下缘含有酰肼基团的硫杂杯芳烃衍生物的银离子载体1,其核磁研究证实硫杂杯芳烃以1,3-交替构象存在,并且通过非竞争萃取实验和竞争萃取实验研究了它对碱金属和过渡金属离子（Li⁺, Na⁺, K⁺, Cs⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Ag⁺）的键合能力和选择性。实验结果表明：将酰肼基团引入1,3-交替构象的硫杂杯芳烃骨架的下缘可以提高其对Ag⁺的键合能力和选择性,同时,对Cu²⁺的萃取能力较弱,对碱金属离子和其它的重金属离子几乎没有萃取能力。进一步的核磁滴定和电喷雾质谱实验显示化合物1与银离子形成配合物的配合计量比为1：1,由此推断主要由“N-Ag⁺”配位键以及硫杂杯芳烃骨架的协同作用构成了化合物1与银离子的配合模式。     

Synergistic extraction of cesium,strontium, and europium with adamantylated thiacalix[4]arenes in the presence of chlorinated cobalt dicarbollide

Synergistic extraction of long-lived fission products ¹³⁷Cs⁺, ⁸⁵Sr²⁺, and ¹⁵²Eu³⁺ from dilute HNO3 into dichloroethane with ligands derived from p-(1-adamantyl)thiacalix[4]arene in mixtures with chlorinated cobalt dicarbollide was studied. An extraordinary synergistic effect is observed in extraction of europium with p-(1-adamantyl)thiacalix[4]arene tetraacetate derivative. Amides of p-(1-adamantyl)thiacalix-[4]arene tetracarboxylic acid are selective toward europium, although their extraction ability toward the examined ions is lower than that of the classical extractant, p-(1-adamantyl)calix[4]arene tetracarboxylic acid diethylamide.