99314-01-9Relevant academic research and scientific papers
Enhanced etherification of calix[4]arenes by microwave irradiation
Xu, Zhen,Lü, Zao Sheng,Chen, Lei
, p. 77 - 83 (2017/05/12)
Microwave irradiation has been found to be a highly efficient method for etherification of p-tert-butylcalix[4]arene with alkyl bromides or ditosylate. The corresponding products were obtained as a pure form in modest yield within short reaction time when
Structures of potassium calix[4]arene crown ether inclusion complexes and application in polymerization of: Rac -lactide
Li, Yingguo,Zhao, Hongwei,Mao, Xiaoyang,Pan, Xiaobo,Wu, Jincai
, p. 9636 - 9645 (2016/07/06)
Reaction of 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L1H2) with KN(SiMe3)2 afforded a one-dimensional (1D) chain complex [K2L1]n (1). Upon reaction with 1 equivalent 18-crown-6, complex 1 can convert to complex [K2(18-crown-6)L1] (2) which possesses a sandwich structure. Treatment of two calix[4]arene-crown ligands of 1,3-dihydroxy-p-tert-butyl-calix[4]arene-crown-5 (L2H2) and 1,2-dihydroxy-p-tert-butyl-calix[4]arene-crown-5 (L3H2) with KN(SiMe3)2 gave the dinuclear complex [K2L2] (3) and the mononuclear complex [K(THF)L3H] (4), respectively. Complexes 1-4 were all characterized by single-crystal X-ray diffraction techniques. The variable temperature 1H NMR spectrum indicates there is a quick rotation equilibrium of the two phenoxy groups in complex 3. In addition, complexes 1-4 have been tested for the ring-opening polymerization (ROP) of rac-lactide and the results showed that complexes 2 and 3 are highly active for the ROP of rac-lactide. The obtained polymers displayed low dispersity values (D) and the molecular weights are close to the calculated ones. Furthermore, complexes 2 and 3 show moderate isoselectivities of Pm = 0.67 and Pm = 0.73, respectively.
Synthesis of a cone-conformer bimodal calix[4]arene-crown-5 which forms a sensitive cesium ion sensing layer on gold-coated microcantilevers
Valluru, Gopikishore,Rahman, Shofiur,Georghiou, Paris E.,Dawe, Louise N.,Alodhayb, Abdullah N.,Beaulieu, Luc Y.
, p. 5868 - 5872 (2015/01/08)
A "bimodal" or upper- and lower-rim functionalized "calix-crown-5" reported herein was unexpectedly formed preferentially in a cone conformation. This was confirmed both by NMR spectroscopy and by single-crystal X-ray crystallography. The thioacetate functionalities on the new calix-crown-5 enabled it to form stable SAMs on the Au surface of a microcantilever, and a sensitive cesium ion sensor. This journal is
Optical and electrochemical properties of heteroditopic ion receptors derived from crown ether-based calix[4]arene with amido-anthraquinone pendants
Chailap, Benjamat,Tuntulani, Thawatchai
experimental part, p. 3617 - 3625 (2012/06/01)
Two heteroditopic receptors based on a calix[4]arene crown ether containing amidoanthraquinone pendants in cone and 1,3-alternate conformations (1 and 2, respectively) were synthesized. Photophysical properties of 1 and 2 were studied by UV-vis and fluorescence spectrophotometry in dried CH3CN. Both 1 and 2 showed the highest sensitivity towards F- through the appearance of a new charge transfer band at 500 nm and the enhancement of the emission spectra at λem = 542 nm and 528 nm respectively. Interestingly, in the presence of K+, the fluorescence intensity of 1 at 542 nm increased around 2 fold compared to that in the absence of K + upon addition of F-, while this phenomenon was not observed in the case of receptor 2. Cyclic voltammograms of receptors 1 and 2 showed two consecutive one-electron reversible waves in 40% v/v CH3CN in CH2Cl2, corresponding to two single-electron reductions to give mono- and dianions species at E1/2I = -1.21 V and E1/2II = -1.66 V as well as E1/2I = -1.25 V and E 1/2II = -1.71 V, respectively. H2PO4 - gave remarkable potential shifts (ca. 200 mV) of the second reduction waves (E1/2II) of both free 1 and 2. In the presence of K+, only receptor 1 gave remarkable potential shifts in its redox wave II upon adding F- and AcO-. Therefore, receptors 1 and 2 exhibited dual sensing modes by fluorescence spectrophotometry and cyclic voltammetry. The topology of ligands also played an important role in cooperative binding properties of heteroditopic receptor 1 possessing a closer distance between a cation and an anion binding. On the other hand, the two ion binding sites of receptor 2 were separated by a longer distance and did not support the cooperative binding. This resulted in the abstraction of K + from receptor 2 upon addition of anions.
Facile synthesis of cone p-tert-butylcalix[4]arene-crown conformers
Alekseeva, Elena A.,Basok, Stepan S.,Mazepa, Alexander V.,Gren, Andrei I.
, p. 330 - 331 (2008/03/30)
The series of p-tert-butylcalix[4]arene-crowns in the cone conformation was synthesised in high yields under conditions producing disubstituted calix[4]arenes in the presence of K2CO3 in acetonitrile; the formation of calix-bis(crown)s and doubly(calix)-doubly(crown) in these reactions was established.
Synthesis and alkaline earth metal cation extraction by proton di-ionizable p-tert-butylcalix[4]arene-crown-5 compounds in cone, partial-cone and 1,3-alternate conformations
Zhou, Hui,Surowiec, Kazimierz,Purkiss, David W.,Bartsch, Richard A.
, p. 1104 - 1114 (2008/02/04)
Synthetic strategies for novel, proton di-ionizable p-tert-butylcalix[4] arene-crown-5 compounds in cone, partial-cone and 1,3-alternate conformations are reported. Selective linkage of the two diametrical phenolic oxygens in p-tert-butylcalix[4]arene wit
Synthesis, crystal structures, cation-binding properties and the influence of intramolecular C-H...O interactions on the complexation behaviour of a family of cone p-tert-butylcalix[4]arene-crown-5 compounds
Agnihotri, Pragati,Suresh, Eringathodi,Paul, Parimal,Ghosh, Pushpito K.
, p. 3369 - 3381 (2007/10/03)
A family of cone p-tert-butylcalix[4]arene-crown-5 compounds with various substituents (H, COCH3, CH2CO2C 2H5 and CH2CO2H) appended at the opposite phenolic oxygen atoms have been synthesised to evaluate their efficiency and selectivity towards different alkali and alkaline-earth metal ions, and also to ascertain the role of the appended side-arms in the complexation process. The selectivity of these ionophores towards Na +, K+, Mg2+, and Ca2+ has been evaluated with an aqueous solution containing an equimolar mixture of these ions. The concentration of metal ion in the extract (organic phase) has been estimated by ion chromatographic assay. Among these ions, K+ shows the highest selectivity in all cases except one, where the two phenolic oxygen atoms contain COCH3 substituents. All the ionophores show poor selectivity towards Mg2+ and Ca2+. Association constants (Ka) for the binding of Na+ and K+ to these ionophores have been determined spectrophotometrically. Ka (7.2 × 107) is highest for the binding of K+ to the ionophore with CH2CO2C2H5 substituants. The molecular structures of four of the ionophores and four of the metal complexes have been established by single-crystal X-ray crystallography. Analysis of the structures revealed that in case of the ionophore with two COCH3 substituents, the C-H...O interactions form an eight-membered zigzag ring almost perpendicular to the crown ring, which prevents entry of the metal ions into the calix-crown cavity. The ionophore with CH2CO2C2H5 substituents, where no such interaction is observed, forms metal complexes easily and exhibits the highest association constant. 1H and 13C NMR studies have also been, carried out to investigate the conformational behaviour of these ionophores and their metal complexes in solution. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Selective O-alkylations with glycol chlorohydrins via the Mitsunobu reaction. A versatile route to calix[4]- and 1,1′-binaphthocrowns
Grün, Alajos,Koszegi, éva,Bitter, István
, p. 5041 - 5048 (2007/10/03)
Selective monoalkylation of p-tert-butylcalix[4]arene and BINOL with oligoethylene glycol chlorohydrins was achieved under the Mitsunobu protocol using DEAD/TPP. The method provides a simple access to ether precursors capable of cyclising to various crowns.
Unprecedented cyclisations of calix[4]arenes with glycols under the Mitsunobu protocol. Part 1: A new perspective for the synthesis of calixcrowns
Csokai, Viktor,Grün, Alajos,Bitter, István
, p. 4681 - 4684 (2007/10/03)
Selective ring closures of p-tert-butylthiacalix[4]arene and p-tert-butylcalix[4]arene with oligoethylene glycols were performed under the Mitsunobu protocol using the DEAD/TPP system. The method opens a new perspective for the syntheses of 1,3-calixcrowns.
Catalysis of acyl group transfer by a double-displacement mechanism: The cleavage of aryl esters catalyzed by calixcrown - Ba2+ complexes
Baldini, Laura,Bracchini, Cecilia,Cacciapaglia, Roberta,Casnati, Alessandro,Mandolini, Luigi,Ungaro, Rocco
, p. 1322 - 1330 (2007/10/03)
The scope of the barium salt of p-tert-butylcalix[4]arene-crown-5 as a transacylation catalyst has been defined by evaluating its efficiency in the methanolysis of a series of aryl acetates at 25.0 °C in MeCN/MeOH 9:1 (vlv) under slightly basic conditions. In this system a phenolic hydroxyl is the acyl-receiving and -releasing unit in a double-displacement mechanism. The complexed barium ion acts both as a nucleophile carrier and a built-in Lewis acid in providing electrophilic assistance to the ester carbonyl both in the acylation and deacylation step (nucleophilic - electrophilic catalysis). Turnover capability is ensured by the acylated intermediate reacting with the solvent more rapidly than the original ester, but a serious drawback derives from the incursion of backacylation of the liberated phenol. A gradual shift from rate-determining deacylation (p-nitrophenyl acetate) to rate-determining acylation (phenyl acetate) is observed along the investigated series. It is shown that the scope of the catalyst is restricted to acetate esters whose reactivity lies in the range approximately defined by the phenyl acetate-p-nitrophenyl acetate pair, with a maximum efficiency for p-chlorophenyl acetate. Moreover, the catalyst effectively promotes ester interchange between phenols, showing that its activity is not limited to solvolysis reactions. The very high sensitivity of the rate of acylation of the catalyst to leaving group basicity has been interpreted as due to rate-determining decomposition of the tetrahedral intermediate, which is believed to arise from the presumably low basicity of the metal ion stabilized nucleophile. The turnover frequency was in the range of 3.8 × 10-4 min-1 for phenyl acetate to 7.4 × 10-3 min-1 for p-nitrophenyl acetate ([ArOAc]0= 4.0 mM]). A first attempt to enhance the rate of acylation of the catalyst through intramolecular general acid catalysis is also described.
