E. A. Shokova

Thiacalixarenes: A new class of synthetic receptors

The review summarizes and analyzes published data on the synthesis, modification, and com- plexing properties of sulfur-bridged analogs of calixarenes, which constitute a new class of metacyclophanes.

Molecular recognition of organic vapors by adamantylcalix[4]arene in QCM sensor using partial binding reversibility.

The parameters of stability, guest binding reversibility, and Gibbs energy of guest inclusion were determined for clathrates of adamantylcalix[4]arene (1). These data provide a new insight into the structure-property relationships in vapor sensor applications of clathrate-forming hosts. A thin layer of 1, used in the quartz microbalance (QCM) sensor, demonstrates a selectivity for organic vapors, which depends on the regeneration technique after the guest binding. Complete regeneration of 1 on the sensor surface was reached through the exchange of bound guest with ethanol vapor, which forms an unstable clathrate with 1. The efficiency of the used regeneration technique was proved by comparing the QCM data with the isotherms of guest vapor sorption by guest-free host 1 and with the data of simultaneous thermogravimetry and differential scanning calorimetry for the saturated clathrates of 1. In sensor, the extent of host regeneration without guest exchange depends on the guest molecular structure. This extent, or guest-binding reversibility parameter, being determined in a combination with the sensor responses of completely regenerated 1 to guest vapors, increases the recognition capability of single sensor device. Using this technique, 13 of 15 studied guests were discriminated. The structural hints on the suitable sensor properties of 1 were found in the determined X-ray monocrystal data for clathrate of this host with toluene.

First synthesis of adamantylated thiacalix[4]arenes

p-(1-Adamantyl)thiacalix[4]arene was synthesized both by condensation of p-(1-adamantyl)phenol with sulfur in the presence of NaOH and by alkylation of p-H-thiacalix[4]arene with 1-adamantanol in trifluoroacetic acid. Using the latter method, the first thiacalix[4]arene carboxylated at the upper rim was obtained from p-H-thiacalix[4]arene and 3-carboxy-1-adamantanol. The X-ray structural analysis revealed that p-(1-adamantyl)thiacalix[4]arene adopts a cone conformation leading to an inclusion complex with chloroform under the conditions of crystallization.

Calixarene-based anionic receptors

The review summarizes and analyzes recent (2004–2008) published data on anionic receptors based on calixarenes.

Extraction of americium and europium by CMPO-substituted adamantylcalixarenes

Summary Eight p-adamantylcalix[4]arene derivatives, bearing four CMPO-like functions [(CH2)nNHC(O)CH2- P(O)Ph2] at the wide (4a,b, n = 0, 1) or narrow (5a–c and 6a–c, n = 2–4) rims were synthesized for the first time. Studies of the extraction of americium(III) and europium(III) from 3 M HNO3 solutions to organic phases (dichloromethane, m-nitro-trifluoromethylbenzene) showed: (i) The extraction ability for all the adamantylcalixarene ligands is much better than for their monomeric analogues –N-(1-adamantyl)-, N-(1-adamantylmethyl)- and N,N-(dibutyl)carbamoylmethyldiphenylphosphine oxides 7a, 7b, 8; (ii) The extraction percentage increases strongly with increasing length of the spacer for all types of ligands 4–6, and best extraction results were found for 4b (n = 1) and 5c (n = 4); (iii) The separation coefficient DAm/DEu for the investigated compounds did not exceed 2, which is close to the narrow rim CMPO calixarenes, studied earlier; (iv) Variation of the spacer length between CMPO groups attached to the 1,3- and 2,4-positions of the calixarene platform in 6 did not lead to appreciably improved extractants, neither with respect to the extraction abilities (D) nor to the selectivities (DAm/DEu).

Adamantane functionalization. synthesis of polyfunctional derivatives with various substituents in bridgehead positions

Published data on the methods of the synthesis of polyfunctional adamantane derivatives with various substituents at the tertiary carbon atoms of the adamantane framework are generalized and analyzed.

Homooxacalixarenes: I. Structure, Synthesis, and Chemical Reactions

Data published on the structure, preparation, and chemical reactions of homooxacalixarenes with various number of aromatic fragments and dihomooxabridges in macrocycles were analysed and summarized.

(CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

Summary A very simple and convenient reaction for 1,3-diketone preparation from carboxylic acids and aromatic ketones in TFAA/TfOH system is described. When the β-phenylpropionic acids were used as starting materials, they initially gave 1-indanones and then underwent further acylation with the formation of 2-(β-phenylpropionyl)-1-indanones as the main reaction products. In addition, the application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones.

1,3-Diketones. Synthesis and properties

The review generalizes and analyzes published data on the synthesis and chemical transformations of 1,3-diketones over the past 10–15 years.

Surfactant Ion Selective Membrane Electrodes

Abstract Calix[8]arene ethers, carboxylic esters having various p-substituents and acid are synthesized and studied. In a bulk membrane transport of dodecylpyridinium the better carrier is the simplest host, calix[8]arene octamethyl ether. Inversely, it is the worst carrier for dodecyltrimethylammonium; the better here is carboxy ester with adamantyl p-substituents. Various calixarenes are successfully used in plasticized membrane ion-selective electrodes (ISE) for both above ammonium and pyridinium surfactants. Operational characteristics, potentiometric selectivity and optimal membrane compositions are reported. Typical limit of detection is at the level of nx10−6 - 1x10−5 M, response time 5-10 s, and lifetime is at least 6 months. ISEs selectivity is significantly better than that of ion-association and crown-ether based electrodes.