Methods were developed for the synthesis of ω mercaptoalkoxy derivatives of thiacalix [4] arenes in the 1,3 alternate conformation containing different numbers (2-5) of methylene spacers at the lower rim. The hydrazinolysis of the corresponding thioacetates is the most efficient method for the synthesis of these compounds.Natural and synthetic macrocyclic compounds show promise for studies in the field of supramolecular chemi stry, because the structural features of these compounds are favorable for a sharp enhancement of the complex ation properties due to the formation of multicenter intermolecular interactions with substrates and the pre organization of coordination centers. Calixarenes 1 have additional advantages associated primarily with the unique possibilities of their functionalization and the fine tuning between the three dimensional structures of the host and the desired guest. The use of thiacalix[4]arene 2 (see Refs 1-5) as a molecular platform for the design of intel lectual receptor and self organized supramolecular sys tems is very attractive, because the replacement of the methylene bridges in the classical calixarene by sulfur atoms gives rise to new properties. 3,4,6-11 In this connec tion, it is important to develop approaches to the directed functionalization of this macrocycle, in particular, by introducing organosulfur fragments. The presence of func tional sulfur containing groups at the lower or upper rim of the macrocycle, in addition to four bridging sulfur atoms of the thiacalixarene platform, offers great possi bilities for the design of highly selective host molecules based on thiophilic metal ions, 12 the construction of highly organized nanolayers on the metal surface, 13-17 and the design of sensors based on ion selective electrodes. 18-20 In addition, these sulfur containing groups have a great synthetic potential for further modifications of the macro cyclic structure. * Dedicated to Academician A. I. Konovalov on his 75th birthday. Results and DiscussionIn the present study, we synthesized new O substi tuted thiacalix[4]arenes in the 1,3 alternate conformation containing ω bromo (3), ω acetoxy (4), or ω mercapto alkyl groups (5) linked by methylene spacers of different length (from two to five units). The structures of the new compounds were determined by different physical methods, such as 1D and 2D NMR spectroscopy, IR spectroscopy, and MALDI TOF mass spectrometry. The purity of the compounds was checked by TLC and elemental analysis.CH 2 H 2 S H 3a-e S (CH 2 ) n Br, n = 2 (a), 3 (b), 4 (c), 5 (d), 6 (e) 4a-d S (CH 2 ) n SC(O)CH 3 , n = 2 (a), 3 (b), 4 (c), 5 (d) 5a-d S (CH 2 ) n SH, n = 2 (a), 3 (b), 4 (c), 5 (d)

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The design of polymacrocyclic structures is of high importance for the improvement of recognition ability to various guests. We present a convenient approach towards two types of dendrimer-shaped pentakis-thiacalix[4]arenes with triazolyl linkers using the click reaction of tetraazidoalkoxycalixarenes with monoalkynyloxy derivatives, as well as tetraalkynyloxycalixarenes with monoazidoalkoxy derivatives. Mitsunobu alkylation of hydroxyl groups has been employed to afford tetrasubstituted derivatives in 1,3-alternate configuration. A facile procedure for the synthesis of monosubstituted cone precursors in high yields by the hydrolysis of one ether fragment in disubstituted counterparts under basic conditions (n-BuNH 2 or NaN 3 in DMF) has been suggested and optimized. CuAAC reaction has been conducted in microwave reactor and on a hot plate. It has been found that microwave irradiation promotes the reaction and the yields of products are as high as 40-80 %.

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Understanding the interaction of ions with organic receptors in confined space is of fundamental importance and could advance nanoelectronics and sensor design. In this work, metal ion complexation of conformationally varied thiacalix[4]monocrowns bearing lower-rim hydroxy (type I), dodecyloxy (type II), or methoxy (type III) fragments was evaluated. At the liquid–liquid interface, alkylated thiacalixcrowns-5(6) selectively extract alkali metal ions according to the induced-fit concept, whereas crown-4 receptors were ineffective due to distortion of the crown-ether cavity, as predicted by quantum-chemical calculations. In type-I ligands, alkali-metal ion extraction by the solvent-accessible crown-ether cavity was prevented, which resulted in competitive Ag+ extraction by sulfide bridges. Surprisingly, amphiphilic type-I/II conjugates moderately extracted other metal ions, which was attributed to calixarene aggregation in salt aqueous phase and supported by dynamic light scattering measurements. Cation–monolayer interactions at the air–water interface were monitored by surface pressure/potential measurements and UV/visible reflection–absorption spectroscopy. Topology-varied selectivity was evidenced, towards Sr2+ (crown-4), K+ (crown-5), and Ag+ (crown-6) in type-I receptors and Na+ (crown-4), Ca2+ (crown-5), and Cs+ (crown-6) in type-II receptors. Nuclear magnetic resonance and electronic absorption spectroscopy revealed exocyclic coordination in type-I ligands and cation–π interactions in type-II ligands.