Novel chromogenic pyridinium derivatives of calix[4]arenes, I

Selective ipso-Nitration of tert-Butylcalix[4]arene Tripropylether

“…to afford the 23-mononitro calix(4)arene 2 in 85% yield. Compared to the published procedure [7], the present method offers both milder reaction conditions and an improved yield. In the 1 H-NMR spectrum of 2, the aromatic meta protons in the nitrated phenolic ring shift downfield from δ 5.41 (in 1) to δ 7.22 (in 2), and the protons ortho to the nitro group appears at δ 8.06.…”

“…Several methods have been reported for selective substitution of nitro groups at the upper rim [3][4][5]. Selective ipso-nitration of partial ethers has only been described for a few ethers of tertbutylcalix [4]arene [6][7][8][9]. In this paper we report the selective substitution of one or two nitro group(s) by direct replacement of tert-butyl group(s) via an ipso-aromatic nitration.…”

Comparative studies on the solvent extraction of transition metal cations by calixarene, phenol and ester derivatives

“…Shinkai et al have synthesized a new calix [4]arenebased, chromogenic ionophore through molecular design. This chromogenic calix [4]arene showed high Li + selectivity in solid-liquid two-phase solvent extraction [17].…”

“…Studies have been conducted on calixarene derivatives; their role as receptors for metal ions. As neutral ones, esters [4][5][6][7][8], ketones [6,7], amides [7,9,10] and so on were synthesized and their extraction properties for metal ions, such as alkali metal cations [11] and alkaline-earth metal cations were investigated.…”

“…Calix [4]arenes and their derivatives have been attracting much attention as novel types of interesting host compounds [1][2][3]. Studies have been conducted on calixarene derivatives; their role as receptors for metal ions.…”