Chromogenic Indoaniline Armed-Calix[4]azacrowns

Abstract

Two novel chromogenic 1,3-alternate calix[4]azacrown (1) and calix[4]-bis-azacrown (2) in which an indoaniline chromophore was attached on the nitrogen atom of the azacrown unit with one methylene spacer were synthesized. The 1H NMR spectrum of the ligand 1 and Ca2+ proved that the metal ion is entrapped by the calix[4]azacrown unit and by the conjugated indoaniline system. From the UV/vis band shifts upon metal ion complexation, Zn2+ ion was found to give the largest band shifts compared to other metal cations, indicating that Zn2+ ion (K(a) = 18 760 M(-)(1) for 1 and K(a) = 19 930 M(-1) for 2) was selectively encapsulated by the calix[4]azacrown cavity with assistance of the pendent indoaniline sidearm.

N,N’-Bis(acylvinylated) diaza-18-crown-6 ether as a lanthanide-selective macrocyclic complex-forming agent

“…If coordination to the metal cation occurs through the oxygen atom, the excited state is stabilized to a larger extent, resulting in a decrease in the electron transition energy (Scheme 3). 27, 28 This coordination mode of the rare earth cations through the oxygen atom of the C=O group is additionally supported by a comparison of the IR spectra of the yttrium and lanthanum complexes with the spectrum of free crown ether 1.…”

Synthesis of Two Branched Fluorescent Receptors and Their Binding Properties for Dicarboxylate Anions

“…), with the molar fraction of host continuously varying. [14] The results illustrate that receptor-anion complex concentration approaches a maximum when the molar fraction of host { complexes with the adipate anion. In the same way, it was deduced that the receptors (1, 2) and other dicarboxylate anions also formed 1:1 complexes.…”

“…UV/Vis spectra of 1 (2.5 ϫ 10 Ϫ5 mol·L Ϫ1 ) in the presence of adipate in DMSO; the equivalents of adipate anion are: 0, 0.4, 0.8, 1.2, 1.6, 2, 2. 4,2.8,3.2,3.6,4,4.8,5.6,6.4,7.2,8,10,12,14,16,20,and 24;Inset: changes in absorbance at 304 nm upon addition of adipate anion; the solid line is the best-fit curve; the correlation coefficient (R) of non-linear curve fitting is 0.9975 Figure 4. UV/Vis spectra of 2 (2.5 ϫ 10 Ϫ5 mol·L Ϫ1 ) in the presence of adipate in DMSO; the equivalents of adipate anion are: 0, 0.…”

Spectroscopic and electrochemical studies of two distal diethyl ester azocalix[4]arene derivatives

“…introduced into various calix [4]arenes including bridged derivatives [4,16,19,20]. In pursuit of a selective metal ion chemosensor, two distal diethyl ester azocalix [4]arene derivatives 1 and 2 ( Fig.…”