Photoinduced Formation of a Cryptand from a Coronand: An Unexpected Switch in Cation Binding Affinity

Abstract

Aza‐crown ethers 2 and 3 with anthracene‐containing pendant arms have been synthesised and characterised. Both compounds bind Group 1 metal cations in solution, forming complexes of 1:1 stoichiometry. The properties of compound 2 and its complexes have been studied by a range of techniques, including NMR, UV and fluorescence spectroscopy and X‐ray crystallography. The pendant arms can adopt either a cis or a trans geometry, the cis geometry favoured with larger cations. The geometry of the complex affects the fluorescence properties of the system, with larger cations giving higher excimer/monomer ratios. Upon irradiation at λ>300 nm, coronand 2 forms the cryptand 5 through a reversible intramolecular [4π+4π] cycloaddition reaction. The rates of the forward and reverse reactions of this photochromic process are cation dependent; in particular the rate of the thermal reverse reaction is decreased by smaller cations and increased by larger cations, especially Rb+. The metal binding constants in methanol for 2 and 5 have been determined, revealing that the cryptand 5 binds Na+ and Rb+ more weakly than crown ether 2 by over two orders of magnitude.

New derivatization strategies for the ultrasensitive analysis of non-aromatic analytes with APLI-TOF-MS

“…3-(9-Anthryl)-propionic acid chloride (1) was synthesized by treating 3 with oxalyl chloride [20]. 3-(9-Anthryl)-propylamine hydrochloride (2) was made by treating 1 first with ammonia and then with hydrochloric acid [20].…”

“…3-(9-Anthryl)-propionic acid chloride (1) was synthesized by treating 3 with oxalyl chloride [20]. 3-(9-Anthryl)-propylamine hydrochloride (2) was made by treating 1 first with ammonia and then with hydrochloric acid [20]. 3-(9-Anthryl)-propionic acid 2,5-dioxo-pyrrolidin-1-yl ester (4) and 3-(9-Anthryl)-propanol (5) were prepared following the procedure in the literature [21,22].…”

Templating Photoreactions in Solution

“…The effect of the metal ion template may at times be counterintuitive, as in the photoconversion of a crown ether to a cryptand through dimerization of pendant anthracenes, where the presence of bound metal ions induces a decrease in dimerization effi ciency. 85 Instead, the intramolecular photodimerization of a macrocylic system incorporating two anthracence is sensitive to the presence of bound sodium ions, which direct the formation of the 9,10 -photodimer ( Fig. 2.17 ).…”

1‐(Methylamino)anthracene – An Accessible Building Block for Photoresponsive Compounds

“…[3][4][5][6][7][8][9][10][11][12][13][14] Substitution of anthracene in position 1 or 2 provides a wider diversity of possible products (Figure 1), however, such building blocks are basically less available. [3][4][5][6][7][8][9][10][11][12][13][14] Substitution of anthracene in position 1 or 2 provides a wider diversity of possible products (Figure 1), however, such building blocks are basically less available.…”