Photoswitchable Macrocycles Incorporating Acridane Moieties

Abstract

Novel crown ethers incorporating one to three 9-phenylacridinium units were synthesized in moderate yields. The acridinium units within the macrocycles were converted into the photoactive N-methyl-9-methoxy-9-phenyl-9,10-dihydroacridine (N-methyl-9-methoxy-9-phenylacridane) units.

Comparison in practical applications of crown ether sensor molecules containing an acridone or an acridine unit – a study on protonation and complex formation

“…These studies -in accordance with the present work -support that the 9-hydroxyacridine tautomeric form is preferred during the complex formation. Theoretically, the pK a of the protonated acridono-crown ether complex could be determined by the protonation of the basic nitrogen of its 9-hydroxyacridine tautomeric form (5). However, based on this study it is assumed that the heteroaromatic unit is converted back to its tautomeric acridone form upon protonation, which inhibits complex formation.…”

“…However, in the cases of both crown ethers (host molecules 4 and 3) a high competition took place between protonation and complex formation. In the case of acridono-macrocycle 4, the acidic medium partially suppressed the conversion to the preferred 9-hydroxyacridine tautomer (5), while the stabilized acridino-crown ether (3) was unable to coordinate Pb 2+ due to the protonation of its nitrogen atom. It also indicates the key role of the nitrogen atom among the other donor atoms of the macrocycle in molecular recognition.…”

“…The first acridino-and acridono-crown ethers were synthesized in the late 1990 s [2]. Since then, several sensor molecules containing an acridone or an acridine unit have been synthesized for various applications [3][4][5][6][7][8][9][10][11][12][13][14]. As we are interested in the synthesis and application of new acridino-and acridono-host molecules, a study on the application influencing properties and their molecule structural background plays an important role in the effective future development.…”

Two Acridone Units in One Crown Ether

“…2 are the first and only bisacridono-hosts. They were synthetized with moderate yields (12-18%) starting from N-methyl-2,7dihydroxy-acridone in a 2:2 type macrocyclization, but as intermediates for photoswitchable receptors, their applicability was not discussed [14,21].…”