Photo‐Cleavable Cryptands: Synthesis and Structure

Abstract

The four photo-cleavable ligands 1 4 of the macrobicyclic-cryptand type have been synthesized by introducing a photo-sensitive 2-nitrobenzyl-or 4,5-dimethoxy-2-nitrobenzyl-ether bond into one of the bridges. These compounds are expected to retain the selective binding features of the parent cryptands and to allow the photolytically induced release of alkali ions in aqueous solution. The crystal structures of the ligand 5-(2-nitrophenyl)-4,7,13,16,21,24-hexaoxa-l,l0-diazabicyclo[8.8.8]hexacosane (3) and of its KSCN complex 13 have been determined. They are analogous to those of the corresponding parent species, confirming the macrobicyclic geometry and the cryptate nature of the complex. Spectroscopic properties are reported.

Reversible Bulk Photorelease of Strontium Ion from a Crown Ether-Linked Merocyanine

“…[5,6] The major drawback of most of those structures is that the cation photorelease is irreversible and does not allow the repetition of the experiment over a large number of triggering shots, for improving the signal-to-noise ratio by accumulation.…”

Managing Tight Binding Receptors for New Spearations Technologies

“…This strategy closely follows that reported earlier by Lehn and Quinkert. 68 A second strategy is also reported in which a true "catch and release" protocol is employed for capture of selected metal ions. In this strategy, the metal ion participates in the closure of the Nsubstituted 7,16-diazacyclo [8.8] macrocycle (8) by a template closure of the third bridge to produce the identical cryptate (i.e., 16) formed from metal ion sequestering by cryptand 1.…”

“…[59][60][61][62] The onitrobenzyl group is the most frequently employed member of this type of cage or "phototriggers". 59,60,[63][64][65][66][67] We have completed two syntheses of a photo-cleavable, ultra tight-binding polyether cryptand, originally designed by Lehn and Quinkert, 68 in which a photoactive o-nitrobenzyl group has been strategically placed on one of the bridges of the macrobicyclic structure. We have employed these photolabile cryptands to capture selected target metal ions to form cryptates and followed this by the photorelease of the metal ions from the cryptates by UV irradiation.…”

“…Cryptand 1 was synthesized according to the strategy outlined by Lehn and Quinkert 68 . A second synthetic strategy was also explored.…”

A new concept of photogeneration of cations: Evidence for photoejection of Ca2+ and Li+ from complexes with a crown-ether-linked merocyanine by picosecond spectroscopy

“…Photochemical processes can induce very fast and spatially controllable concentration changes. Photorelease of cations from a "cage" is indeed possible by means of photocleavable chelators [1] or cryptauds [2] or by photoinduced changes in the chemical structure of chelators [3].…”