Coumarin-Strapped Calix[4]pyrrole:  A Fluorogenic Anion Receptor Modulated by Cation and Anion Binding

Abstract

A new strapped calix[4]pyrrole containing a fluorophore as part of the strap has been synthesized and characterized. Association constants with various anions have been determined using both fluorescence titration and isothermal titrations calorimetry (ITC). The two sets of association constants were found to be in good agreement with one another. The fluorescence emission properties of this new receptor could be controlled by addition of Na+ (or H2O) and anions. However, the fluorescence quenching by anions is only observed in the presence of Na+ (or H2O). All the experimental evidence is consistent with the notion that independent PET processes are modulated by separate cation and anion recognition events. As such, this system operates as an elementary logic gate wherein anion and cation concentrations serve as the input and fluorescence intensity changes provide the output.

Factors That Regulate the Conformation of m‐Benziporphodimethene Complexes: Agostic Metal–Arene Interaction, Hydrogen Bonding, and η2,π Coordination

“…[23,24] In general, they have no extended p-conjugated system to offer real-time spectroscopic information and require the introduction of an additional chromophore. [25][26][27] Benziporphodimethene (BPDM, see Scheme 1B) with sp 3 -hybridized carbon atoms at the meso positions and a tripyrrin moiety in the macrocycle blends the features of porphyrin and calixpyrrole to provide both photophysical advantages and molecular flexibility. However, reports on the chemistry of BPDM are still rare, and 6,6,21,21-tetraphenylm-benziporphodimethene (TPBPDM; 1) has been the only comprehensively studied case.…”

Photoinduced Electron Transfer in Photorobust Coumarins Linked with Electron Donors Affording Long Lifetimes of Triplet Charge‐Separated States

“…[2, 5, [18][19][20][21] For example, photophysical properties of donor-substituted coumarin dyes such as 7-aminocoumarin and its derivatives have been the subject of extensive investigations, which focus on twisted intramolecular charge-transfer (TICT) states.…”

Calix[n]pyrroles as Anion and Ion-Pair Complexants

“…Presumably, this reflects the fact that these latter species bind to the carbonyl moiety in coumarin, thereby turning off an inherent photoinduced electron transfer (PET) quenching process. In contrast, the fluorescence intensity of 50 could reduced via the addition of anions that are known to bind within the calix [4]pyrrole core [69]. Such systematic, substrate-dependent changes in fluorescence emission intensity means this receptor acts as a rudimentary supramolecular logic device.…”