Bis crown ethers—VI. The first single crystal structure of the complex of schiff base type bis benzo-15-crown-5 and potassium picrate

A Highly Selective Fluorescent Chemosensor for K+ from a Bis-15-Crown-5 Derivative

“…As shown in Scheme above, the adduct could either be a 2:2 complex of K + and 1 (a discrete complex) or a complex in which each crown of one molecule of 1 forms K + sandwich complexes with crowns from two other moles of 1 (which could lead to K + sandwich bridged oligomers in solution). Recently, the crystal structure of a closely related bis-15-crown-5 compound was reported as a 2:2 adduct with K + , indicating such adducts can form . While the assignment of the structure of the K + adduct in the system reported here is not definitive, it is consistent with the data and serves to explain the remarkable difference in the fluorescence behavior between adducts with K + and those with other ions.…”

“…Recently, the crystal structure of a closely related bis-15-crown-5 compound was reported as a 2:2 adduct with K + , indicating such adducts can form. 13 While the assignment of the structure of the K + adduct in the system reported here is not definitive, it is consistent with the data and serves to explain the remarkable difference in the fluorescence behavior between adducts with K + and those with other ions. Complexes of 1 with Na + do not produce bridged sandwiches 2,3 and very little change in the fluorescence behavior is observed.…”

New bis(azobenzocrown)s with dodecylmethylmalonyl linkers as ionophores for sodium selective potentiometric sensors

“…However, intermolecular complexes may be formed instead. In particular cases, a 2:2 (biscrown:ion) stoichiometry is possible, with two cations being shared by two ligand molecules [18, 19]. Such is the case, for example, in bis(azobenzocrown) with a short, dioxyethylene linker that forms an intermolecular sandwich-type complex of 2:2 stoichiometry with sodium ions [3].…”

Structural and selectivity of 18-crown-6 ligand in lanthanide–picrate complexes

“…These complexes include the benzo-15-crown-5 [21,22] and 1,3-phenylenebis(formyloxyacetyl-4'-benzo-15-crown-5) [23]. The cyclic polyether 18C6 ligand that is thought to control 0022-328X/$ -see front matter Ó 2008 Elsevier B.V. All rights reserved.…”