[14]Tetraazaannulene derivatives 1–4 with various substituents were synthesized as ion recognition compounds. All solvent polymeric membrane electrodes incorporating [14]tetraazaannulene derivatives 1–4 showed rapid response for the Cu2+ ion and exhibited excellent selectivity over other mono‐ and divalent cations such as Ag+ and Ni2+ ions. The solvent polymeric membrane electrode based on [14]tetraazaannulene derivative 1 has a linear response to the Cu2+ ion from 5.01 × 10−7 – 2.63 × 10−4 M with a slope of 29.56 mV per decade. DFT calculations showed that the selectivities for the Cu2+ ion of the ISEs based on [14]tetraazaannulene derivatives 1–4 depended on both their topological and electrostatic properties caused by the introduced substituents.

A new malonate possessing two pyrene moieties was synthesized as a fluoroionophore, and its structure and fluorescence spectroscopic properties were investigated. When excited at 344 nm in acetonitrile/chloroform (9:1, v/v), the synthesized bispyrenyl malonate has the fluorescence of intramolecular excimer (λem = 467 nm) emissions and not a pyrene monomer emission (λem = 394 nm). A large absolute fluorescence quantum yield was obtained in the solid state (ΦPL = 0.65) rather than in solution (ΦPL = 0.13). X-ray crystallography analysis clarified the molecular structure and alignment of the bispyrenyl malonate in the crystal phase, elucidating its fluorescence spectroscopic properties. Such analysis also suggests there are intramolecular C–H···π interactions and intermolecular π···π interactions between the pyrenyl rings. Interestingly, the synthesized bispyrenyl malonate exhibits excellent fluorescence sensing for the Cu2+ ion. Remarkable fluorescence intensity enhancement was only observed with the addition of the Cu2+ ion.

The cover picture shows a graphical image of the ionophore for the Cu2+‐selective electrode. This ionophore captures the Cu2+ ion at the topside of the saddle‐shaped structure and transports the Cu2+ ion in the potentiometric liquid membrane. Details are discussed in the article by T. M. Kawakami and T. Moriuchi et al.; DOI: 10.1002/elan.201700011.