Arenedicarboximide Building Blocks for Fluorescent Photoinduced Electron Transfer pH Sensors Applicable with Different Media and Communication Wavelengths

N-(aminoalkyl)-4-chloronaphthalene-<br/>1,8-dicarboximides 1, N-<br/>(aminoalkyl)-4-acetamidonaphthalene-<br/>1,8-dicarboximides 3 and N,N'-bis(aminoalkyl)-<br/>perylene-3,4:9,10-tetracarboxydiimides<br/>4 show good fluorescent off ±<br/>on switching in aqueous alcoholic solution<br/>with protons as required for fluorescent<br/>PET sensor design. The excitation<br/>wavelengths lie in the ultraviolet<br/>(lmaxˆ345 and 351 nm) for 1 and 3 and<br/>in the blue-green (lmaxˆ528, 492 and<br/>461 nm) for 4; the emission wavelengths<br/>lie in the violet (lmaxˆ408 nm) for 1, in<br/>the blue (lmaxˆ474 nm) for 3 and in the<br/>yellow-orange (lmaxˆ543 and 583 nm)<br/>for 4. Compound 4b shows substantial<br/>fluorescence enhancement with protons<br/>when immobilized in a poly(vinylchloride)<br/>matrix, provided that 2-nitrophenyloctyl<br/>ether plasticizer and potassium<br/>tetrakis(4-chlorophenyl)borate additive<br/>are present to prevent dye crystallization<br/>and to facilitate proton diffusion<br/>into the membrane, respectively.