Structural control of the photoluminescence of silole regioisomers and their utility as sensitive regiodiscriminating chemosensors and efficient electroluminescent materials

We synthesized a group of silole regioisomers 1_x,y, whose photoluminescence varied dramatically with its regiostructure. By internally hindering the intramolecular rotation, we succeeded in creating a novel silole (1_3,4) that is strongly luminescent in solutions and whose fluorescence quantum yield in acetone is as high as 83%. We revealed that 1 _3,4 was a sensitive chemosensor capable of optically discriminating nitroaromatic regioisomers of p-, o-, and m-nitroanilines. Against general belief, crystal formation of 1_2,4 blue-shifted its emission color and boosted its emission efficiency. The light-emitting diode based on the crystal of 1_2,4 emitted a strong blue light (464 nm) in a high current efficiency (5.86 cd/A).