Self-assembled nanoparticles of p-phenylenediacetonitrile derivatives with fluorescence turn-on

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2012-06, Vol.14 (6), Article 877
• Main Authors: Kazlauskas, Karolis, Miasojedovas, Arūnas, Dobrovolskas, Darius, Arbačiauskienė, Eglė, Getautis, Vytautas, Šačkus, Algirdas, Juršėnas, Saulius
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Inorganic Chemistry; Lasers; Materials Science; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Research Paper
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-012-0877-6

Absence of emission concentration quenching accompanied by high emission efficiency in a solid state is highly challenging though very attractive, for example, for fabrication of solid state light emitters or fluorescent organic nanoparticles (FONs). Here, formation of FONs based on novel p -phenylenediacetonitrile derivatives by re-precipitation method in aqueous solutions is demonstrated. The exceptionality of the derivatives employed is manifested by nitrile groups-induced steric hindrance effects inhibiting concentration quenching of emission. Consisting of different size and polarity end-groups, phenyl groups in one compound and hexyl-carbazolyl in another, the derivatives were examined and compared in regard to nanoparticle formation morphology, size tunability, spectral signatures, and fluorescence turn-on efficiency. The variation of solvent/non-solvent ratio allowed to achieve tuning of the FON sizes from 55 nm up to 360 nm and resulted in maximal fluorescence on/off ratio of 38. Spectrally resolved confocal fluorescence microscopy revealed somewhat different molecule arrangement in different FONs suggesting dominant amorphous-like phase, which was confirmed by small angle X-ray scattering measurements. The FONs were verified to be stable against degradation or conglomeration into larger clusters at least over a couple of months thus implying their feasibility for practical applications. Finally, potential application of the fluorescent p -phenylenediacetonitrile nanoparticles for organic vapor sensing via fluorescence on/off switching was demonstrated.