Photochromic Modulation of the fluorescence of CdSe/ZnS in a nanoparticle-organogel material

LUCIANA C. SCHMIDT; EDELSZTEIN VALERIA C.; JULIA PÉREZ PRIETO; SPAGNUOLO CARLA; DI CHENNA PABLO. H; RAQUEL E. GALIAN

Cordoba

Congreso; Tercera Reunión NanoCórdoba 2014; 2014

Semiconductor nanoparticles known as Quantum Dots (QDs) have been extensively used due to their unique optical properties that can be tuned with their size. Incorporation of these nanoparticles in organogels has been recently reported, where the symbiosis between the components gives rise to an enhancement of the CdSe fluorescence and a reduction of the critical gelation concentration (cgc), preserving the morphology of the organogel fibers.[1] A reversible modulation of the QDs luminescence has been reported for a cationic dithienylethene directly attached to the nanoparticle surface. The isomerization of the photochromic ligand was used to regulate the QDs fluorescence properties at least for 8 cycles.[2] Similar photocromic compounds were used for organic fluorophore-doped steroid organogel.[3] The results reported herein, combine the preparation of a QDs-organogel hybrid and the modulation of the luminescence properties of the QD by a photochromic compound embedded into the system. The preparation and characterization of a luminescent organogel based on CdSe/ZnS quantum dots and a non-cholesteryl steroid low-molecular mass organogelator (LMOG) will be described. The photophysical properties of the system will be discussed together with the interaction studies by di↵erent techniques such as nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR) and steady state and time resolved fluorescence. The ON-OFF photoswitching cycles of the QDs fluorescence in the organogel was repeated more than 20 times and the readout capability of both isomers was followed by 100 minutes. This novel, photostable and fluorescent QD-Organogel hybrid is a promising system for the development of new controllable luminescent materials. [1] P. D. Wadhavane, R. E. Galian, M. A. Izquierdo, J. Aguilera- Sigalat, F. Galindo, L. Schmidt, M. I. Burguete, J. P´erez Prieto, S. V. Luis, J. Am. Chem. Soc., 2012, 20554-20663. [2] Z. Erno, I. Yildiz, B. Gorodetsky, F. M. Raymo, N. R. Branda, Photochem. Photobiol. Sci., 2010, 9, 249-253 [3] V. C. Edelsztein, E. A. Jares-Erijman, K. M¨ullen, P. H. Di Chenna, C. C. Spagnuolo, J. Mater. Chem., 2012, 22, 21857-21861