Photocontrol of luminescent inorganic nanocrystals via an organic molecular switch

Abstract

A photo-controlled and quasi-reversible switch of the luminescence of hexadecylamine-coated ZnO nanocrystals (ZnO@HDA Ncs) is operated via a molecular photoswitch (dithienylethene, DTE). The interaction between the DTE switch and the ZnO@HDA Ncs is thoroughly investigated using NMR spectroscopy techniques, including DOSY and NOESY, showing that the DTE switch is weakly adsorbed at the surface of the Ncs through the formation of hydrogen bonds with HDA. Steady state and time-resolved luminescence quenching experiments show a complex behavior, related to the spatial distribution of the emitting defects in the Ncs. Analysis of the data using models previously developed for Ncs supports static quenching. Both isomeric forms (open or closed) of the DTE switch quench the emission of Ncs, the efficiency being more than ten times higher for the closed isomer. The mechanism of quenching is discussed and we show that quenching occurs mainly through resonant energy transfer for the closed isomer and through electron transfer for the open one. The HDA layer mediates the quenching efficiency as only defects located near the surface are quenched.

Tailoring the Schiff base photoswitching – a non-adiabatic molecular dynamics study of substituent effect on excited state proton transfer

“…Molecular switches, among other single molecule electronic units, are characterized as bi-stable systems in which reversible switching of various physical and chemical properties is achieved through exposure to external stimulus. The two forms of the switching molecule may differ by numerous attributes such as cis-trans isomerism [21][22][23][24] , chirality 25 , open-closed ring structure, [26][27][28] or tautomeric structure [29][30][31][32][33] . Up to date, the palette of experimentally studied factors allowing for the switching control includes an external electromagnetic irradiation 21,26,34 , electric current transmission 29,35 , static electric 22 and magnetic 26 fields, short-range forces 36 , temperature 26,37 , chemical reactions, 38,39 and mechanical stretching 40 .…”

Visible tunable lighting system based on polymer composites embedding ZnO and metallic clusters: from colloids to thin films

“…Thus, other solutions, such as free HM and RE luminescent nanocrystal or metal clusters, may be also considered, as recently reported. [11–17]…”

Insight into the Role of Ligands in the Yellow Luminescence of Zinc Oxide Nanocrystals

“…[4][5][6][7] For many of these applications, a high degree of control of the optical properties is required. [23][24][25] Herein, we report the effects of solvent and ligand exchange on the emission of colloidal ZnO NCs in the visible range. [8] Previous investigations into the optical properties of ZnO colloids have mostly focused on the impact of the synthesis protocols.…”