Under pressure: An anionic organic fluorophore (a stilbene derivative, BTZB) assembled into a layered double hydroxide host has reversible optical responses, including changes in absorption spectra, luminescence color, and fluorescence lifetime, on changing the external pressure (see picture). These changes are not observed for pristine BTZB.

Multicolor luminescent fi lms have great potential for use in optoelectronics, solid-state light-emitting materials, and optical devices. This work describes a systematic investigation of the ordered assembly of two-(blue/green, blue/ orange, red/blue, red/green) and three-color (blue/red/green) light-emitting ultrathin fi lms (UTFs) by using different photofunctional anions [bis( Nmethylacridinium)@polyvinylsulfonate ion pairs and anionic derivatives of poly( p -phenylene), poly(phenylenevinylene), and poly(thiophene)] and Mg-Al-layered double hydroxide nanosheets as building blocks. The rational combination of luminescent components affords precise control of the emission wavelengths and intensity, and multicolored luminescent UTFs can be precisely tailored covering most of the visible spectral region. The assembly process of the UTFs and their luminescence properties, as monitored by UV-vis absorption and fl uorescence spectroscopy, resulted in a gradual change in luminescence color in the selected light-emitting spectral region upon increasing the number of deposition cycles. X-ray diffraction demonstrates that the UTFs are periodic layered structures involving heterogeneous superlattices associated with individual photoactive anion-LDH units. These UTFs also exhibit well-defi ned multicolor polarized fl uorescence with high polarization anisotropy, and the emissive color changes with polarization direction. Therefore, this work provides a way of fabricating heterogeneous UTFs with tunablecolor luminescence as well as polarized multicolor emission, which have potential applications in the areas of light displays and optoelectronic devices.have been reported (semiconductor nanocrystals, [ 2 ] rare-earth compounds, [ 3 ] metal complexes, [ 4 ] and polymers [ 5 ] ), several challenges remain unresolved. Firstly, the differences in luminous effi ciency and intensity between different color components complicate the balance of the color display; as a result obtaining fi nely tunable luminescent colors is diffi cult and challenging. Secondly, a prerequisite for most optoelectronic applications is the development of transparent ordered fi lms; unfortunately, such fi lms have been much less frequently studied than solution and powder systems. [ 6 ] Thirdly, effi cient whitelight-emitting phosphors for substituting conventional light sources are rather limited, owing to the complicated synthesis procedures involved. [ 7a ] Additionally, the energy/charge transfer processes occurring between the different color components make it diffi cult to fi nely control the color purity and stability of the resulting white light. [ 7b ] Furthermore, although white-light emissions have been observed using both organic [ 7c ] and inorganic materials, [ 7d ] white-light materials with special performance, such as polarized emission, for instance, are still very rare; such materials need to be developed in order to solve the problems occurring in the backlighting of liquid-crystal displays. [ 8 ] Therefore, to meet the requireme...

A cationic functional molecule (BNMA) was assembled with a positively-charged LDH monolayer through a polyanion (PVS) as the intermediary. The approach allows fine-tuning and ordered assembly of functional cations with LDH monolayers for designing and achieving novel organic-inorganic ultra-thin films.

Neutral poly(N-vinyl carbazole) (PVK) and perylene are coassembled within the interlayers of layered double hydroxide (LDH) nanosheets to form (perylene@PVK/LDH)(n) ultrathin films by the hydrogen-bond layer-by-layer assembly method. An efficient 2D fluorescence resonance energy transfer (FRET) process from PVK to perylene is demonstrated, and this FRET process can be inhibited/recovered reversibly by the adsorption/desorption of common volatile organic compounds (VOCs).

Members of the layered rare-earth hydroxides (LRHs) family with the generalized formula (Y(1-x)Ln(x))(2)(OH)(5)NO(3)·nH(2)O (Ln = Tb, Eu; 0% ≤x≤ 100%) (named as YTb-LRHs, YEu-LRHs) have been synthesized via a hydrothermal route. Crystal structures and elemental compositions have been investigated by X-ray diffraction (XRD), elemental analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These results show that Ln(3+) species are successfully incorporated into the LRH host lattice to form layered hydroxide solid solutions. The YTb-LRHs and YEu-LRHs samples exhibit well-defined photoluminescence. The color of the luminescence can be tuned by changing the concentration of Ln(3+). Furthermore, the ternary YTbEu-LRH system was also synthesized, an example of the host layers containing variable types of the lanthanide cations. This provides the possibility to tune the chemical composition and the luminescent properties of the lanthanide species with the flexibility of intercalation hosts for potential applications in luminescent materials and field emission displays.