Tunable Two-color Luminescence and Host–guest Energy Transfer of Fluorescent Chromophores Encapsulated in Metal-Organic Frameworks

Abstract

Co-assembly of chromophore guests with host matrices can afford materials which have photofunctionalities different from those of individual components. Compared with clay and zeolite materials, the use of metal–organic frameworks (MOFs) as a host structure for fabricating luminescent host–guest materials is still at an early stage. Herein, we report the incorporation of a laser dye, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), into stilbene-based and naphthalene-based MOF systems. The resulting materials exhibit blue/red two-color emission, and the intensity ratio of blue to red fluorescence varies in different planes within the MOF crystal as detected by 3D confocal fluorescence microscopy. The observed changes in ratiometric fluorescence suggest the occurrence of energy transfer from MOF host to DCM molecules, which can be further confirmed by periodic density functional theoretical (DFT) calculations. Moreover, selective changes in luminescence behavior are observed on treating the guest@MOF samples with volatile organic compounds (methanol, acetone and toluene), indicating that these host–guest systems have potential applications as fluorescence sensors. It can be expected that by rational selection of MOF hosts and guest chromophores with suitable emissive colors and energy levels, a wide variety of multi-color luminescent and energy-transfer systems can readily be prepared in a similar manner.

Efficient multicolor and white light emission from Zr-based MOF composites: spectral and dynamic properties

“…As said in the Introduction part, excited MOFs-based systems have been reported to show energy transfer (ET) to trapped molecules like 4-(dicyanomethylene)-2-methyl-6-(4dimethylaminostyryl)-4H-pyran (DCM), 23 Rhodamine B, 24 dihexylsexithiophene (DH6T) 26 or bisanthracene. 30 They also can act as energy acceptors from other systems like quantum dots.…”

“…Moreover, one of the most favorable morphological characteristics of MOFs is their porous structure, which permits the inclusion of different guests. 23,24 Zn(OPE) 20,21 For example, an efficient ET was observed by incorporating an europium β-diketonate complex into the porous matrix of HKUST-1 MOF, making the material a photoantennae enhancing the emission of the lanthanide complex.…”

Binuclear Bi(iii) halide complexes with 4,4′-ethylenepyridinium cations: luminescence tuning by reversible solvation

“…Anyway, additional studies in this field, allowing the collection of extended statistics, are required. Solvatochromism is a well-known phenomenon, appearing in diverse classes of compounds, in particular, in metal-organic frameworks [32][33][34] and various aromatic substrates. 35 Discovery of this effect in the post-transition metal halides provides the opportunities of their further use in development of new materials.…”

Effect of Aggregation of Acridine Orange on the Luminescent Characteristics of Its Composites with a Zinc-Containing Coordination Polymer

“…In recent years a series of publications have appeared on study of the sorption of dyes by porous CPs and investigation of the properties of the obtained nanocomposites. It was shown that the presence of additional luminophores in the CPs makes it possible to obtain materials with controllable luminescence [11,12] and nonlinear optical characteristics [13] and also novel sensor systems for the selective determination of small organic molecules [14,15].…”