2,2‘-Bipyridyl-3,3‘-diol Incorporated into AlPO₄-5 Crystals and Its Spectroscopic Properties as Related to Aqueous Liquid Media

Abstract

A novel fluorescent host−guest material, molecular sieves of AlPO4-5-type doped with 2,2‘-bipyridyl-3,3‘-diol, was prepared and spectroscopically characterized. The composite crystals show a pronounced optical anisotropy, indicating a high degree of alignment of the guest molecules within the zeolitic pore system. A mean tilting angle of 22° was found for the orientation of the individual dye molecules in the straight channels. The corrected fluorescence emission spectra were determined, and time-resolved fluorescence studies revealed that the dye molecules are preferentially found in three different types of microenvironment. By invoking pH-dependent studies of the dye in aqueous solution, we could trace these spectroscopic features back to two main influences, coadsorbed water within AlPO4-5 pores and guest−host interactions with a few relatively weak Brønsted acid (defect) sites of the inorganic host network.

Optical pH Sensor with Rapid Response Based on a Fluorescein‐Intercalated Layered Double Hydroxide

“…The fluorescence lifetimes were obtained by fitting the decay profiles with one‐exponential and double‐exponential forms ( Table 1 ); the fitting results obtained from the double‐exponential function is better (based on the χ 2 value). Multiexponential decay curves were usually observed in solid samples and can be attributed to highly heterogeneous environments for the molecules in the solid surfaces 20. A similar conclusion has been reported by other researchers studying intercalation of Rhodamine 6G (R6G) into Laponite clay 21.…”

A highly efficient solution and solid state ESIPT fluorophore and its OLED application

“…A single-exponential decay was observed with a fluorescence lifetime of 4.64 ns, which is superior to that of 3.2 ns reported for BP(OH) 2 in the same solvent. 27 This emission is not sensitive to oxygen as the same decay was obtained in degassed dichloromethane.…”

“…23 The target linker derives from 2,2'-bipyridine-3,3'-diol (BP(OH) 2 , Scheme 2), a molecule featuring two intramolecular hydrogen bonds and well-documented for its intense doubleproton-transfer based fluorescence and applications. [24][25][26][27][28][29][30][31][32] More importantly, even in protic solvents such as MeOH and EtOH, where most ESIPT dyes are not or only weakly fluorescent, BP(OH) 2 keeps a more than decent quantum yield of 10 and 18%, respectively. 26 However, to our surprise, very few fluorescent derivatives of BP(OH) 2 have been reported in the literature.…”

A photochromic thin film based on salicylideneaniline derivatives intercalated layered double hydroxide

“…S8. The double-exponential decay curves were used in the film samples, which were usually observed in highly heterogeneous environment for the molecules in the solid surfaces [29][30][31]. As shown in Table 1, the fluorescence lifetime of AMH/PS-LDH (x %) decreases significantly as x increases from 2 to 100, due to the formation of aggregation as indicated by the results of fluorescence spectra.…”