Tuning the Behavior of a Hydrotalcite-Supported Sulfonated Bithiophene from Aggregation-Caused Quenching to Efficient Monomer Luminescence

Abstract

The synthesis, electronic spectral and photophysical properties of a new bithiophene derivative, (2,2′-bithiophene)-3,5,5′-trisulfonic acid, a2-SO 3H, were investigated in organic or aqueous solution, in neat oil form, and in the solid state by cointercalation with different amounts of the surfactant 1-heptanesulfonate (HS) into a layered double hydroxide (LDH). In solution the fluorescence quantum yield (fF) of a2-SO 3H increases by one order of magnitude when compared to the unsubstituted bithiophene (a2) counterpart. However, the most dramatic change is obtained when a2-SO 3H is incorporated with HS into a Zn,Al-LDH, where values of fF up to 58% are obtained in comparison with values of 4% for neat a2-SO 3H (as an oil) and 2% for an LDH containing only a2-SO 3H. In the solid state (LDH), in addition to the monomeric form of a2-SO 3H, H-and other types of aggregates are present, which are found to be dependent on the percentage HS content. Time-resolved fluorescence studies further rationalize this behaviour with single and double exponential decays mirroring the contributions of monomers and aggregates. The study validates a strategy of increasing fluorescence in the solid state by introduction of electrodonating groups and isolation of the a2-SO 3H units within the LDH structure with an appropriate surfactant (HS).

Regioselective Palladium-Catalyzed Chain-Growth Allylic Amination Polymerization of Vinyl Aziridines

“…Specifically, polymers containing nitrogen (i.e., polyamines) are valuable materials that can ionize to produce water-soluble macromolecules or provide reactive sites for postpolymerization functionalization. These attributes have made polyamines versatile in the fields of carbon fixation, 45,46 water purification, 47,48 chemosensing, 49,50 and biotechnology. 51−53 Within the biotechnology space, polyamines such as linear polyethylenimine (l-PEI) have been used as nucleic acid delivery agents, 54 responsive drug delivery systems, 24 and antimicrobial materials.…”

An Unlimited Color Palette from Perylene Derivative Molecules Dispersed within Hybrids

“…Indeed, because of the dense molecular packing provided by the LDH exchange material, the fluorescent molecules must be further dispersed by cointercalation with nonphotoactive molecules such as surfactant molecules. Usually, long alkyl chain surfactants are preferred, such as dodecylsulfate (DS) or dodecylbenzenesulfonate (DBS), because they space the layers and allow the phosphors to be well accommodated and ensconced within the LDH galleries. − …”