White light and colour-tunable emission from a single component europium-1,8-naphthalimide thin film

Chemically fueled dynamic switching between assembly-encoded emissions

Self-assembly provides access to non-covalently synthesized supramolecular materials with distinct properties from a single building block. However, dynamic switching between functional states still remains challenging, but holds enormous potential in material chemistry to design smart materials. Herein, we demonstrate a chemical fuel-mediated strategy to dynamically switch between two distinctly emissive aggregates, originating from the self-assembly of a naphthalimide-appended peptide building block. A molecularly dissolved building block shows very weak blue emission, whereas, in the assembled state (Agg-1), it shows cyan emission through π stacking-mediated excimer emission. The addition of a chemical fuel, ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC), converts the terminal aspartic acid present in the building block to an intra-molecularly cyclized anhydride in situ forming a second aggregated state, Agg-2, by changing the molecular packing, thereby transforming the emission to strong blue. Interestingly, the anhydride gets hydrolyzed gradually to reform Agg-1 and the initial cyan emission is restored. The kinetic stability of the strong blue emissive aggregate, Agg-2, can be regulated by the added concentration of the chemical fuel. Moreover, we expand the scope of this system within an agarose gel matrix, which allows us to gain spatiotemporal control over the properties, thereby producing a self-erasable writing system where the chemical fuel acts as the ink.

A terpyridyl-imidazole based europium tris-(β-diketonate) complex as an efficient molecular luminescent thermometer and single component white light emitter via synergy in energy transfer between ligands and Eu3

The thermosensing and thermochromic behavior of one of our recently reported terpyridyl-imidazole based ternary europium tris-(β-diketonate) complexes of the composition [Eu(tta)3(tpy-HImzphen)] (tta = 2-thenoyltrifluoroacetone and tpy-HImzphen = 2-(4-[2,2':6',2''] terpyridin-4'-yl-phenyl)-1H-phenanthro[9,10-d]imidazole) has been thoroughly investigated in this work. The said Eu(III) complex exhibits magnificent thermosensing as well as thermochromic properties and can be recommended as an excellent temperature sensor in a wide temperature domain of 273-343 K in terms of both emission intensity ratio (Sm = 5.78% K-1 at Tm = 343 K, δT = 0.012 K) and lifetime values (Sm = 3.36% K-1 at Tm = 333 K, δT = 0.009 K) or even in terms of its emitting color (red at 268 K, violet at 303 K, and blue at 343 K). Additionally, it displays remarkable solvent-induced luminescence behavior by displaying various emitting colors instead of its sole characteristic red emission upon varying the nature of the solvent. Finally, amalgamating these two features, we are able to attain white light emission (Commission Internationale de l'Eclairage coordinates: x = 0.34, y = 0.38) at 283 K from a single component. A plausible energy transfer mechanism has also been proposed in light of the existence of the ligand-to-metal charge transfer (LMCT) state as the quencher.

Synthesis, Characterization, Cytotoxicity, Cellular Imaging, Molecular Docking, and ADMET Studies of Piperazine-Linked 1,8-Naphthalimide-Arylsulfonyl Derivatives

To reduce the mortality and morbidity associated with cancer, new cancer theranostics are in high demand and are an emerging area of research. To achieve this goal, we report the synthesis and characterization of piperazine-linked 1,8-naphthalimide-arylsulfonyl derivatives (SA1-SA7). These compounds were synthesized in good yields following a two-step protocol and characterized using multiple analytical techniques. In vitro cytotoxicity and fluorescent cellular imaging of the compounds were assessed against non-cancerous fibroblast (3T3) and breast cancer (4T1) cell lines. Although the former study indicated the safe nature of the compounds (viability = 82-95% at 1 μg/mL), imaging studies revealed that the designed probes had good membrane permeability and could disperse in the whole cell cytoplasm. In silico studies, including molecular docking, molecular dynamics (MD) simulation, and ADME/Tox results, indicated that the compounds had the ability to target CAIX-expressing cancers. These findings suggest that piperazine-linked 1,8-naphthalimide-arylsulfonyl derivatives are potential candidates for cancer theranostics and a valuable backbone for future research.