Synthesis of Structurally Diverse Emissive Molecular Rotors with Four-Component Ugi Stators

Abstract

The use of the multicomponent Ugi reaction to rapidly prepare a library of dumbbell-like molecular rotors is highlighted here. The synthetic strategy consisted of the atom-economic access to 15 bulky and structurally diverse iodinated stators, which were cross-coupled to the 1,4-diethynylphenylene rotator. From those experiments, up to six rotors 1a-c and 1l-n were obtained, with yields ranging from 35 to 69% per coupled C-C bond. In addition to the framework diversity, five of these compounds showed aggregate-enhanced emission properties thanks to their conjugated 1,4-bis(phenylethynyl)benzene cores, a property that rises by increasing the water fraction (f) in their THF solutions. The results highlight the significance of the diversity-oriented synthesis of rapid access to new molecular fluorescent rotors.

Review on the Ugi Multicomponent Reaction Mechanism and the Use of Fluorescent Derivatives as Functional Chromophores

“…A close look in the literature will show the readers a few more examples − (only five) of functional chromophore derivatives synthesized using the Ugi MCR applying the scaffold approach. This is a clear indication of the vast field to be explored in the next years by using these two approaches (Figure ).…”

Nanoscale Organization and Solid-State Dynamics of Carbazole-[π]-Carbazole Rotors Edged with Aliphatic Chains

“…Subsequently, we explored the association of these molecules by gradually changing the media from 100% THF to 100% hexane. Previously, we employed a similar strategy with other fluorescent molecular rotors using increasingly higher water fractions ( f w ), resulting in an enhanced emission. , In the case of the molecular rotors 2–4 , the reason to use hexane was twofold: (a) these compounds showed limited solubility in this solvent and (b) the aliphatic solvent was anticipated to have attractive van der Waals interactions with the peripheral chains, favoring aromatic interactions between the neighboring rotors. Therefore, we carried out experiments using different THF/hexane fractions ( f hex ), as indicated in Figure .…”

Dual-State Emission (DSE) in Organic Fluorophores: Design and Applications

“…Motions at the molecular level may occur at different time scales, depending on the size of the mobile component. Naturally, the frequency of these reorientations may be altered if they occur in solution , or the solid state . This section includes representative examples that document the inner motion of conjugated molecules.…”