Tuning the Solubility of Self-Assembled Fluorescent Aromatic Cages Using Functionalized Amino Acid Building Blocks

Abstract

We previously reported novel fluorescent aromatic cages that are self-produced using a set of orthogonal dynamic covalent reactions, operating simultaneously in one-pot, to assemble up to 10 components through 12 reactions into a single cage-type structure. We now introduce N-functionalized amino acids as new building blocks that enable tuning the solubility and analysis of the resulting cages. A convenient divergent synthetic approach was developed to tether different side chains on the N-terminal of a cysteine-derived building block. Our studies show that this chemical functionalization does not prevent the subsequent self-assembly and effective formation of desired cages. While the originally described cages required 94% DMSO, the new ones bearing hydrophobic side chains were found soluble in organic solvents (up to 75% CHCl 3 ), and those grafted with hydrophilic side chains were soluble in water (up to 75% H 2 O). Fluorescence studies confirmed that despite cage functionalization the aggregation-induced emission properties of those architectures are retained. Thus, this work significantly expands the range of solvents in which these self-assembled cage compounds can be generated, which in turn should enable new applications, possibly as fluorescent sensors.

Quadruple Functionalization of a Tetraphenylethylene Aromatic Scaffold with Ynamides or Tetracyanobutadienes: Synthesis and Optical Properties

“…In both cases, a weak emission could be recorded from 550 to 1300 nm for tetra‐TCBD 4 (with a maximum at 760 nm), and from 650 to 1300 nm for mono‐TCBD 13 (with a maximum at 800 nm). These observations are in line with previous reports from our group about the solid‐state luminescence in the near‐infrared (NIR) range of TCBD connected to polyaromatic cores, [20,21] and, again, in stark contrast with the fluorescence emission of the starting TPE tetra‐aldehyde 9 which is centered around 520 nm [39–41] …”

“…These observations are in line with previous reports from our group about the solid-state luminescence in the near-infrared (NIR) range of TCBD connected to polyaromatic cores, [20,21] and, again, in stark contrast with the fluorescence emission of the starting TPE tetra-aldehyde 9 which is centered around 520 nm. [39][40][41]…”

Expanding Structural Diversity In A Library Of Disulfide Macrocycles Through In-Situ Imide Hydrolysis

“…4a) with expectation of rapid and full conversion. 36,37 After 3 days we observed via LC-MS the selective formation of only one product, which was identi ed as dimeric macrocycle A 2 with two disul de bonds (Fig. 3b).…”

Expanding structural diversity in a library of disulfide macrocycles through in-situ imide hydrolysis

“…We started with A dissolved in pure DMSO (Fig. 4 a) with expectation of rapid and full conversion 36 , 37 . After 3 days we observed via LC–MS the selective formation of only one product, which was identified as dimeric macrocycle A 2 with two disulfide bonds (Fig.…”