Cooperative Au(I)···Au(I) Interactions and Hydrogen Bonding as Origin of a Luminescent Adeninate Hydrogel Formed by Ultrathin Molecular Nanowires

Abstract

Two water-soluble [Au( N-adeninate)(PR)] complexes (PR = PMe (1); PTA (3)) were synthesized by the coordination of the respective cationic [Au(PR)] fragment to the N position of the adeninate anion. Both complexes crystallize as dimers by aurophilic contacts of 3.2081(6) Å in 1 and 3.0942(7) and 3.0969(7) Å in 3, but different packings are observed due to the crystallizing solvent choice and the nature of the ancillary phosphine ligand. At this regard, different supramolecular behavior is observed in water, ranges from the formation of ultrathin nanowires of 5.3 ± 1.9 nm of diameter and up to 1.5 μm in length and leads to a blue-luminescent hydrogel for 1, to the single-crystallization of 3. Parallel computational studies carried out show that aurophilicity and N-H···N or O-H···N hydrogen bonding are comparable in strength, suggesting a competition between all types of weak forces in the final observed macroscopic properties.

Recent Progress on Supramolecular Luminescent Assemblies Based on Aurophilic Interactions in Solution

“…Other miscellaneous gold chemical structures studied in the last years are shown in Figure 31. In 2018, López-de-Luzuriaga and coworkers reported the adeninate gold(I) complex 80 [54]. The complex was able to form a supramolecular luminescent hydrogel at unexpected high concentrations (250 mM).…”

Aggregation induced emission of a new naphthyridine-ethynyl–gold(i) complex as a potential tool for sensing guanosine nucleotides in aqueous media

“…between two Au(I) atoms 5 , which comparable to strong hydrogen bonds. 6,7 This self-assembly into larger supramolecular aggregates can promote additional interactions between alkynyl ligands from neighboring complexes, such as π-π stacking, which can originate new luminescence bands, resulting in Aggregation Induced Emission (AIE). 8,9 The structure of the alkynyl ligands strongly influences both the luminescence as well as the size and shape of the obtained supramolecules.…”

Fluorination Effects in XPhos Gold(I) Fluorothiolates

“…Gold chemistry has emerged as one of the most interesting, fruitful, and promising trends in coordination and organometallic chemistry [1][2][3]. Taking in many cases advantage of the recurrent aurophilic interactions [4,5], gold compounds have been exploited in materials chemistry to generate light emitters [6][7][8], gelators [9,10], liquid crystals [11], and other self-assembled materials [12][13][14][15]. In medicinal chemistry, several gold compounds are being investigated as potentially therapeutic and theranostic agents against different diseases [16][17][18][19].…”