Self-Assembly and Mechanochromism Behavior of Gold(I) Supramolecular Cluster

Abstract

Aurophilicity interaction has played a crucial role in the controllable selfassembly of polynuclear clusters with high nuclear structures and tunable photoluminescence properties. We proposed a multi-component synergistic self-assembly strategy for the controlled synthesis of a hexadeca-nuclei gold(I) supramolecular cluster through spontaneous ligand substitution and conformation rearrangement driven by Au I •••Au I bonding interactions. In supramolecular cluster 1 2+ •2BF 4 − , multi-components could be highly accurately aggregated together when thiolate-chloride/phosphine coordination exchange reactivity is partially activated by changing the stoichiometric ratio between digold(I) corners, dppmAu 2 Cl 2 , and ditopic linkers, trithiocyanuric salt. Mass spectra confirmed the stepwise self-assembly mechanism in solution, which was also supported by crystallographic data. Supramolecular cluster 1 2+ •2BF 4 − displayed intense emission properties either in the solid state or in solution. Moreover, cluster 1 2+ •2BF 4 − exhibited a reversible mechanochromic luminescence behavior in the crystalline state and aggregation-caused blue-shifted emission in solution. Hence, emissive gold(I) cluster with strong aurophilicity interactions has great potential value in the fluorescence imaging for 3D printing hydrogels.

Self-Assembly of Polynuclear Coordination Cage and Organic Dyes Adsorption Behavior in Water

“…The UV–vis absorption spectrum of the capsule cluster [C1] 2 6+ ·6PF 6 – displays a prominent shoulder peak at approximately 267 nm (Figure S18), which can be attributed to the admixture of a 1 (d → p) electronic transition, characteristic of [Au 2 (P^P) 2 ] 2+ species and the intraligand π–π transitions of dppm and/or pipzdtc ligands. − The low-energy signal appearing at about 300 nm was gradually enhanced with an increasing capsule cluster [C1] 2 6+ ·6PF 6 – concentration in MeCN (Figure a). As shown in Figure S19a, the absorption profile at 300 nm shows a linear relationship with the complex concentration, suggesting that the gold(I)-based polynuclear cluster [C1] 2 6+ ·6PF 6 – could not self-aggregate into higher oligomers . Meanwhile, in MeCN solution, the capsule cluster [C1] 2 6+ ·6PF 6 – showed a concentration-dependent emission enhancement due to aggregation, which increased exponentially when the concentration reached 9.4 × 10 –5 M and blue-shifted to 441 nm as the concentration increased from 9.4 × 10 –5 M to 1.2 × 10 –4 M (Figure d).…”

“…Upon the adsorption of MO and MB, the zeta potential values shifted to −0.75 and 5.15 mV respectively. This observation indicates that the positively charged capsule cluster [C1] 2 6+ ·6PF 6 – can readily bind to anionic dyes through electrostatic attractions and π–π stacking interactions, ,, which are primary contributors to the selective adsorption of anionic dyes MO and AR. Although the capsule cluster [C1] 2 6+ ·6PF 6 – exhibits a positive charge, it also displays a modest adsorption capacity for the cationic dye MB.…”

“…As shown in Figure S19a, the absorption profile at 300 nm shows a linear relationship with the complex concentration, suggesting that the gold(I)-based polynuclear cluster [C1] 2 6+ •6PF 6 − could not self-aggregate into higher oligomers. 38 Meanwhile, in MeCN solution, the capsule cluster [C1] 2 6+ •6PF 6 − showed a concentration-dependent emission enhancement due to aggregation, which increased exponentially when the concentration reached 9.4 × 10 −5 M and blueshifted to 441 nm as the concentration increased from 9.4 × 10 −5 M to 1.2 × 10 −4 M (Figure 2d). To gain insight into the self-aggregation behavior driven by intermolecular metal− metal bonding interactions in the solution, electronic absorption was taken as a function of the concentration measurement spectra of capsule cluster [C1] 2 6+ •6PF 6 − in acetonitrile solution at room temperature (Figures 2a and S19a).…”

“…•6PF 6 − can readily bind to anionic dyes through electrostatic attractions and π−π stacking interactions, 38,49,50 which are primary contributors to the selective adsorption of anionic dyes MO and AR. Although the capsule cluster [C1] 2 6+ •6PF 6 − exhibits a positive charge, it also displays a modest adsorption capacity for the cationic dye MB.…”