Anthracene-induced formation of highly twisted metallacycle and its crystal structure and tunable assembly behaviors

Abstract

Polycyclic aromatic hydrocarbons (PAHs) continue to attract increasing interest with respect to their applications as luminescent materials. The ordered structure of the metal−organic complex facilitates the selective integration of PAHs that can be tuned to function cooperatively. Here, a unique highly twisted anthracene-based organoplatinum metallacycle was prepared via coordination-driven self-assembly. Single-crystal X-ray diffraction analysis revealed that the metallacycle was twisted through the cooperation of strong π···π stacking interactions and steric hindrance between two anthracene-based ligands. Notably, the intramolecular twist and aggregation behavior introduced restrictions to the conformational change of anthracenes, which resulted in increased emission intensity of the metallacycle in solution. The emission behaviors and suprastructures based on the highly twisted metallacycle can be modulated by the introduction of different solvents. This study demonstrates that this metallacycle with highly twisted structure is a promising candidate for sensing and bioimaging applications.

Beyond Platonic: How to Build Metal–Organic Polyhedra Capable of Binding Low-Symmetry, Information-Rich Molecular Cargoes

“…The strict spatial separation enforced by the metal–organic architecture preserved the fluorescence in both high- and low-concentration regimes, allowing white-light emission. Similar principles were recently reported in a metallacycle where a high degree of intramolecular twist constrained the incorporated anthracenes, increasing the emission intensity . Furthermore, the same group, working with the Sun group, showed that metal–organic capsules can self-assemble into soft superstructures of up to the millimeter scale …”

Chirality-Governed UCST Behavior in Polypeptides

“…This hysteresis in 1 H NMR spectra between heating and cooling cycles is in accordance with the hysteresis observed in transmittance spectra (Figure a). For DL-A 20 (Figure b), all the resonances of proton on DL-A 20 maintain the similar peak shape as the temperature increased or decreased (Figure S8), indicating no significant hydration or dehydration of polypeptides because of their random coil structures. , …”

“…After heating from 45 to 55 °C, sharper peaks of the protons on the side chains are observed as the temperature increased to 55 °C (Figure S7), indicating the less conformation restriction and faster molecular movements due to deaggregation of polypeptides, and the deaggregation is induced by the hydration of polypeptides at temperature higher than T cp . 47,48 The sharp transition of peak shape when heating from 45 to 55 °C can be attributed to the simultaneous fracture of cooperative hydrogen bonds between chiral polypeptides (Figure 5a). 49 However, when cooling from 55 to 25 °C, the peaks become broader gradually (Figure S7), meaning the blunt re-formation of hydrogen bonds between chiral polypeptides and slow reaggregation of polypeptides.…”

“…For DL-A 20 (Figure 4b), all the resonances of proton on DL-A 20 maintain the similar peak shape as the temperature increased or decreased (Figure S8), indicating no significant hydration or dehydration of polypeptides because of their random coil structures. 47,48 The aggregation behavior of L-A 20 and DL-A 20 was studied via dynamic light scattering (Figures S9 and S10). At higher pH (pH = 6), both the mean sizes of L-A 20 and DL-A 20 aggregates are lower than 200 nm and exhibit negligible changes upon heating (Figures S9a and S10a).…”

Entropy directs the self-assembly of supramolecular palladium coordination macrocycles and cages

“…Self-assembled macrocycles, [1][2][3][4][5][6][7] cages, [8][9][10][11][12][13] and oligomers [14][15][16] featuring palladium-coordination nodes are a mainstay of supramolecular chemistry due to their unique mechanical, [14][15][16][17][18] optoelectronic, [19][20][21][22][23][24][25][26][27][28] and catalytic [29][30][31][32][33][34][35][36][37][38][39][40][41][42] applications. The squareplanar coordination geometry of the coordination node permits the synthesis of well-dened constructs invoking simple geometric design principles.…”