In addition, the amphiphilic Pt(II) complexes with sulfonate pendants could assemble into ordered nanoaggregates, such as vesicles and nanofibers, in solutions through the switching-on of the intermolecular Pt Upon the introduction of the sterically demanding bulky substituent groups on the terpyridine ligands of the amphiphilic complex, in stark contrast to the formation of nanotubes, helical ribbons are formed and attributed to a lesser extent to intermolecular Pt For example, an oligo( p-phenylene ethynylene)-containing amphiphilic alkynylplatinum(II) terpyridine complex has been found to exhibit the formation of nanotubes assisted by the intermolecular Pt Pt interactions can be turned on through the proximity of the molecules and can serve as an additional driving force for the self-assembly ( 14, 24, 25) and consequently results in the formation of assembled nanostructures that are different from those without the contribution from Pt.By reducing solvation through the introduction of nonsolvents, intermolecular Pt Pt interaction between pairs of Pt(II) complexes and other nonbonded intermolecular interactions such as π−π interactions ( 4, 22, 23).The amphiphilic platinum(II) complex, termed Pt(II) amphiphile, is a special family of metallo-amphiphiles that displays the coexistence of the unique Pt Unlike organic and polymer amphiphiles ( 17– 21), metallo-amphiphiles are relatively less extensively explored ( 10). These assembled structures are determined at thermodynamic equilibrium by the balance of various nonbonded interactions, such as hydrophobic interactions, hydrogen bonding, and π−π interactions ( 9, 11– 13) and have broad implications in various applications, ranging from drug delivery, biosensors, cell imaging, to optoelectronic devices ( 8, 14– 16). In particular, amphiphiles, which contain both hydrophilic and hydrophobic parts, have demonstrated the ability to assemble into various nanostructures (e.g., micelles, nanotubes, nanorods, nanosheets, and vesicles), attracting broad interests of chemists and material scientists. Scientists have also designed numerous functional materials by strategically altering molecular building blocks, as slight modifications in these building blocks may significantly change the morphology of the assembled structures due to a change in the relative strength of various noncovalent interactions (NCIs) ( 8– 10). This organization of molecular building blocks in a noncovalent manner is highly prevalent in nature and vital for living organisms examples include protein folding, bilayer membrane formation, DNA, and viruses ( 2, 5– 7). Supramolecular assembly, which uses randomly oriented molecules to form ordered structures, offers a bottom-up approach to design functional materials at multiscale levels ( 1– 4). Pt and π−π interactions that result in an isodesmic growth.On the contrary, the self-assembly in aqueous solution forms spherical nanostructures of PtB, which is primarily due to the predominant contribution from the less directional hydrophobic interactions over the directional Pt Pt interaction, leading to the cooperative growth and the formation of fibrous nanostructures.Our results suggest that the self-assembly of PtB in acetone–water (7:1, vol/vol) solution is predominantly driven by the directional noncovalent Pt Pt interaction can indeed facilitate the formation of linear structures packed in a helix-like fashion.In subsequent oligomer MD simulations, we demonstrate that this directional Pt Pt interactions arising from the interaction between the p z and d z 2 orbitals play a crucial role in determining the formation of ordered self-assembled structures.To reveal the underlying reasons and driving forces for these self-assembly processes, we performed QM calculations and show that the Pt In contrast, a cooperative growth is found for the self-assembly of PtB in acetone–water (7:1, vol/vol) solution, which is further verified by the stopped-flow experiments, which clearly indicates the existence of a nucleation phase in the acetone–water (7:1, vol/vol) solution. Interestingly, we found that the self-assembly mechanism of PtB in aqueous solution follows a nucleation-free isodesmic model, as revealed by the temperature-dependent UV-Vis experiments. Pt interactions in directing self-assembly by combining temperature-dependent ultraviolet-visible (UV-Vis) spectroscopy, stopped-flow kinetic experiments, quantum mechanics (QM) calculations, and molecular dynamics (MD) simulations.Here, we report the use of an amphiphilic Pt(II) complex, K (PtB), as a model to elucidate the key role of Pt
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