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We report the facile construction of a molecular 818 knot and a molecular Borromean rings assembly through self-assembly directed by Cp*Rh corner units. Two curved ligands of similar size and shape were used in this study. The slight steric differences between the two ligands induce the formation of distinctly different topologies of the assembled products. The structures were confirmed by single-crystal X-ray analysis and nuclear magnetic resonance spectroscopy. [ABSTRACT FROM AUTHOR]

In this work, a noncoplanar terphenyl served as a building block to synthesize a novel 3,3′‐substituted bipyridyl ligand (L1) which further reacted with binuclear half‐sandwich units A/B, giving rise to two aesthetic 41 metalla‐knots in high yields via a coordination‐driven self‐assembly strategy. Furthermore, given the inherent compactness of the 41 metalla‐knots, it creates favorable conditions for the emergence of steric repulsion. We focused on progressively introducing nitrogen atoms featuring a lone pair of electrons (LPEs) into ligand L1 to manipulate the balance of H⋅⋅⋅H/LPEs⋅⋅⋅LPEs steric repulsion during the assembly process, ultimately achieving controlled assembly from 41 metalla‐knots to the pseudo‐Solomon link and then to molecular tweezer‐like assembly facilitated by stacking interactions. All the assemblies were well characterized by solution‐state NMR techniques, ESI‐TOF/MS, and single‐crystal X‐ray diffraction. The evolutionary process of the topological architectures is equivalent to visualizing the synergistic effect of steric hindrance and stacking interactions on structural assembly, providing a new avenue for achieving the controlled synthesis of different topologies. [ABSTRACT FROM AUTHOR]

A method was developed to link two or three o‐carborane moieties to form a series of carboranyl dithioester bridging ligands via in situ substitution of haloalkanes by tetraphenylphosphonium carboranyldithiocarboxylates. Based on these ligands, direct B−H activation without the assistance of Ag(I) and alkali was successfully achieved with half‐sandwich Ir(III) substrate [Cp*IrCl2]2 to yield corresponding bimetallic or trimetallic complexes. Single crystal structure analyses of the B−H activated complexes and corresponding SnCl2‐inserted derivatives confirm the selective B(3)‐H activation in these complexes. [ABSTRACT FROM AUTHOR]

Through a coordination‐driven self‐assembly method, four 412 ${4_1^2 }$ metalla‐links and one tetranuclear monocycle were constructed with high selectivity and yield by adjusting the substituent species of the building blocks, as evidenced using X‐ray crystallographic analysis, electrospray ionization‐time‐of‐flight/mass spectrometry (ESI‐TOF/MS), elemental analysis and detailed solution‐state nuclear magnetic resonance (NMR) spectroscopy. Based on X‐ray crystallographic analysis and independent gradient model analysis, a significant factor leading to the formation of 412 ${4_1^2 }$ metalla‐links was the introduction of F, Cl, Br and I atoms, which generated additional weak C−H⋅⋅⋅X (X=F, Cl, Br and I) interactions. Furthermore, the dynamic conversion of 412 ${4_1^2 }$ metalla‐links to monocyclic rings in methanol solution was systematically investigated using quantitative 1H NMR techniques. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Making full use of coordination‐driven self‐assembly strategy, we herein described the selective synthesis of a molecular Borromean rings and two cases of "U"‐shaped tweezer‐like molecular assemblies in high yield by using bipyridyl ligands based on biphenyl unit and half‐sandwich binuclear rhodium(III)/iridium(III) building blocks. The selective synthesis was realized by adjusting the length of dipyridyl arms. The utilization of curved U‐shaped bipyridyl ligand L1 led to tweezer‐like molecular assemblies. Subsequently, olefinic bonds were introduced to elongate dipyridyl arms obtaining ligand L2. The ligand L2 has two stable conformations, U‐shape and Z‐shape, which facilitated the formation of different topologies including the tetranuclear macrocycle and Borromean rings with different building blocks in this work. These structures in solid and solution all have been further confirmed by single‐crystal X‐ray diffraction, NMR analysis, and mass spectrometry. In addition, as an important driving force, π‐π stacking interactions not only played a significant role in the stability of structures but also further triggered photothermal conversion in solution. The experimental results demonstrated that compounds 1a and 2 had good NIR photothermal conversion efficiency (11.83% and 17.76%), and further analysis found the photothermal conversion efficiency had a gradual increase in the trend with the π‐π stacking interactions increasing. This research expands the application of topological structures in materials science and provides a new idea for the synthesis of novel photothermal conversion materials. [ABSTRACT FROM AUTHOR]

By exploiting coordination‐driven self‐assembly, high yields of two 818 molecular metalla‐knots could be obtained using a thiazole‐moiety‐containing asymmetric dipyridyl ligand 2‐(pyridin‐4‐yl)‐5‐(pyridin‐4‐ylethynyl)benzo[d]thiazole (L1), as confirmed using X‐ray crystallographic analysis, electrospray ionization‐time‐of‐flight/mass spectrometry (ESI‐TOF/MS), and detailed liquid‐state nuclear magnetic resonance (NMR) spectroscopy. To modulate the self‐assembled structures, m‐chloroperbenzoic acid (m‐CPBA) was utilized to oxidize thiazole‐based ligand L1 to N‐thiazole‐oxide‐based ligand 2‐(pyridin‐4‐yl)‐5‐(pyridin‐4‐ylethynyl)benzo[d]thiazole 3‐oxide (L2), which enabled the selective construction of the corresponding tetranuclear macrocycles. Notably, two molecular metalla‐knots could be topologically transformed from 818 knots to simple monocycles because the L1 alkyne bond was inert toward m‐CPBA, as confirmed by liquid‐state NMR spectroscopy, ESI‐TOF/MS, and elemental analysis. [ABSTRACT FROM AUTHOR]