New stimulus‐responsive scaffolds are of interest as constituents of hierarchical supramolecular ensembles. 1,3,5–2,4,6‐Functionalized, facially segregated benzene moieties have a time‐honored role as building blocks for host molecules. However, their user as switchable motifs in the construction of multi‐component supramolecular structures remains poorly explored. Here, we report a molecular cage
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Kueckmann, Theresa ; Maas, Frank ; Su, Xin ; Tobey, Suzanne ; Welckgenannt, Nathalie (Ed.)
Abstract 1 , which consists of a bent anthracene dimer3 paired with 1,3,5‐tris(aminomethyl)‐2,4,6‐triethylbenzene2 . As the result of the pH‐inducedababab ↔bababa isomerization of the constituent‐functionalized benzene units derived from2 , this cage can reversibly convert between an open state and a closed form, both in solution and in the solid state. Cage1 was used to create stimuli‐responsive hierarchical superstructures, namely Russian doll‐like complexes with [K⊂18‐crown‐6⊂1 ]+and [K⊂cryptand‐222⊂1 ]+. The reversible assembly and disassembly of these superstructures could be induced by switching cage1 from its open to closed form. The present study thus provides an unusual example where pH‐triggered conformation motion within a cage‐like scaffold is used to control the formation and disassociation of hierarchical ensembles.Free, publicly-accessible full text available June 13, 2025 -
LeBot, Nathalie ; Larochelle, Stephane ; Bergin, Enda ; Saini, Prabhjot (Ed.)
Abstract Carbaporphyrin dimers, investigated for their distinctive electronic structures and exceptional properties, have predominantly consisted of systems containing identical subunits. This study addresses the associated knowledge gap by focusing on asymmetric carbaporphyrin dimers with Janus-like characteristics. The synthesis of a Janus-type carbaporphyrin pseudo-dimer
5 is presented. It displays antiaromatic characteristics on the fused side and nonaromatic behavior on the unfused side. A newly synthesized tetraphenylene (TPE) linked bis-dibenzihomoporphyrin8 and a previously reported dibenzo[g,p]chrysene (DBC) linked bis-dicarbacorrole9 were prepared as controls. Comprehensive analyses, including1H NMR spectral studies, single crystal X-ray diffraction analyses, and DFT calculations, validate the mixed character of5 . A further feature of the Janus pseudo-dimer5 is that it may be transformed into a heterometallic complex, with one side coordinating a Cu(III) center and the other stabilizing a BODIPY complex. This disparate regiochemical reactivity underscores the potential of carbaporphyrin dimers as versatile frameworks, with electronic features and site-specific coordination chemistry controlled through asymmetry. These findings position carbaporphyrin dimers as promising candidates for advances in electronic structure studies, coordination chemistry, materials science, and beyond.Free, publicly-accessible full text available April 4, 2025 -
Free, publicly-accessible full text available February 14, 2025
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Carreira, Erick M (Ed.)A nanographene-fused expanded carbaporphyrin (5) and its BF2 complex (6) were synthesized. Single-crystal X-ray structures revealed that 5 and 6 are connected by two hexa-peri-hexabenzocoronene (HBC) units and two dipyrromethene or BODIPY units, respectively. As prepared, 5 and 6 both show nonaromatic character with figure-of-eight carbaoctaphyrin (1.1.1.0.1.1.1.0) cores and adopt tweezers-like conformations characterized by a partially confined space between the two constituent HBC units. The distance between the HBC centers is >10 Å, while the dihedral angles between the two HBC planes are 30.5 and 35.2° for 5 and 6, respectively. The interactions between 5 and 6 and fullerene C60 were studied both in organic media and in the solid state. Proton NMR spectral titrations of 5 and 6 with C60 revealed a 1:1 binding mode for both macrocycles. In toluene-d8, the corresponding binding constants were determined to be 1141 ± 17 and 994 ± 10 M−1 for 5 and 6, respectively. Single-crystal X-ray diffraction structural analyses confirmed the formation of 1:1 fullerene inclusion complexes in the solid state. The C60 guests in both complexes are found within triangular pockets composed of two HBC units from the tweezers-like receptor most closely associated with the bound fullerene, as well as an HBC unit from an adjacent host. Femtosecond transient absorption measurements revealed subpicosecond ultrafast charge separation between 5 (and 6) and C60 in the complexes. To the best of our knowledge, the present report provides the first example wherein a nanographene building block is incorporated into the core of a porphyrinic framework.more » « less
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We report a molecular switching ensemble whose states may be regulated in synergistic fashion by both protonation and photoirradiation. This allows hierarchical control in both a kinetic and thermodynamic sense. These pseudorotaxane-based molecular devices exploit the so-called Texas-sized molecular box (cyclo[2]-(2,6-di(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene); 14+, studied as its tetrakis-PF6−salt) as the wheel component. Anions of azobenzene-4,4′-dicarboxylic acid (2H+•2) or 4,4′-stilbenedicarboxylic acid (2H+•3) serve as the threading rod elements. The various forms of 2 and 3 (neutral, monoprotonated, and diprotonated) interact differently with 14+, as do the photoinduced
cis ortrans forms of these classic photoactive guests. The net result is a multimodal molecular switch that can be regulated in synergistic fashion through protonation/deprotonation and photoirradiation. The degree of guest protonation is the dominating control factor, with light acting as a secondary regulatory stimulus. The present dual input strategy provides a complement to more traditional orthogonal stimulus-based approaches to molecular switching and allows for the creation of nonbinary stimulus-responsive functional materials. -
The third industrial revolution has brought mankind into the information age. The development of information storage materials has played a key role in this transformation. Such materials have seen use in many application areas, including computing, logistics, and medicine. Information storage materials run the gamut from magnetic information storage media to molecular-based information storage materials. Among these, fluorescent-based information storage materials are of particular interest due to their unique properties, including an ability to store information with high levels of security, maintain mechanical stability, and respond to appropriately chosen external stimuli. In this review, we focus on recent advances involving the preparation and study of fluorescent materials-based information storage codes. For organisational purposes, these codes are treated according to the dimensionality of the code system in question, namely 1D-, 2D-, and 3D-type codes. The present review is designed to provide a succinct summary of what has been accomplished in the area, while outlining existing challenges and noting directions for future development.more » « less