Publications by authors named "Burhan A Hussein"

Herein we demonstrate that the rapid 'shapeshifting' constitutional isomerization of a substituted bullvalene is influenced by the -to- configurational isomerization of a remote carbamate group, giving rise to correlated motion. We find that, while the -configurational isomer of a bulky carbamate favors the -bullvalene constitutional isomer, a noncovalent bonding interaction within the -carbamate tips the equilibrium toward the -bullvalene form. Using DFT modelling and NMR spectroscopy, this long-range interaction is identified as being between the bullvalene core and a pendant phenyl group connected to the carbamate.

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Article Synopsis
  • Stereogenic sp-hybridized carbon centres are crucial in forming chiral molecules, but they typically require intermolecular reactions for configuration changes, unlike more dynamic motifs.
  • The study reveals that certain rigid carbon structures (fluxional carbon cages) can undergo internal enantiomerization via strain-assisted Cope rearrangements, mimicking behaviors seen in more dynamic stereogenic centers.
  • These carbon cages not only transmit stereochemical information to their surroundings but also adapt their dynamic properties to influence various chemical processes like catalysis and ion pairing.
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Porphyrins are cornerstone functional materials that are useful in a wide variety of settings, ranging from molecular electronics to biology and medicine. Their applications are often hindered, however, by poor solubilities that result from their extended, solvophobic aromatic surfaces. Attempts to counteract this problem by functionalizing their peripheries have been met with only limited success.

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A bio-inspired family of organic dyes with bichromic-bipodal architectures were synthesized and tested in dye-sensitized solar cells (DSSC). These dyes are comprised of a D-π-D-A motif with two triphenylamine (TPA) units acting as donors (D) and two cyanoacetic acid acceptors (A) capable of binding to a titania semiconductor. The role of the thiophene π-spacer bridging the two TPA units was examined and the distal TPA (relative to TiO) was modified with various substituents (-H, -OMe, -SMe, -OHex, -3-thienyl) and contrasted against benchmark .

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Shapeshifting molecules exhibit rapid constitutional dynamics while remaining stable, isolable molecules, making them promising artificial scaffolds from which to explore complex biological systems and create new functional materials. However, their structural complexity presents challenges for designing their syntheses and understanding their equilibria. This minireview showcases (1) recent applications of highly dynamic shapeshifting molecules in sensing and distinguishing complex small molecules and (2) detailed insights into the adaptation of tractable bistable systems to changes in their local environment.

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