Anomalous Halogen–Halogen Interaction Assists Radial Chromophoric Assembly

Abstract

The design of highly efficient supramolecular architectures that mimic competent natural systems requires a comprehensive knowledge of noncovalent interactions. Halogen bonding is an excellent noncovalent interaction that forms halogen–halogen (X2) as well as trihalogen interacting synthons. Herein, we report the first observation of a symmetric radial assembly of chromophores (R3̅c space group) composed of a stable hexabromine interacting synthon (Br6) that further push the limits of our understanding on the nature, role, and potential of noncovalent halogen bonding. Contrary to the destabilization proposed for Type-I X2 interactions, Br6-synthon-possessing Type-I X2 interactions exhibit a stabilizing nature owing to the exchange-correlation component. The radial assembly of chromophores is further strengthened by intermolecular through-space charge transfer interaction. Br6-synthon-driven 3-fold symmetric radial assembly render a lattice structure that reminisces the chromophoric arrangement in the light harvesting system 2 of purple bacteria.

Halogen‐Bonded Assemblies of Arylene Imides and Diimides: Insight from Electronic, Structural, and Computational Studies

“…Depending on the angle between the two CÀX•••Y-ÀC (X = Br and Y = Br/O) units ( Figure 6), these interactions are classified as type I( symmetrical interactions with q 1 % q 2 )a nd type II (bent interactions with q 1 %1808 and q 2 % 908). [23,24] In the case of 1,t wo molecules in the 1D layer (shown in the same color) interactw ith an intermolecular Br A sareference, the sum of the van der Waals radii of two Br atoms has been found to be 3.74 . [22] The 1D arrangement in 2 involves type Ii ntermolecular Br Finally,i n9 only the Br atoms at the bay positionsp articipate in type IB r •••Oh alogen-bonding interactions with q 1 and q 2 values of approximately 163 and approximately 1748 (Figure 8d).…”

Triptycene End‐Capped Quinoxalinophenanthrophenazines (QPPs): Influence of Substituents and Conditions on Aggregation in the Solid State

“…For certain fields of materials chemistry,i ti so fu tmost importance to control the molecular self-assembly in the solid state. [13][14][15][16][17][18] However,o ther supramolecular interactions, such as dipole-dipole interactions and p-p stacking are less directing than for example, hydrogen bonds and are therefore harder to control and predict. [13][14][15][16][17][18] However,o ther supramolecular interactions, such as dipole-dipole interactions and p-p stacking are less directing than for example, hydrogen bonds and are therefore harder to control and predict.…”

“…There are structurally motifs, such as hydrogen or halogen bonds, [10][11][12] that are of high directionality and,t herefore, often used in crystal engineering. [13][14][15][16][17][18] However,o ther supramolecular interactions, such as dipole-dipole interactions and p-p stacking are less directing than for example, hydrogen bonds and are therefore harder to control and predict. [19][20][21] This is unfortunate, because the kind of arrangement of extended p sys-tems to each other is responsible for charget ransfer in organic electronic devices, such as organic field-effectt ransistors (OFETs).…”

Metastable Chiral Azobenzenes Stabilized in a Double Racemate

“…Our persistent efforts towards comprehending the origin of anomalous crystalline architectures of distorted polyaromatics and twisted bichromophores motivated us to analyze the energetically favored pattern adopted by core-twisted octabrominated perylenediimide (OBPDI) upon crystallization, followed by exploring potential applications of the resultant crystalline motif. [25][26][27][28][29] Bay-halogenated perylenediimides (such as OBPDI) exhibit ac onformational chirality generated by the sterically induced twisting of the p-core and feature as ignificant activation barrier (DG°3 03 K %98 kJ mol À1 for chloro-substituted perylenediimide) for the interconversion between the axially chiral enantiomers. [30][31][32] The P/M isomers of the OBPDI chromophore assembled as independent stacks to yield highly symmetric racemic crystals from the parent solution.…”