Stereochemistry‐Controlled Supramolecular Architectures of New Tetrahydroxy‐Functionalised Amphiphilic Carbocyanine Dyes

Abstract

The syntheses of novel amphiphilic5 ,5',6,6'-tetrachlorobenzimidacarbocyanine( TBC) dye derivatives with aminopropanediol head groups, whicho nly differ in stereochemistry (chiral enantiomers, meso form and conformer), are reported. For the achiral meso form, an ew synthetic route towards asymmetric cyanine dyes was established. All compounds form Ja ggregates in water,t he opticalp roperties of which were characterised by means of spectroscopic methods. The supramolecular structure of the aggregates is investigated by means of cryo-transmissione lectron micros-copy,c ryo-electron tomographya nd AFM, revealing extended sheet-like aggregates for chiral enantiomers andn anotubesf or the mesomer,r espectively,w hereast he conformer formsp redominately needle-like crystals. The experiments demonstrate that the aggregation behaviour of compounds can be controlled solelyb yh ead group stereochemistry, whichi nt he case of enantiomerse nables the formation of extended hydrogen-bond chains by the hydroxyl functionalities. In case of the achiral meso form, however,s uch chains turnedo ut to be sterically excluded.

J‐aggregation strategy of organic dyes for near‐infrared bioimaging and fluorescent image‐guided phototherapy

“…These hydrophilic groups include mainly sulfonic acid group, quaternary ammonium cation, and PEG blocks. The aggregation of amphiphilic dyes in water is driven by multiple different forces, mainly including hydrophilic and hydrophobic interactions, π-π interactions between planes of chromophores as well as steric hindrance of substituent groups (Schade et al, 2020). Early in the last century, the J-aggregation of ICG and other amphiphilic cyanine dyes in aqueous solution was discovered (Mishra et al, 2000).…”

Near-Atomic Resolution Structure of J-aggregated Helical Light Harvesting Nanotubes

“…39 LHNs also possess a strong circular dichroism signature, though the structural origin of this chirality is yet to be elucidated. 38,[40][41][42][43] Extended Data Table 1 shows a literature survey of structural studies on pristine LHNs, their methodologies and key findings. As shown in Extended Data Table 1, all the nanoscale structural information was derived from low-resolution electron microscopy, excitonic modeling, and molecular dynamics simulations that were validated by comparing to the optical spectra.…”

Aggregation of Amphiphilic Carbocyanines: Fluorination Favors Cylindrical Micelles over Bilayered Tubes

“…Recent atomistic simulations of the C8S3 bilayer concluded that the octyl tails should be splayed and strongly interdigitated, to balance the area deficit . However, the estimated bilayer thickness on the order of ∼2.5 nm proved to be too small compared with the experimental cryogenic transmission electron microscopy (cryo-TEM) data, amounting to about 4 nm. ,, A second characteristic of C8O3 and C8S3 tubes pointing to unbalanced molecular packing is known for a long time but is so far unexplained: the isolated tubes are not stable but tend to form hexagonally packed bundles after longer storage in solution, , in particular when alcohols are present. , By using cryogenic electron tomography (cryo-ET), , it has been shown that the outer chromophore layer of individual tubes is lost during the bundling process, finally leading to a hexagonally packed assembly of single-layered tubes with a water-filled interior. This morphology can be considered as the precursor of an inverse hexagonal liquid-crystalline phase (H II ), typical of lipids .…”

“…In recent years, the aggregation behavior of a class of derivatives of the well-known 5,5′,6,6′-tetrachlorobenzimidacarbocyanine (TBC) chromophore has been investigated by several groups − using a wide range of analysis and characterization methods. The dye was diversely functionalized by attaching different polar or non-polar substituents at the nitrogen atoms in the 1,1′- and 3,3′-positions.…”

“…14,23,24 A second characteristic of C8O3 and C8S3 tubes pointing to unbalanced molecular packing is known for a long time but is so far unexplained: the isolated tubes are not stable but tend to form hexagonally packed bundles after longer storage in solution, 14,25 in particular when alcohols are present. 26,27 By using cryogenic electron tomography (cryo-ET), 20,27 it has been shown that the outer chromophore layer of individual tubes is lost during the bundling process, finally leading to a hexagonally packed assembly of single-layered tubes with a water-filled interior. This morphology can be considered as the precursor of an inverse hexagonal liquid-crystalline phase (H II ), typical of lipids.…”