In an attempt to gather experimental evidence for the influence of carbon allotropes on supramolecular chirality, we found that carbon nanotubes (CNTs) facilitate amplification of the molecular chirality of a π-gelator (MC-OPV) to supramolecular helicity at a concentration much lower than that required for intermolecular interaction. For example, at a concentration 1.8×10(-4) m, MC-OPV did not exhibit a CD signal; however, the addition of 0-0.6 mg of SWNTs resulted in amplified chirality as evident from the CD spectrum. Surprisingly, AFM analysis revealed the formation of thick helical fibers with a width of more than 100 nm. High-resolution TEM analysis and solid-state UV/Vis/NIR spectroscopy revealed that the thick helical fibers were cylindrical cables composed of individually wrapped and coaxially aligned SWNTs. Such an impressive effect of CNTs on supramolecular chirality and cylindrical-cable formation has not been reported previously.
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http://dx.doi.org/10.1002/anie.201605354 | DOI Listing |
Chemistry
January 2025
Indian Institute of Technology Kanpur, Department of Chemistry, Kanpur, 208016, Kanpur, INDIA.
Herein, we report the precise control of molecular to supramolecular chirality induction at the single-molecule level just upon subtle modification in an achiral 'nano-size' trizinc(II) porphyrin trimer. A slight variation in the projection of the substituent at the periphery of the central porphyrin unit in a porphyrin trimer (host) resulted in pronounced changes in the interchromophoric arrangement, leading to distinct 'open' and 'closed' conformations. While 'open' form generates 'monomeric' complex with low CD amplitude, 'closed' form produces exclusive 'polymer' with large, amplified CD signal with opposite sign due to stronger intermolecular excitonic coupling.
View Article and Find Full Text PDFACS Nano
January 2025
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, P. R. China.
Crown ethers (CEs), macrocyclic polyethers, have attracted significant attention in supramolecular chemistry. It is known that they have many isomers due to their flexibility. It is challenging to select some exact conformation and tune the following self-assembly structure of CEs, and it has rarely been reported to date.
View Article and Find Full Text PDFNat Commun
January 2025
Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
Studying the self-assembly of chiral molecules in two dimensions offers insights into the fundamentals of crystallization. Using scanning tunneling microscopy, we examine an uncommon aggregation of polyaromatic chiral molecules on a silver surface. Dense packing is achieved through a chiral triangular tiling of triads, with N and N ± 1 molecules at the edges.
View Article and Find Full Text PDFNanoscale
January 2025
CBMN, CNRS, UMR 5248, University of Bordeaux, 33600 Pessac, France.
Cast films of racemic helicene derivatives adsorbed onto the surface of nanometric silica helices with controlled handedness exhibited distinct CD signals, whereas no CD signal was observed in the absence of silica nanohelices. These CD signals originate from the helical supramolecular assemblies formed by the racemic mixture of helicenes, with no evidence of enantiospecific adsorption. Interestingly, when enantiomerically pure forms of these helicenes were drop-cast onto the silica helices, different CD spectra were observed depending on the combination of the helicenes' handedness with that of the silica nanohelices.
View Article and Find Full Text PDFChem Asian J
December 2024
Department of chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, West Bengal, India.
Metal-organic gels (MOGs) are a type of supramolecular complex that have become highly intriguing due to their synergistic combination of inorganic and organic elements. We report the synthesis and characterization of a Ni-directed supramolecular gel using chiral amino acid L-DOPA (3,4-dihydroxy phenylalanine) containing ligand, which coordinates with Ni(II) to form metal-organic gels with exceptional properties. The functional Ni(II)-gel was synthesized by heating nickel(II) acetate hexahydrate and the L-DOPA containing ligand in DMSO at 70 °C.
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