Chiral nanostructures, normally formed by chiral molecules, play an essential role in natural systems. The helical assemblies constructed by achiral molecular building blocks are still rare and their regulating mechanisms have not been well studied. An achiral cinnamoyl-terminated bolaamphiphile with three methylene unit spacers was found to self-assemble into hierarchically helical nanostructure. The photo-triggered changes in a small number of achiral molecular building blocks would dramatically and reversibly lead to great variations in the helical nanostructures. Thus, the helical supramolecular assemblies can be altered through changing a very small number of achiral molecular building blocks. Moreover, the co-assembly of the achiral bolaamphiphiles with ds-DNA produced uniform left-handed helices, which were also changed upon slight photoirradiation.
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http://dx.doi.org/10.1016/j.jcis.2014.08.014 | DOI Listing |
Soft Matter
January 2025
Department of Materials Science, University of Patras, 26504 Patras, Greece.
Monte Carlo molecular simulations of curve-shaped rods show the propensity of such shapes to polymorphism revealing both smectic and polar nematic phases. The nematic exhibits a nanoscale modulated local structure characterized by a unique, polar, -symmetry axis that tightly spirals generating a mirror-symmetry-breaking organization of the achiral rods-form chirality. A comprehensive characterization of the polarity and its symmetries in the nematic phase confirms that the nanoscale modulation is distinct from the elastic deformations of a uniaxial nematic director in the twist-bend nematic phase.
View Article and Find Full Text PDFChem Sci
January 2025
School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 PR China
Noncovalent forces have a significant impact on photophysical properties, and the flexible employment of weak forces facilitates the design of novel luminescent materials with a variety of applications. The arene-perfluoroarene (AP) force, as one type of π-hole/π interaction, shows unique directionality, involving an electron-deficient π-hole interacting with a π-electron-rich region, facilitating precise orientation and stabilization in supramolecular structures. Here we present an amination engineering protocol to build a perfluoroarene library based on an octafluoronaphthalene skeleton with various steric and electronic properties.
View Article and Find Full Text PDFAchiral metasurfaces with near-field optical chirality have attracted great attention in molecular sensing and chiral emission control. Here, the circular dichroism (CD) response of an achiral metasurface induced by spatially selective coupling with polymethyl methacrylate (PMMA) molecules is demonstrated. A designed achiral metasurface with a V-shaped resonator exhibits large optical chirality with a strongly dissymmetric distribution under circular polarization.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Laboratoire Softmat, UMR au CNRS no 5623, Université Paul Sabatier, F-31062 Toulouse, France.
Simulations on an ODE-based model shows that there are many common points between Viedma deracemization and chiral self-assemblies of achiral building blocks towards chiral nanoparticles. Both systems occur in a closed system with energy exchange but no matter exchange with the surroundings and show parallel reversible growth mechanisms which coexist with an irreversible cluster breaking (grinding). The various mechanisms of growth give rise to the formation of polymerization/depolymerization cycles while the consecutive transformation of achiral monomer into chiral cluster results into an indirect enantioselective autocatalysis.
View Article and Find Full Text PDFAnal Chim Acta
February 2025
Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, 0179, Tbilisi, Georgia. Electronic address:
Background: Isotopologues resulting from the labelling of molecules with deuterium have attracted interest due to the isotope effect observed in chemistry and biosciences. Isotope effect may also play out in noncovalent interactions and mechanisms leading to intermolecular recognition. In chromatography, differences in retention time between isotopologues, as well as between isotopomers have been observed resulting in two different elution sequences (isotope effects): the normal isotope effect when heavier isotopologues retain longer than lighter analogues, and the inverse isotope effect featuring the opposite elution order.
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