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Monolayer Filaments versus Multilayer Stacking of Bent‐Core Molecules
Author(s) -
Matraszek Joanna,
Topnani Neha,
Vaupotič Natasa,
Takezoe Hideo,
Mieczkowski Jozef,
Pociecha Damian,
Gorecka Ewa
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201510123
Subject(s) - monolayer , lamellar structure , stacking , materials science , molecule , crystallography , elongation , core (optical fiber) , phase (matter) , saturation (graph theory) , bent molecular geometry , liquid crystal , chemical physics , chemistry , nanotechnology , ultimate tensile strength , optoelectronics , composite material , mathematics , organic chemistry , combinatorics
Bent‐core materials exhibiting lamellar crystals (B4 phase), when dissolved in organic solvents, formed gels with helical ribbons made of molecular monolayers and bilayers, whereas strongly deformed stacks of 5–6 layers were found in the bulk samples. The width and pitch of the helical filaments were governed by molecular length; they both increased with terminal‐chain elongation. It was also found that bulk samples were optically active, in contrast to the corresponding gels, which lacked optical activity. The optical activity of samples originated from the internal structure of the crystal layers rather than from the helicity of the filaments. A theoretical model predicts a strong increase in optical activity as the number of layers in the stack increases and its saturation for few layers, thus explaining the smaller optical activity for gels than for bulk samples. A strong increase and redshift in fluorescence was detected in gels as compared to the sol state.