RETRACTED: Supramolecular Nanotube Reactors for Production of Imine Polymers with Controlled Conformation, Size, and Chirality

Abstract

A series of supramolecular nanotubes with inner diameters of 1, 4, 9, 12, 16, and 29 nm are prepared from amino acid lipids. The hydrophobic channels of the nanotubes act as reactors for the formation of imine polymers by not only effectively encapsulating the benzaldehyde and diacetyleneamine precursors of the imine monomers but also markedly accelerating imine formation. The nanotube inner diameter determines whether the imine monomers self‐assemble into nanoparticles, nanotapes, nanocoils, or twisted nanofibers in the channels. UV‐induced polymerization of the diacetylene units in the imine nanostructures followed by decomposition of the nanotubes into molecular dispersions of the constituent amino acid lipids results in expulsion of the polymerized imine nanostructures with retained conformation. The isolated nanocoils and twisted nanofibers retain the helicity and circular dichroism induced by the nanotubes, which exhibits supramolecular chirality, even though the components of the imine monomers are achiral. These supramolecular nanotubes with tunable diameters and functionalizable surfaces can be expected to be useful for the production of polymers with controlled conformation, size, and chirality without the need for rational design or chemical modification of the monomers or optimization of the polymerization conditions.

Influences of Hydrogen Bonding-Based Stabilization of Bolaamphiphile Layers on Molecular Diffusion within Organic Nanotubes Having Inner Carboxyl Groups

“…In chemical separations, their nanospaces provided a means for analyte preconcentration, chiral separations, and the stabilization of proteins such as enzymes ,, and green fluorescent proteins (GFP) . In chemical reactions, ONTs offered hydrophobic environments that were required to accelerate synthetic reactions in aqueous solutions. , In addition, the nanoconfinement of reactants to the hollow nanospaces led to stereoselective synthesis, size-selective enzymatic reactions, and morphology-controlled polymerization . Furthermore, ONTs have been explored as drug delivery vehicles owing to their unique properties, including slow and continuous molecular release from their open ends and also their dissociation controlled by external stimuli. − …”

“…The functionalities of the inner surface are determined by the smaller terminal group of the constituent bolaamphiphile and can be tuned by mixing bolaamphiphiles of different terminal groups or via a covalent reaction selective to the inner functional groups . The control of the inner diameter and surface functionalities provides a means to enhance steric and chemical interactions between molecules and the ONTs, permitting the design of unique nanoscale media for selective chemical separations and reactions. , …”

“…13,14 In addition, the nanoconfinement of reactants to the hollow nanospaces led to stereoselective synthesis, 15 sizeselective enzymatic reactions, 11 and morphology-controlled polymerization. 16 Furthermore, ONTs have been explored as drug delivery vehicles owing to their unique properties, including slow and continuous molecular release from their open ends and also their dissociation controlled by external stimuli. 17−21 In particular, ONTs based on asymmetric bolaamphiphiles 22,23 have been explored for the aforementioned applications and also for fundamental studies on nanoconfinement effects owing to their stable and uniform tubular structures with distinct inner and outer surface functionalities.…”

“…3 The control of the inner diameter and surface functionalities provides a means to enhance steric and chemical interactions between molecules and the ONTs, permitting the design of unique nanoscale media for selective chemical separations 9 and reactions. 11,16 The performances of ONTs as chemical separation and reaction media are strongly affected by the dynamic behavior, such as partitioning and diffusion, of molecules incorporated in the materials. The distribution of solutes that results from their partitioning to different regions of ONTs (e.g., the wall, and inner/outer surfaces) has been investigated using TEM, 25,26 NMR, 27 and X-ray scattering.…”

Self‐Assembly of a Pyridine‐Based Amphiphile Complexed with Regioisomeric Dihydroxy Naphthalenes into Supramolecular Nanotubes with Different Inner Diameters

“…[1e] The chemical structures of the organic components of nanotubes are the predominant determinants of their IDs. In particular, the number of aromatic units, [2] the ortho-, meta-, para-disubstituents of aromatic units, [3] the length of the spacer units, [4] the nature of the substituents on the side chains, [5] and the position of hydrogen bonding units [6] in the organic components strongly influence the IDs. Namely, variation of the organic components was shown to be indispensable for production of nanotubes with different IDs.…”