TY  - JOUR
A1  - Görl, Daniel
A1  - Zhang, Xin
A1  - Stepanenko, Vladimir
A1  - Würthner, Frank
T1  - Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides
JF  - Nature Communications
N2  - New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (A\(_{m}\)BB)\(_{n}\). The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.
KW  - cylindrical micelles
KW  - water
KW  - amplification
KW  - association
KW  - emission
KW  - organization
KW  - polymerization
KW  - dyes
KW  - fluorescent
KW  - aqueous medium
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148657
VL  - 6
IS  - 7009
ER  - 
TY  - JOUR
A1  - Wehner, Marius
A1  - Röhr, Merle Insa Silja
A1  - Stepanenko, Vladimir
A1  - Würthner, Frank
T1  - Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers
JF  - Nature Communications
N2  - Homo- and heterochiral aggregation during crystallization of organic molecules has significance both for fundamental questions related to the origin of life as well as for the separation of homochiral compounds from their racemates in industrial processes. Herein, we analyse these phenomena at the lowest level of hierarchy - that is the self-assembly of a racemic mixture of (R,R)- and (S,S)-PBI into 1D supramolecular polymers. By a combination of UV/vis and NMR spectroscopy as well as atomic force microscopy, we demonstrate that homochiral aggregation of the racemic mixture leads to the formation of two types of supramolecular conglomerates under kinetic control, while under thermodynamic control heterochiral aggregation is preferred, affording a racemic supramolecular polymer. FT-IR spectroscopy and quantum-chemical calculations reveal unique packing arrangements and hydrogen-bonding patterns within these supramolecular polymers. Time-, concentration- and temperature-dependent UV/vis experiments provide further insights into the kinetic and thermodynamic control of the conglomerate and racemic supramolecular polymer formation. Homo- and heterochiral aggregation is a process of interest to prebiotic and chiral separation chemistry. Here, the authors analyze the self-assembly of a racemic mixture into 1D supramolecular polymers and find homochiral aggregation into conglomerates under kinetic control, while under thermodynamic control a racemic polymer is formed.
KW  - perylene bismide dye
KW  - nucleation-elongation
KW  - PI stacking
KW  - polymerization
KW  - complexity
KW  - mechanism
KW  - crystals
KW  - kinetics
KW  - growth
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230580
VL  - 11
ER  -