ABSTRACT
Supramolecular chirality is essential for the development of functional materials. In this study, we report the synthesis of twisted nanobelts based on charge-transfer (CT) complexes using self-assembly cocrystallization starting from asymmetric components. An asymmetric donor, DBCz, and a typical acceptor, tetracyanoquinodimethane, were used to construct a chiral crystal architecture. An asymmetric alignment of the donor molecules induced polar ±(102) facets that, accompanied with free-standing growth, resulted in a twisting along the b-axis due to the electrostatic repulsive interactions. Meanwhile, the alternately oriented ±(001) side-facets were responsible for the propensity of the helixes to be right-handed. Addition of a dopant significantly enhanced the twisting probability by reducing the surface tension and adhesion influence, even switching the chirality preference of the helixes. In addition, we could further extend the synthetic route to other CT systems for formation of other chiral micro/nanostructures. Our study offers a novel design approach for chiral organic micro/nanostructures for applications in optically active systems, micro/nano-mechanical systems and biosensing.
ABSTRACT
The derivatization of perylenediimides (PDIs) by bay decoration is essential for the development of PDI-based semiconductors owing to their excellent photoelectric properties. Herein, four bis-azabenz-annulated PDIs (bis-AzaBPDIs) are concisely synthesized in high yields through ultraviolet-induced photocyclization, where the reaction processes including aldimine condensation, cyclization, and oxidative re-aromatization are investigated. The optical characterizations and theoretical simulation reveal that the unique properties of the four bis-AzaBPDIs are comparable to their parent PDI. Organic field effect transistors with compounds 2, 3, or 4 as active layers indicated that all compounds showed unipolar electron transport properties with the mobilities of 1.1×10-3 , 5.8×10-4 , and 8.5×10-6 â cm2 â V-1 s-1 , respectively. These results suggest the great potential of bis-AzaBPDIs as organic semiconductors. The easy preparation approach reported in this work would renew research interest in developing bis-AzaBPDI-based optoelectronic molecules.
ABSTRACT
The development of synthetic helical structures from achiral molecules and stimulus-responsive shape transformations are vital for biomimetics and mechanical actuators. A stimulus regarded as the force to induce chirality modulation plays a significant role in the helical supramolecular structure design through symmetry breaking. Herein, we synthesized a metastable complex Form 1 crystal composed of pyrene and (4,8-bis(dicyanomethylene)-4,8-dihydrobenzo[1,2-b:4,5-b']-dithiophen-e) DTTCNQ components with a torsional backbone by C-Hâ¯N hydrogen bonds via a quick cooling method. The helix motion kinetics of Form 1 depends on the intrinsic factor (crystal thickness) and external stimuli (polar solvents). The self-assembled helical microstructures grow into needle-like crystals in liquid media via an untwistingprocess. Furthermore, they undergo predictable deformation of untwisting or breaking under a stimulus-responsive strain-relaxing phase transformation. This work illustrates a new approach in the mediated formation of helical morphologies from achiral binary supramolecules and dynamic motion, which is vital for biomimetics and mechanical actuators.
ABSTRACT
Fullerene host-guest constructs have attracted increasing attention owing to their molecular-level hybrid arrangements. However, the usage of simple carbazolic derivatives to bind with fullerenes is rare. In this research, three novel carbazolic derivatives, containing a tunable bridging linker and carbazole units for the capturing of fullerenes, are rationally designed. Unlike the general concave-convex interactions, fullerenes could interact with the planar carbazole subunits to form 2-dimensional hexagonal/quadrilateral cocrystals with alternating stacking patterns of 1 : 1 or 1 : 2 stoichiometry, as well as the controllable fullerene packing modes. At the meanwhile, good electron-transporting performances and significant photovoltaic effects were realized when a continuous C60â â â C60 interaction channel existed. The results indicate that the introduction of such carbazolic system into fullerene receptor would provide new insights into novel fullerene host-guest architectures for versatile applications.
ABSTRACT
Self-assembled charge-transfer complexes based on supramolecular interactions have attracted immense research interest due to their unique packing and (opto)electronic applications. Herein, two new binary cocrystals with a similar 1:1 mixed-stack arrangement are synthesized by solvent evaporation or grinding method using N,N'-dimethyl-1,4,5,8-naphthalene tetracarboxylic diimide (Me-NDI) as the receptor. Single-crystal X-ray diffraction analysis confirms the successful molecular-level recognition and various weak interaction networks. Upon thermal treatment of 1,4,8,11-tetramethyl-6,13-triethylsilylethynyl pentacene (TMTES-P)/Me-NDI complex, in situ cocrystal-to-crystal conversion is observed, and the receptor is gradually released, while the perylene/Me-NDI cocrystal disassembles in the same manner as a single-component compound. The aligned short-contact network, good stability of TMTES-P, and anisotropic attachment energies of the TMTES-P/Me-NDI cocrystal disassemble in a manner same to that of a single-component compound. The aligned short-contact network, good stability of TMTES-P, and anisotropic attachment complexes are believed to promote the release of specific molecules. These structure-property relationship results provide new insights into the design of a supramolecular class with desired functionalities in terms of self-assembled recognition, release, or crystal conversion.
