Variable segment roles: modulation of the packing modes, nanocrystal morphologies and optical emissions

Abstract

Three isomers were prepared by covalently grafting carbazole (Cz) onto spiro[fluorene-9,9'-xanthene] (SFX) at different positions. Due to the complicated and variable roles of molecular segments, an evolution of the corresponding molecular packing mode was realized, accompanied by the change of nanocrystal morphology and photoluminescence properties.

Hierarchical Uniform Supramolecular Conjugated Spherulites with Suppression of Defect Emission

“…In this study, we established a molecular design principle of supramolecular conjugated macromolecules with orthogonal hydrogen-bonding interactions to enable a secondary planar conformation toward controlling and improving photonic behavior, defined as supramolecular plastic photonics (SPPs: photonic behavior of polymeric system can be significantly improved by supramolecular approach). This oriented planar conformation self-organizes into ordered tertiary microstructure supramolecular spherulites in accordance with the synergistically molecular attractor-repulsor theory (Scheme 1, Figures 1A and 1B) (Li et al., 2018, Wang et al., 2018, Xu et al., 2018). A hierarchical supramolecular artificial architecture with a series of multidimensional orthogonal hydrogen bonds in rigid crystalline framework is obtained from our bulky supramolecular spiro-terfluorene, 2,7-bis(3′,6′-bis(octyloxy)spiro[fluorene-9,9′-xanthen]-2-yl)spiro[fluorene-9,9′-thioxanthene]-10′,10′-dioxide (DOSFX-SFXSO).…”

Tunable Mechanical and Optoelectronic Properties of Organic Cocrystals by Unexpected Stacking Transformation from H- to J- and X-Aggregation

“… 15 − 18 Molecular stacking modes are generally classified into three types of aggregations, namely, face-to-face stacking (H-aggregation), staggered stacking (J-aggregation), and crossed stacking (X-aggregation) ( Figure S1 ). 19 − 21 Each of the stacking modes shows different contributions to the optoelectronic properties; for example, H-aggregation with strong π–π interactions facilitates efficient charge transport but often leads to aggregation-caused quenching (ACQ), 22 − 24 while J-aggregation with smaller dipole–dipole interactions might ensure fluorescence emission as well as charge transport properties. 25 − 28 In most cases, X-aggregation effectively prevents the ACQ and results in rigid stacking structures.…”

The Dimensionality Transition between Three-Dimensional and Two-Dimensional Organic Microcrystals: Specific Symmetry and Selective Adhesion

“…21 Furthermore, by jointing a planar supramolecular segment to the bulky molecular scaffold, the original 3D polyhedral particles can undergo a transformation to 2D nanosheets, which adopt an interdigital lipid bilayer-like (ILB) packing motif. 22,23 Besides the molecular design strategy, here, we show a dimensionality transition of 2,7di(9H-carbazol-9-yl)spiro[fluorene-9,9′-xanthene] (2,7-DCz-SFX) microcrystals with the selective coverage of a P123 surfactant. By precisely controlling the area decrease−increase of the eight exposed facets, a series of polyhedrons, including elongated octahedrons, oblique octahedrons, diamond-like particles, and parallelograms, have been generated in sequence during this gradual evolution from 3D to 2D.…”