Organic multicomponent microparticle libraries

An Alloy Engineering Strategy toward Helical Microstructures of Achiral π-Conjugated Molecules for Circularly Polarized Luminescence

Helical assembly has been demonstrated to efficiently facilitate the circularly polarized luminescence (CPL) performances, but the synthesis of micro- and nanohelices from rigid achiral π-conjugated compounds remains challenging due to the absence of bilayer structures or complementary hydrogen-bonding interactions. Here, we develop an alloying strategy for the realization of helical microstructures from achiral anthracene/anthracene derivatives with x-/x-axis modification or anthracene/tetracene derivatives with x-/y-axis modification via solution coassembly. Interestingly, two anthracene derivatives bearing asymmetric phenyl/phenylethynyl groups and symmetric phenylethynyl groups can assemble into spiral microribbons with a fractal branching pattern. Using such an alloying strategy, color-tailorable ternary spiral microtubules/microribbons referring to high-efficiency energy transfer processes are achievable. Molecular dynamics simulations reveal that the Von Mises stress produced by symmetry differences of two components induces symmetry breaking of alloy structures associated with twisting. Additionally, the contents of the guest and H2O also play a vital role in the formation of intricate helical microstructures. Single binary and ternary spiral microribbons present considerable CPL properties with a dissymmetric factor ('glum') of more than 0.01. The present work provides new insights into the formation of helical microcrystals with complex topologies and new optoelectronic functions.

Vaporchromic Domino Transformation and Polarized Photonic Heterojunctions of Organoplatinum Microrods

Photonic heterostructures with codable properties have shown great values as versatile information carriers at the micro- and nanoscale. These heterostructures are typically prepared by a step-by-step growth or post-functionalization method to achieve varied emission colors with different building blocks. In order to realize high-throughput and multivariate information loading, we report here a strategy to integrate polarization signals into photonic heterojunctions. A U-shaped di-Pt(II) complex has been assembled into highly polarized yellow-phosphorescent crystalline microrods (Y-rod) by strong intermolecular Pt⋅⋅⋅Pt interaction. Upon end-initiated desorption of the incorporated CH2Cl2 solvents, the Y-rod is transformed in a domino fashion into tri-block polarized photonic heterojunctions (PPHs) with alternate red-yellow-red emissions or red-phosphorescent microrods (R-rods). The red emissions of these structures are also highly polarized; however, their polarization directions are just orthogonal to those of the yellow phosphorescence of the Y-rod. With the aid of a patterned mask, the R-rod can be further programmed into multi-block PPHs with precisely controlled block sizes by side-allowed adsorption of CH2Cl2 vapor. X-ray diffraction analysis and theoretical calculations suggest that the solvent-regulated modulation of the crystal packing and excited-state property is critical for the construction of these PPHs.

Conformation-Driven Responsive 1D and 2D Lanthanide-Metal-Organic Framework Heterostructures for High-Security Photonic Barcodes

Development of luminescent segmented heterostructures featuring multiple spatial-responsive blocks is important to achieve miniaturized photonic barcodes toward anti-counterfeit applications. Unfortunately, dynamic manipulation of the spatial color at micro/nanoscale still remains a formidable challenge. Here, a straightforward strategy is proposed to construct spatially varied heterostructures through amplifying the conformation-driven response in flexible lanthanide-metal-organic frameworks (Ln-MOFs), where the thermally induced minor conformational changes in organic donors dramatically modulate the photoluminescence of Ln acceptors. Notably, compositionally and structurally distinct heterostructures (1D and 2D) are further constructed through epitaxial growth of multiple responsive MOF blocks benefiting from the isomorphous Ln-MOF structures. The thermally controlled emissive colors with distinguishable spectra carry the fingerprint information of a specific heterostructure, thus allowing for the effective construction of smart photonic barcodes with spatially responsive characteristics. The results will deepen the understanding of the conformation-driven responsive mechanism and also provide guidance to fabricate complex stimuli-responsive hierarchical microstructures for advanced optical recording and high-security labels.

Living Self-Assembly of Metastable and Stable Two-Dimensional Platelets from a Single Small Molecule

This study reports the design of a donor-acceptor (D-A) molecule with two fluorene units on each side of a benzothiadiazole moiety, which allows multiple intermolecular interactions to compete with one another so as to induce the evolution of the metastable 2D platelets to the stable 2D platelets during the self-assembly of the D-A molecule. Importantly, the living seeded self-assembly of metastable and stable 2D structures with precisely controlled sizes can be conveniently achieved using an appropriate supersaturated level of a solution of the D-A molecule as the seeded growth medium that can temporarily hold the almost-proceeding spontaneous nucleation from competing with the seeded growth. The stable 2D platelets with smaller area sizes exhibit higher sensitivity to gaseous dimethyl sulfide, illustrating that the novel living self-assembly method provides more available functional structures with controlled sizes for practical applications. The key finding of this study is that the new living methodology is separated into two independent processes: the elaborate molecular design for various crystalline structures as seeds and the application of a supersaturated solution with appropriate levels as the growth medium to grow the uniform structures with controlled sizes; this would make convenient and possible the living seeded self-assembly of rich 1D, 2D, and 3D architectures.

Directional Self-Assembly of Facet-Aligned Organic Hierarchical Super-Heterostructures for Spatially Resolved Photonic Barcodes

Organic multicolor heterostructures with spatially resolved luminescent colors and identifiable patterns have exhibited considerable potential for achieving micro-/nanoscale photonic barcodes. Nevertheless, such types of barcodes reported thus far are exclusively based on a single heterostructure with limited coding elements. Here, a directional self-assembly strategy is proposed to achieve high-coding-capacity spatially resolved photonic barcodes through rationally constructing organic hierarchical super-heterostructures, where numerous subheterostructure blocks with flat hexagonal facets are precisely oriented with their specific facets via a reconfigurable capillary force. The building blocks were prepared through a one-pot sequential heteroepitaxial growth, which enables the effective modulation of the structural and color characteristics in coding structures. Significantly, a directional facet-to-facet attraction between particles via facet registration leads to the formation of well-defined 1D super-heterostructures, which contain multiple coding elements, thus providing a good platform for constructing the high-coding-capacity photonic barcodes. The results may be useful in fabricating organic hierarchical hybrid super-heterostructures for security labels and optical data recording.

Dimerization Triggered Magnetoelectric Coupling Effect and Magnetic Anisotropy in Organic Ternary Crystals

Developing a new universal strategy to design all organic ferromagnets or multiferroics with satisfactory properties always remains challenging. In this work, ternary charge transfer crystals are fabricated to realize organic multiferroic magnetoelectric coupling effect. Through incorporating the third component into binary crystals, a dimerization between neighbor donor and acceptor is induced to form a lattice symmetry breaking, where a nonpolar to polar phase transition is ensuing to lead to a dipolar polarization. Magnetic field can effectively tune the dipolar polarization to present a magnetoelectric coupling effect. Moreover, the introduction of the third component can result in a rearrangement in molecular configuration to modify the electron-phonon interaction. As a result, anisotropic magnetism is observed due to anisotropic electron-phonon coupling in ternary crystals. Overall, this study forecasts that incorporating an appropriate third component is a potential method for designing all organic multiferroics.

Fractal Branched Microwires of Organic Semiconductor with Controlled Branching and Low-Threshold Amplified Spontaneous Emission

Fractals are quite normal in nature. However, fractal self-assembly of organic semiconductors remains challenging. Herein, we develop a facile solution assembly route to access organic microwires (MWs) comprising an oligo(p-phenylenevinylene) derivative (OPV-A) with and without branching. Instead of kinetically controlled β-OPV-A microrods (MRs), thermodynamically favored α-OPV-A gives fractal branching MW patterns. As-prepared 9,10-dicyanoanthracene (DCA) alloyed assemblies function as seeds to allow for the heteroepitaxial growth of branching α-OPV-A MWs via either coassembly or two-step seeded growth. Consequently, fractal MWs with single- and multisite growth were both achieved, accompanied by tailorable branching densities and hierarchies. Thermodynamic control and a well-matched epitaxial relationship should be crucial to the formation of fractal MW patterns. Importantly, the aligned α-OPV-A MW array functions as a multichannel optical gain medium and exhibits low-threshold amplified spontaneous emission (ASE). The present work deepens the research into fractal self-assembly of functional organic semiconductors.

A new strategy: realization of organic heteroepitaxy and organic alloys based on the similarity of CC and NN

The similarity of NN and CC in trans-4,4′-azobis(pyridine) and trans-1,2-bis(pyridin-4-yl)ethene offers an innovative approach for creating controllable and versatile organic heterostructure and organic alloy.

I-LIFT (image-based laser-induced forward transfer) platform for manipulating encoded microparticles

Encoded microparticles have great potential in small-volume multiplexed assays. It is important to link the micro-level assays to the macro-level by indexing and manipulating the microparticles to enhance their versatility. There are technologies to actively manipulate the encoded microparticles, but none is capable of directly manipulating the encoded microparticles with homogeneous physical properties. Here, we report the image-based laser-induced forward transfer system for active manipulation of the graphically encoded microparticles. By demonstrating the direct retrieval of the microparticles of interest, we show that this system has the potential to expand the usage of encoded microparticles.

Vapor-Phase Living Assembly of π-Conjugated Organic Semiconductors

In contrast to well-studied amphiphilic block copolymers (BCPs) and π-stacked dyes, living assembly of hydrophobic π-conjugated materials has not yet been explored to date. Using a microspacing physical vapor transport (PVT) technique, the prefabricated microrods of organic semiconductors involving 9,10-dicyanoanthracene (DCA, A) or its binary alloy (B) can act as seeds to initiate living homoepitaxial growth from their ends, giving elongated microrods with controlled length. Red-green-red tricolor fluorescent microrod heterostructures with low dispersity are further realized by living heteroepitaxial growth of B microrod blocks on A seed microrod tips. Upon varying the growth sequence of each block, reverse triblock microrods are also accessible. Such a seed-induced living growth is applicable to triblock microrod heterostructures of more binary combinations as well as even more complex penta- and hepta-block heterostructures comprising A and B. By virtue of a convenient vapor-phase growth method, the present work demonstrates the generality of living assembly of π-conjugated materials.

Hyperbranched Microwire Networks of Organic Cocrystals with Optical Waveguiding and Light-Harvesting Abilities

We report the synthesis of hyperbranched organic microwire (MW) networks comprising 1,4-bis(pentafluorostyryl)benzene (10Ft) and 9,10-bis(phenylethynyl)anthracene (BA) using a simple solution co-assembly route. Pure 10Ft or BA assemblies cannot produce such complex MW networks; in contrast with a binary cocrystal of 10Ft and BA with a 2:1 molar ratio ((2:1)10Ft:BA), which is formed via intermolecular arene-perfluoroarene (AP) interactions. A new generation of multiple MWs grow epitaxially on the previous generation of MWs to form MW arrays in which BA may also act as an intermediate product to facilitate the regeneration of (2:1)10Ft:BA. Highly aligned and well-connected MW networks enable superior optical waveguiding ability. Moreover, a red-emitting dopant, 5,12-bis(phenylethynyl)naphthacene (BN) was incorporated into (2:1)10Ft:BA host MWs, giving light-harvesting hierarchical MW networks via an energy-transfer (ET) process. The realization of the hyperbranched MWs provides us with deep insight into the rational creation of complex branched arrays from functional organic cocrystals.