Self-assembled Triazole AIE-Active Nanofibers: Synthesis, Morphology, and Photophysical Properties

Abstract

A series of seven low molecular weight compounds containing triazole, pyridine-N-oxide, and one substituted aromatic ring linked together by heteroatoms containing spacers was synthesized by click chemistry reaction. The compounds were structurally characterized by FTIR, NMR, as well as single-crystal X-ray diffraction. Their morphologic, thermotropic, and photophysical properties were determined by dynamic light scattering, scanning electron microscopy, atomic force microscopy, polarized light microscopy, UV–vis, and photoluminescence spectroscopy. The triazole derivatives proved to have porous 3D supramolecular architectures determined by an extensive nonclassical hydrogen bonding network. They spontaneously crystallized into long nanofibers and exhibited typical molecular glass behavior, aggregation induced emission as well as crystallization induced emission enhancement.

Reducing aggregation caused quenching effect through co-assembly of PAH chromophores and molecular barriers

“…Organic semiconductors, especially π-conjugated metal-free luminescent organic materials, are crucial for human beings to deliver and illuminate information 1–3 via modern technologies (e.g., photonics, optoelectronic devices, biological probes, and fluorescent sensors 4–9 ) due to their flexibility, brightness, easy-processability, tunable photophysical properties 10–12 , high optical gain 13 , and possible biocompatibility 14 . In general, most of the above-mentioned applications require solid or aggregate-state luminescent materials, such as thin films, bulk crystals, or nanoparticles 15 . However, the features of planar aromatic structures of conventional organic chromophores, which facilitate the π–π stacking of the chromophores and other physical interactions (e.g., energy transfer, inter-, or intramolecular charge transfer, and excited states reactions) 16–18 , further makes these materials suffer from the well-known aggregation caused quenching (ACQ) effect 4–7,19–22 .…”

Low Molecular Weight Microfibers with Light Sensing Properties

“…A series of organic low molecular weight compounds consisting in a combination of aromatic/heteroaromatic rigid moieties and flexible units (scheme 1) have been synthesised and their ability to form microfibers has been studied in detail. The compounds were prepared according to a synthetic procedure reported elsewhere and their right structure has been confirmed by FTIR and NMR spectroscopy, and elemental analysis [17,20].…”

“…All the compounds used for the microfiber preparation were synthesised in agreement with a procedure reported elsewhere [17,20].…”

“…Depending on the targeted application, the micro-, nano-fibers are prepared from polymers [10], biopolymers [11] inorganic salts [12], organic blends [13], organic-inorganic composites [14,15] or inorganic-inorganic blends [16]. The latest research revealed the possibility to prepare micro/ nanofibers from organic low molecular weight compounds [17][18][19][20][21]. The structural design which appears to facilitate their formation is the presence of flexible spacers as internal building blocks.…”

Dual Ligand Strategy for Constructing a Series of d10 Coordination Polymers: Syntheses, Structures, Photoluminescence, and Sensing Properties

“…The porous zeolitic imidazolate frameworks (ZIFs), such as ZIF-8, ZIF-67, and so on, are representative of such CPs. − The bridging angle with 145° in the M–Im–M (M = Zn 2+ , Co 2+ , etc., and Im = imadazolate) could give the opportunity to make novel ZIFs with topological structures based on those of tetrahedral zeolites, wherein the Si–O–Si angle prefers to be 145°. Besides that, other five-membered aromatic N -heterocycles together with imidazole derivatives have afforded a large number of metal azolate frameworks (MAFs) when assembling with various metal centers, which lead to a new metal–ligand system and have attracted much interest during the past few years. − In addition, some CPs constructed from triazole-pyridine, triazole-pyrazine, triazine-pyridine, etc., ligands, which are equipped with strong coordination ability, have been widely reported recently. − By contrast, 5-(pyrazinyl)­tetrazole (Hptz) ligands with more N donors, integrating the features of both tetrazole and pyrazine, have been rarely studied. In Hptz molecules, the multiple coordination sites can give rise to numerous CPs with diverse topologies as well as promising properties when acting as a multidentate ligand.…”