Design, syntheses and aggregation-induced emission properties of two new enlarged tetraarylethene-based luminogens

Synthesis, crystal structure and optical property of 1,6-bis(p-tolylthio)pyrene, C30H22S2

C30H22S2, triclinic, P 1 ‾ $P‾{1}$ (no. 2), a = 7.5621(2) Å, b = 8.6787(3) Å, c = 9.8951(3) Å, α = 110.4180(10)°, β = 97.6810(10)°, γ = 108.8430(10)°, V = 553.33(3) Å3, Z = 1, R gt(F) = 0.0413, wR ref(F 2) = 0.1160, T = 200(2) K.

Tuneable Emission of Polyhedral Oligomeric Silsesquioxane Based Nanostructures that Self-Assemble in the Presence of Europium(III) Ions: Reversible trans-to-cis Isomerization

Hybrid nanostructures with switchable and reversible "blue-red-green" emission were efficiently synthesized. These nanostructures comprise polyhedral oligomeric silsesquioxanes (POSS) that behave as a nanocage that can be functionalized with terpyridine-based organic ligands, which can be easily complexed with europium (III) ions. The complexes were characterized by UV-Vis and fluorescence spectroscopy and their stoichiometry was also confirmed by ¹ H NMR spectroscopy. In the presence of the Eu(III) ions, the octafunctionalized nanocages self-assemble to form 3D architectures that display an intense red-emission, especially in the solid state. The presence of an alkenyl group bridging the inorganic core to the organic moiety was employed to tune the emission properties by trans-cis isomerization of the double bond. In the case of the octafunctionalized nanocages (O-POSS), this isomerization was monitored in the presence of Eu(III) cations and was accompanied by an evident colour change from blue (trans-O-POSS) to red (Eu@trans-O-POSS) and finally to green (cis-O-POSS) as consequence of the release of the metal cations. This behaviour, together with the easy dispersion of the dry powder and the possibility of coating as a film in presence of small amounts of solvent, makes the emissive solid promising for applications in materials science.

Crystal structure of 1,1-di(4-cyanophenyl)-2,2-diphenylethene, C28H18N2

C28H18N2, orthorhombic, Pccn (no. 56), a = 9.8955(6) Å, b = 11.0163(6) Å, c = 19.9752(14) Å, V = 2177.5(2) Å3, Z = 4, R gt(F) = 0.0402, wR ref(F 2) = 0.1012, T = 123(2) K.

Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-diphenyl-2-[4-(pyren-1-yl)phen-yl]acrylo-nitrile

The title organic compound, C37H23N, crystallizing in the triclinic space group P [Formula: see text], has been designed, synthesized and characterized by single-crystal X-ray diffaction, MS, NMR and elemental analysis. There are alternating relatively strong and weak intermolecular π-π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE) characteristics.

A series of 4,5,9,10-tetrahydropyrene-based tetraarylethenes: synthesis, structures and solid-state emission behavior

By controlling the number of 4,5,9,10-tetrahydropyrene segments around the tetraarylethene core, a series of 4,5,9,10-tetrahydropyrene-based tetraarylethenes were synthesized and structurally characterized. An aggregation-induced emission (AIE) study indicated that all the compounds are AIE active: they are weak emitters in good solvents but highly emissive in the condensed phase, and hence are potential solid-state emitters. Their optical properties, electrochemical properties and theoretical calculations were investigated, and the results prove that the π-conjugation degree of these compounds increases with the increasing number of 4,5,9,10-tetrahydropyrene units. However, the fluorescence quantum yield in the solid state doesn't increase with increasing π-conjugation. We studied the reason for this by analyzing the crystal structures of some compounds, and proposed that the close degree of molecular packing in the solid state may be responsible for it. Loose packing of tetraarylethenes in the solid state can restrict the rotation of the aromatic rings but cannot constrain other non-radiative pathways efficiently, such as vibration, which leads to the unpredictable emission of the compounds.

Tetraarylethenes with different π-conjugation degrees can be realized by controlling the number of 4,5,9,10-tetrahydropyrene segments. However, the fluorescence quantum yield of these compounds in films doesn't increase with the π-conjugation degree.

A series of tetraphenylethene-based benzimidazoles: syntheses, structures, aggregation-induced emission and reversible mechanochromism

A new series of tetraphenylethene-based benzimidazoles (2a–2d) were designed and synthesized. These compounds exhibit bifunctional AIE and reversible mechanochromic properties.

A new TICT and AIE-active tetraphenylethene-based Schiff base with reversible piezofluorochromism

A new tetraphenylethene-based Schiff base N-5-nitrosalicylidene-4-tetraphenylethenylamine (NSTPE) exhibits an interesting “on–off–on” optical switching property and reversible piezofluorochromic properties.