The absolute fluorescence quantum yield (Φfl) of a polyfluorenyl azomethine homopolymer was measured as a function of solvent polarity. The solvent induced and temperature dependent fluorescence of the homopolymer were also investigated and they were compared to the corresponding monomer and copolymer. The Φfl of the homopolymer was consistent (45-70%), regardless of solvent polarity with Stokes shifts up to 7460 cm(-1) in ethanol. In contrast, the Φfl of its corresponding monomer decreased from 60% in ethanol to 1% in toluene, whereas a Φfl < 5% for its analogous copolymer was measured. Moderate fluorescence yields (Φfl ≈ 25%) were also possible in thin film when co-depositing the homopolymer with PMMA. Cryofluorescence was used to probe the excited state deactivation modes. Deactivation by internal conversion was found to compete with fluorescence. The fluorescence deactivation pathways of the homopolymer and its corresponding monomer could be suppressed at 77 K, resulting in fluorescence turn-on. Both fluorophores were found to detect nitroaromatics.

A series of thiophenoazomethines connected to a central triphenylamine were prepared. The effect of the type of aminothiophene used to prepare the conjugated azomethines and the number of azomethine bonds, ranging from one to three, flanking the triphenylamine on the spectral, electrochemical, and spectroelectrochemical properties were investigated. Both the absorption and fluorescence of the azomethines (6–8) derived from 2,5-diaminothiophene (1) were found to be contingent on the number of the azomethines. The spectral properties were red-shifted with increasing the number of azomethine bonds. In contrast, the azomethines (9–11) derived from 2-aminothiophene (2) were not perturbed by the number of azomethines. However, their spectral properties were red-shifted relative to their triphenylamine counterparts derived from 1. The oxidation potentials of the azomethines were also contingent on structure. They were shifted to more positive potentials with increasing number of azomethines. The oxidation potentials of 6–8 were less positive than 9–11, owing to the electron-donating effect of the terminal amine. Reversible oxidation was observed with the triphenylamine having methyl groups in the 4′-positions. All the compounds examined underwent color changes upon both electrochemical and chemical oxidation. The oxidized state was shifted upward of 165 nm for the series 6–8 relative to the neutral state, whereas it was shifted at most by 85 nm for 9–11. The most pronounced color changes between the neutral and oxidized states occurred with the triphenylamine–thiophene–triphenylamine bisazomethine derivative (12).

The synthesis and characterization of six triarylisocyanurates, featuring 2,7‐fluorenyl or 9,10‐anthracenyl groups incorporated in their peripheral arms are reported. Photophysical studies reveal that these new octupolar derivatives are more fluorescent (ΦF≥0.60 for all new compounds except for 1,3,5‐tri(9H‐fluoren‐2‐yl)‐1,3,5‐triazinane‐2,4,6‐trione 3) and present a red‐shifted lowest absorption and emission compared to their known phenyl analogues of comparable size. Depending on the nature of the terminal substituent, fast intramolecular energy transfer among the three arms or localization of the excitation on a single branch occurs after population of their first singlet excited state. The latter effect was only observed in the presence of strongly electron‐releasing substituents in polar media. These new chromophores are also better two‐photon absorbers than the 1,4‐phenylene‐based isocyanurates reported so far, with cross sections σ2≥500 GM at 770 nm for 4‐NPh2 the fluorenyl group containing (13) and the anthracenyl group containing (14) chromophores. All these spectroscopic features, analyzed with the help of quantum chemical calculations, are crucial for the design of new biphotonic fluorescent dyes.

In the title compound, C31H31N3O5S, the regioselective substitution of the thiophene is confirmed with the amine and the amide at the 2- and 5-positions, respectively. In the molecule, the thiophene ring is twisted by 12.82 (3)° with respect to the aromatic ring of the benzamido group. Intramolecular N—H...O hydrogen bonds are present involving the N atoms of the primary amine and the amide groups, forming S(6) ring motifs. In the crystal, centrosymmetrically related molecules are linked by pairs of N—H...O hydrogen bonds involving the amide carbonyl O atoms and the primary amine N atoms to form dimers of R 2 2(16) ring motif.