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A series of novel monodisperse, structurally well defined vinylene‐linked phenothiazine oligomers containing up to 7 phenothiazine units have been designed and synthesized by Heck reaction and McMurry reaction with a convergent approach. These conjugated oligomers showed a progressive bathochromic shift of the absorption maxima and high fluorescence quantum yields in solutions. Notably, the oligomers without strong donor and acceptor units exhibit two‐photon absorption properties, and the two‐photon absorption cross sections (δ) increase with the number of covalently linked phenothiazine units, and δ reaches up to 2071 GM for the one with 7 phenothiazine units at 800 nm. The oligomers might be used as models to study structure–property relationship for their corresponding polymers or applied in organic electronic materials. [ABSTRACT FROM AUTHOR]

An L-phenylalanine derivative ( C12PhBPCP) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self-assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self-assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H-aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self-assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively. [ABSTRACT FROM AUTHOR]

Nanofibers based on phenanthroimidazole derivatives PCC, PDC, and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber-based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC, in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber-based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber-based film and in spin-coated film, respectively. The results suggested that the high surface-to-volume ratio and large interspace in the nanofiber-based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance. [ABSTRACT FROM AUTHOR]

Two L-phenylalanine derivatives with 5,8-bis(2-(carbazol-3-yl)vinyl)quinoxaline ( PCQ) and 5,8-bis[2-(carbazol-3-yl)]-2,3-dimethylquinoxaline ( DCQ) as fluorophores were synthesized, and their photophysical properties were measured and compared. The two compounds were found to gelate some organic solvents and self-assemble into 1D nanofibers in gels. The wet gel of PCQ emitted a weak orange fluorescence, but the DCQ gel had a strong green one. This result can be due to the presence of two methyl groups and the nonplanar conformation of fluorophore in DCQ. The gel film of DCQ also showed significantly stronger fluorescence than that of PCQ. Thus, the wet gel and xerogel film of DCQ were selected to study their sensing properties to acids. The yellow wet gel of DCQ transformed into a brown sol upon the addition of 0.2 equiv trifluoroacetic acid (TFA), accompanied by emission quenching. The xerogel film of DCQ rapidly responded to volatile acids, such as TFA, HCl, and HOAc. The fluorescence of the xerogel film was gradually quenched with increased concentration of volatile acid vapors. The fibrous film exhibited low detection limits for volatile acid. The detection limits of the thin films for TFA, HCl, and HOAc reached 43, 122, and 950 ppb, respectively. [ABSTRACT FROM AUTHOR]

Fluorescent organic molecules with C3-symmetry consisting of tris{2-cyano-2-[4-(dodecyloxybenzoylamino)phenyl]-1-ethenyl}phenylbenzene (CN-DBAPPBn, n = 1, 2, 3) were synthesized. It was observed that these compounds can spontaneously self-assemble into organogels in many organic solvents. Scanning electron microscopy (SEM), light microscopy, and fluorescence microscopy images of the air-dried gels showed the presence of either heavily entangled amorphous or fibrous structures, or rods. FTIR, UV/Vis absorption, excitation and emission spectra suggest that π-π interactions and H-bonding are the driving forces for the formation of the gel phases. Moreover, spherical or cubic fluorescent nanoparticles based on CN-DBAPPBn were prepared by using a reprecipitation method in a mixture of tetrahydrofuran and water. It is interesting that aggregation-induced emission behavior of CN-DBAPPBn was detected in both the gel phase and in the nanoparticle suspensions. The fluorescent molecular aggregates of CN-DBAPPBn with different architectures and emission properties fabricated by using these self-assembling methods could find potential applications in sensors and optoelectronic devices. [ABSTRACT FROM AUTHOR]

We study the photophysical characters of two oligofluorenes-functionalized anthracenes molecules with different fluorine-vinylene ( FV) units, which exhibits that 'excimer' state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of 'excimer'. The fast one is controlled by the arene-arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM-dependent 'excimer' and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution. [ABSTRACT FROM AUTHOR]