Texaphyrins are pentaazadentate macrocycles with interesting photophysical properties and potential applications as nonlinear optical (NLO) materials, photosensitizers, magnetic resonance imaging (MRI) contrasting reagents, and radiation sensitizers, etc. To further red-shift the Q-like band of the texaphyrins, a benzotexaphyrin with an extensively delocalized pi-electron system was synthesized for the first time. Its photophysical characteristics were systematically investigated. Due to the extended pi-conjugation, the Q(0,0) band of benzotexaphyrin bathochromically shifts to 810 nm, and it emits at 825 nm with a singlet excited-state lifetime of 895 ps. Its triplet excited-state energy is estimated to be 119 kJ/mol. The triplet excited-state lifetime is approximately 2.2 micros, and the quantum yield of the triplet excited-state formation is 0.78. It also exhibits a triplet-triplet transient absorption in the region 505-590 nm. In addition, benzotexaphyrin exhibits high efficiency in generating singlet oxygen in methanol (Phi(Delta) = 0.65). Therefore, benzotexaphyrin could potentially be a NIR photosensitizer and emitter for photodynamic therapy and bioimaging applications.

Two novel 8-hydroxyquinoline metallic derivatives, (E)-2- [(2,3,4,5-tetrafluorophenyl)ethenyl]-8-hydroxyquinolate zinc (5) and (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinolate zinc (6) were synthesized and characterized by 1 H NMR, ESI-MS, FT-IR and elemental analysis. Photoluminescence spectra revealed that the complexes showed strong fluorescence with maximum emissions at 575 and 607 nm. Compared with that of complex 5, the fluorescence quantum yield and average fluorescence lifetime of complex 6were efficiently reduced. The heavy atom effect of Cl and distinct molecular interactions were found to play an important role in modulating or improving the properties of the complexes. Multilayer organic light-emitting diodes (OLEDs) were fabricated using these complexes. The results show they are good candidates for yellow OLEDs with maximum luminance of 7123 cd m À2 for compound 5 and 9143 cd m À2 for compound 6, as well as luminance efficiencies of 2.26 cd A À1 and 2.60 cd A À1 , respectively. As the substituents are changed from fluorine to chlorine, the organic electroluminescent device based on the complex 6 shows overall better performance than that of complex 5. The calculated HOMO-LUMO energy gaps for complexes 5 and 6 were in good agreement with the experimental results.