Diarylamino Groups as Photostable Auxofluors in 2-Benzoxazolylfluorene, 2,5-Diphenyloxazoles, 1,3,5-Hexatrienes, 1,4-Distyrylbenzenes, and 2,7-Distyrylfluorenes

Abstract

The relationship of structure to optical spectral properties was determined for five types of fluors in a search for an optimum-wavelength shifter to be used as part of the detection systems for high-energy particles from accelerators. In a search for photostable fluors to serve as waveshifters in plastic fibers it was found that the wavelengths of interest, absorption max 410 +/- 10 nm and fluorescence emission max 480 +/- 20 nm, along with other properties, such as high solubility and short fluorescence decay time, could be obtained from fluorophors composed of aromatic rings and vinyl groups only by using amino groups as auxochromes to give bathochromic shifts of wavelengths. Since primary, monoalkyl, and dialkylamino groups were not sufficiently photostable, a number of fluorophores bearing diarylamino groups were investigated. Syntheses of the fluors made use of the Buchwald amination, an improved version of the Emmons-Horner reaction, and other common reactions. The fluor types were the following: a 2-benzoxazolyl-7-(4-diarylamino)fluorene 7, 2-(4-cyanophenyl)-5-(4-aminophenyl)oxazoles 14 and 20, 1,3,5-hexatrienes 24a-d and 26a-c, 1,4-distyrylbenzenes 31d-g and 32a-e, and 2,7-distyrylfluorenes 40a,d-e. The unsymmetrical fluors 7, 14, and 20 were not as bright as the best hexatrienes, distyrylbenzenes, and distyrylfluorenes, which were all symmetrical. Where the 1,6-diaryl-1,3,5-hexatrienes 24a-d had high fluorescence quantum yield (Phi(f)), the 1,1,6,6-tetraryl-1,3,5-hexatrienes 26a-c had both lower epsilon and Phi(f). Where the 1,4-distyrylbenzenes 31d-g had high Phi(f), the 1,4-bis(2-phenylstyryl)benzenes 32a-e had Phi(f) = 0. Diarylamino groups as auxofluors conferred higher photochemical stability than dialkylamino groups on similar fluorophores. The 1,4-distyrylbenzenes 31d,e and the 2,7-distyrylfluorenes 40d,ehad the most desirable properties overall, which included fast decay times of 2 ns. Computer simulations predicted absorption and emission wavelengths fairly well, but were of little help for the prediction of brightness, stability, Phi(f), or decay time.

Recent Development of Blue Fluorescent OLED Materials and Devices

“…We chose to work with a similar but much simpler dopant of the structure of (diphenyl)aminostyryl benzene [23] hitherto abbreviated as DSA-Ph, as shown in Fig. 7.…”

Highly Efficient, Deep‐Blue Doped Organic Light‐Emitting Devices

“…[9] Ionic liquids have many properties which make them highly suitable for use in rechargeable lithium batteries: these properties include excellent thermal stability, effectively zero volatility and flammability, high conductivity, and a wide electrochemical window. Nevertheless, despite improved cycling performance when compared to most traditional solvent-based electrolytes, dendrite formation still occurs when practical current densities are used.…”

2‐Diphenylaminofluoren‐7‐ylstyrene Derivatives with Various Aromatic End‐Capping Groups for Highly Efficient Blue and White Organic Light‐Emitting Diodes

“…[13] In this doped-emitting system, energy transfer from the host to the dopant molecule allows emission to originate from the dopant with emission properties dominated by the dopant as well. Various blue-emitting dopants have been developed, including 4,4Ј-bis{2- [4-(N,N-diphenylamino)phenyl]vinyl}biphenyl (BDAVBi), [14] diphenylaminobis(styryl)arylene, [15] 4-diphenylaminophenylethylenylterphenyl, [16] and 9-ethyl-3-(4-phenylquinolin-2-yl)-9H-carbazole. [17] In addition, fluorenes, spirofluorenes, oligomeric fluorenes, and their derivatives are used as blue dopant emitters, exhibiting high fluorescent efficiency, thermal stability, and good solubility.…”