Synthesis and photoluminescent properties of geometrically hindered cis-tris(diphenylaminofluorene) as precursors to light-emitting devices

• Published in: Molecules (Basel, Switzerland) Vol. 20; no. 3; pp. 4635 - 4654
• Main Authors: Kang, Nam-Goo, Kokubo, Ken, Jeon, Seaho, Wang, Min, Lee, Chang-Lyoul, Canteenwala, Taizoon, Tan, Loon-Seng, Chiang, Long Y
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13-03-2015; MDPI
• Subjects: Acetamides - chemical synthesis; Acetamides - chemistry; Agglomeration; cis-tris(diphenylaminofluorene); Devices; Fluorescence; geometrically hindered diphenylaminofluorene; light emitting chromophore; Light emitting diodes; light-harvesting nanostructure; Luminescent Agents - chemical synthesis; Luminescent Agents - chemistry; Modulation; Molecular Conformation; Molecular structure; nonplanar stereoisomer; Photoluminescence; Polyvinyl carbazole; Spectrophotometry; Stereoisomerism; Three dimensional; United States > US
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules20034635

A novel highly luminescent tris-fluorenyl ring-interconnected chromophore tris(DPAF-C9) was synthesized using a C3 symmetrical triaminobenzene core as the synthon. This structure bears three light-harvesting 2-diphenylamino-9,9-dialkylfluorenyl (DPAF) ring moieties with each attached by two branched 3',5',5'-trimethylhexyl (C9) arms. A major stereoisomer was chromatographically isolated and characterized to possess a 3D structural configuration of cis-conformer in a cup-form. Molecular calculation at B3LYP/6-31G* level revealed the unexpected stability of this cis-cup-conformer of tris(DPAF-C9) better than that of the stereoisomer in a propeller-form and the trans-conformer. The structural geometry is proposed to be capable of minimizing the aggregation related self-quenching effect in the condensed phase. Fluorescence emission wavelength of tris(DPAF-C9) was found to be in a close range to that of PVK that led to its potential uses as the secondary blue hole-transporting material for enhancing the device property toward the modulation of PLED performance.