This paper reports on novel electron transport materials, 1,3,5-triazine derivatives (TRZ), which have been useful in high-efficiency electrophosphorescent (EP) organic light-emitting diodes (OLEDs). We synthesized four 2,4,6-tris(diarylamino)-1,3,5-triazine derivatives (TRZ1−TRZ4) that had electron-donating substituents and examined their OLED characteristics. Of these, we found that TRZ 2, 3, and 4 function as a host for tris(2-phenylpyridine)iridium (Ir(ppy)3) and, in particular, 2,4,6-tris(carbazolo)-1,3,5-triazine (TRZ2) demonstrated a very high external electroluminescent (EL) quantum efficiency (ηext) of ∼10.2 ± 1.0% and an energy conversion efficiency (ηenergy) of 14.0 ± 2.0 lm/W. Detailed transient photoluminescent (PL) measurement revealed that the triplet energy level of TRZ2 (E T1 = 2.81 eV) is higher than that of conventional 4,4‘-N,N‘-dicarbazol-biphenyl (CBP) (E T1 = 2.56 eV), suggesting that TRZ2 has excellent capabilities in confining Ir(ppy)3 triplet excitons.

Chiral bis-phosphoric acid 1 was designed to identify a new class of structural features in chiral Brønsted acid catalysts. X-ray diffraction analysis revealed the single atropisomer 1, bearing S axial chirality at 3,3'-biaryl substituents on (R)-binaphthyl and intramolecular hydrogen bonding between the two phosphoric acid moieties. The newly designed bis-phosphoric acid 1 was evaluated in the Diels-Alder reaction of α,β-unsaturated aldehydes 4 with 1-N-acylamino-1,3-butadienes 3. After systematic variation of the catalyst substituents, as well as the N-acyl substituents of 1,3-butadiene, the use of an N-Cbz amidodiene 3a in the presence of bis-phosphoric acid 1e with a 2,4,6-tri-isopropylphenyl group was found to be optimal to yield the 1S,6R enantiomeric product 5aa in a Diels-Alder reaction of acrolein (4a). Application of this method to substituted substrates was found to be an efficient approach to the enantioselective synthesis of 3- and 3,6-substituted cyclic formylcarbamates 5. The specific character as well as the utility of 1e was further established by comparing its enantioselectivity, absolute stereochemistry, and catalytic efficiency with those of mono-phosphoric acid 2.

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