Imidazolyl-Phenylcarbazole-Based Host Materials and Their Use for Co-host Designs in Phosphorescent OLEDs.

In recent years, owing to the demand for high-efficiency phosphorescent organic light-emitting devices (PhOLEDs), many studies have been conducted on the development of bipolar host materials. A series of imidazolyl-phenylcarbazole-based host materials, i. e., im-CzP, im-CzPCz, im-CzPtBu, and im-OCzP, were synthesized to obtain high-efficiency green and red-emitting PhOLEDs. With im-OCzP as the host, satisfactory peak efficiencies of 22.2 (77.0 cd A-1 and 93.1 lm W-1 ) and 14.1 % (9.0 cd A-1 and 10.1 lm W-1 ) could be obtained, respectively. To further improve the performance of the devices, an electron transport material, bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (B3PyMPM) was selected to construct a co-hosted system. The efficiency of im-OCzP combined with B3PyMPM forming co-hosts could also achieve high values of 23.0 (80.0 cd A-1 and 98.8 lm W-1 ) and 16.5 % (10.2 cd A-1 and 13.4 lm W-1 ) for green and red PhOLEDs, respectively. These results exhibited that the proposed bipolar hosts have great flexibility in adjusting the carrier balance of EML in OLEDs, demonstrating their ingenious design and high potential.

[Thermodynamics studies on the reaction characteristics of hemoporphyrin with human serum albumin].

The quenching reaction of hemoporphyrin with human serum albumin (HSA) was studied by using fluorescence spectraand absorption spectra. The formation constants of them were analyzed at different temperature according to Stem-Volmer equation and double-reciprocal equation, which are smaller at high temperature than at low temperature. The binding site was calculated (r = 4.36) by Foster energy transfer mechanism, and the thermodynamic parameters were obtained. H-bond and Van der Waals are two main reactions between HP and HSA.

[Molecular recognitions of purines by hematoporphyrin and metalloporphyrin receptors].

The present paper studies the interactions of purines and porphyrin by fluorescence, UV, and NMR spectra. The optimal conditions (acidity and ion intensity) of the interaction of purines and hematoporphyrin and metalloporphyrin were investigated in detail. The result shows that hematoporphyrin and metalloporphyrin exhibit significant recognition of purines. The binding constants of metalloporphyrin: K(Ni(II)-HP) > K(Co(II)-HP) > K(Zn(II)-HP) > K(Cu(II)-HP) in pH 11.2 Kolthoff buffer solution. The mechanism of recognition was further discussed. Recognition is achieved by cooperative functions of three recognition groups (metalloporphyrin) and two recognition groups (hematoporphyrin).