TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The electroluminescent device comprises a cathode, an anode, and a light emitting layer containing a host material and a phosphorescent light-emitting material, between the cathode and the anode, where (A) is the host material. The electroluminescent device contains: an electron transport layer comprising (A); or a hole blocking layer comprising (A).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of (II) comprises: condensation of a 3-chloro-propiophenone compound of formula (R-COCH2CH2Cl) with 1,2-diaminobenzene under concomitant oxidation with chloranil to give a 4,7-disubstituted 1,10-phenanthroline compound of formula (1a); and reaction of (1a) with an organolithium compound of formula (R1a-Li) followed by dehydrogenation with manganese dioxide to give 4,7-disubstituted-1,10-phenanthroline compound of formula (IIa) (representative of (II)).R, R1a = not defined. Preferred Definitions:    R1, R2 = phenyl, biphenylyl, naphthyl, fluorenyl, anthrenyl, anthracenyl, phenanthrenyl, perylenyl or pyrenyl (all optionally substituted);    R3 = T;    T = pyrryl, thienyl, triazolyl, pyrazolyl, oxazolyl, imidazolyl, pyridyl, pyrimidyl, pyridazyl, triazinyl, quinolyl, isoquinolyl, carbazolyl, quinazolinyl, quinoxylinyl, phenazinyl, phthalazinyl, acridinyl, pteridyl, benzimidazolyl, benzofuranyl, benzoxazolyl, xanthenyl, phenoxazinyl or phenothiazinyl (all optionally substituted);    R4 = phenyl, biphenylyl, naphthyl, fluorenyl, anthrenyl, anthracenyl, phenanthrenyl, perylenyl or pyrenyl (all optionally substituted), H, 6-12C alkyl or T; and    R5 = phenyl, biphenylyl, naphthyl, fluorenyl, anthrenyl, anthracenyl, phenanthrenyl, perylenyl or pyrenyl (all optionally substituted) or T.    SPECIFIC COMPOUNDS - 143 Compounds (A) are disclosed e.g. 4,7-bis-(3-(4-pyridyl)-phenyl)-2,9-diphenyl-1,10-phenanthroline of formula (Aa), 4,7-diphenyl-2-(2-pyridyl)-1,10-phenanthroline, 2,9-bis-(4-(4-pyridyl)phenyl)-4,7-diphenyl-1,10-phenanthroline, 2,4,7,9-tetrakis-(2-thienyl)-1,10-phenanthroline and 2,9-bis-(4-bromophenyl)-4,7-diphenyl-1,10-phenanthroline.    EXAMPLE - To the deoxygenated mixture of 4,7-bis-(3-bromophenyl)-2,9-diphenyl-1,10-phenanthroline (1.615 g), pyridine-4-boronic acid (1.031 g), potassium carbonate (3.475 g), ethanol (10 ml), water (5 ml) and toluene (25 ml) was added tetrakis-(triphenylphosphine)palladium (0.23 g). The mixture was then stirred under reflux in argon atmosphere for 18 hours. The mixture was then cooled to room temperature and diluted with dichloromethane (500 ml) and water (50 ml). The organic layer was separated, washed with water and evaporated. The residue was purified and the pure fractions were crystallized from dimethylformamide to afford 4,7-bis-(3-(4-pyridyl)-phenyl)-2,9-diphenyl-1,10-phenanthroline (1.16 g).