A series of three pentacene derivatives featuring substituted aryl groups at the 6,13-position, namely, 6,13-diphenylpentacene, 6,13-bis(2,6-dimethylphenyl)pentacene, and 6,13-bis(4-tert-butylphenyl)pentacene, have been synthesized and characterized. The optical properties of each compound have been determined in solution and in the solid state. Films containing the pentacene derivatives dispersed in tris(quinolin-8-olato)aluminum(III) (Alq3) emit in the red with small contribution from the Alq3 host, signaling efficient energy transfer from host to guest molecules. The absolute photoluminescence quantum yield (φPL) of composite films is ∼30−32% at optimum dopant concentration. Organic light-emitting diodes based on these composite films as the active emitting layers have been fabricated and characterized. External electroluminescence quantum efficiencies near the theoretical limit have been achieved.

Poly(chloromethylstyrene-co-divinylbenzene) (PCD) with 2% cross-linkage is developed as a backbone of immobile artificial enzymes. As the first artificial enzyme built on PCD, an artificial metalloproteinase is prepared by attaching the Cu(II) complex of cyclen as the catalytic center and guanidinium ion as the binding unit. The PCD derivatives prepared were characterized by scanning electron microscopy, IR spectroscopy, elemental analysis, titration of chloromethylphenyl moiety with triethylamine, complexation of p-nitrobenzoate ion to the guanidinium moiety, quantification of the cyclen moieties retaining high affinity for the Cu(II) ion, and determination of log K f for the Cu(II) binding sites. The proteinase activity was measured with γ-globulin (Gbn) by following cleavage of the two chains of Gbn by electrophoresis. The catalytic activity of the Cu(II) complex of cyclen toward Gbn was enhanced by more than 104 times upon attachment to PCD. Gbn complexed to the PCD derivative containing both Cu(II)-cyclen and guanidinium moieties was cleaved by hydrolysis into many pieces with a half-life as short as 10−30 min at pH 4.5−7 and 4 °C. Kinetic data revealed that guanidinium ions attached to PCD acted as effective binding sites for the protein, contributing considerably to the overall catalytic power of the immobile artificial metalloproteinase.

A series of four asymmetrically aryl-substituted 9,9'-spiro-9-silabifluorene (SSF) derivatives, 2,2'-di-tert-butyl-7,7'-diphenyl-9,9'-spiro-9-silabifluorene (PhSSF), 2,2'-di-tert-butyl-7,7'-dipyridin-2-yl-9,9'-spiro-9-silabifluorene (PySSF), 2,2'-di-tert-butyl-7,7'-dibiphenyl-4-yl-9,9'-spiro-9-silabifluorene (BPhSSF), and 2,2'-di-tert-butyl-7,7'-bis(2',2' '-bipyridin-6-yl)-9,9'-spiro-9-silabifluorene (BPySSF) are prepared through the cyclization of the corresponding 2,2'-dilithiobiphenyls with silicon tetrachloride. These novel spiro-linked silacyclopentadienes (siloles) form transparent and stable amorphous films with relatively high glass transition temperatures (T(g) = 203-228 degrees C). The absorbance spectrum of each compound shows a significant bathochromic shift relative to that of the corresponding carbon analogue as a result of the effective sigma-pi conjugation between the sigma orbital of the exocyclic Si-C bond and the pi orbital of the oligoarylene fragment. Solid-state films exhibit intense violet-blue emission (lambda(PL) = 398-415 nm) with high absolute photoluminescence quantum yields (phi(PL) = 30-55%).

Two aryl-substituted red emitting pentacenes, 5,6,13,14-tetraphenylpentacene (asym-TPP) and 5,14bis(2,6-dimethylphenyl)-6,13-diphenylpentacene (DMPDPP), have been prepared and spectroscopically characterized. Guest-host films of pentacene derivatives dispersed in tris(quinolin-8-olato)aluminum(III) (Alq 3 ) exhibit narrow red emission (λ max ) 663-680 nm), indicative of efficient Fo ¨rster energy transfer from the Alq 3 host to the guest molecules. Solid-state absolute photoluminescence quantum yields of the films were measured as a function of guest molecule concentration (Φ PL ∼20% at 0.20-0.50 mol %). Red light-emitting diodes based on the fluorescent DMPDPP yield external electroluminescence quantum efficiency (η EL ∼1%) close to the theoretical limit.