Synthesis,Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems

A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro‐Diels–Alder reaction of bicyclo[2.2.2]octadiene‐fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time‐dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π‐molecular orbitals.     

Src Mediates Epigallocatechin-3-O-Gallate-Elicited Acid Sphingomyelinase Activation

Epigallocatechin-3-O-gallate (EGCG) is one of the major bioactive compounds known to be present in green tea. We previously reported that EGCG shows selective toxicity through activation of the protein kinase B (Akt)/cyclic guanosine monophosphate (cGMP)/acid sphingomyelinase (ASM) axis via targeting its receptor 67-kDa laminin receptor (67LR), which is overexpressed in cancer. However, little is known about upstream mechanisms of EGCG-elicited ASM activation. In this study we show that the proto-oncogene tyrosine-protein kinase Src, also known as c-src, plays a crucial role in the anticancer effect of EGCG. We showed that EGCG elicits phosphorylation of Src at Tyr 416, a crucial phosphorylation site for its activity, and that the pharmacological inhibition of Src impedes the upstream events in EGCG-induced cell death signaling including upregulation of Akt activity, increase in cGMP levels, and activation of ASM. Moreover, focal adhesion kinase (FAK), which is involved in the phosphorylation of Src, is colocalized with 67LR. EGCG treatment enhanced interaction of FAK and 67LR. Consistent with these findings, pharmacological inhibition of FAK significantly neutralized EGCG-induced upregulation of Akt activity and activation of ASM. Taken together, FAK/Src play crucial roles in the upstream signaling of EGCG.     

Effective synthesis of diiodinated picene and dibenzo[a,h]anthracene by AuCl-catalyzed double cyclization

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.     

Statistics of Gaussian Speckles with Enhanced Fluctuations

Some first-order statistics of speckle fields obeying the complex Gaussian probability density are investigated with the special emphasis on a possibility for the speckle contrast to exceed unity. It is shown that such enhanced fluctuations of speckle fields are generated when the probability density of the complex amplitude is non-circular with the vanishing mean. This means that Gaussian speckles having the contrast of unity are not necessarily fully developed speckles. Some practical situations producing such enhanced fluctuations in speckle fields are discussed.     

Optical Spatial Filter Sensor for Ground Speed

The prototype for a ground speed sensor has been designed, fabricated and evaluated. It works on the principle of optical spatial filtering and uses pulse driven light emitting diodes as a source of illumination. The sensor was tested at speeds ranging from 2 to 50 km/h, and an accuracy of 1.5 km/h was obtained with response time of 30 ms, height from ground of from 230 to 370 mm and on various road surfaces. The sensor is viewed as beneficial for use in a vehicle’s antilock braking system and will contribute to traffic safety.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.     

Asymmetric anionic polymerization of 2,6-dimethyl-7-phenyl-1,4-benzoquinone methide

Asymmetric anionic polymerizations of 2,6-dimethyl-7-phenyl-1,4-benzoquinone methide ( 1 ) were performed with various chiral anionic initiators, and the specific rotations of the obtained polymers were investigated. Optically active poly( 1 )s with configurational chirality were obtained with all the initiators, and a complex of fluorenyllithium (FlLi) with (−)-sparteine [(−)-Sp] produced poly( 1 ) with the largest negative specific rotation ([α]₄₃₅ = −26.8°). The specific rotations of poly( 1 )s obtained with FlLi/(−)-Sp depended on the initiator concentration and the solvent polarity. The maximum specific rotations were obtained at an almost constant initiator concentration (ca. 0.03 mol/L), regardless of the monomer concentration, in toluene, whereas a higher initiator concentration was required in more polar solvents. These results suggested that the aggregation state of the propagating chain end significantly affected the specific rotation of poly( 1 ). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4548–4555, 2004     

Spontaneous polymerization mechanism of electron‐accepting substituted quinodimethane with vinyl ether and cyclic ketene acetal

The spontaneous reactions of 1‐(2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione‐5‐ylidene)‐4‐(dicyanomethylene)‐2,5‐cyclohexadiene (QM‐1) with a vinyl ether, butyl vinyl ether (BVE), and a cyclic ketene acetal, 2‐methylene‐1,3‐dioxepane (MDOP), were investigated. The reaction of QM‐1 with BVE produced a terpolymer composed of QM‐1, 7‐butoxy‐8,8‐dicyanoquinodimethane, and BVE units as a hexane‐insoluble product and a one‐to‐one adduct of methylene Meldrum's acid and BVE as a hexane‐soluble product. The spontaneous reaction of QM‐1 with BVE produced, in the presence of 2,2,6,6‐tetramethylpiperidine‐1‐oxy (TEMPO), a terpolymer carrying TEMPO units in the chain ends, and in the presence of methanol, a one‐to‐one‐to‐one adduct of QM‐1, BVE, and methanol was isolated. The spontaneous reaction with bulkier, electron‐donating MDOP produced a low‐molecular‐weight alternating cooligomer of QM‐1 with MDOP. The spontaneous polymerization was proposed to proceed via a zwitterionic intermediate taking two forms, gauche and trans, depending on the bulkiness of the comonomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3800–3811, 2004