Various π-conjugated copolymers constituted of π-excessive thiophene, selenophene, or furan units (Ar) and π-deficient pyridine or quinoxaline (Ar‘) units have been prepared in high yields by the following organometallic polycondensation methods:  (i) n X−Ar−Ar‘−X + n Ni(0)Lm → (-Ar−Ar‘)- n (X = halogen, Ni(0)Lm = zerovalent nickel complex), (ii) n X−Ar−X + n Me3Sn−Ar‘−SnMe3 → (-Ar−Ar‘)- n (palladium catalyzed), and (iii) a X−Ar−X + b X−Ar‘−X + (a + b)Ni(0)Lm → (-Ar) x (Ar‘)- y . Powder X-ray diffraction analysis confirms an alternative structure of a polymer prepared by the method ii. The copolymers have a molecular weight of 5.4 × 103 to 3.3 × 105 and an [η] value of 0.37 to 4.4 dL g-1. π−π* absorption bands of the copolymers generally show red shifts from those of the corresponding homopolymers, (-Ar)- n and (-Ar‘)- n , and the red shifts are accounted for by charge-transferred CT structures of the copolymers. For example, an alternative copolymer of thiophene and 2,3-diphenylquinoxaline gives rise to an absorption band at λmax = 603 nm, whereas homopolymers of thiophene and 2,3-diphenylquinoxaline exhibit absorption peaks at about 460 and 440 nm, respectively. The CT copolymers are electrochemically active in both oxidation and reduction regions, showing oxidation (or p-doping) peaks in a range of 0.39 to 1.32 V vs Ag/Ag+ and reduction (or n-doping) peaks in a range of −1.80 to −2.22 V vs Ag/Ag+, respectively. Copolymers of pyridine give unique cyclic voltammograms exhibiting p-undoping peaks at potentials much different (about 2−3 V lower) from the corresponding p-doping potentials, and this large difference between p-doping and p-undoping potentials is explained by an EC mechanism. They are converted into semiconductors by chemical and electrochemical oxidation and reduction. Copolymers of thiophene with pyridine and quinoxaline show the third-order nonlinear optical susceptibility χ(3) of about 5 × 10-11 esu at the three-photon resonant wavelength, which is 5−7 times larger than those of the corresponding homopolymers and related to the CT structure in the copolymers.

Palladium-catalyzed polycondensation between dihalo aromatic compounds X-Ar-X (3hexyl-2,5-diiodothiophene, 2,5-dibromoselenophene, and 3,4-dinitro-2,5-dibromothiophene) and diethynyl aromatic compounds HC=C-Ar'-C=CH (2,5-diethynylpyridine, 3-hexyl-2,5-diethynylthiophene, and p-diethynylbenzene) in the presence of triethylamine gives soluble -conjugated poly(aryleneethynylene) (PAE) type polymers (-Ar-C=C-Ar'-C=C-)" when Ar and/or Ar' contains the long alkyl substituent and/or pyridine ring. The PAE type polymers are obtained in high yields (86-100 %), have molecular weights of 9.6 X 10 59 X 104 and pv (degree of depolarization) values of 0.005-0.034 as determined by the light scattering method, and show absorption bands in the range 350-462 nm, which are shifted from the absorption bands of the corresponding aromatic units (HArH and HAr'H), indicating the occurrence of -conjugation along the polymer chain. The polymers exhibit fluorescence in solutions, and the position of the fluorescence is shifted to a longer wavelength in films of the polymers, suggesting the formation of excimer-like adducts in the solid state. The polymer films give a (3) (third-order nonlinear optical susceptibility) value of about 5 x 10"u esu when the Ar group has the hexyl group. Cyclic voltammetry of the PAE type polymers indicates that they receive reduction (n-doping) at about -2 V vs Ag/Ag+ whereas oxidation (p-doping) of the polymer is difficult presumably due to the electron-withdrawing effect of the -C=Cgroup. HBr addition to the -C=Cgroup of the polymer gives a polymer having a -CH=CH(Br)group, which can be further converted into ester and amide groups.

Poly(4,4‘-dialkyl-2,2‘-bithiazole-5,5‘-diyl)s (PRBTz, alkyl = methyl (PMeBTz), butyl (PBuBTz), and heptyl (PHepBTz)) and their analogues comprised of 33−150 thiazole rings have been prepared by organometallic polycondensation, and their chemical and physical properties are compared with those of π-conjugated poly(thiophene-2,5-diyl) (PTh) and poly(pyridine-2,5-diyl) (PPy). Electrochemical n-doping of PRBTz takes place at E° = −1.77 to −2.30 V vs Ag/Ag+ and is accompanied by the appearance of a new absorption band in the near-infrared. PMeBTz assumes a relatively stiff structure in solution and shows a large refractive index increment of 0.55 cm3 g-1; powder X-ray diffraction analysis of PMeBTz supports a face-to-face type stacking of the polymer chains in the solid state. All of the polymers show photoluminescence in solutions and in the solid, and an electroluminescence device using PMeBTz as the emitting layer gives emission of light at λmax = 680 nm with 100 cd m-2 at 8 V. A thin film of PMeBTz gives an optical third-order nonlinear susceptibility χ(3) of 2.5 × 10-11 esu, which is larger than observed with PTh and PPy films, and comparison of the χ(3) value with that (0.3 × 10-11 esu) of nonregioregular poly(4-methylthiazole-2,5-diyl) (PMeTz) reveals the importance of the regioregular structure of PMeBTz to give the larger χ(3) value.

Humidity dependence of the refractive index of deuterated polymethylmethacylate (d-PMMA) is examined at a wavelength of 1.3 μm using the return loss method. The refractive index of d-PMMA increases as humidity increases at room temperature, while it decreases as humidity increases at temperatures higher than 60 °C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swelling. Some hydrophobic polymers, such as silicone resin and fluorinated epoxy resin were affected by humidity to a lesser degree than d-PMMA.

Humanin (HN) and S14G HN (HNG) are recently discovered polypeptides that rescue cells from death induced by multiple different types of familial Alzheimer's disease genes and by amyloid-beta. However, the cytoprotective activity of these peptides against other cell death-inducing stimuli remains unclear. In this study, we demonstrated, using three different methods (MTS assay, caspase-3 assay, and detection of DNA fragmentation), that both HN and HNG protect PC12 cells from death elicited by serum deprivation. This implies the potential of the peptides to rescue cells from a broad spectrum, if not all, of cell death-inducing factors. Further investigations on HN may lead the possible application of this peptide as therapeutic agent for the treatment of other neurodegenerative diseases.

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Palladium-catalyzed polycondensation between p-diethynylbenzene (HCtCsPhsCtCH) and 2,5-diiodo-3-hexylthiophene (IsTh(Hex)sI) has been carried out under various conditions by changing the polymerization temperature, medium, and added amines. The polycondensation gives the polymer (PAE-1) with a Mn of about 3 × 10 4 (by GPC, polystyrene standards) and an [η] value of 0.8 dL g -1 . By using neat NEt3 as the medium, the polymerization proceeds fast. 1 H-NMR spectroscopic analysis indicates that oligomeric PAE-1 obtained at short polymerization time has a CsI bond (sTh(Hex)sI bond) as the major terminal group, which is consistent with results of the basic Pd-catalyzed CsC coupling reaction. The CsI terminal bond of oligomeric PAE-1 reacts with 1,3,5-triethynylbenzene and 1,2,4,5tetraethynylbenzene to give polymers with M n values of 8.7 × 10 5 and 2.3 × 10 6 (by GPC), respectively, and the polymers are considered to have star-type structures. All the polymers show two (main and sub) photoluminescence PL peaks at 456 ( 3 and 486 ( 2 nm. The CtC bond of PAE-1 is susceptible to trans-type hydrogenation with SMEAH (sodium bis(2-methoxyethoxy)aluminum hydride) and DIBAL (diisobutylaluminum hydride) as well as to chlorofluorination by a mixture of N-chlorosuccinic imide and a pyridinium salt of (HF) xF -.

We have developed the first silica-based PLC type 32 x 32 optical matrix switch. The switch is the largest scale waveguide type switch yet reported, which has excellent optical characteristics with an average insertion loss of 6.6 dB.