SYNTHESIS,CHARACTERIZATION AND OPTICAL PROPERTIES OF THE COPOLYMERS OF C_(60) AND 1-PHENYL-1-PROPYNE

While WCl_6-Ph_4Sn fails to polymerize 1-phenyl-1-propyne (PP) at room temperature, highmolecular weight (M_w up to 410× 10~3) polymers are obtained in high yields (up to 80%) when thepolymerizations of PP are carried out in the presence of C_(60) using the W catalyst under the same conditions.The polymers are soluble in common organic solvents such as THF, chloroform, and toluene. Molecularstructures of the polymers are characterized by FT-IR, UV, NMR, GPC and XRD, and it is found that C_(60) iscopolymerized with PP. Thus C_(60) plays the dual roles of comonomer and cocatalyst in the polymerizationreaction. C_(60) contents of the copolymers can be easily changed by varying the C_(60) amounts in the feedmixtures. The copolymers effectively limit strong 532 nm laser pulses, whose limiting performance issuperior to that of parent C_(60).

SYNTHESIS AND OPTICAL PROPERTIES OF POLY (THIENYLACETYLENES)

3-Ethynyl-4-(trimethylsilyl)thiophene (1a) and 3-ethynyl-4-bromothiophene (1b) selectively undergo acetylene polymerizations in the presence of the MoCl5- and WCl6-Ph3SiH catalysts to give soluble, high-molecular-weight poly(thienylacetylenes) (2) (M-w up to 602000) in high yields (up to 100%). Light transmission spectra of THF solutions of 2 continuously red-shift with increasing concentration. The concentratochromism shows a logarithmic concentration dependence; that is, the optical transitions of 2 are predictably tunable by simply changing their concentrations.

SYNTHESIS AND PROPERTIES OF POLY(AROMATIC DIACETYLENE)S CONTAINING FLUORENE

Novel fluorene-based poly(aromatic diacetylene)s have been synthesized by CuCl-catalyzed oxidative coupling of aromatic diynes.New aromatic diynes 2,7-diethynyl-9,9-bis(triphenylamine)fluorene(M_1)is synthesized by multistep reactions.The structures and properties of the polymers are characterized and evaluated by IR,NMR,TGA,UV, photoluminescence(PL),and cyclic voltammetry analyses.These polymers possess good thermal stability.All the polymers are completely soluble in coammon solvents such as toluene,THF,c...

INFLUENCE OF BACKBONE RIGIDITY ON THE LIQUID CRYSTALLINITY OF MESOGEN-CONTAINING POLYACETYLENES

Two acetylene polymers containing cyanobiphenyl-based mesogens, poly{10-[((4'-cyano-4-biphenylyl)oxy)carbonyl]-1-decyne} (PA8CN), which has a relatively flexible polyalkyne backbone, and poly {[4-(((12-((4'-cyano-4-biphenylyl)oxy)dodecyl)oxy) carbonyl) phenyl]-acetylene} (PB12CN), which has a fairly rigid poly(phenylacetylene) backbone, were synthesized using respectively WCl6 and [Rh(nbd)Cl](2) as the catalysts. PA8CN exhibits enantiotropic interdigitated smectic A phase (S-Ad) over a temperature range as wide as ca. 100 degrees C, whereas PB12CN is non-mesomorphic, demonstrating that the backbone rigidity plays an important role in determining the liquid crystallinity of the polyacetylenes.

FULLERENE POLYMERS WITH TUNABLE OPTICAL PROPERTIES

Light transmission spectra of THF solutions of poly (C-60-co-methyl methacrylate)s and poly(C-60-co-styrene)s continuously red-shift with increasing concentration. Formation of fullerene nanoclusters may be responsible for the unusual spectral shift, with concentration. It has long been scientists' dream to ''tune'' material's properties by simple means, and the C-60-containing polymers represent such a group of novel materials whose optical properties are predictably and reversibly tunable by a simple change in concentration.

Crystalline Behavior and Structure of a Liquid Crystal Com- pound, 5-{[4＇-（（（Pentyl）oxy）-4-biphenylyl）carbonyl]oxy}- 1 -pentyne

Single crystals of two liquid crystal compounds, 5-{[4＇-（（（pentyl）oxy）-4-biphenylyl）carbonyl]oxy}-1-pentyne （A3EO5） and 5-{[（4＇-nonyloxy-4-biphenylyl）carbonyl]oxy}-1-pentyne （A3EO9）, have been prepared by solution growth technique. The morphologies and structures of A3EO5 and A3EO9 crystals were investigated by wide angle X-ray diffraction （WXRD）, atom force microscope （AFM） and transmission electron microscope （TEM）. In contrast to the same series of compounds which have a longer alkyl tail, 5-{[（4＇-heptoxy-4-biphenylyl）carbonyl]oxy}-1-pentyne （A3EO7）, 5-{[（4＇-heptoxy-4-biphenylyl）oxy]carbonyl}-1-pentyne （A3E＇O7） and A3EO9, A3EO5 shows strikingly different crystalline behavior. The former three compounds have only one crystal form, whereas A3EO5 exhibits polymorphism. Specifically, A3EO5 crystals grown from toluene solution show two crys- tal forms. The first one is crystal I which adopts a monoclinic P112/m space group with unit cell parameters of a= 5.79A, b=8.34A, c=43.92/k, y=96°, and the other one is crystal II which adopts a monoclinic P112 space group with unit cell parameters of a=5.55A, b=7.38A, c=31.75 ]k, y=94°. When using dioxane as the solvent to grow A3EO5 crystal, we can selectively obtain crystal Ⅰ. A3EO5 melt-grown crystals also have two crystal forms which derive from crystal I and crystal Ⅱ, respectively. The different crystalline behavior of the compounds should correlate with their different electron dipole moment resulting from the different length of alkyl tail.

Red fluorescent siloles with aggregation-enhanced emission characteristics

Aseries of new red fluorescent siloles consisting of a silole core and dimesitylboranyl substituent connected with a furan,thiophene,and selenophene bridges were synthesized and characterized.The optical properties,electronic structures,and electroluminescence (EL) performances were investigated.The emission wavelengths were red-shifted from the siloles with furan,to those with thiophene,and then selenophene.The thiophene,and selenophene-containing siloles,(MesB)_2DTTPS,and(MesB)_2DSTPS,showed the typical aggregation-enhanced emission (AEE) feature,while furan-containingone,(MesB)_2DFTPS,showed slight emission decrease as the aggregate formation.Theoretical calculations were carried out to explain the difference in the optical properties.Undoped OLEDs using these red siloles as light-emitting layers were fabricated.The device of (MesB)_2DTTPS exhibited the bestper formance.It radiated red ELemission at 589 nm,and afforded good maximum luminance,current,power,and external quantum efficiency of13300cdm^(-2),4.3cd A^(-1),2.9 lmW^(-1),and1.8%,respectively.