Two isomers of a multifunctional π-expanded macrocyclic oligothiophene 8-mer, E,E-1 and Z,Z-1, were synthesized using a McMurry coupling of a dialdehyde composed of four 2,5-thienylene and three ethynylene units under high dilution conditions. On the other hand, cyclo[8](2,5-thienylene-ethynylene) 2 was synthesized by intramolecular Sonogashira cyclization of ethynyl bromide 5. From STM measurements, both E,E-1 and Z,Z-1 formed self-assembled monolayers at the solid-liquid interface to produce porous networks, and from X-ray analyses of E,E-1 and 2, both compounds had a round shape with a honeycomb stacked structure. E,E-1 formed various fibrous polymorphs due to nanophase separation of the macrorings. E,E-1 and Z,Z-1 in solution exhibited photochromism upon irradiation with visible and UV light, respectively, and this photoisomerization was confirmed by using STM. Furthermore, amorphous films of Z,Z-1 and E,E-1 showed photoisomerization, although single crystals, fibers, and square tubes of E,E-1 remained unchanged under similar conditions. E,E-1 with a 12.5-14.7 Å inner cavity incorporated fullerene C60 in the cavity in solution and the solid state to produce a Saturn-like complex, whose structure was determined by X-ray analysis. 2 also formed a Saturn-like complex with C60 in the solid state. These Saturn-like complexes are stabilized by van der Waals interactions between the sulfur atoms of 8-mer and C60. The complexes exhibited charge-transfer interactions in the solid state. Like E,E-1, Saturn-like complex E,E-1⊃C60 formed small cube and fiber structures depending on the solvent used, whereas those of Saturn-like complex 2⊃C60 were limited due to the rigidity of the macroring of 2.

A facile one-pot synthesis of end-functionalized star polymers consisting of PFVs has been achieved by olefin metathesis and Wittig-type coupling.

A precise, one-pot synthesis of end-functionalized block copolymers consisting of poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs) and oligo(2,5-dialkoxy-1,4-phenylenevinylene) or terthiophene units as the middle segment have been prepared by olefin metathesis of the vinyl group in the PFV chain ends followed by subsequent Wittig-type coupling. Formation of the block copolymers and the quantitative efficiency in the end-functionalization can be confirmed by synthesis of amphiphilic block copolymers containing poly-(ethylene glycol) at the both polymer chain ends. Effect of PFV conjugation length, middle segment, and the end groups toward the emission properties have been studied: the polymers containing ferrocene moiety at the chain ends displayed unique emission/quenching properties.

Time-resolved fluorescence study has been explored for end-functionalized conjugated triblock copolymers consisting of poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs, FV repeat units ca. 10 or 20) and oligo(2,5-dialkoxy-1,4-phenylenevinylene)s [OPV, alkoxy = O(CH 2 ) 2 OSi i Pr 3 , 3 or 7 PV repeat unit] as the middle segment. Unit (FV and PV) length dependence of each block on fluorescence was examined. The polymer sample having three PV repeat units as the middle segment with C 6 F 5 end-groups, [10PFV-3PV]F 2 , showed time-dependent fluorescence spectra, in which relative intensities of the vibronic bands increase in later delay time, whereas similar observations were not seen in the other polymer samples containing 7PV as the middle segment even by varying the PFV chain lengths (ca. 20) or the end-group (C 6 F 5 vs C 6 H 5 ). Timeresolved of fluorescence signals for [10PFV-3PV]F 2 can be analyzed by assuming two components: one is a faster decay component and the other is a slower red component, which rises with the time constant of the former one. On the other hand, the other three polymer samples showed single-exponential decays without significant wavelength dependence. Dynamical structural relaxation in the excited state is proposed as the origin of time dependence of the fluorescence spectra in the polymer having 3PV repeat unit on the basis of analysis of time-resolved fluorescence signals as well as viscosity dependence. ■ INTRODUCTIONConjugated polymers are of continuing interest as organic electronics due to their promising applications in optoelectronic and electrochemical devices, 1−5 such as photovoltaic cells, 3b light-emitting diodes, 5c,6 sensors, 5d,7 electrochromics, 8 and field-effect transistors. 5a,b,9 The synthesis of structurally regular, chemically pure polymers by development of new synthetic methods attracts notable attention 1 because their device performances are governed by the structural regularity, chemical purity, and supramolecular order. 2,3 Emerging applications of conjugated polymers require the patterning of materials on the nanometers length scale, and block copolymers made of covalently linked polymers represent an ideal route to control the self-assembly of the nanosized morphologies. Formation of regular one-dimensional conjugated structures on the nanoscale should be thus expected by exploiting the specific assembling properties of rod−coil block copolymers. 10−13 End-group modification of conjugated polymers has also been considered as an attractive topic of investigation because the important properties that have been demonstrated for end-functional conjugated polymers and the significant effect end-groups can have on electronic properties. For example, simple end-capping of conjugated polymers via postpolymerization reactions showed improvement in the performance of bulk heterojunction photovoltaic devices by eliminating traps for charge carriers. 14 Many reports concerning poly(fluorene)s (PFs) containing discrete end-groups (such as triarylamines, perylene mon...

The propagation, antibacterial activity and phytochemical profiles of Litsea glutinosa have been focused. Percentage of viable seed was 70 by tetrazoliumchloride staining technique, while germination rates were 75, 70, 55 and 20% in clay loam soil, clay loam: compost, compost and sand, respectively. Propagation of basal cutting in clay loam soil under the sun was faster than the apical stem cuttings. Both the ethanolic and water soluble extracts of the leaves and bark showed against Escherichia coli, Enterobacter intermedium, Salmonella sp., Staphylococcus aureus and Staphylococcus epidermis. Phytochemical profiling of the bark of L. glutinosa showed the presence of a number of secondary metabolites including steroids and terpenoids. The isolated compounds from ethanolic bark extract (T-1 and T-3) were identified as stigmasterol and -sitosterol, respectively by comparing the 1 H-NMR data of the isolated compounds with that of the published data.