Dipolar cycloadditions have been used to prepare a series of functionalized poly(pphenyleneethynylene)s (PPEs). This was accomplished by employing a PPE with pendent triisopropylsilylacetylene groups. The triisopropylsilyl groups can be removed in situ, exposing free alkynes in the side chains of the polymer to react with azides in a postpolymerization functionalization strategy in a 1,3-dipolar cycloaddition. The properties of these polymers were explored and compared to polymers of the same molecular structure but synthesized by a prepolymerization functionalization approach. Polymers of the same structure exhibit identical 1 H NMR, 13 C NMR, and IR spectra regardless of whether they were obtained by a conventional route or by postfunctionalization of a suitable PPE. UV-vis and fluorescence spectra are similar in solution. Postmodification through click chemistry, when compared to premodification, is an excellent method to produce functionalized, defect-free PPEs. Reaction of the azides with the main chain alkyne units is not observed.

We describe the synthesis of two cyclobutadiene(cyclopentadienyl)cobalt-containing poly(p-phenylene ethynylene)s (PPEs) and their use as precursors for stable ceramic surface coatings. Organometallic PPEs were shaped into hexagonally ordered assemblies by using the breath-figure method. Such breath figures can be washed away with an appropriate solvent. Upon pyrolysis at 500 degrees C under either nitrogen or air, the bubble arrays persist as ceramics and are insoluble in organic solvents or water. The formed pyrolyzed bubble arrays were analyzed by optical and scanning electron microscopy, as well as energy dispersive X-ray microanalysis (EDX). The composition of the ceramic materials is discussed based on EDX and IR data.

Micrometer-sized, spherical, non-fullerene carbon is found in meteorites.[1] Similar spheres have been prepared in the laboratory by pyrolysis of a) polyethylene/poly(vinyl chloride) (PVC) mixtures under high pressure, b) methane over an (undisclosed) mixed metal oxide catalyst, c) aqueous acidic solutions of glucose, d) poly(tetrafluoroethylene) (PTFE) in supercritical water, e) ferrocene, f) hexachlorobenzene with sodium metal in an autoclave, and g) tetrachloromethane with sodium amide. [2±7] In cases where transition metals are involved in the process, metal kernels were observed in the center of the spheres as they seem to function either as a catalyst and/or as a nucleation site. [4] Spheres in which the metal is distributed evenly and homogeneously (either as an alloy or as a carbide/ ceramic) are unknown: [2±7] the high-yield formation of homogeneous cobalt/carbon spheres by pyrolysis of metallated poly(p-phenyleneethynylene) (PPE 7a) is reported.Tetrabenzohexadehydro [20]annulene (1) explodes to form carbon nanotubes and onions.[8] Trisdicobalt hexacarbonyl complex 2, the dicobalthexacarbonyl complex of tolane (3), and a multinuclear cobalt complex of a hexaalkynylated hexabenzocoronene derivative (4) do likewise, but under just conflagration (as opposed to explosion) or even without visible heat evolution.[9±11] The pyrolytic approach works for the ferrocene-ligated dehydroannulene 5, which deflagrates into bagel-shaped, tube-like all-carbon objects. [12] Structures 1±5 are shown in Figure 1. Synthesis and investigation of the thermal decomposition of metallated PPEs 7 was a natural yet promising extension of these reports. Post-functionalization of PPEs [13] is difficult but reduction or appendage of organo±platinum fragments [14,15] has been described. The PPEs 6a±c reacted in good-to-excellent yields (Scheme 1) with dicobalt octacarbonyl in toluene (room temperature) to give the metallated species 7a±c after precipitation into methanol. [13,16] Both IR and NMR spectroscopy indicate complete occupancy of the alkyne sites by dicobalt hexacarbonyl fragments. The organometallic PPE 7a is intrinsically less soluble than its precursor 6a. A sample of 7a of high solubility was produced when PPE 6a of low molecular weight (P n = 15, where P n is the degree of polymerization) was reacted with dicobalt octacarbonyl. The diagnostic signals in the , representing the C±O stretch vibrations of the carbonyl ligands. These C±O stretch vibrations are shifted with respect of those of Co 2 (CO) 8 , assuring that no unreacted cobalt octacarbonyl was left in the product.[17] The reaction of 7a with HCl in chloroform leads to full demetallation and the re-isolation of intact 6a, as expected for a carbonyl complex. Attempts to make 7a more lipophilic by a ligand exchange reaction with triphenylphosphine furnished a material with abysmally low solubility; the use of tributylphosphine should lead to a more soluble polymer. The metallation of 6b and the alkoxy-PPE 6c was likewise facile and gave the polycomplexes 7b and 7c...

Nanotechnology has emerged as a field of science and engineering which offers many new product possibilities and potential solutions for a variety of problems. Nanomaterials come in many shapes and forms and contribute to potential products that do everything from sense analytes on a molecular level to function as self cleaning surfaces. With new and significant applications, it is likely that nanomaterial containing products may replace many of the products we use on a daily basis, leading to an increased presence of these materials in the environment. This will result in new needs and requirements from detection tools. It is likely that the analytical methods used to monitor nanomaterials in the environment will be very different than those used in risk assessment and exposure studies. This paper briefly outlines the history, impacts, and uses of nanomaterials and discusses possible methods of detection and quantification for environmental samples. The discussions in this article are specific to those matrices relating to wastewaters and sludge.

A series of dendronized poly(p-phenyleneethynylene)s were synthesized by the Pd-catalyzed coupling of a tetraphenylbenzene-substituted aromatic diiodide to 2,5-didodecyl-1,4-diethynylbenzene to form PPEs in excellent yield and high degree of polymerization. The tetraphenylbenzene-substituted monomer was obtained by a Diels-Alder reaction of a diethynylated arene with tetraphenylcyclopentadienone. The influence of the tether length (connecting the tetraphenylbenzene units to the main chain of the polymer) on the optical properties of the polymers was investigated. The closer the tetraphenylbenzene units were placed to the main chain, the larger is their effect upon the PPE's optical properties. In the case where the tether is shortest, i.e., two atoms, the optical properties of the PPE in the solid state and in solution are identical.