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A model compound, as well as linear and cross-linked polymers polyazomethine and polyphenylene, were synthesized based on 1,2-bis(4-acetylbenzyl)-o-carborane. The thermal stability of polymers was investigated. The structure of polymers was studied by X-ray photoelectron spectroscopy (XPS).

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A branched oligophenylene has been synthesized based on 1,3,5-tri(4′-bromophenyl)benzene. Absorption and fluorescence spectra were studied and fluorescence quantum yields and lifetimes were measured for the compound in solution. It is demonstrated that the absorption spectrum is a superposition of p-quaterphenyl, p-terphenyl, and biphenyl chromophore absorption bands in a 1:2:1 ratio. The oligomer fluorescence spectrum is found to depend on the excitation wavelength. It is shown that the oligomer fluorescence is determined by two fluorochromic groups, namely fragments with branched p-terphenyl and p-quaterphenyl units. The main fluorescence maxima for these fluorochromic groups coincide with each other and lie in the vicinity of λ = 360 nm. A very weak fluorescence band found in the region 380-440 nm is excited by light with a wavelength lying beyond the oligomer self-absorption region. The reasons for a decrease in fluorescence quantum yields of branched models and the studied oligophenylene as compared with those of linear p-polyphenylene chromophores are discussed.Introduction. Branched oligomers have become very interesting in the last decade in connection with the search for novel materials with combinations of practically useful properties [1-3]. A promising area for application of branched oligomers containing luminophores is the development of new active additives to plastic scintillators [4], dye lasers [5,6], and light-emitting diodes in semiconducting photodiodes [7][8][9]. The preparation of branched oligomers and polymers with luminophores is a relatively new area. Comparatively few systems of this type have been prepared. Furthermore, their photophysical properties and their property-structure relationships are almost uninvestigated. One of the reasons for this situation is the difficulty of determining their molecular structures because the process for forming branched oligomers is random in nature [10,11].Herein a synthesized branched polymer (the Experimental section describes the synthetic method) is analyzed using spectrophotometry and fluorescence. According to the putative reaction, the produced macromolecule should have p-quaterphenyl (PQP) units at the branches and diphenyl (DP) and p-terphenyl (PTP) chromophores as the terminal groups. Issues with the determination of the ratio of these three chromophores in the produced macromolecule are examined. The units responsible for the fluorescence of the oligomer and the interactions between them are identified. These problems are resolved using a comparison of spectral data for the oligophenylene and the model low-molecularweight compounds PTP, PQP, and their branched analogs containing three PTP and PQP moieties.Experimental. The monomer 1,3,5-tri(4′-bromophenyl)benzene was prepared via the trimerization of 4-bromoacetophenone in benzene in the presence of triethylorthoformate and dry gaseous HCl by the standard method [12]. The oligophenylene was produced by Ni-catalyzed polycondensation of 1,3,5-tri(4′-bromophenyl)benzene by the literature me...

Two branched oligophenylenethynylenes with phenylene or biphenylene moieties as inter‐nodal fragments are synthesized by the Sonogashira reaction for optoelectronic applications. The branching of polyphenylenethynylenes influences the electro‐optical properties, but cannot be precisely controlled, while its determination is often hardly addressed. The optical investigation, supported by nuclear magnetic resonance (NMR) studies, of oligophenylenethynylenes and the properly synthesized model compounds is performed to get insights on the branching and related effect on the material performance. The proposed branched oligophenylenethynylenes are good ultraviolet emitters in solution, while in solid‐state aggregation phenomena strongly affect emission properties. However, the interactions between π‐electrons on phenylene and ethynylene of neighboring molecules in films enhance intermolecular charge transport (hole mobility = 3.2 × 10−3 cm2 V−1s−1) making them optimal candidates as hole transport materials in optoelectronic devices. The insertion of the oligophenylenethynylene film as a hole transporting layer in multilayered solution processes blue, green, and red electroluminescent diodes, enhances OLEDs electro‐optical properties.