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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...

Pyridin‐2‐yl‐ and 4,6‐dimethylpyrimidin‐2‐yl‐cyanamides entered into an alkylation reaction in the form of sodium salts. Pyridin‐2‐yl cyanamide 2 was alkylated at endo‐nitrogen atom of pyridine ring, while 4,6‐dimethylpyrimidin‐2‐yl cyanamide 1 was effectively alkylated at exo‐nitrogen atom of amino cyanamide group. The alkylation of cyanamides 1 and 2 with phenacylbromide gave the corresponding acetophenone derivatives. As a result of their intramolecular cyclization reactions 3‐(4,6‐dimethylpyrimidin‐2‐yl)‐5‐phenyloxazol‐2(3H)‐imine in the case of cyanamide 1 and 2‐amino‐3‐benzoylimidazo[1,2‐a]pyridine in the case of cyanamide 2 were formed. The alkylated derivatives of pyridin‐2‐ylcyanamide 2 possess visible blue fluorescence with the main peak at 421 – 427 nm.

Herein, syntheses, crystal structures, and photoluminescence properties of 24 new ammonia and alkali metal ATCN salts characterized via single-crystal X-ray diffraction are reported. Moreover, ten structure types of these salts have been described, three of which are predominant. Some ATCNs were obtained as two crystalline polymorphs. It was estimated that most ATCN powders exhibited yellow-green fluorescence (at 450-600 nm). For samples that possess fluorescence of low intensity in the solid state, several optical centers of emission exist. It was speculated that the obtained spectral features were due to anion-anion intermolecular interactions. ATCN being a new representative of stable tetracyanoallyl salts is a promising candidate for creation of various 1D, 2D, and 3D supramolecular structures and potential functional materials.

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