Synthesis and photophysical properties of soluble polyimides and polyquinazolones containing side-chain chalcones or azo chromophores

Soluble aromatic and carboxyl- and hydroxyl-containing polyimides, mixed polyimides, and polyquinazolones of various chemical structures, as well as a series of new dicyanoazobenzene chromophores, are synthesized. From 20 to 80 mol % of chromophore groups are incorporated into side chains of the polymers. The thermal, photosensitive, and nonlinear optical properties (second-harmonic generation) of the chromophore-containing polymers are investigated. The polymers with covalently attached groups of the dye DR-13 or azo-derivatives of 4-phthalonitrile demonstrate the highest nonlinearity. The T _g values of the polyimides vary from 165 to 215°C; their temperatures corresponding to 5% weight loss lie in the range 290–350°C; and the measured coefficients of second-harmonic generation, d ₃₃, for a number of polarized films based on chromophore-containing polymers attain several tens of picometers per volt. The incorporation of chromophore groups into the side chains of the polymers causes an increase in the photosensitivity of polyimides by an order of magnitude relative to that of the parent polymers (S _0.1 = (3?4) × 10⁵ cm²/J in the range of dye absorption).     

Stereoselective synthesis of novel functionalized cyclohexanone derivatives via the condensation of aromatic aldehydes with acetoacetamide and the influence of the ortho-effect and autocondensation

A simple, inexpensive and stereoselective synthesis of novel functionalized cyclohexanone derivatives via the reaction of acetoacetamide with aromatic aldehydes in ethanol at room temperature is described. Additionally, the presence of substituents such as NO₂ and Cl in the ortho-position of the aldehyde aromatic ring resulted in the formation of novel piperidines. The use of Lewis acids such as iron(III) chloride and bismuth(III) nitrate as catalysts led to autocondensation of acetoacetamide and the formation of 2,4-dimethyl-6-oxo-1,6-dihydropyridine-3-carboxamide.     

Synthesis of 5-(4-bromophenyl)- and 5-(5-bromothiophen-2-yl)-substituted 3-aryl[1,2,4]triazolo[4,3-c]quinazolines

Russian Chemical Bulletin - A series of [1,2,4]triazolo[4,3-c]quinazolines, bearing 3-positioned p-bromophenyl or 5-bromothiophen-2-yl fragment, was synthesized by oxidative cyclization of the...     

Fluorine-containing heterocycles: XIX. Synthesis of fluorine-containing quinazolin-4-ones from 3,1-benzoxazin-4-ones

Reactions of fluorine-containing 3,1-benzoxazin-4-ones with ammonium acetate, hydrazine, and heteroaromatic amines gave new 3H-, 3-amino-, and 3-hetarylquinazolin-4-ones, respectively. Differences in the conditions of formation of benzoxazinones from anthranilic acids with different fluorination patterns and in the reactions of fluorinated 3,1-benzoxazinones with nitrogen-centered nucleophiles were revealed.     

Fluorine-containing heterocycles: XVIII. Monofluoro derivatives of quinazolines and 1,3-benzothiazin-4-ones

5- and 7-Fluoro-substituted quinazolines and 1,3-benzothiazin-4-ones were synthesized starting from 2-amino-6-fluorobenzonitrile and mono- and difluoro-substituted benzoic acid derivatives. The reactivities of di- and tetrafluoro-substituted benzoyl chlorides and benzoyl isothiocyanates in cyclocondensations leading to fluorinated quinazolines and 1,3-benzothiazines were compared.     

Synthesis of alkyl 5-aryl-7-methyl-1,5-dihydrotetrazolo-[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-6-carboxylates

Alkyl 5-aryl-7-methyl-1,5-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylates were obtained by melting acetoacetic acid esters with 5-aminotetrazole and aromatic aldehyde.     

Photosensitivity of polyimides and polyquinazolones based on aromatic and heteroaromatic diamines

Soluble polyimides containing triphenylamine residues as substituents at the imide nitrogen atom and polyquinazolones with diphenyl oxide, diphenylpropane, benzimidazole, benzoxazole, benzothiazole, oxadiazole, and triphenylamine moieties in the diamine component of the repeating unit have been synthesized. The spectroscopic study of polyquinazolones indicates their capability for donor-acceptor interactions. Emission bands of the polymers are of the exciplex nature. The photogeneration of current carriers in the polymers under study has been examined by the method of surface potential photoinduced decay. It has been shown that the intrinsic photosenitivity of polyquinazolones is nearly the same as (or somewhat higher than) that of the corresponding polyimides, but the former polymers are characterized by a less efficient spectral sensitization by dyes and donor-acceptor additives.