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A series of bis(phenylethynyl)benzenes 3 and 9,10-bis(phenylethynyl)anthracenes 4 was synthesized by bromination–dehydrobromination reaction or newly developed direct CC triple bond formation reaction from styrylstilbenes 1 or distyrylanthracenes 2. Subsequently systematic investigations were carried out on their absorption and fluorescence spectra, and their chemiluminescence properties. The following points are apparent; (a) a linear relationship between ν and Hammett's σp of compounds 3 and 4 was observed, (b) a significant relationship between the Stokes' shift of 4 and σp was observed and (c) in the series of compounds 4 the electron-donating ability of the substituents has a pronounced effect on the chemiluminescence properties.

The syntheses and properties of 1,1-dicyano-1,3-butadienes and 3-dicyano-methylene-1,4-pentadienes, readily obtained by Knoevenagel condensations of benzaldehydes with α-methylbenzylidenemalononitriles and 1,1-dicyano-2-methyl-4-phenyl-1,3-butadienes, respectively, are described. Color-constitution relationships and their possible use for nonlinear optics are discussed. Calculations of excitation energies using the PPP method are in good agreement with experimental values. In contrast, the INDO/S procedure only leads to a satisfactory correlation if solvent effects are included in the calculations.

One-component colorformers were obtained from 4-dicyanomethylene pyrazolone derivatives and anilines or tetramethyl-dihydroquinoline in excellent yields. They were transformed into dyes of maximum absorption wavelengths between 527 and 628 nm by thermolysis as well as by photolysis. Different substituents and donor elements (anilines and quinoline) showed a remarkable and partially unexpected influence on the dye properties and they were evaluated using semi-empirical quantum chemical calculations (AM1, CNDO/S-CI).

The two nitrogen atoms in 1,8-di(3‘-pyridyl)naphthalene were quaternized by the addition of either benzyl or methyl groups to give dications; the latter was oxidatively converted to the di(6‘-pyrid...

The title compound prepared by Pd-catalyzed coupling of 1,8-dibromonaphthalene and diethyl(3-pyridyl)borane shows syn-anti diastereoisomerism due to restricted rotation at ambient temperatures. AM1 and PM3 computations indicate the preferred T-shaped transition state for rotation has a highly deformed naphthalene ring. There is a slight preference for H4′ and not the nitrogen lone electron pair to be directed at the face of the other pyridyl ring.

Dicationic 1‘,1‘-dimethyl (6a), dipolar 1‘,1‘-dioxide (6b), and 6‘,6‘-dipyridone (7) derivatives of 1,8-di(2‘-pyridyl)naphthalene were prepared. Proton NMR failed to reveal the presence of individual anti-syn atropisomers over a wide range of temperatures. By contrast, the 1‘,1‘‘-dimethyl derivative of 1-(2‘-pyridyl)-8-(3‘‘-pyridyl)naphthalene (8), a positional isomer of 6a, existed in DMSO-d6 as a 2:1 mixture of anti to syn atropisomers at ambient temperatures. Electrostatic repulsion is believed to cause the anti atropisomer to be favored, especially in 6a where the charged regions are closer together than in 8, owing to the splayed-out arrangement of the rings. AM1 and PM3 computations confirm that the anti is highly favored over the syn isomer for 6a, 6b, and 7.

Semi-empirical molecular orbital (AM1 and PM3) calculations including solvent effects by the SCRF model on the mechanism of the addition of nucleophiles to unsaturated five- and six-membered bislactones of the Pechmann dye type indicate a similar mechanism for both systems. The rate-determining step appears to be the addition of a second nucleophile to the enol of the ring-opened monolactone. The five-membered lactones are found to be more reactive than their six-membered analogues. Electron donor substituents (p-Me, p-MeO) increase and acceptor substituents (p-Cl, m-NO2) decrease the activation energy.

Density functional (B3LYP/6-311+G) and ab initio (MP2/6-311+G and MP4(SDTQ)/6-311+G//MP2/6-311+G) calculations on the ring closure reactions of (E)- and Z-iminodiazomethane ((E)-5, (Z)--5), vinyldiazomethane 7, and formyldiazomethane 9 to 1H-1,2,3-triazole 6, 3H-pyrazole 8, and 1,2,3-oxadiazole 10, respectively, are reported. (E)-5 cyclizes via a low barrier (ca. 10 kcal mol(-)(1)) pseudopericyclic nonrotatory transition state. Ring closure of (Z)-5 and 7 proceeds by a monorotatory movement of the imino or vinyl group with a substantially higher barrier (ca. 25 kcal mol(-)(1)). Despite being endothermic, for the reaction 9 --> 10 also a rather low activation energy (ca. 10 kcal mol(-)(1)) is computed. The NBO analysis is used to interpret the electronic structures of the respective transition states in terms of their pericyclic monorotatory (TS ((Z)-5 --> 6), (TS (7 --> 8)) or pseudopericyclic nonrotatory ((TS ((E)-5 --> 6), (TS (9 --> 10)) nature.

Reaction of 4-methylamino-5,6-dihydropyridinone with acetyl chloride yielded exclusively the 3-acetyl derivative. When the methylamino group of the latter was removed by alkaline hydrolysis, a mixture of two hydroxy derivatives was formed. Those cyclized upon treatment with hydroxylamine exclusively to the isoxazolo[4,5-c]pyridinone, whereas the 4-methylamino analogue yielded, depending on pH, mainly the isoxazolo[4,3-c]pyridinone or the isoxazolo[4,5-c]pyridinone. The configurations of the latter compounds were established by NMR experiments..

This paper presents quantitative structure−activity relationship (QSAR) models for a series of 21 heterocyclic monoazo dyes applied on cellulose fiber by comparative molecular field analysis. The electronic and structural properties of these dyes were calculated by the semiempirical PM3 method; the results indicate the predominance of electrostatic interactions in dye−cellulose binding. The dominant contribution of the LUMO orbital molecular energy, used as descriptor, can be explained by the contribution to the solvation of the dye molecules.

Synthesis, absorption and fluorescence spectra, as well as quantum yields of a series of donor-acceptorsubstituted carbostyrils (a quinolin-2(1H )-ones), are reported. Unprecedented strong absorption maxima (ea 10000 ‐ 20000) close to the visible spectrum, large Stokes shifts up to 130 nm, and quantum yields up to 0.7 are obtained with derivatives containing donor substituents at C(6) and C(7), and either one Ph substituent at C(3) or one CF 3 residue at C(4). For analytical applications in biochemistry and medicine, N(1)-functionalization, or amidoacylation at C(3) in the case of the CF 3 derivatives, is possible without a concomitant hypsochromic shift of their absorption and emission maxima. Semiempirical molecular-orbital calculations ( AM1 for structures, ZINDO for electronic transition energies) prove to be a suitable tool for the prediction of absorption properties of these compounds. The crystal-structure analysis of 6,7-dimethoxy-1-methyl-3-nitro-4-(trifluoromethyl)quinolin-2-(1H )-one (7 )( C 13H11F 3N2O5, monoclinic, P21/c, aa 12.372(2), ba 12.154(2), ca 10.119(2)a, ba 112.95(2)8) shows that the NO2 group, squeezed between the CF 3 and the CaO group, is oriented almost perpendicularly (87.8(4)8) to the ring plane. The intramolecular F ··· N distance between the CF 3 and the NO2 group is only 2.513(4)a.

A UV–Vis spectroscopic study based on the recently developed chemometric approach for quantitative analysis of undefined mixtures is performed on a series of donor and acceptor substituted Schiff bases of 2-hydroxynaphthaldehydes. In CCl4 solution all compounds preferentially exist as the phenol tautomer independent of the nature of the respective substituent. With increasing polarity the tautomeric equilibrium is shifted towards the quinone form. In CHCl3 and, especially, ethanol a clear distinction between the effect of donors (stabilization of the quinone form) and acceptors (stabilization of the phenol tautomer) is evident. Ab initio calculations including solvent effects via the polarized continuum model of solvation as well as the supermolecule approach are used to rationalize the experimental findings.