- Experimental and theoretical insights into molecular and solid-state properties of isomeric Bis(salicylaldehydes)
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A series of five bis(salicylaldehydes), including four isomeric compounds based on a benzene scaffold and a closely related naphthalene derivative, were investigated in order to elucidate the impact of resonance effects and intramolecular hydrogen bonds (HBs) on the macroscopic properties of these systems. Density functional theory (DFT) computations revealed important differences between isomers on the molecular level, which was reflected in different charge distributions, aromatic C-C bond orders, and aromaticity characters. The consequences of these features were evidenced by the UV-vis absorption spectra: for 1,3-diformyl-4,6-dihydroxybenzene (2), the longest wavelength absorption band is observed at 285 nm, while its isomers 1,4-diformyl-2,5-dihydroxybenzene (1), 1,4-diformyl-2,3-dihydroxybenzene (3), and 1,2-diformyl-3,6-dihydroxybenzene (4) are characterized by absorption in the visible range (379-407 nm). The specificity of 2 results from simultaneous lowering and elevation of HOMO and LUMO energy levels, respectively. We have found that the HOMO/LUMO energy variations follow trends observed in isomeric dihydroxybenzenes (HOMO) and phthalaldehydes (LUMO), and these effects operate separately to some extent. Furthermore, theoretical calculations indicate that the UV-vis spectral properties of bis(salicylaldehydes) are directly transferable to the corresponding bis(salicylaldimines) and their boron complexes. Finally, the influence of structural and molecular stabilization effects was analyzed by means of X-ray structural analysis and periodic DFT computations.
- Durka, Krzysztof,Górski, Bartosz,B?ocki, Krzysztof,Urban, Mateusz,Wo?niak, Krzysztof,Barbasiewicz, Micha?,Luliński, Sergiusz
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p. 8674 - 8689
(2019/10/11)
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- The synthesis of symmetrically octa-substituted phthalocyanines and their physical and photo-physical properties
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A series of symmetrically substituted phthalocyanines have been synthesized from 3,6-dialkoxy-phthalonitrile and the corresponding metal salts. All of these complexes are extremely soluble in chloroform. Their melting points vary greatly with their different substituents. Their structures are confirmed by elemental analysis, 1H NMR, UV-VIS.
- Gao, Detao,Xu, Haitao,Van Tiantang,Peng, Bixian
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p. 1189 - 1196
(2007/10/03)
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- Octa-alkoxy Phthalocyanine and Naphthalocyanine Derivatives: Dyes with Q-band Absorption in the Far Red or Near Infrared
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The lithium alkoxide-catalysed cyclic tetramerisation of various 3,6-dialkoxy-4,5-dichlorophthalonitriles, 1,4-dialkoxynaphthalene-2,3-dicarbonitriles and 3,6-dialkoxyphthalonitriles to give the corresponding metal-free octa-alkoxyoctachlorophthalocyanines, octa-alkoxynaphthalocyanines and octa-alkoxyphthalocyanines is described.An unexpected trans-alkoxylation reaction occurs during the cyclisation of the first two series of precursors.Metal-free phthalocyanines and naphthalocyanines have been converted into derivatives containing various metal ions.Compounds show Q-band absorption in the region 739-862 nm in toluene solution.The fluorescence spectra of selected examples are reported.The solubility of some of the compounds has been measured in a formulation of liquid crystal materials.
- Cook, Michael J.,Dunn, Adrian J.,Howe, Steven D.,Thomson, Andrew J.,Harrison, Kenneth J.
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p. 2453 - 2458
(2007/10/02)
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- Process for the preparation of 1,3-disubstituted-2-azetidinones from triazines
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A process for preparing an azetidinone of the formula: STR1 which comprises reacting a C-unsubstituted methyleneamine of the formula: STR2 with R2 --CH2 COOH, its acid halide or anhydride, in the presence of boron trihalide and an organic base, wherein R1 is an organic residue bearing a carboxy group or its derivative and R2 is azido, substituted amino, halogen, acyloxy, alkoxy, aryloxy or aralkoxy.
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- 2-Azetidinone compounds and processes for preparation thereof
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This invention relates to new 2-azetidinone compounds, which have antimicrobial activities, and to processes for the preparation thereof, and more particularly, this invention provides new 2-azetidinone compounds, especially ones having various substituted carboxyalkyl radicals at the first position and having various groups at the fourth position of the azetidinone nucleus, which have antimicrobial activities against various pathogenic microorganisms and are useful as antibiotics in treatment for microbial infections in mammal including human being and animals.
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