MOLECULAR STRUCTURES AND CRYSTAL PACKINGS OF STYRYLDIAZINES

Journal of Structural Chemistry - Crystal structures of three isomeric styryldiazine derivatives (E)-2-(3,4-dimetoxystryl)pyrazine, (E)-2-(3,4-dimetoxystryl)pyrimidine, and...     

Synthesis of new functionalized 1,10-phenanthrolines

Styrylphenanthroline derivatives containing the fragments dithia-18-crown-6, aza-18-crown-6, and azadithia-15-crown-5 were obtained for the first time. The conditions for their synthesis were optimized.     

Self-organization of crown-containing hetarylphenylethenes,phthalic acid,and potassium cations into supramolecular assemblies

Multicomponent molecular assemblies of 15-crown-5-containing 4-styrylpyridine with phthalic acid in the presence of potassium perchlorate were studied. The structure of the obtained complicated assemblies was determined by ¹H and ¹³C NMR spectroscopy, UV spectroscopy, and X-ray analysis. The composition of the supramolecular complexes was established by spectrophotometric titration, and the stability constants were calculated. The quantum yields of fluorescence for the ligand and its complexes of various nature were determined.     

The complex formation properties of 18-crown-6-2-styrylbenzothiazole and the product of its photocyclization

Complex formation of 18-crown-6-2-styrylbenzothiazole and a crown-containing benzothiazolquinoline derivative with alkaline earth metal perchlorates was studied. The structures and stability constants of the complexes were determined. Original Russian Text ? O.A. Fedorova, E.N. Gulakova, I.E. Lobazova, Yu.V. Fedorov, N.E. Shepel’, L.G. Kuz’mina, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 6, pp. 1178–1182.     

Photoinduced in situ generation of a DNA-binding benzothiazoloquinolinium derivative

A styrylbenzothiazole substrate that has no significant affinity towards DNA was transformed photochemically into a DNA-binding benzothiazoloquinolinium ion. The photoreaction may be performed directly in the presence of DNA thus establishing the DNA-ligand interaction in situ with temporal control.     

Molecular structures and crystal packings of 2-styrylquinoxaline derivatives

The crystal and molecular structures of 2-styrylquinoxaline derivatives with different substituents in the styryl fragment are determined. The degree of planarity of the molecules studied varies in a very wide range, from 1.7° to 33.5°. In the ethylene fragment, the double bond is essentially localized. The bicycle-pedal disordering of the ethylene fragment is found in the crystals of the methoxy and oxyacetyl derivatives of 2-styrylquinoxaline. None of the packings contains packing motifs favorable for the photocycloaddition (PCA) reaction with single crystal retention. The crystal packings of these compounds and that of 2-(4-methylstyryl)quinoxaline are characterized by a stacking motif of the head-to-head type, which eliminates the possibility of PCA taking place with single crystal retention but is suitable for this reaction in polycrystalline films. The crystal packing of 2-(3,4-dimethoxystyryl)quinoxaline does not contain elements with stacking interactions.     

Metal-ion induced FRET in macrocyclic dynamic tweezers

We report here about effective FRET process (73–99%) in mono-Mg²⁺ complexes of symmetrical crown ether bis(styryl) dyes. The FRET process has not been observed in the free state and in binuclear complexes. The formation of mononuclear complex provides two styrylic fragments with appropriate positions of absorption and emission bands for FRET. The other important parameter for FRET is the proper geometric orientation of both chromophores, which attain sandwich conformation with close positioning of complexed and free styryl fragments induced by ion-modulated geometry reorganization of the bis-dye.     

Synthesis and structure of styryl-substituted azines

New photochromic derivatives of 2-styrylquinoline and 2-styrylquinoxaline were obtained by the condensation of the methyl derivatives of the mentioned heterocycles with substituted benzaldehydes in the presence of basic and acidic catalysts, and also under the conditions of Wittig reaction. The structure of compounds obtained was proved by physicochemical analysis methods including XRD.     

Synthesis and Spectral and Photochemical Properties of Newortho-Styryl-Substituted Nitrogen Heterocycles

Russian Journal of Organic Chemistry - Previously unknown bis-styryl derivatives in which two ortho-styryl-substituted nitrogen heterocycles are linked together through a polymethylene spacer have...     

Metal Ions Drive Thermodynamics and Photochemistry of the Bis(styryl) Macrocyclic Tweezer

UV/Vis and NMR spectroscopy were used for the structural elucidation and thermodynamic and photochemical studies of the metal‐coordinated crown‐containing macrocyclic tweezer (E,E)‐ 1 . The bis(styryl) tweezer (E,E)‐ 1 formed two types of complexes with magnesium(II): a 1:1 intramolecular asymmetric sandwich complex [(E,E)‐ 1 ]?Mg²⁺ and a 1:2 complex [(E,E)‐ 1 ]?(Mg²⁺)₂. In the former case, there is direct cation intramolecular exchange (0.299 s^?1, ΔG^≠=69.4 kJ mol^?1) between two parts of the bis(styryl) tweezer (E,E)‐ 1 . Addition of barium(II) to the bis(styryl) tweezer (E,E)‐ 1 led to an intramolecular centrosymmetric sandwich 1:1 complex [(E,E)‐ 1 ]?Ba²⁺. Irradiation of [(E,E)‐ 1 ]?Ba²⁺ afforded reversible intramolecular [2π+2π] photocyclization with excellent stereoselectivity and quantitative yield. In contrast, irradiation of [(E,E)‐ 1 ]?(Mg²⁺)₂ resulted in reversible stepwise E,Z‐isomerization.