Self-assembly of thiacyanine dyes in water for the synthesis of active hybrid nanofibres

Water-soluble self-assembled nanostructures were synthesised by simple counter ion exchange of thiacyanine dyes which helps in the formation of nematic (N) and hexagonal (M) chromonic liquid-crystalline (CLCs) phases. Conjugated double bonds as central spacers connected between two benzothiazole segments affect water solubility and liquid crystal formation. Aggregation-dependent properties characterised by ultraviolet–visible, fluorescence and ¹H nuclear magnetic resonance spectroscopy. Sol–gel reaction of dye aggregates with silica species furnishes entangled nanotubular fibres with constant diameter and their length in excess of micrometres, having templates of pore sizes below the mesoporous range. The π–π stacked chromonic aggregate dyes are also of importance in shape selective catalysis, adsorption, desorption micro-patterned materials, and provide a significant step towards biosensor medical applications because of their water-soluble nature.     

Synthesis and liquid crystalline behaviour of substituted (E)-phenyl-4-(phenyldiazenyl) benzoate derivatives and their photo switching ability

Azobenzene derivatives containing phenyl/4-halogen-phenyl 4-{(E)-[4-(pent-4-en-1-yloxy)phenyl]diazenyl}benzoate group with different electronegative substituent (H, F, Cl, Br and I) at other end was synthesised. These azo-based benzoate derivatives have been characterised by FTIR, ¹H-NMR, ¹³C-NMR, elemental analyser, POM and UV-Vis spectroscopy. Photosaturation at 358 nm obtained after 82 s of UV irradiation and the longest thermal back relaxation time of 45 h recorded by UV-Vis. The azo derivative could be possible photolock under UV light, as observed by the improved thermal back relaxation time. The resulting photolockable chain of azobenzene might prove valuable in the development of optical device application. These azobenzene moieties also exhibit liquid crystalline behaviour with respect to the halogen substitution as an electron withdrawing group shows that strong structure property relationship exists among them.     

Mono and dinuclear arene ruthenium complexes containing 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline as chelating ligand: Synthesis and molecular structure

The mononuclear cations of the general formula [(η⁶-arene)RuCl(dpqMe₂)]⁺ (dpqMe₂ = 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline; arene = C₆H₆, 1; C₆H₅Me, 2; p-PrⁱC₆H₄Me, 3; C₆Me₆, 4) as well as the dinuclear dications [(η⁶-arene)₂Ru₂Cl₂(μ-dpqMe₂)]²⁺ (arene = C₆H₆, 5; C₆H₅Me, 6; p-PrⁱC₆H₄Me, 7; C₆Me₆, 8) have been synthesised from 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline (dpqMe₂) and the corresponding chloro complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]₂, [(η⁶-C₆H₅Me)Ru(μ-Cl)Cl]₂, [(η⁶-p-PrⁱC₆H₄Me)Ru(μ-Cl)Cl]₂ and [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂, respectively. The X-ray crystal structure analyses of [1][PF₆], [3][PF₆] and [6][PF₆]₂ reveal a typical piano-stool geometry around the metal centre; in the dinuclear complexes the two chloro ligands, with respect to each other, are found to be trans oriented.     

Selective one-pot synthesis of Z-iodoallylic iodides from propargyl alcohols

A selective one-pot procedure was developed for the production of Z-iodoallylic iodides from the corresponding propargyl alcohols.     

Syntheses and characterization of [(η-C6Me6)Ru(μ-N3)(X)]2 (X = N3 and Cl) complexes and their reactions towards mono- and bidentate ligands

The reaction of the complex [{(η⁶-C₆Me₆)Ru(μ-Cl)Cl}₂] 1 with sodium azide ligand gave two new dimers of the composition [{(η⁶-C₆Me₆)Ru(μ-N₃)(N₃)}₂] 2 and [{(η⁶-C₆Me₆)Ru(μ-N₃)Cl}₂] 3, depending upon the reaction conditions. Complex 3 with excess of sodium azide in ethanol yielded complex 2. These complexes undergo substitution reactions with monodentate ligands to yield monomeric complexes of the type [(η⁶-C₆Me₆)Ru(X)(N₃)(L)] {X = N₃, Cl, L = PPh₃ (4a, 9a); PMe₂Ph (4b, 9b); AsPh₃ (4c, 9c); X = N₃, L = pyrazole (Hpz) (5a); 3-methylpyrazole (3-Hmpz) (5b) and 3,5-dimethyl-pyrazole (3,5-Hdmpz) (5c)}. Complexes 2 and 3 also react with bidentate ligands to give bridging complexes of the type [{(η⁶-C₆Me₆)Ru(N₃)(X)]₂(μ-L)} {X = N₃, Cl, L = 1,2-bis(diphenylphosphino)methane (dppm) (6, 10); 1,2-bis(diphenylphosphino)ethane (dppe) (7, 11); 1,2-bis(diphenylphosphino)propane (dppp) (8, 12); X = Cl, L = 4,4-bipyridine (4,4′-bipy) (13)}. These complexes were characterized by FT-IR and FT-NMR spectroscopy as well as by analytical data.The molecular structures of the representative complexes [{(η⁶-C₆Me₆)Ru(μ-N₃)(N₃)}₂] 2, [{(η⁶-C₆Me₆)Ru(μ-N₃)Cl}₂] 3,[(η⁶-C₆Me₆)Ru(N₃)₂(PPh₃)] 4a and [{(η⁶-C₆Me₆)Ru(N₃)₂}₂ (μ-dppm)] 6 were established by single crystal X-ray diffraction studies.     

A novel discrete dinuclear copper(II)–gadolinium(III) complex derived from a Schiff base ligand [Cu(salbn)Gd(NO3)3·H2O] (salbn): N,N′-butylenebis(salicylideaminato)

The synthesis, X-ray and e.p.r. spectral studies of a 3d–4f couple are described here. The crystal structure of [Cu(salbn)Gd(NO₃)₃·H₂O], (2), salbn = N,N-butylenebis(salicylideaminato), has been determined by X-ray crystallography. Compound (2) crystallizes in the monoclinic system, space group p21/n, with a = 9.025(1), b = 22.912(1), c = 12.790(1) Å, = 99.36(1), Z = 4. The deviations of the four coordinating atoms (O(1)O(2)N(1) and N(2) of salbn and the copper atom is displaced from the plane in spite of the lack of any apical ligand. The gadolinium(III) ion is nine-coordinated by the two oxygen atoms of the salbn moiety, three bidentate nitrate ions and one water molecule. The geometry of Gd^III can be described as a square antiprism, in which compound Cu^II and Gd^III are bridged by the two phenolic oxygens of salbn. The Cu^II–Gd^III distance is 3.269(1) Å. The bridging core CuO2Gd is a butterfly shape. Significant distortion was observed for the complex having the larger diamino string. The title compound exhibits seven e.s.r. transitions with |D| = 0.0467 cm^–1, which demonstrates the existence of zero field splitting. This outcome indicates that compound (2) consists of a perfectly isolated dinuclear Cu–Gd core and steric bulk alters the dihedral angle in the Cu–O–Gd bridge.