A novel single azido bridged one-dimensional Ni(II) chain, which represents the first metamagnetic one-dimensional metal-azido system with only end-to-end azido bridges, has been synthesised and characterised by a low temperature magnetic study.In the last decade chemists have dedicated their efforts to the study of molecular-based magnetic materials owing to the need to understand the fundamental science associated with magnetic interactions between the paramagnetic metal ions and the bridging ligand to develop magneto-structural correlation enabling the designed synthesis of interesting magnetic materials. 1 One strategy for the design of molecular-based magnets involves assembling of paramagnetic metal ions in one-, twoand three-dimensional networks using suitable bridging ligands. 1,2 The azido ligand has been widely used because of its diverse binding modes which yield different types of molecules such as dimers, tetramers, one-, two-, and three-dimensional arrays etc. 3 The prime coordination motif for bridging azido is end-on with ferromagnetic interaction and end-to-end having antiferromagnetic coupling. 4 To the best of our knowledge all compounds of Ni II with end-to-end azido bridges are antiferromagnetic with the exception of two compounds which are weakly ferromagnetic: one is a dimer 5 and the other a onedimensional chain of Ni II using a non-chelating capping ligand. 6 Examples of metamagnetic molecular materials in the metal-azido system with only end-to-end bridging azido mode are still lacking. Here, we report the synthesis, ‡ crystal structure and magnetic properties of a new one-dimensional compound, [Ni(L)(N 3 ) 2 ] n 1 (L is a tridentate Schiff base obtained by condensation of pyridine-2-aldehyde and N,N,2,2-tetramethylpropane-1,3-diamine) which represents the first example of a metamagnetic molecular material of Ni II with only end-to-end azido bridges.A crystal structure determination § reveals that complex 1 is a single azido bridged one-dimensional Ni II chain. A perspective view of the polymeric chain of complex 1 with the atom numbering scheme is shown in Fig. 1. Each nickel atom in the chain has an octahedral coordination environment with a NiN 6 core. In the chain, all nickel atoms are linked to one pendant azido in their axial positions. One nitrogen atom, N(7), of the bridging azido is linked to an equatorial position of one nickel while the other nitrogen atom N(9A) of the same azido is coordinated to an axial position of the neighbouring nickel centre. The equatorial least-square planes of the two Ni II centres are not parallel and form a dihedral angle of 31.3(1)°. The deviation of Ni II from the best fit square plane towards N (4) The thermal variation of c M T is shown in Fig. 2. The nature of the c M T vs. T plot is a signature of global intrachain ferromagnetic interaction. The solid line corresponds to the best fit obtained by considering an uniform ferromagnetically coupled chain of spin triplets (Fig. 2). 8 The best fitting parameters are J = +13.5 cm 21 , g = 2.08 and ...

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The interfacial and micellization behavior of three dicarboxylic amino acid-based anionic surfactants, abbreviated as AAS (N-dodecyl derivative of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) were investigated by surface tension, conductance, UV−vis absorption/emission spectroscopy, dynamic light scattering (DLS), and viscosity studies. Critical micelle concentration (CMC) values of the surfactant mixtures are significantly lower than the predicted values, indicating associative interaction between the components. Surface excess, limiting molecular area, surface pressure at the CMC, and Gibbs free energy indicate spontaneity of the micellization processes compared to the pure components. CMC values were also determined from the sigmoidal variation in the plot of micellar polarity and pyrene UV−vis absorption/ emission intensities with surfactant concentration. The aggregation number, determined by static fluorescence quenching method, increases with decreasing mole fraction of the AAS (α AAS ), where the micelles are mainly dominated by the HTAB molecules. The size of the micelle increases with decreasing α AAS , leading to the formation of larger and complex aggregates, as also supported by the viscosity studies. Micelles comprising 20−40 mol % AAS are highly viscous, in consonance with their sizes. Some of the mixed surfactant systems show unusual viscosity (shear thickening and increased viscosity with increasing temperature). Such mixed surfactant systems are considered to have potential in gel-based drug delivery and nanoparticle synthesis.

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