Trinuclear heterobimetallic Ni2Ln complexes [L2Ni2Ln][ClO4] (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er; LH3=(S)P[N(Me)NCH-C6H3-2-OH-3-OMe]3): from simple paramagnetic complexes to single-molecule magnet behavior

The reaction of LH3 with Ni(ClO4)(2).6H 2O and lanthanide salts in a 2:2:1 ratio in the presence of triethylamine leads to the formation of the trinuclear complexes [L2Ni2Ln][ClO4] (Ln=La (2), Ce (3), Pr (4), Nd (5), Sm (6), Eu (7), Gd (8), Tb (9), Dy (10), Ho (11) and Er (12) and L: (S)P[N(Me)NCH-C6H3-2-O-3-OMe]3). The cationic portion of these complexes consists of three metal ions that are arranged in a linear manner. The two terminal nickel(II) ions are coordinated by imino and phenolate oxygen atoms (3N, 3O), whereas the central lanthanide ion is bound to the phenolate and methoxy oxygen atoms (12O). The Ni-Ni separations in these complexes range from 6.84 to 6.48 A. The Ni-Ni, Ni-Ln and Ln-O phenolate bond distances in 2-12 show a gradual reduction proceeding from 2 to 12 in accordance with lanthanide contraction. Whereas all of the compounds (2-12) are paramagnetic systems, 8 displays a remarkable ST=(11)/2 ground state induced by an intramolecular Ni. . .Gd ferromagnetic interaction, and 10 is a new mixed metal 3d/4f single-molecule magnet generated by the high-spin ground state of the complex and the magnetic anisotropy brought by the dysprosium(III) metal ion.     

Molecular force and compliance constants for some metal-halogen bonds in complexes

The force and compliance constants of some metal-halogen coordinated bonds of MX₂, MX₃^? and MX₄^2? (M = Zn, Cd, Hg; X = Cl, Br, I) for their free state and for solutions in anhydrous tri-n-butyl phosphate (TBP) are evaluated and the effect of complexing with TBP on the compliance of the bonds is studied.     

Cyclophosphazene-supported tetranuclear copper assembly containing 15 contiguous inorganic rings

The cyclophosphazene hydrazide gem-N3P3Ph2[N(Me)NH2]4 was reacted with o-hydroxybenzaldehyde to afford the multisite coordination ligand gem-N3P3Ph2[N(Me)N=CHC6H4-2-OH]4 (LH4). The latter reacted with copper(II) salts to afford a novel tetranuclear copper assembly {N3P3Ph2[N(Me)N=CHC6H4-2-O]4Cu2}2, which contains, remarkably, 15 contiguous inorganic rings.     

Construction of partially balancedn-ary designs using difference sets

Summary Methods of construction of partially balancedn-ary designs using difference sets have been studied in this paper. Some more new series of PBn-ary designs are developed from initial blocks. By this method a general class of partially balancedn-ary designs has also been obtained.     

Communicating with noise: How chaos and noise combine to generate secure encryption keys

An approach for the secure transmission of encrypted messages using chaos and noise is presented in this paper. The method is based on the synchronization of certain types of chaotic oscillators in response to a common noise input. This allows two distant oscillators to generate identical output which can be used as a key for encryption and decryption of a message signal. The noiselike synchronizing input-which contains no message information-is communicated to identical oscillators in the transmitter and the receiver over a public channel. The encrypted message is also sent over a public channel, while the key is never transmitted at all. The chaotic nature of the oscillators which generate the key and the randomness of the signal driving the process combine to make the recovery of the key by an eavesdropper extremely difficult. We evaluate system performance with respect to security and robustness and show that a robust and secure system can be obtained. (c) 1998 American Institute of Physics.     

Studies on conventional and Sankaranarayanan–Ramasamy (SR) method grown ferroelectric glycine phosphite (GPI) single crystals

Transparent single crystals of glycine phosphite were grown by Sankaranarayanan–Ramasamy (SR) method and conventional slow evaporation solution technique (SEST) which had the sizes of 100 mm in length, 30 mm diameter and 10×11×8 mm³. The conventional slow evaporation and Sankaranarayanan–Ramasamy method grown glycine phosphite single crystals were characterized using laser damage threshold, chemical etching, Vickers microhardness, UV–vis–NIR and dielectric analysis. The laser damage threshold value was higher in SR method grown GPI crystal as against conventional method grown crystal. The SR method grown GPI has higher hardness and also higher transmittance compared to conventional method grown crystal. The chemical etching and dielectric loss measurements indicate that the crystal grown by SR method has low density of defects and low value of dielectric loss compared to conventional method grown GPI crystal.