Showing papers by "Dillip Kumar Chand published in 1998"

Heteroditopic cryptands of tunable cavity size: imposition of distorted geometry onto Copper(II) and Nickel(II) and molecular recognition of water molecules

Abstract: Complexation behavior of a previously described heteroditopic cryptand L1 and a newly synthesized cryptand L2 toward transition metal ions is described. The cryptands readily accept a transition metal ion like Cu(II) or Ni(II) at the N4 end of the cavity forming mononuclear cryptates. The Cu(II)-cryptate of L1 further accepts a water molecule to form [Cu(L1)(OH2)]·(picrate)2·(H2O), i.e., C45H53N11O19Cu. This molecule crystallizes in the monoclinic space group C2/c with a = 34.199(8) A, b = 12.286(5) A, c = 23.289(7) A, β = 93.12(4)°, Z = 8. The O atom of the water molecule is strongly bonded to the Cu(II) ion, while its H atoms are H-bonded to the nearest benzene rings. The UV−vis spectral and magnetic studies of the complexes are consistent with the mononuclear nature of the cryptates. Cryptand L1 undergoes diprotonation upon treatment with a mineral acid like HCl or HClO4. This diprotonated cryptand is found to be a good host for two molecules of water inside the cavity. The diperchlorate salt, [H2L1⊂(H...