• Debajit Sarma

      Articles written in Journal of Chemical Sciences

    • Magnetic behaviour in metal-organic frameworks — Some recent examples

      Partha Mahata Debajit Sarma Srinivasan Natarajan

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      The article describes the synthesis, structure and magnetic investigations of a series of metal-organic framework compounds formed with Mn+2 and Ni+2 ions. The structures, determined using the single crystal X-ray diffraction, indicated that the structures possess two- and three-dimensional structures with magnetically active dimers, tetramers, chains, two-dimensional layers connected by polycarboxylic acids. These compounds provide good examples for the investigations of magnetic behaviour. Magnetic studies have been carried out using SQUID magnetometer in the range of 2-300 K and the behaviour indicates a predominant anti-ferromagnetic interactions, which appears to differ based on the M-O-C-O-M and/or the M-O-M (M = metal ions) linkages. Thus, compounds with carboxylate (Mn- O-C-O-Mn) connected ones, [C3N2H5][Mn(H2O){C6H3(COO)3\}], I, [{Mn(H2O)3}{C12H8O(COO)2}]$\cdots$H2O, II, [{Mn(H2O)}{C12H8O(COO)2}], III, show simple anti-ferromagnetic behaviour. The compounds with Mn-O/OH-Mn connected dimer and tetramer units in [NaMn{C6H3(COO)3}], IV, [Mn2($\mu_3$-OH) (H2O)2{C6H3(COO)3}]$\cdot$2H2O, V, show canted-antiferromagnetic and anti-ferromagnetic behaviour, respectively. The presence of infinite one-dimensional -Ni-OH-Ni- chains in the compound, [NiR_2R(HR_2RO)($\mu_3$-OH)2(C8H5NO4], VI, gives rise to ferromagnet-like behaviour at low temperatures. The compounds, [Mn3{C6H3(COO)3}$2], VII and [{Mn(OH)}2{C12H8O(COO)2}], VIII, have two-dimensional infinite -Mn-O/OH-Mn- layers with triangular magnetic lattices, which resemble the Kagome and brucite-like layer. The magnetic studies indicated canted-antiferromagnetic behaviour in both the cases. Variable temperature EPR and theoretical magnetic modelling studies have been carried out on selected compounds to probe the nature of the magnetic species and their interactions with them.

    • The relevance of metal organic frameworks (MOFs) in inorganic materials chemistry

      Srinivasan Natarajan Partha Mahata Debajit Sarma

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      The metal organic frameworks (MOFs) have evolved to be an important family and a corner stone for research in the area of inorganic chemistry. The progress made since 2000 has attracted researchers from other disciplines to actively engage themselves in this area. This cooperative synergy of different scientific believes have provided important edge and spread to the chemistry of metal-organic frameworks. The ease of synthesis coupled with the observation of properties in the areas of catalysis, sorption, separation, luminescence, bioactivity, magnetism, etc., are a proof of this synergism. In this article, we present the recent developments in this area.

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