• Sanjay K Mandal

      Articles written in Journal of Chemical Sciences

    • Construction of diverse supramolecular assemblies of dimetal subunits differing in coordinated water molecules via strong hydrogen bonding interactions: Synthesis, crystal structures and spectroscopic properties

      Sadhika Khullar Sanjay K Mandal

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      Three new supramolecular assemblies (constructed through strong hydrogen bonding) of [Co2(bpta)2(adc)(H2O)4](ClO4)2.2H2O (1), [Cu2(bpta)2(fum)(H2O)2](ClO4)2 (2) and [Cu2(bpta)2(tdc)(H2O) (ClO4)](ClO4).3H2O (3), which are synthesised by one pot self-assembly of the metal salt, bpta ligand and the corresponding dicarboxylate under the same reaction conditions, are reported (where adc = acetylene dicarboxylate, fum = fumarate, tdc = 2,5-thiophenedicarboxylate and bpta = N,N'-bis(2-pyridylmethyl)-tertbutylamine). These compounds have varying degrees of coordinatedwater molecules per dimetal subunits (four for 1, two for 2 and one for 3, respectively). Furthermore, the orientation of the coordinated water molecules in 1 and 2, with respect to the mono (carboxylato)-bridged dimetal subunit, is different (cis and trans, respectively). On the other hand, there is a coordinated perchlorate ion in 3 making the two metal centers inequivalent. Unlike 1 and 3, there are no lattice water molecules in 2. This difference in the dimetal subunit in 1-3 and the presence or absence of the lattice water molecules are the keys to forming the diverse supramolecular assemblies. In 1 and 3, the involvement of lattice water molecules in the construction of such assemblies is distinctly different. In case of 2, the formation of supramolecular assembly depends on the coordinated water molecule (trans to each other) and thus a ladder shaped supramolecular assembly is the result. The strength of hydrogen bonding observed in the networks of 1-3 is indicated in the O…O distances (2.596 Å to 3.160 Å) and the OH…O angles 124° to 176°. All are characterised by elemental analysis, FTIR spectroscopy and single crystal X-ray diffraction studies.

    • Schiff bases of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and its silatranes: Synthesis and characterization

      Gurjaspreet Singh Amandeep Saroa Sadhika Khullar Sanjay K Mandal

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      This paper aims at the introduction of azomethine group by the condensation reaction of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane with different compounds containing carbonyl group such as 2’-hydroxyacetophenone, salicylaldehyde, pyrrole-2-carboxaldehyde, acetylacetone and ethyl acetoacetate. Further, transesterification reaction of these Schiff base modified silanes with triethanolamine as a tripodal ligand leads to the synthesis of corresponding silatranes 1–5 bearing Schiff base functionalized long chain in the axial position. All the synthesized compounds are characterized by spectroscopic methods, elemental analysis and mass spectrometry. The authentication of Schiff base modified silatranes is scrutinized by single X-ray crystal structure of silatrane 1. The thermal stability of the five silatranes is studied by thermo-gravimetric analysis (TGA).

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