Self-assembled Transition Metal Coordination Frameworks of ...

4. 1,5-Bis(di-2-pyridyl ketone) carbohydrazone (H2L4)
5. 1,5 -Bis(2-benzoylpyridine) carbohydrazone (HZLS)
6. 1,5-Bis(quinoline-2-carbaldehyde) carbohydrazone (H2L°)
7. Quinoline-2-carbaldehyde N(4),N(4)-(butane-1,4-diyl) thiosemicarbazone
(HL7)
W Self-Assembled Transition Metal Coordination
8. 2-Benzoylpyridine-N(4),N(4)-(butane-l,4-diyl) thiosemicarbazone (HL8)
Substituents having coordinating groups on attaching at the N‘ and N5
positions of the carbohydrazide and thiocarbohydrazide enhance their denticity. We
have used di-2-pyridyl ketone, 2-benzoylpyridine and quinoline-2-carbaldehyde to
increase the denticity and substituted both the ends of carbohydrazide and
thiocarbohydrazide. In doing so the new ligands, mainly possess two coordinating
pockets, are found to act as building blocks for molecular square grid formation, by
making use of sulfur/oxygen bridging, in a controlled manner. With these ligands we
prepared a series of complexes of copper, nickel, manganese, zinc and cadmium. The
complexes were characterized by various physico-chemical methods such as partial
elemental analysis, molar conductance measurements, MALDI MS, IR, far IR, UV­
visible, EPR and variable temperature magnetic susceptibility measurements. Single
crystal X-ray diffraction studies of some complexes are also reported. MALDI mass
spectra as DCTB mix on positive ion mode are found very useful for characterization
of supramolecular coordination compounds. Isotropic distribution patterns of sensible
peaks were characterized with theoretical calculated patterns. Magnetic data of
molecular square grids are rationalized with fitting into modified van Vleck equation.
EPR spectral parameters of Cu(Il) and Mn(II) complexes under investigation
conditions are reported with spectral simulations.
It is found that the present carbohydrazone and thiocarbohydrazone ligands
are potential candidates as building blocks for molecular square grids of Ni(ll),
Mn(ll), Zn(Il) and Cd(II). Four of the six potential ligands are new candidates for self­