Self-assembled Transition Metal Coordination Frameworks of ...

_ g 7 g _ 7, __H 7 Introduction
industrial uses, many of which are covered by the patent literature [60-64]. The
chelating ability of some thiocarbohydrazones have been reported as useful analytical
reagent for the quantitative extraction of different divalent metals like Co(lI), Ni(ll),
Cu(ll), Zn(ll), Cd(Il), etc and photometric and fluorimetric determinations [70,71].
Carbohydrazones and thiocarbohydrazones are the next higher homologues
of potential biologically important compounds after semicarbazones and
thiosemicarbazones. However little is known about the biological properties of
thiocarbohydrazones [68,72] and likewise for carbohydrazones. Carbohydrazones and
thiocarbohydrazones of various unsaturated ketones and Mannich bases were
evaluated for their cytotoxic properties [73]. Some thiocarbohydrazones are reported
to have antimicrobial activity towards bacteria and fungi [58,68,72,74]. Of these, the
bisthiocarbohydrazones possess the highest antibacterial activity compared to their
monothiocarbohydrazones and are potentially useful as antimicrobial agents against
Gram-positive bacteria [68]. It is reported that many monocarbohydrazone ligands act
as mutagenic agents, whereas bis substituted derivatives are devoid of mutagenic
properties [68]. As an inactivator of HSV-1 ribonucleotide reducmse a series of 2­
acetylpyridine thiocarbohydrazones are found to possess better activity than that of
corresponding thiosemicarbazones [75,76]. Thiosemicarbazones have been
extensively studied since their biological activities were first reported in 1946 [77].
They have drawn great interests for their high potential biological activity especially
their antitumor activity [78] and is still gaining high attention [79,80]. Antitumor
functions of l,2-naphtho-quinone-2-thiosemicarbazone (NQTS) and its metal
complexes {Cu(ll), Pd(lI), and Ni(Il)} against the MCF-7 human breast cancer cells
and the possible mechanisms of action were detennined [81] and there are reports that
the substituents in these compounds affect their antitumor activities strongly. Several
other reports of thiosemicarbazones and their metal complexes as anticancer dmgs
have been reported [82-85]. In this regard, the higher homologues, especially Cu(Il)
complexes, are anticipated as anticancer drug analogues [66,67].
l7