Design and synthesis of supramolecular inorganic structures exhibiting novel host Β± guest interactions and molecular recognition have provided exciting new possibilities. [1, 2] Some of these materials contain cages for ions or cation Β± anion aggregates, polyoxometalates with cages containing ions such as Cl Γ and NO 3 Γ , and ion-pairs such as NH 4
Cl Γ , being good examples. [3] Several classes of inorganic Β± organic hybrid materials wherein the organic molecules subtly determine the structures of metal oxide lattices have also been prepared in recent years. [4] Amongst these, metal Β± organic networks described in the recent literature [5Β±7] are noteworthy, besides the large variety of inorganic open-framework structures, such as the metal phosphates [8] and oxalates [9] synthesized hydrothermally in the presence of organic amines. However, there is no report of materials to date, wherein extended structures of ionic compounds are incorporated in host lattices. Herein we report for the first time novel oxalate materials containing alkali halides with entirely new structures. The structures described include, a three-dimensional expanded KCl, a twodimensional layered RbCl, and a one-dimensional KBr chain. The study makes an important addition to the chemistry of inorganic host Β± guest materials and suggests that many more such structures can indeed be synthesized.
To prepare materials incorporating new alkali halide structures, we have employed the hydrothermal method of synthesis, which is known to yield materials not obtained ordinarily. [4, 10] The basic reaction employed is the simple exchange reaction between a cadmium halide and an alkali metal oxalate, carried out in the presence of an amine. The three new Cd oxalates containing alkali halides obtained by this means have the compositions I Β± III.
brought about by reaction with the epoxide center. Such a hypothesis would be consistent with earlier observations that simple azinomycin analogues based upon just the Βͺleft-handΒΊ domain of the azinomycins are highly cytotoxic. [12,18] Additionally, it is notable that the synthetic agents 5, and 6 retained activity in the two cell lines possessing acquired resistance to the widely used drug cisplatin, which forms a variety of intrastrand and interstrand bifunctional crosslinks on DNA.
In summary, our results suggest that synthetic azinomycin analogues such as 5 can be readily assembled, and induce ISCs in double-stranded DNA along similar lines to the natural products. In view of the limited availability of the azinomycins, we believe that these and other analogues will prove useful in further addressing the molecular mechanism of action of this class of antitumor agent.