title: Metal-assisted oxazolidine/oxazine ring formation in dinuclear zinc(II) complexes: synthesis, structural aspects, and bioactivity.
abstract: Three novel dinuclear Zn(II) complexes of phenol-based compartmental macrocyclic ligands have been synthesized and characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis. The dinuclear macrocyclic complexes 1, 2, and 3 were obtained through a 1:2 condensation reaction of 2,6-diformyl-4-methylphenol and N-(hydroxyalkyl) ethylenediamine (L(1), L(2), and L(3), respectively) in the presence of zinc(II) acetate, followed by the addition of thiocyanate anion [L(1) = N-(2-hydroxyethyl)ethylenediamine, L(2) = N-(3-hydroxypropyl)ethylenediamine, and L(3) = N-(2-hydroxypropyl)ethylenediamine]. The synthesized 18-membered macrocycles are noted to be structurally unique, and their formation proceeds with the generation of two oxazolidine side rings in complexes 1 and 3 and two oxazine side rings in 2, along with the creation of four new chiral centers in each case. Complexes 1 and 2 are characterized by a butterfly-like arrangement with the SCN ligands situated on the same side with respect to the Zn(2)O(2) moiety, whereas the centrosymmetric complex 3 exhibits a stepped arrangement with parallel methyl-phenoxy fragments (spaced at ca. 1.5 A) and trans located SCN ligands with respect to the Zn(2)O(2) core. The formation of these unusual macrocycles is considered to be zinc-mediated. Preliminary studies with the complexes show that all of them exhibit an inhibitory effect, on the cell proliferation of human stomach cancer cell line AGS, though with different degrees, where complex 3 shows the highest efficiency.
authors.affiliation: Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India.
authors.forename: Arpita
authors.initials: A
authors.lastname: Banerjee
authors.forename: Subhalakshmi
authors.initials: S
authors.lastname: Ganguly
authors.forename: Tanmay
authors.initials: T
authors.lastname: Chattopadhyay
authors.forename: Kazi Sabnam
authors.initials: KS
authors.lastname: Banu
authors.forename: Amarendra
authors.initials: A
authors.lastname: Patra
authors.forename: Santanu
authors.initials: S
authors.lastname: Bhattacharya
authors.forename: Ennio
authors.initials: E
authors.lastname: Zangrando
authors.forename: Debasis
authors.initials: D
authors.lastname: Das
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018360:Crystallography, X-Ray; D006801:Humans; D047028:Macrocyclic Compounds / Q000138:chemical synthesis* / Q000494:pharmacology; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000494:pharmacology; D010078:Oxazines / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D010078:Oxazines; D010080:Oxazoles; C064210:oxazolidine; D015032:Zinc