Synthesis, structural characterization and biological activity of helicin thiosemicarbazone monohydrate and a copper(II) complex of salicylaldehyde thiosemicarbazone

From the reaction ofp-t-butylcalix[4]arene with α-chloro-N,N-diethyl acetamide a new lipophilic ether-amide ligand (2) has been obtained in high yield. Solution studies show (2) to be a very strong cation receptor for alkali cations, especially sodium and potassium. The X-ray crystal structure determination of the free ligand (2) and two potassium complexes (KI and KSCN) shows the calix[4]arene in a fixed ‘cone’ structure and the cation completely encapsulated in a polar cavity of eight oxygen atoms.

p-t-Butylcalix[4]arene tetra-acetamide: a new strong receptor for alkali cations [1]

Two new 5-formyluracil thiosemicarbazone (H(3)ut) derivatives, Me-H(3)ut (1) and Me(2)-H(3)ut (2), were synthesized by reacting thiosemicarbazides, mono- and dimethylated on the aminic nitrogen, with 5-formyluracil and were subsequently characterized. These ligands, treated with copper chloride and nitrate, afforded three complexes: [Cu(Me-H(3)ut)Cl(2)].H(2)O (3), [Cu(Me(2)-H(3)ut)Cl(2)].H(2)O (4), and [Cu(Me-H(3)ut)(NO(3))(OH(2))(2)]NO(3) (5). The crystal structures of these complexes have been determined by single-crystal X-ray diffraction. In 3 and 4, a similar pentacoordination is present; the copper atom is surrounded by the ligand SNO donor atoms and by two chloride ions. The structure of 5 consists of [Cu(Me-H(3)ut)(NO(3))(OH(2))(2)](+) cations and nitrate anions. The copper coordination (4 + 2) involves the SNO ligand atoms and a water oxygen in the basal plane; the apical positions are occupied by a second water oxygen and by an oxygen of a monodentate nitrate group. Two biochemical techniques, namely DNA titration in the UV-vis region and thermal denaturation, have been employed to probe the details of DNA binding of these compounds. Analysis of the results suggests that our compounds are able to interact with DNA by electrostatic and groove binding but not by intercalation. The compounds have been also tested in vitro on human leukemic cell line U937, but they are not able to inhibit significantly cell proliferation.

Cu(II) Complexes with Heterocyclic Substituted Thiosemicarbazones: The Case of 5-Formyluracil. Synthesis, Characterization, X-ray Structures, DNA Interaction Studies, and Biological Activity

The macrocyclic [LnNiL]Cl3 complexes (Ln = LaIII, CeIII, PrIII, NdIII, SmIII, EuIII) contain both lanthanide and transition metal ions. The crystal structure of [LaNiL]Cl3 reveals a square planar environment of Ni(II) ion and an 8-coordinate, irregular coordination sphere of La(III) ion. The 1H and 13C NMR spectra of these compounds have been assigned on the basis of 2D techniques. The analysis of isotropic shifts of paramagnetic [LnNiL]Cl3 complexes shows the importance of both contact and dipolar contributions.

Heterodinuclear Macrocyclic Complexes Containing Both Nickel(II) and Lanthanide(III) Ions.

The new chiral ligands 2-butyl-8-chloro-1-(4,8-di-tert-butyl-2,10-dimethoxy-5,7-dioxa-6-phosphadibenzo[a,c]cyclohepten-6-yl)-1,2-dihydroquinoline (BIPHENPHOSHQUIN, 3) and 2-butyl-8-chloro-1-(3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yl)-1,2-dihydroquinoline (BINAPHOSHQUIN, 4; 4a: SaRC, 4b: SaSC) have been synthesized starting from the rigid backbone of 8-chloroquinoline. The reactions of 3 and 4 with rhodium(I), palladium(II), and platinum(II) substrates are reported. The reaction of 3 with [Rh(CO)2Cl]2 in a 2:1 molar ratio in hexane afforded a binuclear chloro-bridged rhodium(III) species by intramolecular oxidative addition of the C–Cl bond of ligand 3 across the rhodium(I) centers. The rhodium(III) complex 5, incorporating the enantiomers SaRC-3 and RaSC-3, has been fully characterized by X-ray diffractometry. Reactions of [Pd(PhCN)2Cl2] with the ligands 3 and 4a in 1:2 molar ratio in toluene afforded the products cis-[Pd(3)2Cl2] (9) and cis-[Pd(4a)2Cl2] (10). Similarly, reaction of [Pt(COD)I2] with 4a in a 1:2 molar ratio afforded the complex cis-[Pt(4a)2I2] (11). An X-ray analysis has been carried out to obtain information on the effect of the ligand 4a on the overall structure of 11.

Franco Ugozzoli

Papers

ABSORB: A computer program for correcting observed structure factors from absorption effects in crystal structure analysis