Phosphorus-nitrogen compounds. part 38. Syntheses, characterizations, cytotoxic, antituberculosis and antimicrobial activities and DNA interactions of spirocyclotetraphosphazenes with bis-ferrocenyl pendant arms

Abstract

The reactions of N4P4Cl8 (1), with two equimolar amounts of N-(1-ferrocenylmethyl)-N-methyl-propylenediamine gave the monoferrocenyl-spiro (as a byproduct), bisferrocenyl-2-trans-6-dispiro (2) and bisferrocenyl-2-cis-6-dispiro (3) cyclotetraphosphazenes. The 2-trans-6-dispiro (2) was reacted with excess monoamines to produce the tetraamino products (2a-2d). The one equimolar amount of the diamines and dialkoxides with 2 afforded the mono-diamino (2e and 2f) and mono-dialkoxy (2g and 2h) cyclotetraphosphazenes. Whereas, excess diamines and dialkoxides with 2 produced the bis-diamino (2i and 2j) and bis-dialkoxy (2k and 2l) bisferrocenyl-2-trans-6-dispirocyclotetraphosphazenes. The structures of the compounds were verified by elemental analyses, ESI-MS, FTIR, HSQC, HMBC, H-1, C-13, and P-31 NMR techniques. The molecular structures of 2 and 2b were established by X-ray crystallography. Compounds 2e and 2f have two stereogenic P-atoms. Additionally, the structures of 2i-2l containing tetraspiro rings in the skeletons look similar a propeller. The Fc groups of the cyclotetraphosphazenes were found to be redox active with two-reversible electron oxidations. The antimicrobial activity of the compounds was examined against some bacteria and yeast strains. The interactions of the compounds with DNA revealed that the compounds caused conformational changes even strand break on super-coiled DNA helix. Furthermore, the compounds (except 2, 2a and 2d) inhibited DNA restriction indicating compounds binding to A/A and G/G nucleotides of the DNA. The evaluations of the cytotoxic activity against L929 fibroblast and DLD-1 colon cancer cell lines were carried out. Some of the compounds were evaluated for antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv, and 2i and 2l displayed antituberculosis activity against H37Rv. (C) 2017 Elsevier B.V. All rights reserved.