Synthesis, micellar properties, DNA binding and antimicrobial studies of some surfactant–cobalt(III) complexes

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Abstract

A new class of surfactant–cobalt(III) complex ions of the type, cis-[Co(X)2(C14H29NH2)Cl]2+ (where X = ethylenediamine (en), or 2,2'-bipyridyl (bpy), or 1,10-phenanthroline (phen)) and cis-[Co(trien)(C14H29NH2)Cl]2+ (trien = triethylenetetramine) were synthesized and characterized by IR, NMR, UV–visible electronic absorption spectra, elemental analysis and metal analysis. The critical micelle concentration (CMC) values of these surfactant–cobalt(III) complexes in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 298, 308, 318 and 328 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellizationG0m, ΔH0m and ΔS0m). Interactions between calf thymus DNA and the surfactant–cobalt(III) complexes in aqueous solution have been investigated by electronic absorption spectroscopy, emission spectroscopy and viscosity measurements. The electrostatic interactions, van der Waals interactions and/or partial intercalative binding have been observed in these systems. The surfactant–cobalt(III) complexes were screened for their antibacterial and antifungal activities against various microorganisms. The results were compared with the standard drugs, Ciprofloxacin and Fluconazole respectively.

Introduction

DNA plays a fundamental role in the storage and expression of genetic information in a cell. DNA is not only an important biological material with a unique double helical rodlike structure, but also an interesting anionic polyelectrolyte. Studies on the interaction of transition metal complexes with DNA have been pursued in recent years [1], [2], [3], [4]. These complexes are stabilized in binding to DNA through a series of weak interactions, such as the π-stacking interactions associated with intercalation of a planar aromatic group between the base pairs, hydrogen-bonding and van der Waals interactions of functionalities bound along the groove of the DNA helix, and the electrostatic interaction of the cation with phosphate group of DNA. Studies directed toward the design of site- and conformation-specific reagents provide rationales for new drug design as well as a means of developing sensitive chemical probes of nucleic acid structure.

Surfactants, sometimes called suface-active agents, are among the most versatile chemicals available. They are amphiphilic molecules consisting of a hydrophilic head group and a hydrophobic (lipophilic) tail and are, thus, able to interact with both polar and non-polar compounds. Accordingly, surfactants are often classified as non-ionic or ionic (cationic, anionic or zwitterionic). Surfactants are major building blocks of many physical, chemical and biological systems. They have been introduced into several commercial products such as antiseptic agents in cosmetics and as germicides [5], and also have found a wide range of applications because of their unique solution properties such as detergency, solubilization and surface wetting capabilities, in diverse areas such as mining, petroleum and pharmaceutical industries [6]. Cationic surfactants offer some additional advantages over other classes of surfactants. These substances, besides their surface activity, do show antitumor properties [7]. Cationic surfactant–DNA interactions have been the subject of many studies over the past few decades because they are of interest both in fundamental science and in biotechnological applications [8], [9], [10]. Studies have shown that the binding of surfactant to DNA is cooperative based on the binding isotherm, and is similar to the interaction of surfactant with a synthetic polymer [11], [12], [13].

Surfactant–metal complexes are a special type of surfactants, where a coordination complex (containing a central ion with surrounded ligands coordinated to the metal) acts as the surfactant (Scheme 1). In these surfactants, the metal complex part containing the central metal ion with its primary coordination sphere acts as the head group and the hydrophobic part of one or more ligands acts as tail part. Like any other well-known surfactants, these metallosurfactant complexes also form micelles at a specific concentration called critical micelle concentration (CMC) in aqueous solution. There are but a few reports [14], [15], [16], [17] on the synthesis, isolation and characterization of surfactant transition metal complexes, in contrast to numerous reports of the formation and study of such surfactants in solution without isolation. We have been interested in the synthesis and micelle forming properties of cobalt(III)/chromium(III) complexes containing lipophilic ligands for a long time [18], [19], [20], [21]. As in biology, such compounds may exhibit novel physical and chemical properties with interesting and useful associated applications.

A characteristic feature of transition metals is their ability to form complexes with a variety of neutral molecules such as bipyridine (bpy) and phenanthroline (phen). These are widely used as a classical N,N΄-bidentate ligand to prepare mixed-ligand complexes in coordination chemistry. Metal complexes of bipyridine and phenanthroline chelators are of great interest since they exhimit numerous biological properties such as antitumor, anticandida and antibacterial activity [22], [23], [24]. At the same time, metal complex bearing ethylenediamine have also been interest because in the classical antitumor agent cis-platinum, one of the ligands must be a N-donor and posses at least one hydrogen atom attached to the nitrogen [25].

In spite of the greatest effort and success in the study of metallosurfactants of cobalt(III) complexes, such complexes still attract much attention due to their interesting properties and the relative simplicity of their synthesis. To the best of our knowledge no previous studies are available to find the interaction of DNA with metallosurfactants. From this point of view the results presented here are of interest . In the present paper, we report the synthesis, CMC determination and DNA binding properties of various surfactant–cobalt(III) complexes using different physico-chemical methods. Also we have reported the antibacterial and antifungal activities of these surfactant–cobalt(III) complexes against certain human pathogenic microorganisms.

Section snippets

Materials and methods

All the reagents were of analytical grade (Aldrich and Merck). Calf thymus DNA obtained from Sigma-Aldrich, Germany, was used as such. The spectroscopic titration was carried out in the buffer (50 mM NaCl-5 mM Tris–HCl, pH 7.1) at room temperature. A solution of calf thymus DNA in the buffer gave a ratio of UV absorbance at 260 and 280 nm of ~ 1.8–1.9:1, indicating that the DNA was sufficiently free of protein [26]. Milli-Q water was used to prepare the solutions.

Absorption spectra were recorded

Spectroscopic characterization

Infrared spectroscopy is used to distinguish the mode of coordination of the ligand with the central metal ion. Various workers have employed the NH2 deformation mode (1700–1500 cm 1 region), the CH2 rocking mode (950–850 cm 1 region) and Co–N stretching mode in the 600–500 cm 1 region to distinguish between cis and trans isomers [34], [35]. The cis-isomers always show two peaks, whereas the trans-isomers usually have only one peak in the CH2 rocking region. In the present study, the NH2

Conclusion

As mentioned in our previous reports [20], [21], the critical micelle concentration values of surfactant–cobalt(III) complexes in the present study are also very low compared to that of the simple organic surfactant, dodecylammonium chloride (CMC = 1.5 × 10 2 mol dm 3). Thus it is concluded that these metal surfactant complexes have more capacity to associate themselves, forming aggregates, compared to those of ordinary synthetic organic surfactants. The binding behavior of these

Acknowledgements

We are grateful to the UGC-SAP & COSIST and DST-FIST programmes. Council of Scientific and Industrial Research (CSIR), New Delhi is gratefully acknowledged for financial support (Grant No. 01(2075)/06/EMR-II) and a Senior Research Fellowship to RSK. We also thank UGC for sanction of a research scheme (F. 32-274/2006) to SA.

References (63)

  • M.N. Hughes et al.

    The infra-red spectra (667–222 cm 1) of some cobalt(III) bis(ethylenediamine) complexes

    J. Inorg. Nucl. Chem.

    (1966)
  • J.S. Strukl et al.

    Infrared and Raman spectra of heterocyclic compounds-IV: the infrared studies and normal vibrations of some 1:1 transition metal complexes of 2,2'-bipyridine

    Spectrochim. Acta. Part A

    (1971)
  • A.A. Schilt et al.

    Infra-red spectra of 1,10-phenanthroline metal complexes in the rock salt region below 2000 cm 1

    J. Inorg. Nucl. Chem.

    (1959)
  • L. Jin et al.

    Synthesis and DNA binding studies of CoIII mixed-ligand complex containing dipyrido[3,2-a:2',3'-c]phenazine and phen

    Polyhedron

    (1997)
  • R. Zana

    Ionization of cationic micelles: effect of the detergent structure

    J. Colloid Interface Sci.

    (1980)
  • J.J.H. Nusselder et al.

    Toward a better understanding of the driving force for micelle formation and micellar growth

    J. Colloid Interface Sci.

    (1992)
  • J. Liu et al.

    DNA-binding and cleavage studies of macrocyclic copper(II) complexes

    J. Inorg. Biochem.

    (2002)
  • S. Zhang et al.

    A novel cytotoxic ternary copper(II) complex of 1,10-phenanthroline and L-threonine with DNA nuclease activity

    J. Inorg. Biochem.

    (2004)
  • S. Bhattacharya et al.

    Interaction of surfactants with DNA. Role of hydrophobicity and surface charge on intercalation and DNA melting

    Biochem. Biophys. Acta

    (1997)
  • M.B. Ferrari et al.

    Heterocyclic substituted thiosemicarbazones and their Cu(II) complexes : synthesis, characterization and studies of substitutent effects on coordination and DNA binding

    Polyhedron

    (2008)
  • T.F. Tadros
  • L.L. Schramm et al.

    Surfactants and their applications

    Annu. Rep. Prog. Chem., Sect. C

    (2003)
  • A.M. Badawi et al.

    Surface and antitumor activity of some novel metal-based cationic surfactants

    J. Cancer. Res. Ther.

    (2007)
  • N. Jiang et al.

    Micellization of cationic gemini surfactants with various counterions and their interaction with DNA in aqueous solutions

    J. Phys. Chem. B

    (2004)
  • S.M. Melnikov et al.

    Transition of double-stranded DNA chains between random coil and compact globule states induced by cooperative binding of cationic surfactant

    J. Am. Chem. Soc.

    (1995)
  • K. Hayakawa et al.

    Study of surfactant–polyelectrolyte interactions. 2. Effect of multivalent counterions on the binding of dodecyltrimethylammonium ions by sodium dextran sulfate and sodium poly(styrene sulfonate) in aqueous solution

    J. Phys. Chem.

    (1983)
  • C.H. Spink et al.

    Thermodynamics of binding of a cationic lipid to DNA

    J. Am. Chem. Soc.

    (1997)
  • N. Aydogan et al.

    Comparison of the surface activity and bulk aggregation of ferrocenyl surfactants with cationic and anionic headgroups

    Langmuir

    (2001)
  • H. Choi et al.

    Nickel(II) macrocyclic complexes with long alkyl pendant chain: synthesis, X-ray structure, and anion exchange property in the solid state

    Inorg. Chem.

    (2003)
  • J. Bowers et al.

    Surface and aggregation behavior of aqueous solutions of Ru(II) metallosurfactans. 3. Effect of chain number and orientation on the structure of adsorbed films of [Ru(bipy)2(bipy')]Cl2 complexes

    Langmuir

    (2005)
  • J.Q. Xie et al.

    Oxidation reaction of phenol with H2O2 catalyzed by metallomicelles made of Co(II) and Cu(II) complexes of imidazole groups and micelle as mimic peroxidase

    J. Dispersion Sci. Technol.

    (2006)
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